1 - KrishiKosh

GEOLOGY OF INDIA
GEOLOGY OF INDIA
BY
D. N. WAD I A,
M.A , B.Sc, F.G.S., F.R.G.S., F.R.A.S.B.
GEOLOGICAL SURVEY OF I N W / ,
WITH
ILLUSTRATIONS'
MACMILLAN AND CO., LIMITED
ST. MARTIN'S STREET, LONDON
1944
COPYRIGHT
Birst Edition 191j
Reviseil92ff,
Second Edition 19ag
Ueprinted 1944,
PRINTED AND PUBLISHED IN t.'JSEAT
BRITAIN
To A. AND F.
t
IN HEAVEN,
THESE PAGES ARE INSCRIBED
.
PEEFACE
As a lecturer in Geology to students preparing for the Punjab University Exanainations I have constantly experienced great difficulty
in the teaching of the Geology of India, because of the absence of any
adequate modern book on the subject. The only work that exists is
the one pubHshed by the Geological Survey of India in 1887, by H. B.
Medhcott and W. T. Blanford, revised and largely rewritten by E. D.
Oldham in 1893—a quarter of a century ago. Although an excellent
official record of the progress of the Survey up to that time, this publication has naturally become largely out of date (now also out of print)
and is, besides, in its voluminous size and method of treatment, not
altogether suitable as a manual for students' preparing for the University Examinations. Students, as well as all other inquirers, have,
therefore, been forced to search for and collect information, piecemeal, from the multitudinous Records and Memoirs of the Geological
Survey of India. These, however, are, too numerous for the diligence
of the average student—often, also, they are inaccessible to him—and
thus much valuable scientific information contained in these admirable publications was, for the most part, unassimilated by the student
class and remained locked up in the shelves of a few Libraries in the
country. I t would not be too much to say that this lack of a handy
volume is in the main responsible for the almost total neglect of the
Geology of India as a subject of study in the colleges of India and as
one of independent scientific inquiry.
The object of the present volume is to remedy this deficiency by
providing a manual in the form of a modern text-book, which summarises all the main facts of the subject within a moderate compass.
It is principally a compilation, for the use of the students of Indian
Geology, of all that has been published on the subject, especially incorporating the later researches and conclusions of the Geological
Survey of India since Oldham's excellent edition of 1893.
In a subject of such proportions as the Geology of India, and on_e
round which such voluminous literature exists, and is yearly growing,
it is not possible, in a compendium of this nature, to aim at perfection
of detail. Nor is it easy, again, to do justice to the devoted labours of
viii
PREFACE
the small body of origiaal workers who, since the '50's of the last
century, have made Indian Geology what it is to-day. By giving,
however, in bold outlines, the maih results achieved up to date and by
strictly adhering to a text-book method of treatment, I have striven
to fulfil the somewhat restricted object at which I have aimed.
In the publication of this book I have received valuable help from
various quarters. My most sincere thanks are due to Sir T. H.
Holland, F.R.S., D.Sc, for his warm sympathy and encouragement.
To Dr. E. H. Pascoe, D.Sc, Director of the Geological Survey of
India, I offer my grateful acknowledgments for the Idan of blocks and
plates from negatives for the illustrations in the book, and for permission to publish this volume. My indebtedness to Mr. C. S.
Middlemiss, C.I.E., F.R.S., retired Superintendent of the Geological
Survey of India, the doyen of'Indian Geologists, I can never sufc
ficiently acknowledge. His guidance and advice in all matters con^
nected with illustrations, correction of manuscript and text, checking
of proofs, etc., have been of inestimable value. Indeed, but for his
help several imperfections and inaccuracies would have crept into the
book. I have also to offer my warm thanks to Dr. G. E. Pilgrim,
D.Sc, for his helpful criticisms and valuable suggestions in revismg
the Tertiary Systems.
In the end, I tender my grateful acknowledgments to Messrs.
Macmillan for their uniform courtesy.
D. N. WADIA.
JAMMU,
December, 1916.
POSTSCRIPT
THE writing of the first editioB of this book was completed in 1916,
since when there has bten no opportunity of revising it on an adequate scale, or ot incorporating in it the results of the activities of the
Geological Survey of India m t!ie last twenty years as well as of the
steadily increasing volume of extra-departmental work pubhshed in
various branches of the Geology of India.
The present edition, though not considerably enlarged in bulk, is
thoroughly revised and brought up to date by incorporating new
research. A geological map of India, on the scale of 96 miles = 1 inch,
is added, embodying all the recently surveyed regions in the Himalayas, Rajputana, Assam and other parts of India.
It is my pleasant duty to tender my grateful acknowledgments for
valuable help received from various quarters—to Dr. A. M. Heron,
D.Sc, F.R.S.E., Director, Geological Survey of India, for permission
to publish the revised book and for his helpful criticisms and suggestions ; to Professor B. Sahni, Sc.D., F.R.S., for the revision of the
Chapters dealing with the GondwanaN System and for a critical examination of the lists of fossil floras of India ; and to Mr. Percy
Evans for many important suggestions regarding several sections of
the book and for assistance in the revision and correction of proofs.
To many of my colleagues of the Geological Survey of India I am
indebted for much ungrudging assistance and for their helpful
attitude throughout in the production of this edition.
D. N. WADIA.
CALCUTTA,
12th July, 1937.
CONTENTS
CHAPTER I
PAGB
PHYSICAL FEATURES
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Geological dfvisions of India ; tlieir characters and peculiarities ; types
of the earth's crust exemplified by these divisfcna. Physical characters of
the plains of India. Rajputana a debatable area. Mountains of India ;
the Himalayan mountains ; physical features of the Himalayas ; meteorological influence of the Himalayas. Limits of the Himalayas. The syntaxial bends at the N.W. and S.E. Classifleation of the Himalayan ranges,
(1) Geographical, (2) Geological. Other ranges of extra-Peninsular India.
Mountain ranges of the Peninsula ; Vindlxyan mountains ; the Satpura
range; the Western Ghats ; the Eastern Ghats. Glaciers: glaciers of the
Himalayas ; their size ; limit of Himalayan glaciers ; peculiarities .of
Himalayan glaciers ; records of past glaciation in the Himalayas. The
drainage system : the easterly drainage of the Peninsula ; the Himalayan
system of drainage not a consequent drainage ; the Himalayan watershed ;
the transverse gorges of the Himalayas ; river-capture or " piracy " ;
the hanging valleys of Sikkim. Lakes ; the lakes of Tibet, Kashmir and
Kumaon ; saHnity of the Tibetan lakes ; their desiccation ; the Sambhar
lake ; the Lonar lake. The Coasts of India ; submerged mountain-chain
and valleys of the Arabian Sea. Volcanoes : Barren Island ; Narcondam ;
Popa; Koh-i-Sultan. Mud-volcanoes. Earthquakes: the earthquake
zone of India ; the Assam earthquake ; the Kangra earthquake ; Bihar
earthquake; Quetta earthquake. Local alterations of level; recent
elevation of the Peninsular tableland; other local alterations; submerged forest of Bombay; alterations of level in Cutch; the Himalayas
yet in a state of tension. Isostasy. Denudation; the monsoonio alternations ; the lateritic regolith; general character of denudation in India
sub-tropical, desert-erosion in Rajputana. Peculiarity of river-erosion
in India : the river-floods. Late changes in the drainage of Northern
India; the Siwalik river, its dismemberment into the Indus and Ganges;
reversal of the north-westerly flow of the Ganges. References.
CHAPTER I I
STRATIGRAPHY OP INDIA—INTRODUCTORY
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43
Difficulty of correlation of the Indian formatipns to those of the world ;
principles involved. The different " facies " of the Indian formations.
Provincial faunas. P^adio-active minerals as an aid to stratigraphy.
The chief geological provinces of India : the Salt-Range ; the N.W.
Himalayas ; the Central Himalayas ; Sind ; Rajputana ; Burma and
Baluchistan; the Coastal tracts. Methodof study of the geology of India.
Table of the geological formations of India. References.
CHAPTER I I I
THE ARCHAEAN SYSTEM
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General. Distribution of the Archaean of India ; petrology of the Archaean system; thechiefpetrologicaltypes : gneisses; granites; syenites;
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xii
CONTENTS
PAGE
Charnockite, Khondalite, Gondito, Kodurite, calo-gnoissea and caloiphyres,
etc. Classificationof the Archaean system. Bengal gneiss ; types of Bengal gneiss. Bundelkhand gneiss. The Charnockite series ; petrological
characters of the Charnockite series ; th'eir microscopic characters. Archaean of the Himalayas. References.
CHAPTER IV
THE DHAEWAR SYSTEM -
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General. Outcrops of the Dharwar rocks; the lithology of the Dharwars ;
plutonic intrusions in the Dharwars ; crystalline hmestones originating by
the metasomatism of the gneisses. Distribution of the Dharwar system.
Type-area Dharwar ; Rajputana : the Aravalli mountains ; the Aravalli
series ; the Raialo series ; the Shillong series ; the Dharwar rocks of
the Central Provinces ; the manganiferous deposits of the Dharwar
system—the Gondite and the Kodurite series : Bihar and Orissa—the
Iron-ore series. Manganese ores of the Dharwar system. The Dharwar
system of the Himalayas. The Vaikrita series; Salkhala series; Jutogh
series and Daling series. Homotaxis of the Dharwar system. The
Archaean-Dharwar controversy. Economics. References.
CHAPTER V
THE CUDDAPAH SYSTEM
86
General. The Cuddapah system ; lithology of the Cuddapahs ; absence
of fossils in the Cuddapahs ; classification of the system. Distribution.
The Lower Cuddapah ; the Delhi system ; Bijawar series ; the Choyair
and Gwalior series. The Upper Cuddapahs ; the Kfallamalai, Kaladgi,
Kistna, etc., series. Economics. Stratigraphic position of the Cuddapahs.
References.
CHAPTER VI
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THE VINDHYAN SYSTEM
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Extent and thickness; rocks; structural features. Life during the
Vindhyan period. Classification. Distribution of the Lower Vindhyan ;
Semri series ; the Kurnool series, Malani series, etc. Meaning of " Lower "
and " Upper" Vindhyan. The distribution of the Upper Vindhyan.
Vindhyan sandstones. Economics of the system. The Himalayan
Vindhyans. The relation of the Himalayan unfossiliferous systems to the
Peninsular Puranas. Homotaxis of the Vindhyan system. References.
CHAPTER VII
THE CAMBRIAN SYSTEM
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The Cambrian of India, (i) The Salt-Range. The principal geological
features of the range. The Cambrian of the Salt-Range ; the purple sandstone ; the Neobolus beds ; magnesian sandstone. Salt-pseudomorph,
shales, (ii) The Spiti area—the Spiti geosyncUne. The Cambrian of
Spiti; Haimanta system ; Cambrian fossils. Autoclastio conglomerates.
The Cambrian of Kashmir. References.
CHAPTER VIII
THE
SILURIAN,
SYSTEMS
DEVONIAN
AND
LOWER
CARBONIFEROUS
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General, (i) The Spiti area ; the Silurian ; the Devonian Muth series ; the
Carboniferous—Lipak and Po series; the Upper Carboniferous unconformity. Table of Palaeozoic systems in Spiti. (ii) Kashmir area, (iii)
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CONTENTS
xiii
PAGE
Chitral. (iv) Burnja—the Northern Shan States ; Ordovician ; Silurian
—Namshim series, Zebingyi series ; Silurian fauna of Burma; Devonian ;
the Devonian fauna ; the Wetwin slates. Carboniferous of Burma ; the
Plateau limestone ; Fusulina limestone. Table of the Palaeozoic formations of Burma. Physical changes at the end of the Dravidian era. References.
CHAPTER I X
THE GONDWANA SYSTEM
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General. The ancient Gondwanaland ; Lemuria ; the Gondwana system
of India ; the geot^ctonic relations of the Gondwana rocks ; their fluviatile nature ; evidences of changes of climate ; organic remains in the
Gondwana rocks ; distribution of the Gondwana rocks ; classification of
the system. The Lower Gondwana: Talchir series; Talchir fossils ; the
Damuda series ; igneous rocks of the Damuda coal-measures ; eflFeots of
contact-metamorphism; the Damuda flora; Damuda series of other areas.
Homotaxis of the Damuda^and Talchir series. Economics. Classification.
CHAPTER X
THE GONDWANA SYSTEM {Continued)
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The Middle Gondwanas: rocks; the Panchet series; the Pachmarhi
or Mahadev series ; Maleri series; Parsora series; Triassic age of the
Middle Gondwanas. The Upper Gondwanas : distribution; hthology;
the Rajmahal series ; the Rajmahal flora ; Satpura and Central Provinces ; Jabalpur stage ; Godavari area ; Kota stage ; Gondwanas of
the East Coast; Rajahmundri, Ongole and Madras outcrops; the
Upper Gondwanas of Cuteh. Umia series. Economics. References.
CHAPTER X I
UPPEK CARBONIFEROUS AND PERMIAN SYSTEMS
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The commencement of the Aryan e r a ; the Himalayan geosyncline;
the nature of geosyncUnes., Upper Carboniferous and Permian of India,
(i) Upper Carboniferous and Permian of the Salt-Range. Boulder-bed ;
Speckled sandstone; Productus limestone; Productus fauna. The
Anthracolithio systems, (ii) Upper Carboniferous and Permian of the
Himalayas.
The Permo-Carboniferous of Spiti. Productus shales.
Kashmir; Hazara; Simla; Burma. Marine beds of Umaria. References.
CHAPTER X I I
T H E TRIASSIC SYSTEM
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General. The principles of classification of the geological record ; the \ iew
of Professors ChamberUn and Salisbury, (i) The Trias of Spiti. The zonal
classification of the system ; Triassic fauna, (ii) Hazara. (iii) The Trias
of the* Salt-Range—the Ceratite beds, (iv) Baluchistan, (v) Burma ;
Napeng series, (vi) Kashmir. References.
CHAPTER X I I I
THE JURASSIC SYSTEM
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Instances of Jurassic development in India. Life during the Jurassic
period, (i) Jura of the Central Himalayas ; the Kioto limestone ; Spiti
shales ; the fauna of the Spiti shales. Mt. Everest region. The Tal series
of the Outer Himalayas, (ii) Juras of Baluchistan, (iii) Hazara ; the
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CONTENTS
FAQS
Spiti shales of Hazara. (iv) Burma—^Namyau beds. (v) Juras of the Salt. Range. Marine transgressions during the Jurassic period ; the nature of
marine transgressions, (vi) The Jurassics of Cutch—Pfttcham, Chari,
Katrol and tfmia series, (vii) Rajpufana—Jaisalmer limestone. References.
CHAPTER XIV
THE CRETACEOUS SYSTEM
Varied facies of the Cretaceous of India, the geography of India during
the Cretaceous period, (i) Cretaceous of Spiti; Giumal sandstone;
Chikkim series; Flysch. (ii) Chitral. Plutonic and volcanic action
during the Cretaceous. Exotic blocks of Johar. (iii) Cretaceous Volcanic
series of Kashmir, (iv) Hazara. (v) Cretaceous of Sind and Baluchistan ;
Hippurite limestone ; Parh limestone ; Pab sandstone. Cardita beaumonti beds, (vi) Salt-Range, (vii) Assam, (viii) Burma. References.
192
CHAPTER XV
T H E CRETACEOUS SYSTEM (CowtWMec^)—PENINSULA
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(i) Upper Cretaceous of the Coromandel coast; geological interest of the
S.E. Cretaceous; the Utatur stage; Trichinopoly stage; Ariyalur
stage ; Niniyur stage ; Fauna of the S.E. Cretaceous ; Utatur, Trichinopoly, and Ariyalur faunas, (ii) The Narbada valley Cretaceous ; Bagh
beds; conclusions from the fauna of the Bagh beds, (iii) The Lameta
series or Infra-trappean beds; metasomatic limestones. Age of the
Lameta series. Cretaceous Dinosaurs of India. References.
CHAPTER XVI
DECCAN TRAP
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The great volcanic formation of India. Area of the plateau basalts;
their thickness ; the horizontality of the lava sheets ; petrology; absence
of magmatic differentiation; microscopic characters of the Deccan
basalts. Stratigraphy of the Deccan Trap. ^ Inter-trappean beds ; a
type-section. The mode of eruption of the Deccan Traps—fissure-eruption.
Fissure dykes in the Traps. Age of the Deccan Traps. Economics. References.
CHAPTER XVII
THE TERTIARY SYSTEMS—INTRODUCTORY
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General. Physical changes a t the commencement of the Tertiary era.
The elevation of the Himalayas ; three phases of upheaval of the Him- ,i
alayas. Distribution of the Tertiary systems in India : 'Peninsula ; extraPeninsula. Dual facies of Tertiary deposits. Geography of India during
early Tertiary. (i)TertiariesofSurat and Broach, (ii) Kathiawar. Dwarka
beds, Perim Island Tertiary, (iii) Tertiaries of Cutch. (iv) Rajputana.
(v) The Coromandel coast—Cuddalore series, (vi) Travancore. Tertiary
systems of the extra-Peninsular India, (i) Sind. Table of formations,
(ii) Salt-Range. Table of formations, (iii) Himalayas—Kashmir Himalayas and Punjab and Kumaon Himalayas. Tertiaries of Inner
Himalayas, (iv) Assam, (v) Burma.* The Tertiary gulf of Burma.
References.
CHAPTER XVIII
THE EOCENE SYSTEM
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Ranikot series; Fossils of the Ranikot series. Laki series. Kirthar
series ; Nummulitio limestone ; Fossils of the Kirthar series, (i) Sind
240
CONTENTS
and Baluchistan, (ii) Salt-Range, (iii) Kohat. (IT) Potwar. (v) Hazara.
(vi) Kashmir, (vii) The Outer Himalayas; Subathu series, (viii) Assam ;
eeonomie utility of the Assam Eocene rocks, (ix) Burma; Eocene
mammals. References.
CHAPTER X I X
PTHE OLIGQCENE AND LOWER MIOCENE SYSTEMS
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Oligocene; restricted ocpurrence. (i) Baluchistan, (ii) Sind; Nari series,
(iii) Assam, (iv) Burma ; Pegu series: petroleum, origin, mode of occurrence, gas, migration ; petroleum areas in India. Lower Miocene, (i)
Sind; Gaj series ; Bugti beds. (ii) Salt-Range,, Potwar, Jammu;
Murree series, (iii) Outer Himalayas, (iv) Assam; Surma series, (v)
Burma; Upper Pegu series. Igneous action. Change in conditions.
References.
CHAPTER X X
THE S I W ^ I K SYSTEM—MIDDLE MIOCENE TO LOWEK PLEISTOCENE
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General. The nsiture of the Siwalik deposits. Geoteetonic relations of
the Siwaliks. The " Main Boundary " Fault. The real nature of the
" Main Boundary " Fault; Middlemiss's views. The Palaeontological
interest of thjj Siwalik sfstewi. Evolution of the Siwalik fauna; migrations into India. Lithology; mode of formation of the Siwaliks in the
• Gangetic trough. Classification. Siwalik A u n a ; fossil anthropoid apes.
Age of Siwalik system. Parallel series of deposits. References.
CHAPTER X X I
THE PLEISTOCENE SYSTEM—GLACIAL AGE IN INDIA • -
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The Pleistocene or Glacial Age of Europe and America. A modified Pleistocene Glacial Age in India. The nature of the evidence for an Ice Age in
India ; Dr. Blanford's views. Ice Age in the Himalayas ; Physical records. The extinction, of the Siwahk mammals—one further evidence.
Interglacial periods. References.
CHAPTER X X I I
THE PLEISTOCENE SYSTEM {Continued)—THE INDO-GANSETIC
ALLUVIUM
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The plains of India. Nature of the Indo-Gangetic depression. Extent and
thickness of the alluvial deposits. Changes in Rivers. Lithology.
Classification; Bhangar; Khadar. The Ganges delta, the Indus delta.
Economics. The Rajputana desert; composition of the desert sand ;
the origin of the Rajputana desert. The Ranu of Cutch. References.
CHAPTER X X I I I
THE PLEISTOCENE SYSTEM {Continued)—LATERITE
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Laterite a regoUth peculiar to India. Composition of laterite ; its distribution. High-level laterite and low-level laterite. Theories of the origin of
laterite, recent views; secondary changes in laterite; resilicification.
The age of laterite. Economics. References.
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xvi
CONTENTS
CHAPTER XXIV
PAGE
PLEISTOCENE AND EECBNT {Continuhd) -
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Examples of Pleistocene and Recent deposits. Ossiferous alluvium of the
Upper Sutlej ; of the Tapti and Narbaila. The Karewas of Kashmir.
Porbander stone. Sand-dunes; Teris. Loess deposits. The Potwar
fluvio-glacial deposits. Cave-deposits. Regur or black cotton-soil; the
origin of Regur. The " Daman " slopes. The Human epoch. References.
CHAPTER XXV
PHYSIOGRAPHY
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308
Principles of physiography illustrated by the Indian region. Mountains :
the structure of the Himalayas ; recent ideas ; the tectonic zones ; cause
of the syntaxial bends of the Himalayas ; the mountains of the Peninsula.
Plateaus and plains : plateau of volcanic accumulation ; •> plateau of
erosion. Valleys : the valley of Kashmir a tectonic valley ; erosion-valleys ; valleys of the Himalayas ; the transverse gorges ; configuration of
the Himalayan valleys ; valleys of the Peninsula. Basins or lakes : functions of lakes ; types of lakes ; Indian examples. The Coast-lines of
India. References.
CHAPTER XXVI
ECONOMIC GEOLOGY
General. Water ; wells, springs, artesian wells; Thermal and Mineral
Springs. Clay ; china-clay, terra-cotta, fire-clay, fuller's earth. Sands ;
glass-sand. Lime ; cements ; mortar ; composition of cements ; production. Building-stones ; granites ; limestones ; marbjes, serpentine ;
sandstones, Vindhyan sandstones, Gondwana sandstones ; laterite, slates,
traps. Coal; production in India ; Gondwana coal; Tertiary coal. Peat.
Petroleum; Burma, Assam, N.W. India ; natural gas. Metals and
ores ; views of Sir T. H. Holland. Gold : its occurrence ; production of
vein-gold; alluvial gold. Copper; the copper-ores of Sikkim. Iron ;
its occurrence on a vast scale ; economic value ; production ; its distribution. Manganese ; distribution of manganese in the geological formations of India ; production ; uses. Aluminium ; bauxite in laterite ; economic value of Indian bauxite ; uses. Lead ; lead-ores of Bawdwin ;
production. Silver and zinc. Tin ; the tin-ore of Mergui and Tavoy.
Wolfram ; wolfram of Tavoy ; uses of tungsten. Chromium j, occurrence;
uses. Antimony ; arsenic ; cobalt and nickel; zinc. Precious and semiprecious stones. Diamonds ; Panna and Goleonda diamonds. Rubies and
sapphires ; Burma rubies ; sapphires of Kashmir. Spinel. Jadeite ;
occurrence; formation. Beryl; emeralds and aquamarines. Chrysoberyl. Garnets. Zircon. TourmaUnes. Other gem-stones of India.
Agates, rock-crystal, amethyst. Amber. Economic mineral products.
Salt; sources of Indian salt; Rock-salt Mines ; other salts. Saltpetre or
nitre. Mode of occurrence of nitre ; its production ; uses. Alum. Borax.
Reh salts ; the origin of reh efBorescence. Mica ; uses of mica ; micadeposits of Nellore and Hazaribagh. Corundum ; occurrence ; distribution ; uses: other abrasives ; millstones, grindstones. • Kyanite and
SiUimanite. Beryl. Monazite; its occurrence; uses. Graphite; its
occurrence ; uses. Steatite ; mode of origin of steatite. Gypsum. Magnesite; occurrence of magnesite. Asbestos. Barytes. Fluor-spar.
Phosphatic deposits. Mineral paints. Uranium minerals ; pitchblende
ofGaya, Titanium. Vanadium. Rare minerals. Pyrite and sulphur;
uses cf sulphur. Soils, soil-formation_^ the soils of India.
32.7
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CONTENTS
xvii
C H A ' P T E R XXVII (APPENDIX)
PAQS
GEOLOGY OF KASHMIR
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General. Physical features of Kashmir ; the chief orographic features.
The Outer ranges; their simple geological structure; the " duns ". The
Middle ranges ; the Panjal range ; " orthochnal " structure of the
Middle ranges. The Inner ranges ; physical aspects of the zone of highest
elevation. The valleys ;• transverse gorges; their coniiguration. The
lakes. Glaciers ; transverse and longitudinal types of glaciers. Becords
of the Pleistocene Ice Age. The Stratigraphy of Kashmir. Introduction. Comparative stratigraphy of Simla and Hazara areas. Table
of the.geological formations. The Archaean and pre-Cambrian systems ;
petrology; distribution. Salhhala series. The Palaeozoic group. Outcrops. The Cambrian. The Ordovician. Distribution; composition.
The Silurian. Distribution; rocks, fossils. The Devonian. Occurrence ; petrology. The Loy;er Carboniferous—Syringothyris limestone
series. Distribution; Lower Carboniferous fossils. The Middk Carboniferous—Fenestella shales ; passage beds ; distribution ; lithology;
fauna ;' age of the Fenestella. series. The mid-Palaeozoic unconformity of
N.Wv Kashmir and Hazara ; the Tanawal series. The Upper Carboniferous
^ P a n j a l , Volcanic series. Middle Carboniferous earth-movements.
Physical history at the end of the Dravidian era. Panjal volcanic series ;
distribution; nature of the Panjal agglomerate slates ; Panjal lavas;
petrology ; age and extension of the Panjal la;vas. Inter-trappean limestones. Lowex Qondwana beds—Gangamopteris beds ; distribution;
lithology; the Golabgarh section; fossils; age. The Permian; Zewan
series ; fossils ; age of the Zewan series. Permo-Carboniferous inliers
in the Sub-Himalayas of Jammu. Krol Series. The Triassic ; Trias
of Kashmir, wide distribution ; lithology ; Lower Trias ; Middle Trias ;
Upper Trias. Relations of the K3,shmir and Spiti provinces during the
Upper Trias. TheJwraSsJc; the Jurassic of Ladakh; Jurassic of Banihal.
The Cretaceous; Chikkim series of Rupshu-Zanskar. Cretaceous volcanics
of Astor, Burzil and Dras. The Tertiary ; Introductory ; Indus Valley
Tertiaries; Tertiaries of the Jammu hills. The Subathu series of Jammu
and the Pir Panjal. The Murree series. The Siwalik system ; Lower,
Middle and Upper Siwaliks. Pleistocene and Recent; Karewas. Relation
of Karewas to Glacial and Inter-Glacial periods. Later deposits. Geoteotonic Features of the N.W. Himalayas.
INDEX
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4^45
LIST OF ILLTJSTKATIONS
(1) PLATES *
PAGE
PtATE
I.
n.
III.
IV.
V.
VI.
VII.
Vlli.
IX.
X.
XI.
XII.
XIII.
XIV.
XV.
XVt.
XVII.
XVIII.
XIX.
XX.
Alukthang Glacier
.
.
.
.
.
.
.
. facing page 14
16
Snout of Sona Glacier from Sona
.
.
.
.
.
.
28
Mud Volcano^^jne of the largest—Minbu, Burma
64
Bellary Granite, Gneiss Country, Hampi
.
.
.
.
Banded Porphyritic Gneiss (Younger Archaean), Nakta Nala,
66
Chhindwara District
.
.
.
.
.
.
.
76
" Marble Rocks " (Dolomite Marble), Jabalpur .
.
.
94
Upper Rewah Sandstone, Rahutgarh, Sangor District Overfolding of the Palaeozoic Rooks, Upper Lidar Valley,
114
Central Himalayas
Reversed Fault in Carboniferous Rocks, Lebung Pass, Central
116
Himalayas - 132
Barrier of Coal across Kararia Nala
.
.
.
.
.
160
Contorted Carboniferous Limestone
.
.
.
.
.
166
Folded Trias Beds, Dhauli Ganga Valley, Central Himalayas
Geological Map of Lidar Valley. Silurian-Trias Sequence in At end of booh
Kashmir
Plan of Vihi District, Kashmir
. " . . . . .
Geological Map of the Pir Panjal
.
.
.
.
.
Sketch Map of the IJimalayan Geosyncline and its Relation to
adjacent Mountain-systems of Central Asia .
.
.
Tectonic Sketch Map of t^e Garhwal Himalayas
. . .
Geological Sketch Map of the Syntaxial Bend of the NorthWest Himalayas
Geological Map of Hazara
.
.
.
.
.
.
.
Geological Map of India
.
.
.
.
.
.
.
(2) IN THE TEXT
ria.
1. Diagrammatic Section through the Himalayas to show their relations to
the Tibetan Plateau and the Plains of India
2. Barren Island Volcano in the Bay of Bengal .
.
.
.
.
.
3. Diagram showing Contortion in the Archaean Gneiss of Bangalore .
4. Section across the Aravalli Range to the Vindhyan Plateau showing the
peneplaned synclinorium of the most ancient mountain range of India
6. Section across the Singhbhum Anticlinorium, Chota Nagpur .
.
.
6. Diagram showing the Relation of Dharwar Schists with the Gneisses
.
7. Sketch Section illustrating the Relation of Cuddapah and Kurnool Rocks .
8. Section showing Relation between Gwalior Series and Rocks of the Vindhyan System
.
.
.
.
.
.
.
.
.
.
.
.
5
26
56
76
79
83
87
i%
XX
FIB.
LIST OF ILLUSTRATIONS
PAGE
9. Section illustrating the General Structure of the Salt-Range (Block-faults).
Section over Chambal Hill (East)
104
10. Section across the Dandot scarp from Khewra to Gandhala, Salt-Range - 105
11. Section along the Parahio River, Spiti
.
.
.
.
.
- 1 1 3
12. Section of Palaeozoic Systems of N. Shan States (Burma), Section across
the Nam-tu Valley at Lilu
117
13. Sketch Map of typical Gondwana Outcrop
.
.
.
.
.
.
127
14. Tectonic Relations of the Gondwana Rocks. .
.
.
128
15. Sketch Map of the Gondwana Rocks of the Satpura Area
.
.
. 137
16. Generalised Section through the Gondwana Basin of the Satpura Region - 139
17. Section from Dhodha Wahan across the western part of Mt. Sakesar, SaltRange
I
.
.
.
150
18. Section across the Salt-Range, western part, showing the Upper Palaeozoic and Mesozoic systems
.
-152
19. Section of the Carbon-Trias Sequence in the Tibetan Zone of the Himalayas
(Spiti)
160
20. Palaeozoic Rocks of the N. Shan States .
.
.
.
- 1 6 4
21. Section of the Trias of Spiti
170
22. Diagrammatic Section of Mt. Sirban, Abbottabad, Hazara
- 172
23. Continuation of preceding Section further South-East to the Taumi Peak - 173
24. Section through the Bakh Ravine from Musa Khel to Nammal
- 174
25. Section of the Jurassic and Cretaceous Rocks of Hundes .
.
.
. 178
26. Sketch Section in the Chichali Pass .
.
.
. 1 8 5
27. View of Dec'can Trap Country
212
28. Section of STummuIitio LiAestone Cliffs; Salt Range
.
.
.
. 243
29. Section across the Potwar Geosyncline
- . - 257
30. Diagrams to illustrate the Formation of Reversed Faults in the Siwalik
Zone of the Outer Himalayas . . .
- 264
31. Section to illustrate the Relations of the Outer Himalayas to the Older
Rocks of the Mid-Himalayas (Kumaon Himalayas) .
.
.
. 266
32. Section across the Sub-Himalayan Zone east of the Ganges River •
• 267
33. Diagrammatic section across the Indo-Gangetic Synclinorium - . - 284
34. Diagrammatic section across the Kashmir Himalaya, showing the broad
Tectonic Features
- - - . . .
- 315
35. Section through the Simla Himalaya
316
36. Section across Western Rajputaha to illustrate the peneplanation of an
ancient mountain chain .
. 3 1 9
37. View of the great Baltoro Glacier
890
38. Section of Pir Panjal across the N.E. Slope from Nilnag-^Tatakuti . 391
39. General Section, Naubug Valley, Margan Pass and Wardwan, to show the
disposition of the Palaeozoic rocks of Kashmir
400
40. Section across Lidar Valley Anticline
.
.
.
.
.
.
.
.
400
41. Section of the Zewan Series, Guryul Ravine
.
.
.
.
.
417
42. Section of the Triassic System of Kashmir
.
.
.
.
.
.
421
43. Section showing the Relation of the Permo-Carboniferous and Eocene of
, the Jammu Hills
432
44. Section across the Outermost Hills of the Sub-Himalaya a t Jammu .
- 439
45. Diagrammatic representation of the nappe structure of Garhwal Himalaya 441
CHAPTER I
PHYSICAL FEATURES
BEFCSRE commencing the study of the stratigraphical, i.e. historical,
geology of India, it is necessary to acquire some knowledge of the
principal physical features. The student should make himself
familiar with the main aspects of its geography, the broad facts
regarding its external relief or contours, its mountain-systems,
plateaus and plains, its drainage-courses, its glaciers, volcanoes, etc.
This study, with the help of physical or geographical maps, is indispensable. Such a foundation-knowledge of the physical facts of the
country will not jonly be of much interest in itself, but the student will
soon find that the physiography of India is in many respects correlated to, and is, indeed, an expression of, its geological structure and
history.
'
Geological divisions of India—The most salient fact with regard to
both the physical geography and geology of the Indian region is that
it is composed of three distinct units or earth-features, which are as
iiulike in their physical as in their geological characters. The first
two of these three divisions of India have a fundamental basis, and
the distincti'sje characters of each, as we shall see in the following
pages, were impressed upon it from a very early period of its geological
history, since wh,ich date each area has pursued its own career independently. These three divisions are :
1. The triangular plateau of the Peninsula (i.e. the Deccan, south
of the Vindhyas), with the island of Ceylon.
2. The mountainous region of the Himalayas which borders India
to the west, north, and east, including the countries of Afghanistan,
Baluchistan, and the hill-tracts of Burma, known as the extra• Peninsula.
3. The great Indo-Gangetic Plain of the j?unjab and Bengal,
separating the two former areas, and extending from the valley of the
Indus in Sind to that of the Brahmaputra in Assam.
• Their characters and peculiarities—As mentioned above, the Peninsula, as an earth-feature, is entirely unlike the extra-Peninsula.
2
GEOLOGY OF INDIA
The following differences summarise tlie main points of divergence
between these two regions : The first is stratigraphic, or that connected with the geological history of the areas. Ever since the dawn
of geological history (Cambrian period), the Peninsula has been a Jand
areaj__a continental fragment of the earth's surfacCj,which since that
epoch in earth-history has never been submefgecf beneath the sea,
except temporarily and locally. No considerable tnarine sediment
of later age than Cambrian was ever deposited in the interior of this
land-mass. The extra-Peninsula, on the other hand, has been a*
region which has.lain under the sea for the greater part of its history,
and has been covered by successive n^^rine deposits charactecstic of
all the great geological periods, commencing with the earliest,
Cambrian.
The second difference is geotectonic, or pertaining to the geological
structure of the two regions. The Peninsula of India reveals quite a ,
different type of architecture of the earth's crust from that shown by
the extra-Per^nsula. Peninsular India is a segment of the earth's
outer shell that is composed in great part of generally horizontally
reposing rock-beds that stand upon a firm and immovable foundation
and that have, for an immense number of'^ges, remained so—impas-'
sive amid all the revolutions that have again and b,gain changed the
face of the earth. Lateral thrusts and mountain-building forces have
had but httle effect in folding or displacing its originally horizontal
strata. The Deccan is, however, subject to one kind of structural disturbance, viz., fracturing of the crust in blocks, due to tension or
compression. The extra-Peninsula, on the contrary, is a portion of ^
what appears to have been a comparatively weak and flexible portion
of the earth's circumference that has undergone a great deal of
crumpling and deformation. Kock-folds, faults, thrust-planes, and
other evidences of movements within the earth are observed in this
region on an extensive scale, and they point to its being a portion of
the earth that has undergone, at a late geological epoch, an enormous
amount of compression and upheaval. The strata everywhere show
high angles of dip, a closely packed system of folds, and other violent
departures from their original primitive structure.
The third difference is the diversity in the physiography of the two
areas. The difference in the external or surface relief of Peninsular and
extra-Peninsular India arises out of the two above-mentioned differences, as a direct, consequence. In the Peninsula, the mountains
are mostly of the " relict " type, i.e. they are not mountains in the
true sense of the term, but are mere outstanding portions of the old
PHYSICAL FEATURES
3
plateau of the Peninsula that have escaped, for one reason or another,
the weathering of ages that has»cut out all the surrounding parts of
the land ; they are, so to say, huge " tors " or blocks of the old
plateau. Its rivers have flat, shallow valleys, with low imperceptible
gradients, because of their channels having approached to the baselevel of erosion. * Contrasted with these, the mountains of the other •
area are all true mountains, being what are called " tectonic " mountains, i.e. those which owe their origin to a distinct uplift in the earth's
crust and, as a consequence, have theii' strike, or line of extension,
more or less conformable to the axis of that uplift. The rivers of this
area are rapid torrential streams, which are still in a very youthful or
immature stage of river development, and are continuously at work
in cutting down the inequalities in their courses and degrading or
lowering their channels. Their eroding powers are always active, and
they have cut deep gorges and precipitous canons, several thousands
of feet in depth, through the mountains in the mountainous part of
their track.
Types of the earth's crust exemplified by these divisions—The type
of crust segments of which the Peninsula is an exaniple, is known as a
Horst—a solid crust-block which has remained a stable land-mass of
great rigidity, and has been unaffected by any folding movement
generated within the earth during the later geological periods. The
only structural disturbances to which these parts have been susceptible are of the nature of vertical, downward or upward, movements of
large segments within it, between vertical (radial) fissures or faults.
The Peninsula has often experienced this " block-movement" at
various periods of its history, most notably during the Gondwana
period.
The earth-movements characteristic of the flexible, more yielding
type of the crust, of which the extra-Peninsula is an example, are of
the nature of lateral (i.e. tangential) thrusts which result in the
wrinkling and folding of more or less linear zones of the earth's surface into a mountain-chain '(orogenic movements). These movements, though they may affect a large surface area, are solely confined to the more superficial parts of the crust, and are not so deepseated as the former class of movements characteristic of horsts.
Physicar characters of the plains of India—The third division of
India, the gre_at alluvial plains of the Indus and the Ganges, though,
humanly speaking, of the greatest interest and importance, as being
the principal theatre of Indian history, is, geologically speaking, the
least interesting part of India. In the geological history of India they
4
GEOLOGY OF INDIA
are only the annals of yester-year, being the alluvial deposits of the
rivers of the Indo-Ganges systems, borne down from the Himalayas
and deposited at their foot. They have covered up, underneath a
deep mantle of river-clays and silts, valuable records of past ages,
which might have thrown much Ught on the physical history of the
Peninsular and the Himalayan areas, and revealed their former connection with each other. These plains were originally a deep depression or furrow lying between the Peninsula and the mountain-region.
With regard to the origin of this great depression there is some difference of opinion. The eminent geologist, Eduard Suess, thought it
was a " Fore-deep " fronting the Himalayan earth-waves, a " sagging " or subsidence of the northern part of the Peninsula, as it .
arrested the southward advance .of the mountain-waves. Colonel Sir
S. Burrard, from some anomalies in the observations of the deflections of the plumb-line, and other geodetic considerations, has suggested quite a different view.^ He thinks that the Indo-Gangetic
alluvium conceals a great deep rift, or fracture, in the earth's subcrust, several thousand feet deep, the hollow being subsequently filled
up by detrital deposits. He ascribes to such sub-crustal cracks or
rifts a fundamental importance in geotectonics, and attributes the
elevation of the Himalayan chain to an incidental bending or curling
movement of the northern wall of the fissure. Such sunken tracts between parallel, vertical dislocations are called " Eift-Valleys " in
geology. The geologists of the Indian Geological Survey have not
accepted this view of the origin of the Indo-Gangetic depression.^
Eajputana a debatable area—The large tract of low country, forming Rajputana, west of the Aravallis, possesses a mingling of the distinctive characters of the Peninsula, with those of the extra-Peninsula, ,
and hence cannot with certainty be referred to either. Rajputana can
be regarded as a part of the Peninsula inasmuch as in geotectonio
characters it shows very little disturbance, while i n its containing
marine, fossiliferous deposits of Mesozoic and Cainozoic ages it shows
greater resemblance to the extra-Peninsular area. In this country,
long-continued aridity has resulted in the establishment of a desert
topography, buried under a thick mantle of sands disintegrated from
the subjacent rocks as well as blown in from the western sea-coast
and from the Indus basin. The area is eut off from the water* The Origin of the Himalayas, 1912 (Survey of India Publication). Presidential
Address, the Indian Science. Congress, Lucknow, 1916.
^ See Dr. Hayden, Relationship of the Himalaya to the Indo-Gangetic Plain and
tho Indian Peninsula, Rec. O.S.I, vol. xliii. pt. 2, 1913, and R. D. Oldham, Mem.
G.-S./. vol.xlii. pt. 2, 1917.
PHYSICAL FEATURES
5
circulation of the rest of the Indian continent, except for occasional
storms of rain, by the akCence of any high range to intercept the
moisture-bearing south-west monsoons which pass directly over its
expanse. The desert conditions are hence accentuated with time, the
water-action of the internal drainage of the country being too feeble
to transport to the sea the growing mass of sands.
There is a tradition, supported by some physical evidence, that the
basin of the Indus was not always separated from the Peninsula by
the long stretch of sandy waste as at present. " Over a vast space of
the now desert country, east of the Indus, traces of ancient river-beds
J testify to the gradual desiccation of a once fertile region; and
throughout the deltaic flats of the Indus may still be seen old channels
which once conducted its waters to the Rann of Cutch, giving life and
prosperity to the past cities of the delta, which have left no living
records of the countless-generations that once inhabited them." ^
MOUNTAINS
The Himalayan mountains—The mountain-ranges of the extraPeninsula have had their origin in a series of earth-movements which
Fio. 1.—^Diagrammatic section through the Himalayaa to show their
relations to the Tibetan Plateau and the plains of India.
* Watershed of the Himalayas. (Vertical scale greatly exaggerated.)
proceeded from outside India. The great horst of the Peninsula,
composed of old crystalline rocks, has played a large part in the history of mountain-building movements in Northern India. It has
limited the extent, and to some degree controlled the form of the
chief ranges. Broadly speaking, the origin of the Himalayan chain,
the most dominant of them all, is to be referred to powerful lateral
thrusts acting from the north or Tibetan direction towards the
' Sir T. H. Holdioh, Imperial Gazetteer, vol. i.
6
GEOLOGY OF INDIA
Peninsula of India. These thrusting movements resulted in the production of fold after fold of the earth's crust, pressing against the
Peninsula. The curved form of the Himalayas^ is due to this resistance offered by the Penins-ular " foreland " to the southward advance
of these crust-waves, aided in some measure by two other -minor
obstacles—an old pene-plained mountain-chain like the Aravalli
mountains to the north-west and the Assam ranges to the north-east. ^
The general configuration of the Himalayan chain, its north-west
south-east trend, the abrupt steep border which it presents to the
plains of India with the much more gentle slope towards the opposite
or. Tibetan side, are all features which are best explained, on the
above view, as having been due to the resistances the mountainmaking forces had to contend against in the Peninsula and in the two
other hill-ranges. The convex side of a mountain range is, in general,
in the opposite direction to the side from which the thrusts are
directed, and is the one which shows the greatest amount of plication,
fracture, and overthrust. This is actually the case with the outer or
convex side of the Himalayas, in which the most characteristic structural feature is the existence of a number of parallel, reversed faults,
or thrust-planes. The most prominent of this system of«thrusts, the
outermost, can be traced from the Punjab Himalayas all through the
entire length of the mountains, to their extremity in eastern Assam.
This great fault or fracture is known as the Main Boundary Fault.
Physical features of the Himalayas—The geography of a large part
of the Himalayas is not known, because immense areas within it have
not yet been explored by scientists ; much therefore remains for
future observation to add to (or alter in) our existing knowledge.
Lately, however, the Mt. Everest and other expeditions to Tibet and
the Karakoram have made additions to our knowledge of large tracts
of Himalayas. The eastern (Assam) section of the Himalayas, however, is geographically still almost a terra incognita. The Himalayas
are not a single continuous chain or range of mountains, but a series
of several more or less parallel, or converging ranges, intersected by
enormous valleys and extensive plateaus. Their width is between
100 and 250 miles, comprising many minor ranges, and the length of
the Central axial range, the " Great Himalaya range ", is 1500 miles.
The individual ranges generally present a steep slope towards the
1 From Sanskrit, Him Al/iya, meaning the abode of snow.
' Another view is that the curvature is the result of the interference of similar folding movements proceeding from the Iranian or the Hindu Kush system of mountains.
(See page 314.)
^ -•
PHYSICAL FEATURES
7
plains of India and a more gently inclined slope towards Tibet. The
northern slopes are, again, clothed with a thick dense growth of forest
ve*^etation, surmounted higher up by never-ending snows, while the
southern slopes are too precipitous and bare either to accumulate the
snows or support, except in the valley basins, any but a thin sparse
jungle. The connecting link between the Himalayas and the other
high ranges of Central Asia—the Hindu Kush, the Karakoram, the
Kuen Lun, the Tien Shan and the Trans-Alai ranges—is the great
mass of the Pamir, " the roof of the world." The Pamirs (Persian
Pa-i-mir^ioot of the eminences) are a series of broad, alluviumfilled valleys, over 12,000 feet high, separated by linear mountainmasses, rising to 17,000 feet. From the Pamirs to the southeast, the Himalayas extend as an unbroken wall of snow-covered
mountains, pierced by passes, few of which are less than 17,000 feet
in elevation. The Eastern Himalayas of Nepal and Sikkim rise very
abruptly from the plains of-Bengal and Oudh, and suddenly attain
their great elevation aboye the snow-line within strikingly short distances from the foot of the mountains. Thus, the peaks of Kanchenjunga and Everest are only a few miles frorn the plains and are visible
to their inhabitants. But the Western Himalayas of the Punjab and
Kumaon rise gradually from the plains by the intervention of many
ranges of lesser altitMes, their peaks of everlasting snows are more
than a hundred miles distant, hidden from view by the mid-Himalayan ranges'to. the inhabitants of the plains.
Meteorological influence of the Himalayas—This mighty range of
mountains exercises as.-dominating an.influence over the meteorological conditions of India as over its physical geography, vitally
affecting both its air and water circulation. Its high snowy ranges
have a moderating influence on the' temperature and humidity of
Northern India. By reason of its altitude and its situation directly
in the path of the monsoons, it is most favourably conditioned for the
precipitation of much of their contained .moisture, either as rain or
snow. Glaciers of enormous magnitude are nourished on the higher
ranges by this precipitation, which, together with the abundant rainfall of the lower ranges, feed a number of rivers, which course down to
the plains in hundreds of fertilising streams. In this manner the
Himalayas protect India from the gradual desiccation which is
overspreading the Central Asian continent, from Tibet northwards, and the desert conditions that inevitably follow continental
desiccation.
Limits of the Himalayas—Geographically, the Himalayas are
8
GEOLOGY OF INDIA
generally considered to terminate, to the north-west, a t the great bend of
the Indus, where it cuts through the Kashmir Himalayas, while the southeastern extremity is defined b y t h e similar bend of the B r a h m a p u t r a in
upper Assam. At these points also there is a well-marked bending of the
strike of the mountains from the general north-west—south-east, to
approximately north and south direction. Some geographers have
refused t o accept this limitation of t h e Himalayan m o u n t a i n system,
because according to t h e m it ignores the essential physical u n i t y of
t h e hill-ranges beyond the Indus and t h e B r a h m a p u t r a with the
Himalayas'. They would extend the term Himalayas to all those
ranges to the east and we&t {i.e. the Hazara and Baluchistan mountains and some ranges of Burma) which originated in t h e same
great system of Pliocene orogenic upheavals.
The Syntaxial Bends of the Himalayas—The trend-line of the Himalayan
chain and its east and west terminations possess much interest from a
structural point of view and need further remarks. For 1500 miles from''
Assam to Kashmir, the chain follows one persistent S.E.-N-.W. direction
and then appears to terminate suddenly at one of the greatest eminences on
its axis, Nanga Parbat (26,620), just where the Indus has cut an extraordinarily deep gorge right across the chain. Geological studies have shown
that just at this point the strike of the mountains bends sharply to the
south and then to the south-west, passing through Chilas and Hazara,
instead of pursuing its north-westerly course through Chitral. All the
geological formations here take a sharp hair-pin bend as if they were bent
round a pivotal point obstructing them. This extraordinary inflexion
affects the whole breadth of the mountains from the foot-hills of Jhelum to
the Pamirs. On the west of this syntaxis (as this acutely reflexed bundle of
mountain-folds is termed) the Himalayan strike swings from the prevalent
N.E, to a N.-to-S. direction in Hazara and continues so to Gilgit; then it
turns E.-to-W., the Pamirs showing a distinct equatorial disposition of their
geological formations. To the south-east of this, the main tectonic strike
quickly takes on a N.W.-S.E. orientation through Astor and Deosai—a
direction which persists with but minor departures to eastern Assam.
The eastern limit of the Himalayas beyond Assam is'yet not quite certain, but from the few geographical and geological observations that have
been made in this region it appears that the tectonic strike here also undergoes a deep knee-bend from an easterly to a southerly trend. In the Arakan
Yomas the geological axis of the mountains for several hundred miles is
meridional, bending acutely to the N.E. near Fort Hertz. Beyond this
point there is an abrupt swing to the N.W., then to E.N.E.-W.S.W. and
finally to E.-W. through Assam and Sikkim.
The cause of these remarkable bends of the mountain-axis is discussed on
page 314.1
' D. N. Wadia; The Syntaxis of the N.W. Himalayas: its Rocks, Tectonics and
Orogeny. Records G.S.I., vol. Ixv. pt. 2, 1931.
PHYSICAL FEATURES
9
Classification of the Himalayan Range
(I.) Geographical—For geographical purposes Burrard has divided
the long alignment of the Himalayan system into four sections : the
Punjab Himalayas, from the Indus to the Sutlej, 350 miles long ;
Kumaon Himalayas, from the Sutlej to the Kali, 200 miles long;
Nepal HimaVayas, from the Kali to the Tista, 500 miles long; and
As%am Himalayas, from the Tista to the Brahmaputra, 450 miles long.
Also the Himalayan system is classified into three parallel or longitudinal zones, each differing from one another in well-marked oro.graphical features :
(1) The Great Himalaya : the innermost line of high ranges, rising
above the limit of perpetual snow. Their average height extends to
20,000 feet; on it are situated the peaks, like Mount Everest, K^,
'Kanchenjunga, Dhaulagiri, Nanga Parbat, Gasherbrum, Gosainthan,
Nanda Devi,'etc.
(2) The Lesser Himalayas, or the middle ranges : a series of ranges
closely related to the former but- of lower elevation; seldom rising
much above 12,000-15,000 feet. The Lesser .Himalayas form an
intricate system of ranges ; their average width is fifty miles.
(3) The Outer Hinihlayas, or the Siwalik ranges, which intervene
between the Lesser Himalayas and the plains. Their width varies
from five^o thirty miles. They form a system of low foot-hills with
an average height of 3000-4000 feet.
(IL)'Geological—As regards geological structure and age the
Himalayas fall into three broad stratigraphical belts or zones.
These zones do not correspond to the geographical zones as a rule.
(1) The Northern or Tibetan Zone, lying behind the line of highest
elevation {i.e. the central axis corresponding to the Great Himalaya).
This zone is composed of a continuous series of highly fossiliferous'
marine sedimentary rocks, ranging in age from the earliest Palaeozoic
to the Eocene age. Except near the north-western extremity (in
' Mount Everest K'
.
Kanchenjunga Dhaulagiri
Nanga Parbat Gasherbrum
Gosainthan
Nanda Devi
Rakaposhi
Namcha Barwa
Badri Nath
Gangotri -
- Nepal Himalaya
- Karakoram
- Nepal Himalaya
,,
- Kashmir Himalaya •
- Karakoram
- Nepal Himalaya
- Kumaon Himalaya
- Kailas range
- Assam Himalaya
- Kumaon Himalaya
-
»
-
..
-
29,002
28,250
28,146
26,795
26,620
26,470
26.291
25,645
25,550
25,445
23,190
21,700
ft
„
,
„
,
,
,
„
5,
„
„
,
10
GEOLOGY OF INDIA
Hazara and Kashmir) roclcs belonging to this zone are not known to
occur south of the Hne of snowy peaks.
(2) The Central or Himalayan Zone, comprising most of the Lesser
or Middle Himalayas together with the Great Himalaya. It is mostly
composed of crystalline and metamorphic rocks—granites, gneisses,
and schists, with unfossiliferous sedimentary deppsits of very ancient
(Purana) age.
(3) The Outer or Sub-Himalayan Zone, corresponding to the
Siwalik I'anges, and composed entirely of Tertiary, and principally
of Upper Tertiary, sedimentary river-deposits.
The above is a very brief account of a most important subject^iij the
geography of India, and the student must refer to the works'^mentioned at the end of the chapter for further information, especially
to that by Sir Sidney Burrard and Sir Henry Hayden, Second Edition,
• 1932, revised by Burrard and Dr. A. M. Heron, which contains t h e '
most luminous account of the geography and the geology of the
Himalayas.
Other ranges of the extra-Peninsula—Eunning transversely to the
strike of the Himalayas at either, of its extremities, and beUeved to
belong to the same system,of upheaval, are the other minor mountainranges of extra-Peninsular India. Those to the west are the flanking
ranges which form the Indo-Afghan and Indo-Baluchistan frontier.
Those to the east are the mountain-ranges of Burma. Many of these
ranges have an approximate north-to-south trend. The names of
these important ranges are :
WEST
The Salt-Eange.
The Suleiman range.
The Bugti range.
The Kirthar range.
EAST
The
The
The
The
Assam ranges.
Manipur ranges.
Arakan Yoma.
Tenassori.m range.
With the exception of the Salt-Range and the Assam ranges, the
other mountains are all of a very simple type of mountain-structure,
and do not show the complex inversions and thrust-planes met with
in the Himalayas. They are again principally formed of Tertiary
rocks. The Salt-Range and the Assam ranges, however, are quite
different, and possess several unique features which we shall discuss
later on. Their rocks have undergone a greater amount of fracture
and dislocation, and they are not composed so largely of Tertiary
rocks.
Mountain ranges of the Peninsula—The important mountain ranges
PHYSICAL FEATURES
11
of the Peninsula are : The Aravalli mountains, the Vindhyas, Satpuras, the Western Ghats (or, as they are known in Sanskrit, the
Sahya'dris), and the irregular broken and discontinuous chain of elevations known as the Eastern Ghats. Of these, the Aravallis are the
only instance of a true tectonic mountain-chain, all the others (with
one possible exception to be mentioned below) are merely mountains y
of circumdenudatiou, i.e. they are the outstanding remnants, or outliers, of the old plateau of the Peninsula that have escaped the denudation of ages. Not one of them shows any axis of upheaval that
is coincident with their present strike. Their strata show an almost
undisturbed horizontaUty, or, at most, very low angles of dip. The
Aravallis were^ prominent feature in the old Palaeozoic and Mesozoic
geography of India, and extended as a continuous chain of lofty
mountains from the Deccan to possibly beyond the northern limit of
India. What we at present see of them are but the deepfy eroded
remnants'of these mountains, their mere stumps laid bare by repeated
cycles of erosion.
Vindhya mountains. Satpura range—The rocky country -^hich
rises gradually from the south of the Gangetic plains culminates in the
hi|hlands of Central India, comprising Indore, Bhopal, Bundelkhand,
etc. The southern edge of this country is a steep line of prominent
escarpments which constitute the Vindhyan mountains, and their
easterly continuation, the Kaimur range. Their elevation is between
2500 and 4000 feet above the sea-level. The Vindhyas are for the most
part composed of horizontally bedded sedimentary rocks of ancient
age, the contemporaries of the Torridon sandstone of Scotland. South
of t i e Vindhyas, and roughly parallel with their direction, are the
Satpura mountains. The name Satpura, meaning •" seven folds ",
refers to the many parallel ridges of these mountains. The chain of
ridges commences from Rewah, runs south of the Narbada valley and
north of the Tapti valley, and stretches westwards through the
Rajpipla hills to the Western Ghats. The Vindhya and the Satpura
chains form together the backbone of middle India. Very large
parts of the Satpuras, both in the west and the east, are formed of
bedded basalts ; the central part is composed, in addition to a capping of the traps, of a core of granitoid and metamorphic rocks, overlain by Mesozoic sandstones. Some parts of the Satpuras give proof
of having been folded and upheaved, the strike of the folding showing
a rough correspondf>nce with the general direction of the range. I t is
probable, therefore, that parts of the Satpuras are, like the Aravallis,
a weather-worn remnant of an old tectonic chain.
12
GEOLOGY OF INDIA
The Western Ghats—The greater part of the Peninsula is constituted by the Deccan plateau. I t is .a central tableland, extending
from 12° to 21° North Latitude, rising about 2000 feet mean elevation
above the sea, and enclosed on all side^ by^hill-ranges. To its west are
the Sahyadris, or Western Ghats, which extend unbroken to the extreme south of Malabar, where they merge into the uplands of the
Nilgiris; some of whose peaks rise to the altitude of 8700 feet above
the sea-level (Dodabetta peak), the highest of the Peninsula. Prom
the Nilgiris the Western Ghats extend (after the solitary opening,
Palghat Gap), through the Anaimalai hills, to the extreme spath of
the Peninsula. The Western Ghats, as the name Ghat denotes, are,
down to Malabar, steep-sided, terraced, flat-topped hills or cliffs facing
the Arabian sea-coast and running with a general parallelism to it.
Their mean elevation is some 3000 feet. The horizontally bedde^
lavas of which they are wholly composed have, on weathering, given
to them a characteristic " landing-stair " aspect. This peculiar mode'
of weathering imparts to the landscapes of the whole of the Deccan
a strikingly conspicuous feature. The physical aspect of the Western
Ghats south of Malabar—that is, the portion comprising the Nilgiris, *
Anaimalai, etc.—is quite'different from these square-cut, steep-sided
hills of the Deccan proper. The former hills are of a more rounded
and undulating outline, clothed under a great abundance of indigenous, sub-tropical forest vegetation. The difference in scenery arises
from the difference in geological structure and composition of the two
portions of the Western Ghats. Beyond Malabar they are composed
of the most ancient massive crystalline rocks, and not of horizontal
layers of lava-flows.
The Eastern Ghats—The broken and discontinuous line of mountainous country, facing the Bay of Bengal, and known as the Eastern
Ghats, has neither the unity of structure nor of outline characteristic of
a mountain-chain. The component parts belong to no one geological
formation, but vary with the country through which the hills pass,
and the high ground is made up of several units, which are formed of
the steep scarps of several of the South Indian formations. Some of .
these scarps are the surviving reUcs of ancient mountain-chains
elevated contemporaneously with the Aravallis.
Among the remaining, less important, hill ranges of the Peninsula
are the trap-built Rajmahal hills of western Bengal; the Nallamalai
hills near Cuddapah, built of gneissose granite, and the gneissio
plateau of Shevaroys and Pachamalai, south-west of Madras.
PHYSICAL FEATURES
13
GLACIERS
The^now-line, i.e. the lowest limit of perpetual snow, on the side of
the Himalayas facing the plains of India, varies in altitude from about
14,000 feet on the eastern part of the chain to 19,000 feet on the
western. On the opposite, Tibetan, side it is about 3000 feet higher,
owing to the great desiccation of that region and the absence of moisture in the monsoon winds that have traversed the Himalayas. In
Ladakh, with a scanty snow-fall, it is 18,000 feet. In the Hindu
Kush the average snow-hne is 17,000 feet high. Owing to the height
of the snow-hne, the mountains of the Lesser Himalayas, whose
general elevation is considerably within 15,000 feet, do not reach it,
and therefore do not support glaciers at the present day. But in some
of the ranges, e.g. the Pir Panjal, there is clear evidence, in the thick
masses of moraines covering their summits and upper slopes, in the
striated and polished rock-surfaces, in the presence of numerous
erratics, and other evidences of mountain-sculpture by glacier-ice,
such as cirques and numerous small lake-basins, that these ranges
were extensively glaciated at a late geological period, corresponding
with the Pleistocene Glacial age of Europe and America.
Glaciers of the Himalayas—The Great Himalaya, or the innermost
hne of ranges of high altitudes reaching beyond 20,000 feet, are the
enormous gathering grounds of snow which feed a multitude of
glaciers, some of which are among the largest in the world outside the
Polar circles. Much attention is being paid now to the scientific study
and observation of the Himalayan glaciers, both by the Indian Geological Survey and by scientiiic explorers of other countries.
Their size—In size the glaciers vary between wide limits, from those
that hardly move beyond the high recesses in which they are formed,
to enormous ice-flows rivalling those of the Arctic circle. The
majority of the Himalayan glaciers are from two to three miles in
length, but there are some giant streams of twenty-four miles and upwards, such as the Milam and Gangotri glaciers of Kumaon and the
Zemu glacier, draining the Kanchenjunga group of peaks in Sikkim.
The largest glaciers of the Indian region are those of the Karakoram,
discharging into the Indus ; these are the Hispar and the Batura of
the Hunza valley, 36 to 38 miles long, while the Biafo and the Baltoro
glaciers of the Shigar tributary of the Indus are about 37 miles in
length. Still larger are the Siachen and the Eemo glaciers, falling into
the Nubra affluent of the Indus, some 45 miles long, and the Fedchenko of the Pamir region of about the same dimensions. Some
14
GEOLOGY OF INDIA
measurements taken at the end of the Baltoro glacier gave a depth o f
400 feet of sohd ice ; the thickness in the middle of the body would be
considerably greater. The 'thickness of ice in the Zemu stream is
650 feet, while the Fedchenko has a depth of nearly 1800 feet of ice.''
These giant ice-streams of the Karakoram are doubtless survivors
of the last Ice age of the Himalayas, as the present day precipitation
of snow in this region is not sufficient to feed these great rivers of ice.
Like the dwindling glaciers of the Kuen Lun, these streams also will
gradually diminish in size and retreat from continuous defect of
" alimentation ".^ The majority of the glaciers are of the type of
valley glaciers, but what are known as hanging glaciers are by no
means uncommon. As a rule the glaciers descending transversely
to the strike of the mountain are shorter, more fluctuating, in their
lower limits, and, since the grade is steeper, they; descend to such
low levels as 7000-8000 feet in some parts of the Kashmir Himalayas.
Those, on the other hand, that move in longitudinal valleys, parallel
to ttife sti^kfe oi tiie Tdo'cratavcis, aT6 oi a \atgei: ^oViTfl%, l«sa s'Kasiitvj^.
to alternating temperatures and seasonal variations, and, their gradients being low, they rarely descend to lower levels than 10,000 feet.
Limit of Himalayan glaciers—The lowest limit of descent of the
glaciers is not uniform in all parts of the Hinialayas. -^While the
glaciers of Kanchenjunga in the Sikkim portion hardly move below
the level of 13,000 feet altitude, and those of Kujnaon and Lahoul to
12,000 feet, the glaciers of the Kashmir Himalayas descend to much
lower limits, 8000 feet, not far above villages and fields. In several
places recent terminal moraines are observed at so low a level as
7000 feet. A very simple cause of this variation has been suggested
by T. D. La Touche. In part it is due to the decrease in latitude, from
36° in the Karakoram to 28° in the Kanchenjunga, and in part to the
greater fall of the atmospheric moisture as rain and not as snow in the
eastern Himalayas, which rise abruptly from the plains without the
intervention of high ranges, than in the westefA Himalayas where,
though the total precipitation is much less, it all takes place in the
form of snow.
Peculiarities of Himalayan glaciers—One notable peculiarity of the
Himalayan glaciers, which may be considered as distinctive, is the
presence of extensive superficial moraine mattef, rock-waste, which
almost completely covers the upper surface to suoh an extent that the
ice is not visible for long stretches. On many of the Kashmir glaciers
it is a usual thing for the shepherds to encamp in summer, with their
» Prof. Kenneth Mason, Secords G.S.I., vol. Ixiii., part 2, 1930.
PHYSICAL FEATURES
15
flocks, on the moraines overlying the glacier ice. The englacial and
sub-glacial moraine stuff is also present in such quantity as sometimes
to choke the ice.. The diurnal motion of the glaciers, deduce'd from
various observations, is between three and five inches at the sides, and
from eight inches to about a foot in the middle. Observations on the
movement of the great Baltoro glacier by the Italian Expedition of
1909 ga-^e as the velocity of ice at the snout the comparatively much
higher tegure of 5 feet 10 inches in 24 hours. The diurnal motion of the
Fedchenko is about 1|- feet, while that of the Zemu is 9 inches. In
many parts of the Himalayas there are local traditions, supported in
many cases by physical evidence, that there is a slow, general retreat
of the glacier-ends ; at the lower ends of most of the Him"alayan
glaciers there are enormous heaps of terminal moraines left behind by
the retreating ends of the glaciers. The rate of diminution is variable
in the different cases, and no general rule applies to all. In some cases,
again, there is an undoubted advance of the glacier ends on their own
terminal moraines. Professor Mason's recent study of the Himalayan
and Karakoram glaciers has given some valuable results : the
velocity of glaciers and their advance and retreat depend on topographical factors and not on climatic factors ; the velocity has been
found to vary in different glaciers from one inch to many feet per day ;
variations in glacier activity, as indicated by movements of the snout,
may be due to causes which are, in distinct cases, secular, periodic,
seasonal, or accidental. Mason observes that the Karakoram and
Himalayan glaciers show no evidence whatever of any regular periodic
variation corresponding with any supposed weather-cycles.
In the summer months there is a good deal of melting of the ice on
-the surface. The water, descending by the crevasses, gives rise to a
considerable amount of englacial and sub-glacial drainage. The
accumulated drainage forms an englacial river, flowing through a
large tunnel, the opening of which at the snout appears as an ice-cave.
Records of past glaciation in the Himalayas—Large and numerous
as are the glaciers and the snow-fields of the Himalayas of the present
day, they are but the withered remnants of an older and much more
extensive system of ice-flows and snow-fields which once covered
Tibet and the Himalayas. As mentioned already, many parts of the
Himalayas bear the records of an " Ice Age " in comparatively recent
times. Accumulations of moraine debris are seen on the tops and sides
of many of the ranges of the middle Himalayas, which do not support
any glaciers at the present time. Terminal moraines, often covered by
grass, are to be seen in the Pir Panjal at heights above 6500 feet, while
16
GEOLOGY OF INDIA
the shapes of the ice-planed mountains and the U-shaped valleys, at
times terminating at the heads in amphitheatre-like hollows (cirques)
are very characteristic features of this range. Ancient moraines are
seen before the snouts of existing glaciers reaching up to such low
elevations as 6000 feet, or even 5000 feet. Sometimes there are grassy
meadows, pointing to the remains of old silted-up glacial lakes.
These facts, together with the.more doubtful occurrences of what may,
be termed fluvio-glacial drift at much lower levels in the hills of the
Punjab, lead to the inference that this part of India atieast, if not the
Peninsular highlands, experienced a Glaciat Age in the Pleistocene
period.^
RIVERS AND RIVER-VALLEYS
Rivfers; with their tributary-systems, are the main channels of
drainage of the land-surface ; they are at the samns time also the chief
agents of land-erosion and sculpture and the main lines for the transport of the products of the waste of the land to the sea. The drainagesystems of the two regions. Peninsular and extra-Peninsular India,
having had to accommodate themselves to two very widely divergent
types of topography, 'are necessarily very different in their character.
In the Peninsula the river-systems, as is obvious, are all of great antiquity, and consequently, by the ceaseless degradation of ages, their
channels have approached the last stage of river-development, viz.
the base-levelling of a continent. The valleys are broad and shallow,
characteristic of the regions where vertical erosion has almost ceased,
a'nd the lateral erosion of the banks, by winds, rain, and stream, is of
greater moment. In consequence of their low gradients the water has
but little momentum, except in flood-time, and therefore a low carrying capacity. In normal seasons they are only depositing agents, precipitating their silt in parts of their basins, alluvial banks, estjiarin^
' The principal glaciers of the Himalayas :
Sikhim—•
Kumaon—
Zemu
. . .
- 16 miles
Milam
Kanchenjunga
- 10 miles
Kedar Nath
Gangotri.
Punjab {Kashmir)—
Kosa Karakoram—
Diyamir
. . .
7 miles
Biafo .
•
Sonapani
. . .
7 miles
Hispar Rundun
. . .
. 12 miles
BAltoro
Punmah
. . .
. 17 miles
Gasherbrum .
Chogo Lungma
Chong Kumdan - 12 miles
Siachen
Niuapin
. . .
- unknown
Batwa .
..
/
.
.
.
.
*
12
9
16
7
miles
miles
miles
miles
39 miles
38 miles
36 miles
24 miles
24 miles
45 miles
36 miles
(Col. K. Mason)
.
.
.
.
.
.
PLATK Jr.
SNOUT OF SOSA GLACIER FROII SOMA.
Photo. J. L. Grinltitton. (Geol. Hun'ey of India, Ilecords, vol. xliv.)
PHYSICAL FEATURES
17
flats, etc, while the streams flow in easy, shallow meandering valleys.
In other words, the rivers of the Peninsula have almost base-levelled
their courses, and are now in a mature or adult stage of their lifehistory. Their " curve offcrosion " is free from irregularities of most
kinds except those caused by late earth-movements, and is more or
less jmiform from their sources to their mouths.^
Easterly drainage, of the Peninsula—One very notable pecuharity in
the drainage-system of the Peninsula is the pronouncedly easterly
trend of its main channels, the Western Ghats, situated so close to the
west border of the Peninsula, being the water-shed. The rivers that
discharge into the Bay of Bengal have thus thfeir sources, and derive
their head waters almost within sight of the Arabian Sea. This feature in a land area of such antiquity as the Peninsula, where a complete hydrographic system has been in existence for a vast length of
geologic time, is quite anomalous, and several hypotheses have been
put forward to account for it. One supposition regards this fact as an
indication that the present Peninsula is the remaining half of a land
mass, which had the Ghats very near its centre as its primeval watershed. This water-shed has persisted, while a great extension of the
country west of it has been submerged underneath the Arabian Sea.
Another view, equally probable, is suggested by the exceptional behaviour of the Narbada and the Tapti. These rivers discharge their
drainage to the west, while all the chief rivers of'the country, from
Cape Comorin through the Western Ghats and the Aravallis to the
Siwalik hills near Hardwar (a long water-shed of 1700 miles), all run
to the east. This exceptional circumstance is explained by* the supposition that the Narbada and Tapti do not flow in valleys of their
own eroding, but have usurped for their channels two fault-planes, or
deep alluvium-filled rifts in the rocks, running parallel with the
Vindhyas. These faults are said to have originated with the bending
or " sagging " of the northern part of the Peninsula at the time of the
* It cannot be said, however, that the channels are wholly free from all irregularities,
for some of them do show very abrupt irregularities of the nature of Falls. Among the
best known waterfalls of South India are : the Sivasamudram falls of the CauveJy in
Mysore, which have a height of about 300 feet; the Gokak falls of the river of that
name in the Belgaum district, which are 180 feet in height; the " Dhurandhar " or
the falls of the Narbada at Jabalpur, in which, though the fall is only 30 feet, the
volume of water is large. The most impressive and best-known of the waterfalls of
India are the Gersoppa falls of the river Sharavati in North Kanara, where the river
is precipitated over a ledge of the Western Ghats to a depth of 850 feet in one single fall.
The Yenna falls of the Mahableshwar hills descend 600 feet below in one leap, while
the falls of the Paikara in the Nilgiri hills descend less steeply in a series of five cataracts
over the gneissic precipice. Indeed, it liay be said that such falls are more characteristic of Peninsular than of extra-Peninsular India and bear evidence to some minor
disturbances in a late geological age.
w.a.i.
B
18
GEOLOGY OF INDIA
upheaval of tlie Himalayas as described before. As an accompaniment of the same disturbance, the Peninsular block, south of the
cracks, tilted slightly eastwards, causing the eastern drainage of the
area.
^ This peculiarity of the hydrography of the Peninsula is illustrated
in the distribution and extent of the alluvial margin on the two coasts.
There is but a scanty margin of alluvial deposit on the western coast;
except in Gujarat, whereas there is a wide belt of river-borne alluvium
on the east coast, in addition to the great deltaic deposits at the
mouths of the Mahanad.i, Godavari, Kistna, Cauvery, etc.
A further peculiarity of the coast is the absence of deltaic deposits
at the mouths of the streams, even of the large rivers Narbada and
Tapti. This peculiarity arises from thafact that the force of the currents generated by the monsoon gales and the tides is too great t o .
allow alluvial spits or iDars—the skeleton.of the deltas—to accumulate.
On the other hand, the debouchures of these streams are broad deep
estuaries daily swept by the recurring tides.
As a contrast to the drainage of Peninsular India, it should be
noted that the island of Ceylon has a " radial " drainage, i.e. the
rivers of the island flow outwards in all directions from its central
highlands, as is well seen in any map of Ceylon.
The Drainage of the Extra-Peninsula Area
The Himalayan system of drainage not a consequent drainage—In
the extra-Peninsula the drainage system, owing to the mountainbuilding movement of the late Tertiary age, is of much more recent
development, and differs radically in its main features and functions
from that of the Peninsula. The rivers here are not only eroding and
transporting agents but are also depositing agents during their journey
across the plains to the sea. Thus they have built the vast plains of
North India out of a part of the silt they have removed from thje
mountains. The most important fact to be realised regarding the
drainage is that it is not in a large measure a consequent drainage,
i.e. its formation was not consequent upon the physical features," or
the relief, of the country, as we now see them ; but there are clear
evidences to show that the principal rivers of the area were of an age
anterior to them. In other words, many of the great Himalayan
rivers are older than the mountains they traverse. During the slow
process of mountain-formation by the folding, contortion, and upheaval of the rock-beds, the old rivers kept very much to their own
PHYSICAL FEATURES
19
channels, although certainly working at an accelerated rate, by reason
of the great stimulus imparted to them by the uplift of the region near
their source. The great momentum acquired by this upheaval was
expended in eroding their channels at a faster rate. Thus the elevation of the mountains and the erosion of the valleys proceeded, 'pari
passu, and the two processes keeping pace with one another to the
end, a mountain-chain emerged, with a completely developed valleysystem intersecting it in deep transverse gorges or canons. These long,
deep precipitous gorges of the Himalayas, cutting right through the
hne of its highest elevations, are the most characteristic features of its
geography, and are at once the best-marked results, as they are the
clearest proofs, of the inconsequent drainage of this region. From the
above peculiarities the Himalayan drainage is spoken of as an antecedent drainage, meaning thereby a system of drainage in which the
main channels of flow were in existence before the present freatures
of the region were impressed on it.
The Himalayan water-shed—This circumstance of the antecedent
drainage also gives an explanation of-the much-noted peculiarity of
several of the great Himalayan rivers, e.g. the Indus, Sutlej, Bhagirathi, Alaknanda, Kali, Karnali, Gandak, Kosi and the Brahmaputra, that they drain not only the southern slopes of those mountains, but, to a large extent, the northern Tibetan slopes as well, the
water-shed of the chain being not along its line of highest peaks, but a
great distance to the north of it. This, of course, follows from what
we have said in the last paragraph. The drainage of the northern
slopes flows for a time in longitudinal valleys, in structural troughs'
parallel to the mountains, but sooner or later the rivers invariably
take an acute bend and descend to the plains of India by cutting
across the mountain in the manner already described.
The transverse gorges of the Himalayas—These transverse gorges of
the Himalayas are sometimes thousands of feet in depth from the
crest of their bordering precipices to the level of the water at their
bottom. The most remarkable example is the Indus valley in Gilgit,
where at one place the river flows through a narrow defile, between
enormous precipices nearly 20,000 feet in altitude, while the bed of the
valley is only 3000 feet above its level at Haiderabad (the head of its
delta). This gives to the gorge the stupendous depth of 17,000 feet,
yet the fact that every inch of this chasm is carved by the river is clear
from the fact that small patches or " terraces " of river'gravel and
sand-beds are observed at various elevations above, the present bed of
the Indus, marking the successive levels of its bed. Other examples
20
GEOLOGY OF INDIA
of similar gorges are numerous, e.g. those of the Sutlej, Gandak, Kosi,
Alaknanda, etc., are deep defiles of from 6000 t^o 12,000 feet depth and
only from 6 to 18 miles width between the summits of the mountains
on the sides.
1
[Although there is not much doubt, how, regarding the true origin of the
transverse gorges of the Himalayas by the process described- above, these
valleys have given rise to much discussion in the past, it being not admitted
by some observers that those deep defiles could have been entirely due to
the erosive powers of the streams that now occupy them. It was thought
by many that originally they were a series of transverse fissures or faults in
the mountains which have, been subsequently widened by water-action.
Another view was that the elevation of the Himalayas dammed back the
old rivers and converted them into Jakes for the time being. The waters of
these lakes on overflowing have cut the gorges across the mountains, in the
manner of retreating waterfalls. The absence of lacustrine deposits at the
head of the principal rivers does not lend support to this view, though it is
probable that this factor may have operated in a secondary way in some
cases. The defile of the Alaknanda again, is known to have carved a part
ofits valley along a hne of fault.
There is no doubt, however, that sOme of these transverse valleys, namely
those of the minor jivers, have been produced in a great measure by the
process of head-erosion, by the combined action of the stream or the glacier^
at the head of the river pushing itself forward into the mountains, whereby
the water-shed receded further and further northwards. It is necessary to
suppose this because the volume of drainage from the northern slopes, in
the early stages of valley-growth, could not have been large enough to give
it sufficient erosive energy to keep its valleys open during the successive
uplifts of the mountains.]
River capture or piracy—Many of the Himalayan rivers, in their
higher courses, illustrate the phenomena, of river-cap.ture or " piracy ".
This has happened oftentimes through the rapid head-erosion of their
'•main transverse streams, capturing or " beheading " successively the
secondary laterals belonging to the Tibetan drainage-system on the
northern slopes of the Himalayas. The best jexamples of rivercapture are furnished by the Bhagirathi and other tributaries of the
Ganges, the Arun in the Everest area' the Tista of Sikkim, and the
Sind * river in Kashmir.
" Hanging valleys " of Sikkim—Some of the valleys of the Sikkim
and Kashmir Himalayas furnish instructive examples of " hanging
valleys ", that is, side-valleys or tributaries whose level is some hundreds or thousands of feet higher than the level of the main stream
into which they discharge. These hanging valleys have in the
majoiity of instances originated by the above process of rapid head1 Oldham, Eec. G.S.I, vol. xxxi. pt. 3, 1904.
PHYSICAL FEATURES
21
erosion and capture of the lateral streams on the opposite slope. A
well-known example is that of a former tributary of the Tista riyer of
Sikkim, discharging its waters by precipitous cascades into the
Eathong Chu, which is flowing nearly 2000 feet below its bed. Prof.
Garwood, in describing this phenomenon, suggests that the difference
in level between the hanging side-valley and the main river'is due not
wholly to the more active erosion of the latter, but also to the recent
occupation of the hanging valley by glaciers, which have protected it
from the effects of river-erosion.
LAKES
Lakes play very little part in the drainage system of India. Even
in the mountainous regions of the extra-Peninsula, particularly in the
Himalayas, where one might expect them to be of frequent occurrence, lakes of any notable size are very few.
Lakes of Tibet, Kumaon and Kashmir—The principal lakes of the
extra-Peninsula are those of Tibet (including the sacred Manasarovar
and Eakas Tal, the reputed source of the Indus, Sutlej, and Ganges of
Hindu traditions but which have now been proved to be the source of
the Sutlej river). The Manasarovar, 200 sq. miles in area and Rakas
Tal, 140 sq. miles, are fresh-water lakes, while Gunchu Tso, 30 miles
to the east, is a saline lake, 15 miles long, it being a closed basin without any outlet. Other examples are : the lakes of Sikkim, Yamdok
Cho, 45 miles in circumference ; Chamtodong, 54 miles ; the group of
small Kumaon lakes (the Nainital, Bhim Tal, etc.); and the few lakes
of Kashmir, of which the Pangkong, Tsomoriri, the Salt Lake, the
Wular and Dal are the best-known surviving instances. There is
some controversy with regard to the origin of the numerous lakes of
Tibet, which occupy thousands of square miles of its surface and are
the recipients of its inland surface drainage. Many are regarded as
due to the damming up of the main river-valleys by the alluvial fans
of tributary side-valleys (F. Drew); ^ some are regarded as due to an
elevation of a portion of the river-bed aka rate faster than the erosion
of the stream (Oldham); ^ while some are regarded as true erosionhollows, scooped out by glaciers—rock-basins.^ The origin of the
Kumaon lakes is yet uncertain; while a few may be due to differential earth-movements like faulting, others may have been pro'duced
' Jammu and Kashmir Territories (London), 1875.
'Sec. O.S.I. vol. xxi. pt. 3, 1888.
' Huntington, Journal of Geology, vol. xiv. 1906, p. 599.
22
GEOLOGY OF INDIA
by landslips, glaciers, etc. The small fresh-water lakes of Kashmir are
ascribed a very simple origin by Dr.^ Oldham. They are regarded by
him as mere inundated hollows in the alluvium of tiie Jhelum, likethe jhils of the Gaiiges delta. The. Manchar lake of Sind, a shallow
depression, only 8-10 feet deep, but attaining an area of 200 sc[. miles
in the monsoon, is in all probability of like, character and origin,
forming a part of the drainage system of the Indus in Sind.
Salinity of the Tibetan lakes—The lakes of Tibet exhibit two interesting pecuharities, viz. the growing salinity of their waters and
their pronounced diminution of volume, since late geological times.
The former circumstance is explained by the fact that the whole lakearea of Tibet possesses no outlet for drainage. The interrupted and
restricted inland drainage, therefore, accumulates in these basins and
depressions of the surface where solar evaporation is very active,
concentrating the chemically dissolved substances in the waters. All
degrees of salinity are met with, from the drinkable waters of some
lakes to those of others saturated with common salt, sodium carbonate,
and borax.
TheJT desiccation—The desiccatioij of the Tibetan lakes is a pheno;
menon clearly observed by all travellers in that region. Old highlevel terraces and sand and gravel beaches, 200 to 300 feet above the
present level of their waters, are seen surrounding almost all the
basins, and point to a period comparatively recent in geological history when the water stood at these high levels. This diminution of
the volume of the water, in some cases amounting to a total extinction
of the lakes, is one of the signs of the increasing dryness or desiccation
of the region north of the Himalayas following a great change in its
climate. This is attributed in some measure to the disappearance of
the glaciers of the Ice Age, and to the uplift of the Himalayas to their
present great elevation, which has cut off Tibet from the monsoonic
currents from the sea.
Lakes of the Peninsula—Besides the few small fresh-water lakes 6f
the Peninsula, two occurrences there are of importance because of some
exceptional circumstances connected with their origin and their present
peculiarities. The one is the group of salt-lakes of Rajputana, the
other is the volcanic hollow or crater-lake of Lonar in the Deccan.
The Sambhar salt-lake—Of the four or five salt-lakes of Rajputana,
the Sambhar lake is the most important. It has an area of ninety
square miles when full during the monsoon, at which period the depth
of the water is about four feet. For the rest of the year it is dry, the
surface being encrusted by a whit& saliferous silt. The. cause of the
PHYSICAL FEATURES
23
salinity of the lake was ascribed to various circumstances, to former
connection witli the Gulf of Cambay, to brine-springs, to chemical
dissolution from the surrounding couiitry, etc. But lately Sir T. H.
Holland and Dr. Christie ^ have discovered quite a different cause of
its origin. They have proved that the salt of the Sambhar and of the
other salt-lakes of Eajputana is-wind-borne ; it is derived partly from
the evapor^ion of the sea-spray from the coasts and partly from the
desiccated surface of the Rann of Cutch, from which sources the dried
salt-particles are carried, inland.by the prevalent winds. The persistent south-west mons_oons which blow through Eajputana for half the
year, carry a large quantity of saUne mud and salt-particles from the
above sites, which is dropped when the velocity of the winds decreases. When once dropped, wind-action is not powerful enough to
hft up the particles again. The occasional rainfall of these parts
gathers in this salt and accumulates it in the lake-hollows which receive the drainage of the small streams. I t is calculated by these
authors, after a series of experiments, that some 130,000 tons of
saline matter is annually borne by the winds in this manner to Eajputana during the hot weather months.
The Lonar lake—The Lonar lake is a deep crater-like hollow or
basin in the basalt-plateau of the Deccan, in the district of Buldana.
The depression is about 300 feet in depth and about a mile in diameter. I t is surrounded on all sides by a rim formed of blocks of
basalts. The depression contains at the bottom a shallow lake of
saline water. The chief constituent of the salt water is sodium carbonate, together with a small quantity of sodium chloride. These
salts are thought to have been derived from the surrounding trap
country by the chemical solution of the disintegrated product of the
traps and subsequent concentration.
The origin of the Lonar lake hollow has been ascribed to a volcanic
explosion unaccompanied by any lava eruption. This is one of the
rare instances of volcanic phenomena in India within recent times.
On this view the lake-hollow is an explosion-crater or a caldera.
Another explanation has been given lately,^ which explains the hollow as due to an engulfment or subsidence produced by the sinking
of the surface between a circular fracture or fractures, into a cavern
emptied by the escape of lava or volcanic vapours into the surrounding places.
» Eec. G.S.I. vol. xxxviii. pt. 2, 1909.
»La Xouche, Beo. G.S.I, vol, xli. pt. 4,1912.
24:
GEOLOGY OF INDIA
THE COASTS
The coasts of India are comparatively regular and uniform, there
being but few creeks, inlets, or promontories of any magnitude. It is
only on the Malabar coast that there are seen a number of lakes,
lagoons or back-waters which form a noteworthy feature of that
coast. These back-waters, e.g. the Kayals of Travancore, are shallow
lagoons or inlets of the sea lying parallel to the coast-line. They form
an important physical as well as economic feature of the Malabar
coast, affording, facilities for inland water-communication. The silts
brought by the recurring monsoon floods support large forests and>
plantations along their shores. At some places, especially along the
tidal estuaries, deltaic fronts, or salt-marshes, there are the remarkable
maiigrove-swamps lining the coasts. The whole sea-board is surrounded by a narrow submarine ledge or platform, the " plain of
marine denudation ", where the sea is very shallow, the soundings
being much less than 100 fathoms. This shelf is of greater Jjreadth
on the Malabar coast and on the Arakan coast than on the Coromandel coast. From these low shelving plains the sea-bed gradually,^
dee_pens, both towards the Bay of Bengal and the Arabian Sea, to
a mean depth of 2000 fa,thoms in the former and 3000 fathoms in the
latter sea. The seas are not of any great geological antiquity, both
having originated in the earth-movements of the Cretaceous or early
Tertiary times, as bays or arms of the Indian Ocean overspreading
areas of a large southern continent (Gondwanaland), which, in the
Mesozoic ages, connected India with Africa and with Australia. The
coast line in front of the deltas of the Indus and Ganges is greatly
changeable owing to the constant struggle between the growth .of the
delta and the erosion of the waves, the formation of lagoons, lakes
and sand-bars. Extensive mangrove-swamps are a feature of these
coasts. The coast of Sind forms part of the plain'of marine denudation, with the sea hardly a few fathoms deep. ..
I t has long been the belief of geologists that the escarpment of
the Western Ghats parallel with the Malabar Coast, has been formed
by scarp-faulting, while Blanford considered the Mekran coast of
Baluchistan to be largely shaped by an E.-W, fault. The south-east
coast of Arabia and the Somaliland coast as far south as Zanzibar are
likewise believed to be determined by scarp-faults. The whole of the
north border of the Arabian Sea is thus surrounded by a series of
steep fractures believed to be of Pliocene or even later age.
The recent researches on the subnaarine topography of the Arabian
PHYSICAL FEATURES
25
Sea conducted by the Murray Expedition of 1933-31 have revealed
some further interesting facts. These have shown that there are
intermittent submerged ridges, 10,000 feet high, some 60 miles from
the Mekran coast and parallel with it. Two parallel ridges, separated
by a deep rift valley, 2000 fathoms below the surface of the sea (extension of the present.valley of the Indus ?), starting from Karachi
extend up to the Gulf of Oman. The axes of these ridges are probably
in tectonic continuation with the Kirthar range of Sind composed of
Eocene and Ohgocene rocks.
Colonel Sewell, the leader of the Murray Expedition, is of the:
opinion that there is a remarkable similarity between the topography
of the floor of the Arabian Sea and the region of the great Eift
Valleys of East Africa.
Important gabdetic data obtained by Colonel E. A. Glennie suggest that the Laccadive archipelago, prolonged northwards by a
chain of shoals, is on a continuation of the axes of the Aravalli mountains. The islands of the seas are continental islands, with the exception of the group of coral islands, the Maldives and the Laccadives,
which are atolls or barrier-reefs, reared on shallow submarine banks, the
unsubmerged, elevated points of the ancient continent. Barren Island
and Narcondam are volcanic islands east of the Andamans.^ The low
level and smooth contours of the tract of country which lies in front
of the S.E. coast below the Mahanadi suggest that it was a submarine
plain which has emerged from the waters at a comparatively'late date*
Behind this coastal belt are the gneissic highlands of the mainland^
the Eastern Ghats—which are marked by a more' varied relief and
rugged topography. Between these two lies the old shore-line.
The Arakan coast of the Bay of Bengal,'with its numerous drowned
valleys and deep inlets owes its" features to recent depression. The
numerous islands of this coast as well as of the Malay archipelago and
the East Indies are regarded as only the unsubmerged portions of a
once continuous stretch of land from Akyab to Australia.
VOLCANOES
Baixen Island volcano—There are no living or active volcanoes anywhere in. the Indian region. The Malay branch of the hne of Uving
volcanoes—the Sunda chain—if prolonged to the north, would connect a few dormant or extinct volcanoes belonging to this region.
* R. B. Seymour Sewell, Geographic and Qceanographio Researoll in Indian
Waters, Memoirs, As. Soc. Beng. vol. ix. pp. 1-7, 1935.
26
GEOLOGY OF INDIA
Of these the most important is the now dormant volcano of Barren
Island (Fig. 2) in the Bay of Bengal, to the east of the Andaman Islands, 12° 15' N. lat.; 93° 54' E. long. What is now seen of it is a
mere truncated remnant of a once much larger cone—its basal wreck
or caldera. It consists of an outer ainphitheatre, about two miles in
diameter, breached at one or two places, the remains of the old cone.
^yW'^.'iJ^^:
w^
^
—
^ " ^ 1 -
Fia. 2.—The Volcano of Barren Island in the Bay of Bengal.
(H. F. Blanford.)
surrounding an inner, much smaller, but symmetrical cone, composed
of regularly bedded lava-sheets of comparatively recent eruption. At
the summit of this newer cone is a crater, about 1000 feet above the
level of the sea. But the part of the volcano seen above the waters is
quite an insignificant part of its whole volume'. The base of the cone
lies some thousands of feet below the surface of the sea.
The last time it was observed to be in eruption was early* in
the nineteenth century; since then it has been dormant, but
sublimations of sulphur on the walls of the crater point to a mild
solfataric phase into which the volcano has declined'. Mr. F. R.
Mallet, of the Geological Survey of India, has given a complete account
of Barren Island in Memoir, vol. xxi. pt. 4, 1885. ^
Naxcondam. Popa—Another volcano, along the same Jine, is that
* Captain Blair has described an eruption of Barren Island in 1795. Glowing cinders
and volcanic blocks up to some tons in weight were discharged from the crater at the
top of the new cone, which was also ejecting enormous clouds of gases and vapours.
Another observer, in 1803, witnessed a series of explosions at the crater at intervals
of every ten minutes, throwing out masses of dense black gases and vapours withgreat
violence to considerable heights.
PHYSICAL FEATURES
'
27
of the island of Narcondam, a craterless volcano composed wholly of
andesitic lavas. From the amount of denudation that the cone has
undergone it appears to be an old extinct volcano. The third example
is the volcano of Popa, a large centrally situated cone composed of
trachytes, ashes, and volcanic breccia, situated about fifty miles
north-east of the oil-field of Yenangyaung. This is also extinct now,
the cone is much weathered, and the crater is only preserved in part.
From the fact that some volcanic matter is found interstratified in the
surrounding strata belonging to the Irrawaddy group, it seems that
this volcano must have been in an active condition as far back as the
PKocene.
Koh-i-Sultan—One more volcano, within the Indian Empire, but
far on its western border, is the large extinct volcano of Koh-i-Sultan
in the Nushki desert of western Baluchistan.
There are some unverified records of a number of fiving and dormant
volcanoes in Central Tibet and in the Kuen-Lun range of mountains to its
north. None of %hese, however, have been proved to be active recently,
although reports about the eruption of some of these having been witnessed
by Tibetan travellers from a distance have been current.
Among the volcanic phenomena, of recent age must also be included
the crateriform lake of Lonar, noticed in the preceding section.
Whatever may be its exact origin, it is ultimately connected with
volcanic action,
Mud-Volcanoes
Distribution of Mud-Volcanoes—^We must here consider a curious
phenomenon—what was once regarded as a decadent phase of volcanic action, but which has no connection whatever with vulcanicity.^
In the Irrawaddy valley and Arakan coast of Burma and the Mekran
coast of Baluchistan, there occur groups of small and, more rarely,
large cones of dried miid ; from small holes (" craters ") at the top
there are discharged hydrocarbon gases (principally marsh-gas),
muddy saline water, and often traces of petroleum. These conical
mounds, known as mud-volcanoes, occur in great numbers in the
Eamri and Cheduba islands on the Arakan coast, the majority being
about twenty to thirty feet high although some are much higher.
Near Minbu in Burma the cones reach about forty feet, but in the dry
climate of Baluchistan some are nearly 300 feet high. The great
majority of mud-volcanoes are associated with a very gentle flow of
* J. Coggin Brown, Sec. O.S.I, vol. xxxvii. pt. 3, 1900, Sir E. H. Pasooe, Mem,
G.S.I. vol. xl. pt. 1, 1912.
"
28
GEOLOGY OF INDIA
muddy water, but in exceptional cases, the mud-volcanoes are subject
to occasional outbursts of great violence, fragments of the country
rock, being thrown out with force ; the friction may even be sufficient
to ignite the accompanying hydrocarbon gases.
. Association with Petroleum—The gas, which is the prime cause of
the mud-volcanoes, has the same origin as petroleum, and not only
do many of the mud-volcanoes exude small quantities of petroleum,
but a large number are in close proximity to small oilfields or to
seepages of petroleum. Most of the mud-volcanoes' are near the
crests of anticlinal folds or on lines of faulting. In the Yenangyai^ng
oilfield of Burma there have been observed veins of dried mud pene-.
trating the Miocene strata ; these veins represent the channels supplying 'mud to mud-volcanoes that have long since disappeared.
The mud is derived from the disintegration of shales of Tertiary age
lying beneath the'surface in close association with the gas-bearing
strata. Where the shale is easily disintegrated, the flow of water
small, and the. climate dry, the mound of dried mud will form a very
conspicuous feature; where the water brings up little mud,»there
may be nothing but a pool of dirty water kept in constant agitation,
by bubbles of gas. There are many seepages of this type in Assam,
and in no case is a permanent'cone formed ; in former days the brine
was an important local'source of salt.
Mud-volcanoes are common accompaniments of petroleum occurrences in other parts of the world, especially in Russia and the Dutch
East Indies.
EARTHQUAKES
The earthquake zone of India—Few earthquakes have visited the
Peninsula since historic times ; but those that have shaken the extraPeninsula form a long catalogue.^ It is a well-authenticated generalisation that the majority of the Indian earthquakes have originated
from the great plains of India, or from their peripheral, tracts.
Of the great Indian earthquakes recorded in history the bestknown are : Delhi, 1720 ; Calcutta, 1737 ; Eastern Bengal and the
Arakan coast, 1762 ; Cutch, 1819 ; Kashmir, 1885 ; Bengal, 1885 ;
Assam, 1897, Kangra, 19,05 ; North Bihar, 1934 ; and West Baluchistan, 1935 ; all of these, in the site of their origin, agr6e with the
above statement.
The area noted above is the zone of weakness and strain implied
by the severe crumpling of the rock-beds in the elevation of the
1 Oldham, List of Indian Earthquakes, 3Iem. O.S.I, vol, xix. pt. 3, 1883.
PHYSICAL FEATURES
29
Himalayas wichin very recent times, which has, therefore, not yet
attained s t a b i h t y or quiescence. I t is also according to some authorities a belt of underload, its rocks being about 18 per cent, lighter
t h a n normal rocks. I t falls within the great earthquake belt which
traverses t h e earth east to west.
'
The Assam EarthquaHe.—On the 12th June, 1897, there occurred in
Assam, heralded by a roar of extraordinary loudness, one of the most disastrous earthquakes of the world on record ; the disturbed area bounded by
the isoseismal of 5 or 6 being no less than 1,600,000 sq. miles. Shillong,
with the surrounding country of 150,000 sq. miles, was laid waste in less
than one minute, all communications were destroyed, the plains riddled
with rents and flooded and the hill-sides were scarred by gigantic landslips.
The seismic motion was a complicated undulatory movement of the
ground, the vertical componentofwhichmusthave been high, for stones on the
roads of Shillong were tossed in the air " like peas on a drum ". The maximum amplitude of horizontal vibration was as much as 7 inches, their
period being one second. Wide, g«ping earth-fissures opened out in all
directions in the alluvial plains, from which issued innumerable jets of
water and sand, like fountains, spouting up to 3 or 4 feet in the air. Beds
of rivers, tanks and even wells were ridged up, or filled, by the outpouring
sand, thus greatly disturbing the drainage system of the land and causing
extensive flooding. Over a wide area encircling the epicentre, the mountains precipitated landslips of unusual dimensions, which further obstructed the drainage.
The main shock was succeeded by hundreds of after-shocks during the
first month, felt all over the shaken area. These shocks originated in a large
number of shifting foci, scattered over the main epicentral tract in a fitful
rqanner, certain districts registering far more shocks than others.
Of great significance geologically are the concomitant structural
changes produced on the surface of the ground, such as fault-scarps and
fractures, local changes of level, compression of the ground, and slight
' changes in the heights' of hill^. The most important fault-scarp ran
-parallel with the Chidrang river for 12 miles, with a vertical throw varying
from 1 to 35 feet, producing a number of water-falls and as many as thirty
lakes in the course of the river.
R. D. Oldham, the author of a valuable memoir on this earthquake, has
stated that the complex phenomena of this quake and the occurrence of many
maxima of intensity are inconsistent with a simple or single fault-dislocation. He believes that there were numerous foci, or centres of disturbance, situated over a tract 200 miles long and 50 miles wide. The original
disruption starting in a thrust fault initiated numerous sympathetic
shocks along branch-faults. The after-shocks were closely Connected with
the subsequent movements of these faults and served in some degree to
locate them.
Oldham has computed the velocity of the earth-waves as about 2 miles
per second and the depth of origin of the main shock at only 5 miles or even
less.^
> R. D. Oldham, Memoirs, G.S.I, vol. xxix, 1899.
30
GEOLOGY OF INDIA
The Kangra Earthquake.—Tlio earthquake took place on the early morning of the 4th April, 1905. The shock, which was felt over the whole of
India jiorth of the Tapti valley, was characterised by exceptional violence
and destructiveness along two linear tracts between Kangra and Kulu,,
and between Mussoorie and Dehra Dun. These were the epifocal tracts.
The destruction grew less and less in severity as the distance from them increased, but the area that was perceptibly shaken, and which is encompassed by the isoseist of Intensity II, of the Eossi-Forel scale, included
such distant places as Afghanistan, Quetta, Sind, Gujarat, the Tapti valley,
Puri and the Ganges delta. The centra or the foci of the original concussion, or blow, were linear, corresponding to the two linear epicentra,
Kangra-Kulu and Mussoorie-Dehra Dun, or areas which were directlj^verhead and in which the vibrations had a large vertical component. The
isoseists, or curves of equal intensity, were hence ellipsoidal.
The velocity of the quake was difficult to judge, because of the absence
of any accurate time-records at the different outlying places. But from a
number of observations, the mean is deduced to be nearly 1- 92 miles per
second as the velocity of the earth-wave.
»
Middlemiss does not support the view that earthquakes of great severity
originate near the surface in a complex network of faults and fractures.
He ascribes to the present earthquake a deep-seated origin, and calculates,
from Dutton's formula for deducing the depth of focus, a depth varying
from 21 to 40 miles.
The main-shock was sudden, with only a few premonitory warnings, bui
the after-shocks, of moderate to slight intensity, which succeeded it for
weeks and months, were several hundred in number. During the whola of
1906 the number of after-shocks was from ten to thirty a month. In 1907
they decreased in number, but scarcely in intensity. In the succeeding
years the number of shocks grew fewer till they gradually disappeared.
The geological effects of the earthquake were not very marked. There
were the usual disturbances of streams, springs, and canals ; a number of
landslips and rock-falls took place, also a few slight alterations in the level
of some stations and hill-tops {e.g. Dehra Dun and the Siwalik hills sho'wed
a rise of about a foot relatively to Mussoorie). No true fissures of dislocations were, however, seen. In the above respects this earthquake offers a
marked contrast to the Assam quake of 1897, where the geological results
were of a more serious description and more permangnt in their effect.'
With regard to the cause of the earthquake, there is no doubt that it was
a tectonic quake. Middlemiss is of opinion that it was due to a slipping 'of
one of the walls or change of strain of a fault parallel to the " Main Boundary
Fault " of the outer Himalayas at two points. Just where the two epicentra lie are two very well-defined " bays " or inpushings of the younger
Tertiary rocks into the older rocks of the Himalayas, showing much packing
and folding of the strata. Relief was sought from this compression by a
shght sinking of one side of the fault.^
The Bihar Earthquake.—On the afternoon of 15th January, 1934, North
Bihar and Nepal were shaken by an earthquake of high intensity. Within
* Memoirs G.8.I. vol. xxxviii., 1910.
•
PHYSICAL FEATURES
31
three minutes tii,e cities of Mongliyr and Bhatgaon (Nepal) were in ruins and
towns so far- apart as Kathmandu, Patna and Darjeeling were strewn with
debris of many public and private buildings. Houses in Purnea and Sitaniarhi tilted and sank under the ground and sand and water were emitted
from countless fissures in the ground opened on either side of the Ganges.
The intensity of the main shock was so great that the recording apparatus
of the majority of the seismographs were thrown out of action, while the
shocks were recorded at seismological stations so far away as Pasadena,
Leningrad and Tokyo. The area enveloped by the Isoseist of Intensity I I
was roughly 1,900,000 sq. miles. The main epicentra, where the intensity
reached the degree of X, were three': (I) Motihari-Madhubani, (2) Kathmandu and (3) Monghyr. 11,000 sq. miles of the Ganges basin was riddled
by fissures and sand-vents which ejected large volumes of water and sand
flooding the cultivated country and killing the standing crops. The total
loss of human life is estimated at more than 12,000.
The effects of the earthquake on the general configuration and drainage
of the country, alterations of level, fault-scarps, landslips, etc., were not so
marked as in the Assam quake of 1897. The period and amplitude of
vibrations and the maximum acceleration of the earth-wave were likewise
not so remarkable. •
Estimates of the depth of focus on the various standard methods of calculation vary largely, b u t j t is probable that the movements responsible
for the shock may have been along a highly inclined fracture or fractures.
With regard to the cause, there is some agreement that this earthquake
was not primarily caused by displacements along the Himalayan Boundary
Faults or thrusts, but that a more probable source of disturbance lay in the
folded and fractured zone of the crust underneath the Gangetic Basin—a
geosynclinal depression the bottom of which must conceivably be under
great strain.'^
West Baluchistan (Quetta) Earthquake.—This seismic disaster, though
rather local in .incidence, brought unusual destruction of life and property
on the town of Quetta on the night of 31st May, 1935. In a few moments
. this large military station was converted into a graveyard entombing
20,000, people. The epicentral tract is calculated to be only a^out 68 miles
long and 16 miles broad, between Quetta and Kalat, away from which the
intensity of damage rapidly decreased. The area over which the shock was
felt, enclosed by Isoseist of Intensity IV and V, was 10,000 sq. miles,
which, considering the extraordinary destruction caused at the epicentre,
is unusually small. From this fact, as also from the one that the intensity
of the quake, as judged by the distribution ofthe damage, fell off rapidly
»from the epicentre, it is evident that the focus of origin of this earthquake
could not be very deep-seated.
Extensive rock-falls took place from the limestone cliffs around Quetta
and the ground, where composed of alluvium or loose soil, was fissured by a
network of cracks. There were however no marked upheavals on the sides
of the cracks, which were mainly superficial.
' Eecorde O.S.I, vol. Ixviii. pt. 2, 1934. A memoir on the subject is under publication.
32
GEOLOGY OF INDIA
The earthquake was of the tectonic kind, though no connection has been
established between this (or the less severe previous quake of 1931), and
the various faults that have been noted in this region of severely compressed and looped fold-axes. The mountains of the Quetta region form a
. deep re-entrant angle, their tectonic axes being as it were festooned around
a pivot near Quetta. The strain on the rock-folds arising from such a
structure is probably responsible fpr the well-known seismic instability
of this part of Baluchistan.^'
Local Alterations of Level
Elevation of the Peninsular tableland—Few hypogene disturbances
have interfered with the stability of the Peninsula as a continental
land-mass for an immense length of geological time, but there have
been a few minor movements of secular upheaval and depression
along the coasts, within past as well as recent times. Of these, the
most important is that connected with the slight but appreciable
elevation of the Peninsula, exposing portions of the plain of Tnarine
denudation as a shelf or platform round its coasts, the west as well as
the east. Raised beaches are found at altitudes varying from 100 to
150 feet at many places round the coasts of India ; a common type
of raised beach is the littoral concrete, composed of an agglutin'ated
mass of gravel, sand with shells and coral fragments ; while marine
shells are found at several places some distance inland, and at a height
far above the level of the tides. The steep face of the Sahyadri
mountains, looking like a line of sea-cliffs, and their approximate
parallelism to the coast lead to the inference that the escarpment is a
result of a recent elevation of the Ghats from the sea and subsequent
sea-action modified by subaerial denudation. Marine and estuarine
deposits of post-Tertiary age are met with on a large scale towards the
southern extremity of the Peninsula.
Local alterations—Besides these evidences of a rather prominei^
uplift of the Peninsula, there are also proofs of minor, more loc^
alterations of level, both of elevation and depression, witlup., subrecent and pre-historic times. The existence of beds of ligmte and
peat in the Ganges delta, the peat deposits below the surface near
Pondicherry, the submerged forest discovered on the eastern coast of
the island of Bombay, etc., are proofs of slow movements of depression.
Evidences of upheaval are furnished by the exposure of some coral reefs
along the coasts, low-level raised beaches on various parts of the Ghats,
and recent marine accumulations above the present level of the sea.
1 W. D. West, Records G.S.I, vol. Ixix. pt. 2, 1935, and Memoirs G.S.I. vol. Ixvii.
pt. 1, 1934.
PHYSICAL FEATURES
33
Submerged forest of Bombay. Alterations of level in Cutch—The
submerged forest of Bombay is nearly 12 feet below low-water mark
and 30 feet below high-water; here a number of tree-stumps are
seen with their roots in situ, embedded in the old soil.i On the Tinnevelli coast a similar forest or fragment of the old land surface, half an
acre in extent, is seen slightly below high-water mark. Further evidence to the same effect is supplied by the thick bed of lignite found at
Pondicherry, 240 feet below ground level, and the layers of vegetable
debris in the Ganges delta. About twenty miles from the coast of
Mekran the sea deepens suddenly to a great hollow. This is thought
to be due to the submergence of a cliff formerly lying on the coast. The
recent subsidence, in 1819, of the western border of the Kann of Cutch
under the sea, accompanied with the elevation of a large tract of land
(the Allah Bund), is the most striking event of its kind recorded in
India, and was witnessed by the whole population of the country.
Here an extent of the country, some 2000 square miles in area, was
suddenly depressed to a depth of from 12 to 15 feet, and the whole
tract converted into an inland sea. The fort of Sindree, which stood on
the shores, the scene of many a battle recorded in history, was also submerged underneath the waters, and only a single turret of that fort
remained, for many years, exposed above the sea. As an accompaniment of the same movements, another area, about 600 square miles,
was simultaneously elevated several feet above the plains, into a
mound which was appropriately designated by the people the " Allah
Bund " (built of God). The elevated tract of land, known as the
Madlmpur jungle, near Dacca, is believed to have been upheaved as
much as 100 feet in quite recent times. This upheaval caused the
deflection of the Brahmaputra river eastward into Sylhet, away from
the Ganges vailey. Since this change the Brahmaputra has again
gradually changed its bed to the west.
Even within historic times the Eann of Cutch was a gulf of the sea,
with surrounding coast towns, a few recognisable relics of which yet
exist. The gulf was gradually silted up, a process aided no doubt by a
slow elevation of its floor, and eventually converted into a low-lying
tract of land, which at the present day is alternately.a dry saline
desert for a part of the year, and a shallow swamp for the other part.
The branching_^'or(^s, or deep, narrow inlets of the sea, in the Andaman
and Nicobar islands in the Bay of Bengal, point to a submergence of
these islands within- late geological times, by which its inland valleys
were " drowned " i n their lower parts. Good, examples of drowned
»Sec. 0.8J. vol. xi. pt, 4, 1878.
W.a.i.
c
34
GEOLOGY OF INDIA
valleys occur on the Arakan coast, wliicli, with its numerous estuaries
and inlets proceeding inland from' a, submarine shelf, gives proof of
recent submergence along the whole stretch of country from Akyab to
the Dutch East Indies. In some of the creeks of Kathiawar near
Porbander, on the other hand, oyster-shells were found at several
places and at levels much above the present height of the tides, while
barnacles and serpulae were found at levels not now reached by
the highest tides. In Sind a number of oyster-banks have been
seen several feet above high-water mark. Oyster-shells discovered
lately at Calcutta likewise point to a slight local rise of the eastern
coast.
Himalayas yet in a state of tension—It is the belief of some geologists
that appreciable changes of level have recently taken place, and are
still taking place, in the Himalayas, and that although the loftiest
mountains of the world, they have not yet attained to their maximum
elevation, but are still rising. That alterations of level'have lately
taken place is clear from a number of circumstances. Many of the
rivers bear incontrovertible proofs of recent rejuvenation, due to the
uplift of their water-shed. Another fact, suggesting t j ^ same,
inference, is the frequency and violence of earthquakes on the_ "Himalayas and in the depressed tract lying at their foot. By far thp
largest number of disastrous Indian earthquakes have occurred, as
already remarked, along these tracts. They indicate that the strata
under the Himalayas are in a state of tension, and are not yet settled
down to their equilibrium plane. Relief is therefore sought by the
subsidence of some tracts and the elevation of others.
ISOSTASY
India is particularly favourably circumstanced for the study of
geodesy (the science of surveying and measuring large areas of the
earth). Its triangular shape provides, from the foot of the Himalayas
to Cape Comorin, a stretch bf 1700 miles of land over one meridian.
Again the deformation of the geoid (the shape, or as it is called, the
figure of the earth) in India is such that in no other part of the world
has the direction of gravity been found to undergo such abnormal
variations as have been detected by the Survey of India in Northern
India and by the Russian surveyors north of the Pamirs in Ferghana.
According to Burrard, in no other country in the world does a surface
of liqxiid at rest deviate so much from the horizontal. It was in India
that it was discovered that a deficiency of matter underlies the vast
PHYSICAL FEATURES
.
35
-1 Q£ superficial matter, the Himalayas ; that, on the other hand, a
chain of dense matter runs hidden to the south of the Indo-Gangetic
nlains • and that sea-ward deflections of the pendulum, rather than towards the Ghats, prevail round the coasts of Deccan. These discoveries led to the formulation of the theory of mountain comfensation in
about 1854 by the Rev. J. H. Pratt, Archdeacon of Calcutta, a theory
which was subsequently elaborated and expanded into the doctrine of
Isostasy. This simple hypothesis, which has had a great vogue, particularly in America, implies a certain amount of hydrostatic balance
between the different segments of the earth's crust and an adjustment between the surface topographic relief and the arrangement of
density in the sul^crust, so that above each region of less density
there will be a bulge, while over tracts of greater density there will be
a hollow—the former will be the continents, plateaus and mountains,
the latter the ocean-basins. The excess of material over portions of
the earth above the sea-level will thus be compensated for by a defect
of density in the underlying n^terial, the continents and mountains
being floated because they are composed of relatively light material.
Similarly the floor of the ocean will be depressed because it is composed of unusually dense rocky substratum. If an extra load is imposed on any part of the surface, e.g. ice-sheets during a glacial epoch,
it must sink under it, while regions exposed to prolonged denudation
must rise until equilibrium is established. The depth at which
i^ostatic compensation is supposed to be complete is found, in the
United States of America, to be about 76 miles (113'7 km.). In India
it is difficult to arrive at any such definite figure, for isostatic conditions must evidently be different in the Peninsula, a region of high
geological antiquity, from those of the extra-Peninsular mountain
region, which have undergone very recent orographic movements of
the crust. In the former area isostatic balance must be more perfect
than in the Himalayas.
^
Plumb-line and pendulum observations at Dehra Dun have shown
that the " topographic deflection ", i.e. that due to the calculated
visible mass of the Himalayas to the north is 86", but the true observed
deflection is only 31*. For Murree the figures are 45* and 12" respectively ; while for Kaliana, near Meerut, which is only 50 miles
from the foot of the Himalayas, the observed deflection is only 1",
whereas it ought to be 58". These observations prove that the
Himalayas are largely compensated ; though not fully, for the differences bet\geen the observed deflections and the theoretical, even
under the assumption of isostatic compensation, are too great. The
36
GEOLOGY OF INDIA
outer and middle Himalayas are found to be under-compensated,
while the central ranges appear to be over-compensated.
On the Indo-Gangetic plains the deflections are invariajjly to the
south and not towards the Himalayas. This southerly deflection
increases till the Lat. 23° N., to the south of which the plumb-line
deflects to the north. These discrepant data have been explained by
Burrard by assuming that there exists underneath the plains a chain
of dense rock, from Orissa north-westwards through Jubblepore to
Kalat—an assumption which is borne out by gravity measurements
of recent years.
• Although measurements of gravity and deviations of the vertical, as
carried out by the geodetic survey of India during the last two decades,
broadly confirm the main postulates of the theory of isostasy, this theory is
found to be inadequate in explaining the large anomalies of gravity which
exist in India, even when there are no surface features present to account
for them. For the main relief features of India, although a certain degree
of compensation does exist, there are serious anomalies between the
theoretical and observed values of the direction and force of gravity,
which remain to be accounted for. For instance, the gravimetric surveys
have definitely proved belts of excess of density and of defects of density ip
North India which are not represented by any surface deeps or heights.
An alternative hypothesis of sub-crustal warping was propounded^ lately to
account for these anomalies, but the subject is stiU in the stage of discussion.
It appears that India as a whole is an area of defective density. Gravity
in India is in deficit by an amount of material that is measured approximately by a stratum of rock 600 feet in thickness, spread over an area of
two milUon square miles.
DENUDATION
. Monsoonic alternations—Among the physical features of India, a
brief notice of the various denudational processes in operation in ,the
country at the present time must be included, inasmuch as climate
is an important determining factor in the denudation of a region, tiie
peculiar features which the climate of India possesses require consideration. The most unique feature in the meteorology of India is
the monsoonic alternations of wet and dry weather. The division of
the year into a wet half, from May to October, the period of the moist,
vapour-laden winds from the south-west (from the Bay of Bengal and
the Arabian Sea) towards Tibet and the heated tracts to the north,
and the dry half, from November to April, the period of the retreating
1 E. A. Glennie, Gravity Anomalies and the Structure of the Earth's Crust (Dehra Dun,
1932).
PHYSICAL FEATURES
37
, -winds blowing from the north-east, has a preponderating influnce on the character and rate of subaerial denudation of the surface
of the country.'^
Lateritic regolith—The intensity of the influence exercised by this
dominating factor in the atmospheric circulation of the Indian region
•^pill be realised when the extent and thickness of the peculiar surface
formation, latent^, is considered. Laterite is a form of regolith highly ,
peculiar to India, which covers the whole expanse of the Peninsula
from the Ganges valley to Cape Comorin; it is believed by most
authorities to have resulted from the subaerial alteration of its surface
rocks under the alternately dry and humid (i.e. monsoonic) weather
of India. Other characteristic products of weathering of the surface
rocks insitu in the Peninsula are the redsoil of Madras and that capping
the gne^ssic tracts of the Deccan generally, and the Black Soil (regur),^
which covers also large tracts of country in South India. The Reh
efflorescences of the plains of North India and the formation of nitre
in some soils should also be noted in this connection.^
General character of denudation sub-tropical. Desert-erosion in
Rajputana—If this factor is excluded, the general atmospheric
weathering or denudation of India is that characteristic of the
tropical or subtropical zone of the earth. This, however, is a very
general statement of the case. Within the borders of 'India every
variety of climate is met with, from the torrid heat of the vast inland
plains of the Punjab and North-east Baluchistan and upland plateaus
(hke Ladakh) to the Arctic cold of the higher ranges of the Himalayas;
and from the reeking tro^cal forests of the coastal tracts of the
Peninsula to the desertic regions of Sind, Punjab and Rajputana.
Rock disintegration is the predominant process in the one area, rock
decomposition in the other. The student can easily imagine the
intensity of frost-action in the Himalayan highlands and the comparative mildness of the other agents of erosion in that area, such as rapid
alternations of heat and cold, chemical action, etc., and the vigorous
chemical and mechanical erosion of the tropical monsoon-swept parts
of the Peninsula, the denudation of some parts of which partakes of
the character of that prevailing in the equatorial belt of the earth.
In the desert tracts of Rajputana, Sind and Baluchistan, mechanical
disintegration due to the prevalent drought with its great extremes of
heat and cold, the powerful insolation and wind-action, is dominant,
to the exclusion of other agents of change. In this belt the action of
' The subject of soils of India is treated in Chap. XXVI. p. 378.
» Chapter XXVI.
38
GEOLOGY OP INDIA
the powerful summer-winds and dust-storms which blow for about
two months preceding the summer, must result in the transport of
vast quantitites of fine detritus, the prolonged accumulation of which
has been the cause of the widespread loess deposits of N.W. India.
The transporting power of winds in the drier regions of India is
enormous. Thousands of tons of dust and fine sand and silt are
carried by the upper currents of winds for distances of some hundred
miles and dropped where their velocity decreases. Considerable
erosion of the suxface and of the soil-c^ps results in this manner in
some Punjab and .Rajputana tracts. Rajputana affords, a notew.orthy example of the evolution of desert topography within comparatively recent geological times. I t also affords excellent illustrations of the geological action of winds in nlodifying the surfacefeatures of a country. (SeeSand-dunes,£Awr lands, etc.) This'change
has been brought about by the great dryness that has overcome this
region since Pleistocene times, leading to the intensity of aeolian
action on its surface.
Denudation by rivers—The geological work of Indian rivers calls for
a few remarks. Some experiments by Everest prove that the Ganges
conveys annually to the Bay of Bengal, at a conservative estimate,
more than 356,000,000 tons of sand and clay—an average over
900,000 tons of silt a day. There are some rivers of India whose waters
are more silt-laden than those of the Ganges for many days of the year.
The solid matter suspended in the Indus waters and discharged below
Hyderabad, in Sind, is roughly estimated at 1,000,000 tons daily. The
Brahmaputra carries down more silt than the Indus or Ganges. To
the mechanically transported d6bris must be added the invisible
amount of chemically dissolved matter in the waters of the rivers. Exact
measurements of these have not been made, but analyses of average
samples of river-water show that amounts of salts, e.g. the sulphate
and carbonate of calcium, silica and the salts of Na, Mg, Fe, etc., removed from the land to the sea in solution by a river such as the
Narbada or the Jhelum run into several millions of cubic feet per
annum. There are wide fluctuations in the saline contents of river
waters draining different rock terrains, from less than 50 to over 400
parts per million. The salinity of the Mahanadi river rising in the
region of Archaean crystalline rocks, near Cuttack, is found to amount
to 86 parts in a million parts of water.
Peculiarity of river-erosion in India—The Indian rivers accomplish
an incredible amount of erosion during the wet half of the year,
transporting to the sea an enormous load of silt, in swollen muddy
PHYSICAL FEATURES
39
streams. A stream in flood-time accomplishes a hundred times the
work it performs in the normal seasons. If the same amount of rainfall therefore, were evenly distributed throughout the year, the denudation would be far less in amount.
Their floods—The Himalayan streams and rivers are specially noted
for their floods of extraordinary severity in the spring and monsoon
seasons. This arises' from the absence in the Indian rivers of lakes
which exercise a restraining influence on the number, violence and
duration of river-floods. Several of the Indus floods are noted in
history, the most recent and best remembered being those of 1841 and
1858. Drew ^ gives a graphic account of the 1841 flood, when, after
a period of unusual low level of the waters in the winter and spring
of that year, the river, all of a sudden, descended in a black mighty
torrent that in a few minutes tore and swept away everything in its
course, including a whole Sikh army that had encamped on its banks
below Attock with its tents, baggage and artillery. The cause of this
flood is attributed to a landslip in the narrow, gorge-like part of the
river in Gilgit, which blocked up the water and converted the basin
of the river above it into a lake thirty-five miles long and some
hundreds of feet in depth. The sudden bursting of the barrier by the
constantly increasing pressure of the water on it after the spring thaw
is supposed to have caused the inundation.
Many mountain channels are known to have been dammed back
by the precipitation of a whole hillside across them. In 1893, ia
Garhwal,' a tributary of the Ganges, the Alaknanda,, was similarly
blocked by the fall of a hillside, and was converted into a lake at
Gohna. The lake spread in extent and steadily rose in height for
several months, till the waters ultimately surmounted the obstacle
and caused a severe flood by the sudden draining of a large part of the
lake.^ A similar flood is recorded of the Sutlej in 1819. The shoulder
of a mountain gave way in the deep gorge of the river, some twenty
miles north-west of Simla, damming up the river to a height of 400
feet, and producing the usual devastating flood when the obstruction
burst. The formation of a lake, 500 feet deep and 15 to 20 miles
around, in the Shyok river of Baltistan, by the interposition of the
snout of the Chong Kundun glacier across the valley, successively
in the spring of the years 1924, 1927 and 1930 are recent instances.
The bursting of the glacier barrier made the Indus at Attock, situated
700 miles downstream of the Shyok dam, rise in flood at each occasion.
^ Jammu and Kashmir Territories, London, 1875.
2 ^ec. G.8.I. vol. xxvii. pt. 2, 1894.
40
GEOLOGY OF INDIA
The increased volume of water, combined with the high velocity of
the rivers in flood-time, multiplies their erosive and transporting
power to an inconceivable extent, aind boulders and blocks, several
feet in diameter, are rolled along their bed, and carried in this manner
to distances of fifty or even a hundred miles from their source, causing
much injury to the banks and wear and tear to the beds of the
channels.
Late Changes in the Drainage Systems of North Indja
Many and great have been the changes in the chief drainage lines
of North India since late Tertiary times ^—changes in fact Which have
produced a complete reversal of the directions of ,flow of the chief
rivers of North India. The formation of the long thin belt of Siwalik
deposits along the foot of the Himalayas from Assam, through
Kumaon and the Punjab to Sind, widening steadily in its westward
extension, is now ascribed to the flood-plain deposits of a great
north-west-flowing river lying south of and parallel with the Himalayan chain fi;om Assam to the furthest north-west corner of the
Punjab, and then flowing southwards to meet the gradually receding
Miocene sea of Sind and Punjab. This river has been named the
" Siwalik River " by Pilgrim and the " Indobrahm " by Pascoe, from
the combined discharge of the Brahmaputra, Ganges and Indus
which it carried at one time. This old river is believed to be the
successor of the narrow strip of the sea—the remnant of the Himalayan sea left after the main uplift of those mountains—as the latter
gradually withdrew, through the encroachment of the delta of the
replacing river, from Naini Tal, Solon, Muzaffarabad and Attock to
Sind. The Nummulitic limestone deposits of these localities testify
to the extent and boundary of the Eocene gulf. The final extinction
• of this gulf, which once stretched from Assam to Sind, left behind it a
wide river-basin in which were laid down the thick series of Murree
and Siwalik deposits during the interval between the Middle
Miocene and the end of Pliocene. Post-Siwalik earth-movements in
N.W. Punjab brought about a dismemberment of this river-system,
which hitherto had flowed from the head-waters in Assam, through
the whole breadth of India, to Potwar and thence to the receding
head of the Sind Gulf, into three subsidiary systems : (1) The present
Indus from north-west Hazara ; (2) the five Punjab tributary rivers
1 E. H. Pascoe, The Indobrahm, Quart. Joum. Geol. Soc., vol. Ixxv. pp. 138-155
(1919); 6 . E. Pilgrim, The Siwalik River, Jcurn. Asiat. Soc. Beng., vol.xv. (New
Series), pp. 81-99 (1919).
PHYSICAL FEATURES
41
of the Indus ; (3) the rivers belonging to the Ganges system which
finally took a south-easterly course.
The elevation of Potwar into a plateau converted the north-west
section of the main river into a separate independent drainage
basin, with the Sutlej as its most easterly tributary. Hitherto the
main river had travelled to its confluence with the Indus along a
track which was a north-western prolongation of the present course
of the Jumna, thence via the present bed of the Soan to the Indus.
After these elevatory movMnents and separation of the north-west
section, the remaining upj^r portion of the main channel was subjected to a process of reversal of flow, its water being forced back by
the Punjab elevations|;o seek an outlet into the Bay of Bengal along
the now aggraded, more or less levelled sub-montane plains. In this
reversal of the old drainage Pascoe assigns the chief share to process
of river-capture by head-erosion of the tributaries. The competence
of the agency of river-capture alone in accomplishing this farreaching change is debatable and differential earth-movement as the
chief contributory cause is suggested, aided by the recently levelled
and uniformly graded drainage-Hnes on the surface of these wide
plains.
The severed upper part of the Siwalik Eiver became the modern
Ganges, it having in course of time captured the transversely running
Jumna and converted it into its own affluent. The transverse Him' alayan rivers, e.g. the Alaknanda, Karnali, Gandak and Kosi, which
are really among the oldest water-courses of North India, continued
to discharge their waters into this new river, irrespective of its ultimate destination, whether it was the Arabian Sea or the Bay of
Bengal. During sub-Recent times some interchange took place between the easterly afiiuents of the Indus and the westerly tributaries
of the Jumna by minor shiftings of the water-shed, now to one side
now to the other. There are both physical and historical grounds for
the belief that the Jumna during early historic times discharged into
the Indus system, through the now neglected bed of the Saraswati
river of Hindu traditions, its present course to Prayag being of late
acquisition.
The Punjab portion of the present Jhelum, Chenab, Ravi, Beas and
Sutlej have originated after the uplift of the topmost stage of the
Siwalik system and subsequent to the severance of the Indus from
the Ganges. The Potwar plateau-building movements could not but
have rejuvenated the small rivulets of southern Punjab, which until
now were discharging into the lower Indus, the vigorous head-erosion
42
GEOLOGY OF INDIA
resulting from this impetus enabled them to capture, one bit after
the other, that portion of the Siwalik River which crossed the Potwar
on its westerly course to the Indus. Ultimately the head-waters
joining up with the youthful torrents descending from the mountains,
these rivers grew much in volume and fornied these five important
rivers of the province, having their sources in the snows of the Great
Himalaya Range and deriving their waters from as far east as the
Manasarowar lake on the Kailas Range. The western portion of the
broad but now deserted channel of the main river, after these mutilating operations, has been occupied to-day by the puny, insignificant
stream of the Soan, a river out of all harmony»with its great basin and
the enormous extent of the fluviatile deposits with which it is choked.
The Himalayas are undergoing a very active phase of subaerial
erosion, being a zone of recent folding and fracture, their disintegration is proceeding at a more rapid rate than is the case with older
earth-features of greater geological stability. The plains of India and
the Ganges delta are a. fair measure of the amount of matter worn
down from a section of the Himalayas since the Pliocene period.
Landslips, soil-creep, breaking off of enormous blocks from the
mountain-tops are phenomena familiar to visitors to these mountains. The denudation in the dense forests of the hill-slopes in the
Eastern Himalayas recalls that of the tropical lands in its intensity
and character.
REFERENCES
H. B. Medlioott and W. T. Blanford, Manual of the Geology of India, vol. i., 1887,
Introduction.
Sir S. Burrard and Dr. A.M. Heron, The Geography and Geology of the Himalaya
Mountains, Second Edition, 1932.
Records of the Geological Survey of India, vol. xxxv. pts. 3 and 4 ; vol. xl. pt. 1 ;
vol. xliv. pt. 4 ; vol. Ixiii. pt. 2, 1930, Glaciers of the Himalayas.
Physical Atlas of Asia, W. & A. K. Johnston.
j
The Bathy-Orographical Map of India, W. & A. K. Johnston.
W. H. Hobbs, Earth-Features and their Meaning, 1912 (Macmillan).
Mt. Everest Expeditions : Publications by. 1921-33.
Sven Hedin, Southern Tibet, vols, i-ix., Stockholm, 1917.
Dainelli, Italian Expedition to the Himalaya and Karakoram (1913-14), vols. i,-xiii.,
Bologna, 1923-35.
R. D. Oldham, The Evolution of Indian Geography, Geographical Jourmil,
London, March, 1894.
. CHAPTEE II
STRATIGRAPHY OP INDIA-^rNTRODUCTORY
Correlation of Indian formations to those of the world—An outstanding
difficulty in the study of the geology of India is the difficulty of
correlating accurately the various Indian systems and series of rocks
with the dilferent divisions of the European stratigraphical scale
which is accepted as the standard for the world. The difficulty becomes much greater when there is a total absence of any kind of fossil
evidence, as in the enormous rock-systems of the Peninsula or in the
outer zone of ^ e Himalayas, in which case the determination of the
geological horizon is lefi?f1^the more or less arbitrary and unreliable
tests of lithological "composition, structure, and the degree of metamorphism acquired by the rocks. These tests are admittedly unsatisfactory, but they are the only ones available for fixing the
homology of the vast pre-Cambrian formations of the Peninsula,
which form such an important feature of the pre-Palaeozoic geology
of India.
The basis of stratigraphy is the determination of the natural order
of superposition of strata; until the exact original succession of
deposits in a stratified series is ascertained no correlation of strata at
different localities is possible. It is the function of stratigraphy to
discover and arrange the sedimentary deposits of the earth's crust •
in the order of their age, so that each originally older bed is lower in
jjosition than the next newer one. Apart from the complications
introduced by folding and faulting, which makes the application of
the principle of superposition difficult, there is the difficulty arising
from frequent lateral variations of sedimentary strata. A sandstone
or limestone lying between two shale beds may thicken or thin out
until the whole series become a group of sandstones or limestones or
shales.
The discovery of WiUiam Smith, at the end of the eighteenth
century, that groups of strata are characterised by the preservation in them of particular fossil organisms, and can be identified
by them, laid the foundation of historical geology. In establishing
43
44
GEOLOGY OF INDIA
correlations of formations in distant areas the following criteria
are employed:
I
(1)
(2)
(3)
(4)
(5)
(6)
(7)
The order of superposition.
Fossil organisms. '
Lithological characters.
Stratigraphicai continuity.
Unconformities.
Degree of metamorphism.
Tectonic and structural disturbance.
There is no question, of course, of establishing any absolute contemporaneity between the rock-systems of India and those of
Europe, because neithei lithological correspondence nor even identity
of fossils is proof of the synchronous origin of two rock-areas so far
apart. Biological facts prove that the evolution of life has not progressed uniformly or in a simple straightforward direc^on all over the
globe in the past, but that in different geographical provinces the
succession of life-forms has been marked by widely varying rates of
evolution due to physical differences existing between them, and thai?
the process of distribution of sj)ecies from the centre of their origin is
very slow and variable. The idea, therefore, of contemporaneity is
not to be entertained in geological deposits of two distant areas, even
when there is a perfect similarity in their fossil contents.
What is essential is that the rock-records of India, discovered in the
various parts of the country, should be arranged in the ordgr of their
superposition, i.e. in a chronological sequence. They should be
classified with the help of local breaks in their sequence, or by the
evidence of their organic remains, and named according to some local
terminology. The different outcrops should then be correlated among
themselves. The last and the most important fitep is to correlate
these, on the evidence of their contained fossils, or failing that, on
lithological grounds, to some equivalent division or divisions of the
standard scale of stratigraphy worked out from the fossiliferous
rock-records of the world.
In illustration of the above it may be remarked that the Carboniferous system of Europe is characterised by the presence of certain
types of fossils and by the absence of others. If in any part of India
a series of strata are found, containing a suite of organisms in which
many of the genera and 'a few of the species can be recognised as
identical with the above, then the series of strata thus marked off is
STRATIGRAPHY OF INDIA
45
correlated with the Carboniferous system of Europe, though on
account of local peculiarities and variations, the system is often designated by a local name. It is not of much significance whether they
were or were not deposited simultaneously, so long as they point to
the same epoch in the history of life upon the globe ; and since the
history of the development of life upon the earth, in other words, the
order of appearance of the successive life-forms, has been proved to
be broadly uniform in all parts of the earth, there is some unity between these two rock-groups. As a substitute for geological synchronism Prof. Huxley introduced the term Homotaxis, meaning
"Similarity of arrangement", and implying a corresponding position
in the geological series. The fauna and flora of the Jurassic system of
Europe are considered homotaxial with those* of some series of deposits in different parts of India, though it is quite probable that in
actual age any of these may have been contemporaneous with the end
of the Triassic deposits in one part of the world or perhaps with the
beginning of the Cretaceous in another.
The different "_facies " of Indian formations—It often happens that
one and the same geological formation in the different districts is
composed of different types of deposits, e.g. in one district it is composed wholly of massive limestones, and in another of clays and sandstones. These divergent types of deposits are spoken of as belonging
to different/act'es, e.g. a calcareous facies, argillaceous facies, arenaceous facies, etc. There may also be different facies of fauna, just
as much as facies of rock-deposits, and the facies is then distinguished
after the chief element or character of its fauna, e.g. coralhne facies,
littoral facies, etc. Such is often the case with the rock-formations of
India. Erom the vastness of its area and the prevalence of different
physical conditions at the various centres of sedimentation, rocks of
the same system or age are represented by two or more widely different facies, one coastal; another deep-water, a third terrestrial, and
sometimes even a fourth, volcanic. The most conspicuous example of
this is the Gondwana system of the Peninsula and its homotaxial
equivalents. The former is an immense system of fresh-water and
subaerially deposited rocks, ranging in age from Upper Carboniferous
tb Upper Jurassic, whose fossils are ferns and conifers, fishes and
reptiles. Rocks of the same age, in the Himalayas, are marine limestones and calcareous shales of great thickness, and containing deepsea organisms like Lamellihranchs, Pephalopods, Crinoids, etc., from
the testimony of which they are grouped into 'Upper Carboniferous,
Permian, Triassic and Jurassic systems. In the Salt-Range these
46
GEOLOGY OF INDIA
same systems often exhibit a coastal facies of deposits like clays and
sandstones, with littoral organisms, .alternating with limestones.
In this connection it must be clearly recognised how these deposits,
which are homota'xial, and more or |ess the time-equivalents of one
another, should come to differ in their fossil contents. The reason is
obvious. For not only are marine organisms widely different from
land animals and plants, but the littoral species that inhabit the sandy
or muddy bottoms of the coasts are different from those pelagic and
abysmal organisms that find a congenial habitat in the clearer waters
of the sea and at great distances from land. Again, the animal life of
the seas of the past ages was not uniform, but it was distributed
according to much the same laws as those that govern the distribution
of the marine biological provinces of to-day. The fossils entombed in
some formations are of markedly local or provincial affinities. Pr,ovincialisation of faunas arises from various causes—the dependence of
organisms on their environments, their isolation, or from relative
preponderance or absence of competing species, or from physical
barriers to migration of species. Pelagic, or free-swimming members'
of a fauna attain a wider horizontal or geographical distribution tham
bottom-living forms. It thus arises that the fossils present in a series
of deposits are not a function of the period only when the deposits
were laid down, but, as Lyell says, are a "function of three variables ",
viz. (1) the geological period at which the rocks were formed, (2) the
zoological or botanical provinces in which the locality was situated,
and (3) the physical conditions prevalent at the time, e.g. depth,
saHnity and muddiness of water, temperature, character of the seabottom, etc.
A new aid to stratigraphy that is slowly coming into vogue may be
just mentioned. The epochal discovery that minerals containing
uranium and thorium break up into other elements through atontic
\ disintegration, producing as a final residuum lead, the change taking
place at a definite and measurable rate, has placed in the hands of the
geologist a new weapon for the determination of the age of the great
azoic pre-Cambrian systems. For India the investigation of leadratio and helium-ratio in some radio-active minerals occurring in the
widely spread Archaean and Purana rock-systems may provide,
when these methods are perfected, a guide to their correlation in.
distant areas, as well as a measure of their absolute ages, facts which,
are at present but vaguely knowable.
The chief geological provinces of India—The following are the important localities in the country, besides some areas of the Peninsula^
STRATIGRAPHY OF INDIA
47
wherein the marine fossiliferous facias of the Indian formations are
more or less typically developed :
1. The Salt-Range.
[This range of mountains is a widely explored region of India. I t was
one of the earliest parts of India to attract the notice of the geologists, both
on account of its easily accessible position as well as for the conspicuous
manner in which most of the geological systems are displayed in its precipices and defiles. Over and above its stratigraphic and palaeontological
results, the Salt-Eange illustrates a number of phenomena of dynamical
and tectonic geology.]
2. The Himalayas.
[As mentioned in the first chapter, a broad zone of sedimentary strata
lies to the north of the Himalayas, behind its central axis, occupying a
large part of Tibet. This is known as the Tibetan zone of the Himalayas.
This zone of marine sediments contains one of the most perfect developments of the geological record seen in the world, comprising in it all the
periods of earth-history from the Cambrian to the Eocene. I t is almost
certain that this belt of sediments extends the whole length of the Himalayan chain, from Hazara and Kashmir to the furthest eastern extremity ;
but so far only two portions of it have been surveyed in some detail, the one
the north-west portion—the Kashmir Himalayas—and the other the
mountains of the central Himalayas north-east of the Simla region,
especially the Spiti valley, and the northern parts of Kumaon and Garhwal.]
(i) North-West Himalayas.
[This area includes Hazara, Kashmir, the Pir Panjal, and the ranges of
the outer Himalayas. A very complete sequence of marine Palaeozoic
and Mesozoic rocks is met with in the inner zone of the mountains, while a
complete sequence of Tertiary development is seen in the outer,' Jammu
hills. The Kashmir'basin, lying between the Zanskar and the Panjal ranges,
contains the most fully developed Palaeozoic system seen in any part of
India. For this reason, and because of the easily accessible nature of the
formations to parties of students, in a country which chmatically forms one
of the best parts of India, the geology of Kashmir is treated in a separate
chapter at the end of the book.]
(ii) Central Himalayas.
'
[Many eminent explorers have unravelled the geology of these mountains since the early 'thirties of the last century, and parts of this region,
hke Spiti, form the classic ground of Indian geology.
The central Himalayas include the Simla hills, Spiti, Kumaon and Garhwal provinces: The great plateau of Tibet ends in the northern parts of
these areas in a series of gigantic south-facing escarpments, wherein the
stratigraphy of the northern or Tibetan zone of the Himalayas, referred to
above, is typically displayed. The Spiti basin is the best known for its
fossil wealth as well as for the completeness of the stratigraphic succession
48
GEOLOGY OF INDIA
from tlie Cambrian to Cretaceous. The systems of Kashmir are on a northwest continuation of the strika of the Spifi basin. Much detailed work has
been done of late years in the Simla-ChaMrata area.]
3. Sind.
[Sind possesses a highly fossiliferous marine Cretaceous and Tertiary
record. The hills of the Sind-Baluchistan frontier contain the bestdeveloped Tertiary sequence, which is recognised as a type for the rest of
India.]
4. Eajputana.
'
[Besides the development of a very full sedimentary record, divided into
three pre-Palaeozoic systems of Arohaean-Dharwar age and an interesting
facies of the Yindhyan system in the Aravalli range, Western Rajputana
contains a few isolated outcrops of marine Mesozoic and early Tertiary
strata underneath the Pleistocene desert sand, which has concealed by far
the greater part of its solid geology.]
5. Burma and Baluchistan.
[These two countries, at either extremity of the extra-Peninsular area,
contain a large section of the stratified marine geological record which
helps to fill up the gaps in the Indian sequence. Many of these formations
are again highly fossiliferous, and afiord good ground for comparison with
their Indian congeners. Within the geographical term " India " is now included all these regions which are regarded as its natural physical extension
on its two borders—Afghanistan and Baluchistan on the west and Burma
on the east. The student of Indian, geology is therefore expected to know
of the principal rock-formations of Baluchistan and Burma.]
6. Coastal System of India.
[Along the eastern coast of the Peninsula and to a less extent on the
Mekran coast, there is a strip of marine sediments of Mesozoic, Tertiary or
Quaternary ages, in more or less connected patches—the records of several
successive " marine transgressions " on the coasts.]
Peninsular India, as must be clear from what we have seeii regarding its physical history in the first chapter, is a p a r t of India which
contains a most imperfectly developed geological record.
The
Palaeozoic group is unrepresented b u t for the fluviatile Permian for^
m a t i o n s ; the Mesozoic era has a fairly full record, b u t except as
regards the Cretaceous it is preponderatingly made u p of fluviatile,
terrestrial and volcanic accumulations ; while the Tertiary is almost
unrepresented except by. the partly Eocene lavas forming the Deccan
Traps.
The student of Indian geology .should first familiarise himself with
the representatives of the various geological systems t h a t are found
in these provinces of India correlated t o the principal divisions of t h e
E u r o p e a n sequence.
STRATIGRAPHY OF INDIA
49
The idea of a geological system is not confined to a summary of
facts regarding its rocks and fossils. These are the dry bones of the
science ; they must be clothed with flesh and blood, by comparing the
processes and actions which prevailed when they were formed with
those which are taking place before our eyes in the world of to-day.
A sand-grain or a pebble of the rocks is not a mere particle of inanimate matter, but is a word or a phrase in the history of the earth, and
has much to tell of a long chain of natural operations which were concerned in its formation. Similarly, a fossil shell is not a mere chance
relic of an animal that once lived, but a valuable document whose preservation is to be reckoned an important event in the history of the
earth. That mollusc to which the shell belonged was the heir to a long
line of ancestors and itself was the progenitor of a long line of descendants. Its fossil shell marks a definite stage in the evolution of life on
earth that was reached at the time of its existence, which definite
period of time it has helped to register. Often it tells much more than
this, of the geography and climate of the epoch, of its contemporaries
and its rival species. In this way, by a judicious use of the imagination; is the bare skeleton given a form and clothed; the geological
records then cease to be an unintelligent mass of facts, a burden to
memory, and become a living story of the various stages of the earth's
evolution.
In reading stratigraphical geology the student should remind himself to take note of the illustrations of the principles of dynamical and
tectonic geology, of which every page of historical geology is full.
Many of the facts of dynamical and structural geology find a pertinent
illustration by the part they play in the structure or history of a particular country or district. The problems of crust-deformations, of
vulcanicity, of the variations, migrations and extinctions of life-forms
with the passage of time, and a host of other minor questions that are
inscribed in the pages of the rock-register, must be thought over and
interpreted with the clue that modern agencies in the earth's dynamics
furnish.
REFERENCES
Sir T. H. Holland, Imperial Gazetteer of India, vol. i. chapter ii., 1907.
Marr, Principles of Stratigraphic Geology (C.U. Press).
Holland and Tipper, Mem. G.S.I, vol. xliii. pt. 1, Indian Geological Terminology,
1913 and (Second Edition) vol. 11. pt. 1, 1926.
A. W. Grabau, Principles of Stratigraphy (Seller), 1924.
W. H. Twenhofel, Treatise on Sedimentation (Williams & WiUdns), 1926.
w.a.i.
50
GEOLOGY OP INDIA
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CHAPTER III
THE ARCHAEAISI SYSTEM
General—The oldest rocks of the earth's crust that have been found at
the bottom of the stratified deposits, in all countries of the world,
exhibit similar characters regarding their structure as well as their
composition. They form the core of all the great mountain-chains of
the world and the foundations of all its-.great ancient plateaus. They
are all azoic, thoroughly crystalline, extremely contorted and faulted,^
are largely intruded by plutonic intrusions, and generally have a welldefined foliated structure. These conditions have imparted to the
Archaean rocks such an extreme complexity of characters and relations that the system is often known by the names of the " Fundamental Complex ", the " Basement Complex ", etc. (Fig. 3.)
The way in which the Archaean crystalline rocks have originated is
not well understood yet, and various modes of formation have been
ascribed to these rocks : (1) Some are believed to represent, in part at
least, the first-formed crust of the earth by the consolidation of the
gaseous or molten planet. (2) Some are believed to be the earliest
sediments formed under conditions of the atmosphere and of the
oceans in many respects different from those existing at later dates,
and which have undergone an extreme degree of thermal and regional
metamorphism. (3) Some are thought to be the result of the bodily
deformation or metamorphism of large plutonic igneous masses under
great earth-movements or stresses. (4) Some are believed to be the
result of the consolidation of an original heterogeneous magma
erupted successively in the crust (cf. the banded granites and
gabbros).
Distribution—The crystalline and gneissic rocks of the Archaean
system form an enormous extent of the surface of India. By far the
largest part of the Peninsula, the central and southern, is occupied
by this ancient crystalline complex. To the north-east they occupy
wide areas in Orissa, Central Provinces and Chota Nagpur. Towards
the north the same rocks are exposed in an extensive outcrop covering
66
66
GEOLOGY OF INDIA
the whole of Bundelkhand ; wHile to the north-west they are found in
a number of isolated outcrops, extending from north of Baroda to a
long distance in the Aravallis and Eajputana.
O
In the extra-Peninsula, gneisses and crystalline rocks are again
exposed along the whole length of the Himalayas, building all their
highest ranges and forming the very backbone of the mountainsystem. This Crystalline axis runs as a broad central zone from the
(about i/jg natural size)
EmarjWklkcr
IM.M.
FiQ. 3.—Diagram showing contortion in the Archaean gneiss of Bangalore.
westernmost Kashmir ranges to the eastern extremity in Burma. The
eastern part of the Himalayas, from Nepal eastwards, has not been
explored, with the exception of Sikkim, but it is certain that the
crystalline zone is quite continuous. It is a matter of great uncertainty, however, what part of the great gneissic complex of the
Himalayas (designated as the " Central " or " Fundamental " gneiss)
represents the Archaean system, bec^ause much of it is now ascertained
THE ARCHAEAN SYSTEM
57
to be highly metamorphosed granites or other intrusives of late
Mesozoic or even Tertiary ages.
it( fairly broad crystalline zone, similar to the gneisses of the
Peninsula, runs along Burma from north to south, constituting the
so-called Martaban system ^ of the southern or Tenasserim division,
and the Mogoh gneiss of North Burma.
Petrology of the Archaean system—Over all these areas of many
hundred thousand square miles, the most common Archaean rock is
gneiss—a rock which in mineral composition may vary from granite
to gabbro, but which possesses a constant, more or less fohated or
banded structure, designated as gneissic. This characteristic banded
or streaky character may be either due to an alternation of bands or
layers of the different constituent minerals of the rock, or to the
association of layers of rocks of varying mineral compositioil. At
many places the gneiss appears to be a mere intrusive granite, exhibiting clearly intrusive relations to its neighbours. The gneiss,
again, frequently shows great lack of uniformity either of composition
or of structure, and varies from place to place. At times it is very
finely fohated, with folia of exceeding thinness alternating with one
another ; at other times there is hardly any foliation or schistosity at
all, the'^^ock looking perfectly granitoid in appearance. The texture
also varies between wide limits, from a coarse holocrystalhne rock,
with individual phenocrysts as large as one or two inches, to almost a
felsite with a texture so fine that the rock appears quite homogeneous to the eye.
The constituent minerals of the commoner types of the Archaean
gneiss are : orthoclase, ohgoclase or microcline, quartz, muscovite,
biotite, and hornblende with a variable amount of accessory minerals
and some secondary or alteration products, like tourmaline, apatite,
magnetite, zircon, chlorite, epidote and kaolin. Orthoclase is the
most abundant constituent, and gives the characteristic pink or white
colour to the rock. Plagioclase is subordinate in amount; quartz
also is present in variable quantities ; hornblende and biotite are the
most usual ferro-magnesian constituents, and give rise to the horn- blende and biotite-gneisses, which are the most prevalent rocks of the
central ranges over wide tracts of the Himalayas. Tourmahne is an
essential constituent of some gneisses of the Himalayas. Chlorite
occurs as a secondary product, replacing either hornblende or biotite.
Less frequent minerals, and occurring either in the main mass or in
* Recent work shows that the Martaban gneisses &re probably largely Mesozoio
. granites.
58
GEOLOGY OF INDIA
the pegmatite veins that cross them, are apatite, epidote, garnets,
cordierite, scapolite, wollastonite, beryl, tremolite, actinolite, jadeite,
corundum, siUimanite, kyanite, together with spinels, ilmenite, rutile,
graphite, iron ore, etc. Besides the composition of the gneiss being
very variable over wide areas, almost all gradations are to be seen,
from thoroughly acid to intermediate and basic composition (granitegneiss, syenite-gneiss, diorite-gneiss, gabbro-gneiss).
By the disappearance of the felspars the gneisses pass into schists,
which are the next abundant componen ts of the Archaean system of
India. The schists are for the most part thoroughly crystalline,
mica-, hornblende-, talc-, chlorite-, epidote-, sillimanite- and graphiteschists. Mica-schists are the most common, and are often garnetiferous. Less common rocks of the Archaean of India, and occurring
separately or as interbedded lenses or bands in the main complex, >are
granulites, crystalline limestones (marbles), ^ dolomites, graphite,
iron-ores, and some other mineral masses. The gneisses and schists
are further traversed by an extensive system of basic trap-dykes of
dioritic or doleritic composition.
But the Archaean group of .India, as.of the other countries of the
world, is far more complex in its constitution than is expressed by the
above few simple statements. In it, though several concrete" petrological elements have been recognised, yet their relations are so very
intimate that separation of these is very difficult or impossible.
Among these gneisses and schists those which, by reason of their
chemical and mineralogical composition, are believed to be the highly
deformed and metamorphosed equivalents of plutonic igneous masses*
of later ages, are known as ortho-gneisses or ortho-schists, while others
that suggest the characters of highly altered sediments deposited in
the ancient seas are known as para-gneisses or para-schists ; a third
kind again is also distinguished, which, according to some authors,
may be the original first-formed crust of the earth. It thus appears
that the Indian Archaean representatives do not belong to any oive
petrological system, but are a " complex " of several factors : (1) an
ancient fundamental basement complex into which, (2) a series of
plutonic rocks are intruded, like the Charnockites and some varieties
of Bundelkhand gneisses, while there is (3) a factor representing highly
metamorphosed schistose sediments, the para-gneisses and schists,
which probably are mainly of Dharwar age, and are generally younger
than the (1) gneisses.
Petrological types—Associated with the Archaean gneisses and
schists there are some interesting petrological types discovered during
\
THE ARCHAEAN SYSTEM
59
fclie progress of the Indian Geological Survey, which the student should
Jaiow. Some of these are described below :
Of North Arcot, Madras, Eajputana, etc.
Granite.
Augite-granite.
Of Salem.
Augite-syenite
(Laurvikite).
Nepheline-syenite.
Of Coimbatore, Vizagapatam, Kishengarh (RajElaeoUte-syenites and
putana) and Junagadh (Kathiawar). These are
their pegmatites.^
a group of intermediate plutonic rooks foliated
among the gneisses. Among their normal essential minerals are calcite and graphite in a quite
fresh state. The pegmatites of the elaeolitesyenite of Kishengarh ^ contain large crystals of
beautiful blue sodalite with sphene, garnet, etc.,
as accessories.
Blaeolite-syenite.
Of the Coimbatore district, constitute the so-called
Augite-syenite.
Sivamalai series of Holland. These are geneticCorundum-syenite.
ally related rocks, all derived from a common
highly aluminous magma.
1. Charnockite.
Of Madras and Bengal are acid intermediate, basic
2. Augite-norite.
and ultra-basic members respectively of a
3. Norite.
highly differentiated series of holo-crystalline,
4. Hyperite.
granitoid, hypersthene-bearing rocks of the
Peninsula distinguished by Holland and named
• 5. Olivine-norite.
by him Charnockite series from Charnock, the
6. Eyroxenite.
founder of Calcutta. (See Charnockite series
7. Aiorthosite,
below.)
8. GranuUte.
9. Garnetiferousleptynite.
10. Pyroxene-diorite.
11. Scapolite-diorite.
Named after the Khonds of Orissa, occurs in
KhondaHte
Orissa, Central Provinces, etc. : are light(Quartz -t-sillimanite
+garnet -I- graphite). coloured richly garnetiferous gneisses and schists
characterised by the abundance of the mineral
sillimanite and the presence of graphite. They
are regarded as para-gneisses and schists.^
Named from the Gonds of the Central Provinces
. Gondite
(Quartz -I-manganese- by Dr. L. Fermor. These are a series of "rnetamorphosed rooks belonging to the Archaean and
garnet + rhodonite).
Dharwar systems and largely composed of
. Rhodonite rock.
quartz, spessartite, rhodonite and other manganese-silicates. These rooks are supposed to be
the product of the dynamic metamorphism of
* For the soda-bearing syenite suite of N.E. end of the Aravallis, see Heron, liei.
G.S.I. vol. Ixvi. pt. 2, 1924.
' Mem. G.S.I. vol. xxxiii. pt. 3, 1902.
60
GEOLOGY OF INDIA
manganiferous clays and sands deposited during
Dliarwar times. On the chemical alteration of
the manganesp-silicates so produced, these rocks
have yielded the abundant manganese-ores of
the Dharwar system.
Kodurite
From Kodur in Vizagapatam district. These are a
(Orttoclase
group of plutonic rocks, associated "with .the
\ + manganese-garnet
Khondalite series and possibly of hybrid origin.
+ apatite).
The normal type, or Kodurite proper has the
composition noted above, and is a basic plutonic
rock classified with Shonkinites, but there are
acid as well as ultra-basic varieties of the series
like the spandite-rpclc, manganese-pyroxenite,
containing
manganese-garnet,
-amphibole,
-pyroxene, -sphene, etc., at one end, and quartzorthoclase rock and quartz-kodurite at the
other. These rocks also have yielded manganese-ores of economic value by chemical"
alteration.
Calc-gneiss,
The first two of these are highly calcareous rocks
calciphyres and
which are found, associated with the Archaean
crystalline limestones.
rocks of the Central Provinces and some other
localities in India. They are a series of granuUte- *
like rocks with an unusually high preponderance
of lime-silicates, diopside, hornblende, labradorite, epidote, garnet, sphene, and similar
alumino-calcareous silicates.. From such a composition, they are believed to be para-gneisses,
i.e. formed by the metamorphism of a pre-existing calcareous and argillaceous series of sediments.
The oxidation by meteoric agencies of these
series has given rise to the crystalline limestones,
the third class of rocks mentioned in the heading. These are very intimately associated with
the two former rocks in th,e Central Provinces
and in Burma. The abundant lime and magnesian silicates of these gneisses have been
altered by percolating waters, carrying dissolved COj, into calcite and magnesite. Besides
the crystalline limestones and dolomites of the
Central Provinces, the famous ruby-limestone
associated with the Mogok gneiss of Burma is
another example. The origin of these limestones
was a puzzle because they could not be explained
on the supposition of their being of either sedimentary, organic or chemical deposition.'1 Fermor, Sec. G.S.I, vol. xxxui. pt. 3, 1906,
THE ARCHAEAN SYSTEM
Quartz-haematite
schist. (Jaspilit«.)
Quartz-magnetite
schist.
61
Composed of quartz and haematite or quartz
and magnetite. These are of very common prevalence in many parts of South India, especially
among the Dharwar schists. The iron-ore and
jasper or quartz are generally in very intimate
association arranged in thin layers or folia.
Of Madras, Bastar, etc., is a contact-metamorCordierite-gneiss.
phosed, basic aluminous sediment with high
magnesia content. In the more metamorphosed
types anthophyllite, sillimanite and garnet are
frequently developed. Acid plagioclase and
quartz, als'^^biotite, are often present in these
gneisses.
Andalusite (sillimanite, Of Madras and Central Provinces, represent highly
kyanite, chiastolite)
aluminous sediments, contact-metamorphosed
schist.
by granitic intrusions.
" Streaky gneisses."
So called on account of the arrangement of the
leucocratic and melanocratic components of the
rock in parallel streaks and bands. I t is a
composite rock and the origin of the structure is
due in many cases to the lit-far-lit injection of
an acid aplitic material along the foliationplanes of a schistose melanocratic co\mtry-rock.
Felspathic gneiss.
Generally composed of an acid plagioclase, subordinate microcline, small flakes of biotite and
muscovite, and quartz. Often a para-gneiss, it
represents a thoroughly recrystallised aluminous
sediment, the metamorphism being due to
,. granitic intrusions.
Pegmatites.
These coarse-grained differentiates of igneous
rocks, especially acidic ones, are widely distributed in the Archaean complex of India. They
occur chiefly as veins and dykes intersecting the
older rocks, and sometimes as segregationpatches in the body of the rock, of which it is a
differentiate. The acid granite-pegmatites sometimes attain large dimensions and in Nellore,
Hazaribagh, Gaya and Ajmer-Merwara have
been found to contain many rare-earth minerals
and mica deposits of economic importance.
Peiidotite
These ultra-basic rocks, though not widely spread,
(Olivine + femic
are of importance because of their association
minerals).
with minerals of economic uses. They are the
Dunite (Essentially
source of chromite in India and of serpentine and
olivine).
magnesite. The chromite occurs as bed-hke
Saxonite
veins and scattered grains in these rocks.
Among the well-known occurrences are those
(Olivine + rhombic
of Salem, some districts in Mysore, Singhbhum,
pyroxenes).
Hindu Bagh in Baluchistan and Dras in Kashmir.
62
Amphibolites.
Quartaite.
Phyllites.
GEOLOGY OF INDIA
Of widespread distribution in the Peninsula and
extra-Peninsula ; these rocks consist essentially
of tremolite, actinolite, or some other amphibole,
with varying amount of plagioclase. Quartz,
epidote and garnet are often present. They are
products of the metamorphism of basic igneous
masses, tu6s, or sediments.
Common in Archaean and Dharwar and the
older Purana systems, is a granulose, recrystallised metamorphic rock, composed essentially of
quartz with or without sericite, rutile, or other
accessory constituents. I t may be derived from
original silicious sediments or from quartz-reefs,
and vein-quartz. In the absence of stratification planes, ripple marks and other sedimentary
characters, it is difficult to distinguish sedimentary from igneous quartzites.
• Very wide-spread in the Archaean and Dharwar
systems. Often markedly graphitic and interbedded with crystaUine limestones. The Himalayan Dharwars are especially characterised by
the p r e v a l e n c e s ^ graphitic phyllite and schist
(Salkhala and Jutogh series). Passing into mica-, »
chlorite-, talc-, schist by further metamorphism.
Groups—The gneissic Arcliaean rocks of India are generally described under t h e following three areal groups, each of which in its
respective area has some well-defined types :
1. Bengal gneiss—Highly foliated, heterogeneous, schistose gneisses
and schists, of Bengal, Bihar, Orissa, Carnatic and large tracts
of the Peninsula.
2. Bundelkhand gneiss—Massive,
granitoid gneisses of Bundelk h a n d and some p a r t s of t h e Peninsula. This gneiss is regarded as intrusive into t h e former.
3. (Jharnocldte series—Nilgiri
gneiss—Massive,
eruptive, d a r 6 coloured hypersthene-granitoid gneisses of South India.
(1) BENGAL GNEISS is very finely foliated, of heterogeneous composition, the different schistose planes being characterised b y material
of different composition. This gneiss is closely associated with schists
of various composition. The gneiss is often dioritic, owing to t h e
larger proportion of the plagioclase present. Numerous intercalated
beds of limestones, dolomites, hornblende-rock, epidote-rock,
corundum-rock, etc., occur among the gneiss. There is an abundance
of accessory minerals, contained both in the rock, itself and in t h e
accessory beds associated with it, such as magnetite, ilmenite, schorl.
T H E ARCHAEAN SYSTEM
63
jrarnet, calcite, lepidolite, beryl, apatite, ep^dote, corundum, micas,
and sptene. In all the above characters the rocks commonly desigWated Bengal gneiss differ strikingly from those commonly named
Bundelkhand gneiss, in which there are no accessory constituents,
and but few associated schists.
The weathering of some part of the gneiss of North Bengal is very
peculiar ; it gives rise to semi-circular, dome-like hills, or ellipsoidal
masses, by the exfoliating of the rock in regularly circular scales.
From this peculiarity the gneiss has received the name of Dome gneiss.
The gneiss in some places of Bengal closely resembles an intrusive
granite with well-marked zones of contact-metamorphism in the surrounding gneisses and schists in which it appears to have intruded.
Its plutonic nature is further shown in its containing local segregations (autoliths) and inclusions of foreign rock-fragments (xenoliths).
Types of Bengal gneiss—Besides the foregoing varieties some other
petrological types are distinguished in the Bengal gneiss, the most
noted being the SiUimanite-gneiss and Sillimanite-schist of Orissa,
known as Khondalites (from the Khond inhabitants of Orissa).
These give clear evidence of being metamorphosed sediments (f araschists), A large part of the schistose and garnetiferous ^gneiss of
South India, commonly designated " Fundamental gneiss" or
" Peninsular gneiss ", belongs appropriately to this division. The
Bengal gneiss/acies is revealed in the gneisses of Bihar, Manbhum and
Rewah, and some other parts of the Peninsula also. The Carnatic
and Salem gneisses are examples. Carnatic gneiss is schistose, including micaceous, talcose, and hornblendic" schists. The well-known
mica-bearing schists of Nellore, which support the mica mines of the
district, belong to the facies of the Bengal gneisses. The schistose
type of Bengal gneiss is regarded as probably the oldest member of
the Archaean Complex.
(2) BuNDELKHAND GNEISS. Bundellchand gneiss occurs in the
type area of Bundelkhand. It looks a typical pink granite in hand
specimens, the foliation being very rude, if at all developed. In its
field relations, the Bundelkhand gneiss differs from ordinary intrusive
granite only in the enormous area which it occupies. Indeed, it may
be regarded as an intrusive granite, like the Charnookites to be described below, into older gneisses, large patches of which it has remelted. Schists are associated with the gneisses very sparingly, e.g.
hornblende-, talc- and chlorite-schists. No interbedded marbles or
dolomites or quartzites occur in the Bundelkhand gneiss, nor is there
any development of accessory minerals in the mass of the rock or in
64
GEOLOGY OF INDIA
ifhe pegmatite-veins. Bundelkliand gneisG is traversed by extensive
dykes and sills of a coarse-grained diorite, which persist for long distances. I t is also traversed by a large number of coarse pegmatiteveins as in a boss of granite. Quartz-veins or reefs (the ultra-acid,
modification of the pegmatite-veins),, of great length, run as long,
narrow, serrated walls, intersecting each other in all directions, giving
to the landscapes of the country a peculiar feature. They intersect
the drainage-courses of the district and are the cause of the numerous
small lakes of Bundelkhand, whose formation can be easily under-'
stood and requires no explanation.
This type of gneiss is also met with in the Peninsula at several
localities, and is recognised there under various names—Balaghat
gneiss (also named Bellary gneiss), Hosur\aneiss', Arcot gneiss, Cuddapah gneiss, etc. The oldest basement gneiss of some parts of
Eajputana belongs to this system. The rock is quarried extensively
for use as a building-stone, and has in the past contributed material
of excellent quality for tlie building of numerous temples and otter
edifices of South India.
*
(3^ CHAENOCKITE SERIES. This is the name given to a series of
plutonic granitoid rocks of South India, occurring as intrusions into
the older Archaean gneisses and schists of the Peninsula. These rocks
are of wide prevalence in the Madras Presidency, and constitute its
chief hill-masses—the Nilgiris, Palnis, Shevaroys, etc. They are
medium to coarse-grained, dark-coloured, basic holocrystalhne
granitoid gneisses, possessing such a distinctive assemblage of petrological characters a,nd mineral composition that they are easily distinguished from the other Archaean rocks of the Peninsula. This
group includes many varieties and forms which are modifications of a
central type (the Charnockite proper), but these different varieties
exhibit a distinct " consanguinity " or family relationship ^o ea^
other. From this circumstance the Charnockite gneisses of Sout!
India afford a very good instance- of a petrographical province within
the Indian region. The name Charnockite which was originally given
by the discoverer of these rocks. Sir T. H. Holland, to the tjrpe-rock
from near Madras, is now, therefore, extended by him (Charnockite
series) to include all the more or less closely related varieties occurring
in various parts of the Madras Presidency and other parts of the
Peninsula.
Petrological characters—The mineralogical characters which give
to these rocks their distinctive characters are : The almost constant
presence of the rhombic pyroxene, hypersthene or enstatite, and a
THE ARCHAEAN SYSTEM
65
hieli proportion of the dark ferromagnesian compounds which imnart to the rock its usual dark colours. The ordinary constituents of
the rook include blue-coloured quartz, plagioclases, augite, hornblende and biotite with zircon, iron-ores and graphite as accessories.
Garnets are of very common occurrence. The presence, in different
proportions, of the above constituents imparts to the different varieties a composition varying from an acid or intermediate hyperstheneoranite (Charnockite proper) through all gradations of increasing
basicity, to that of the ultra-basic felsparless rocks, pyroxenites.
The specific gravity and silica per cent, range from 2-67 and 75 per
cent, respectively, in the normal hypersthene-granite, to 3-03 and
52 per cent, in the norites and hyperites. In the pyroxenites the
specific gravity rises to 3-37, corresponding to a fall of silica to 48
per cent. These ultra-basic types occur only locally as small lenses
or bands in the more acid and commoner types.
That the Charnockites are of the nature of igneous plutonic rocks,
intruded into the other Archaean rock-masses, is considered to be
established from a number of facts observed relating to their fieldcharacters :
(1) Their usual occurrence in irregular or lenticular sills forming
hill-masses, and possessing a general uniformity of composition and
mineralogical characters characteristic of plutonic intrusions.
(2) They present evidences of the processes of magmatic differentiation and segregation, and show fine-grained basic secretions and
acid excretions (contemporaneous veins, etc.).
(3) They show apophyses and dykes protruding into the surrounding older gneisses and schists.
(4) At some places well-defined contact-phenomena are exhibited
at their junction with the rocks they have invaded. Such rocks as
quartzites and limestone show this in a pronounced manner, e.g.
the production of such minerals as sillimanite and corundum in the
former, and scapolite, sphene and lime-garnets in the latter.
The Charnockite series is mainly confined to the Madras Presidency
and South India ; a few of its types, viz. dnorthosites, a rook principally composed of labradorite felspar, and olivine^orites, are found in
Bengal near Raniganj.
[Microscopic characters.—A thin section of Charnockite of average composition under the microscope shows an hypidiomorphic aggregate of large
plates of nucrocline or any other plagioclase and quartz, with allotriomorphic plates of hypersthene, and a few grains of pink garnet with
irregular outHnes. The accessories are crystals of magnetite, or ilmenite,
W.G.I. -
K
06
GEOLOGY OF INDIA
and sometimes very small grains of zircon. The quartz is often crowded
with acicular inclusions, which are disposed parallel to its crystallographic
axes. The microcline occurs in large (tlear prisms and plates, with its characteristic twin-striations ; it is often perthitic, by intergrowth with another
plagioclase. The quartz at times shows graphic relations to the felspar.
The felspars vary from oligoclase to labradorite. Garnet is commonly seen
in irregular crystals, with numerous, anisotropic inclusions. The garnets
are believed to have originated by the interaction between hypersthene and
felspar, and they are usually found in the zone of reaction between the two.
Free sihca is eliminated during the process, and is distributed as pegmatitic
intergrowth with the garnets. Hypersthene is invariably present as a
primary constitutent, but in variable quantity according to the basicity of
the rock ; ' it is distinctly pleochroic, shows schiller inclusions, straight
extinction, and its characteristic interference colours. I t is generally
accompanied by hornblende and augite in the less basic varieties. Among
the accessories are black opaque crystalline aggregates of magnetite and
ilmenite with apatite and zircon ; the latter is found in very minute grains. The minerals of Charnockite are usually all fresh, there being very little
evidence of decomposition.]
Archaean of the Himalayas—As already said, the bulk of t h e high
ranges of t h e Himalayas forming t h e central or H i m a l a y a n zone
proper is formed of crystalline or metamorphic rocks, like granite^,
granulites, gneisses, and schists. The high snow-peaks of the central
axis extending from Nanga P a r b a t on t h e Indus to Namcha
Barwa on the B r a h m a p u t r a are either entirely built of granite or
gneiss, or have a substraturh largely composed of these rocks. I n this.
complex, known formerly as t h e Central gneiss, from its occupying
t h e central axis of the mountain-chain from one extremity t o the
other, the representatives of the Archaean gneisses of the Peninsula
are to be found. I t "is, however, now known for certain, by the researches of General M'Mahon and later investigators, t h a t much of t h e
gneiss is of intrusive origin, and, therefore, of very much younger age.
I t is found intrusive into the Panjal Volcanic series of Permian age in
t h e Pir Panjal and elsewhere ; into the Jurassic'in Chitral; into the
Cretaceous Orbitolina-hesucmg beds in the Burzil valley of Kashmir ;
a n d into the Eocene of E a s t e r n Tibet. These granites have passed into
gneisses by assuming a foUated structure, while the Archaean gneiss
proper has assumed the aspect, of granites, owing to the high degree of
dynamic metamorphism. I t is again quite probable t h a t a certain
proportion of the central gneiss is t o be attributed to highly metamorphosed ancient (Purana) sediments. I t is therefore difficult t o
separate from this complex the constituent elements of the Archaean
gneiss from gneissose granite or from the metamorphosed sediments
of later age.
^•s
§1
THE ARCHAEAN SYSTEM
67
There is reason to believe that the gneiss and granite composing the
majority of the high peaks of the Himalayas belong to the intrusive category
rather than to the olS Archaean foundation; they probably mark zones of
special elevation connected with the welling up of acidic magma at certain
points at the time of the uplift of the mountains.
The sedimentary Archaean complex of t h e Himalayas is dealt with
in t h e next chapter.
'
REFERENCES
R. D. Oldham, Geology of India, 2nd Edition, chapter ii.
Sir T. H. Holland, Charnookite Series, Mem. G.S.I, vol. xxviii. pt. 2 ; Sivamalai
Series, Mem. O.S.I, vol. xxx. pt. 3, 1901.
R. B. Eoote, Mem. G.S.I, vol. xxv., Geology of Bellary District, Madras Presidency, 1896.
C. A. M'Mahon, Microscopic Structure of some Himalayan Granites, Bee. G.S.I.
vol. xyii. pt. 2, 1884.
Sir L. L. Fermor, Correlation of the Archaean of Peninsular India, Mem. O.S.I.
vol. Ixx. pt. 1, 1936.
Records of Mysore State GeologiiMl Department; all of these deal with the rocks
dealt with in this chapter.
CHAPTER IV
AECHAEAN SYSTEM (contd.)
THE DHAilWAR SYSTEM
General—According to the commonly received interpretation, during
the later stages of the Archaean era the meteoric conditions of the
earth appear to have been changing gradually. We may suppose that
the decreasing temperature, due to continual radiation, condensed
most of the vapours that were held in the thick primitive atmosphere
and precipitated them on the earth's surface. The condensed vapours
collected into the hollows and corrugations of the lithosphere, and
thus gave rise to the first-formed ocean. Further loss of heat produced condensation in^ the original bulk of the planet, and as the outer •
crust had to accommodate itself to the steady diminution of the'
interior, the first-formed wrinkles and inequalities became more and
more accentuated. The oceans became deeper, and the land-masses,
the skeletons of the first continents, rose more and more above the
general surface. The outlines of the seas and continents being thus
established, the geological agents of denudation entered upon their
work. The weathering of the older Archaean gneisses and schists
yielded the earliest sediments which were deposited on the bed of the
sea, and formed the oldest sedimentary strata, known in the geology^
of India as the Dharwar System. The above is only a partial de-^
finition of the term Dharwar system, whose exact limits and relations'
with respect to the Archaean igneous'rocks are not yet fully understood. In the present chapter the term Dharwar System is used as
synonymous with metamorphosed Archaean sediments, and including
all the schistose series below the eparchaean unconformity.
These sedimentary strata appear to rest over the gneisses at some
places with a great unconformity, while at others they are largely
interbedded with them, and in some cases are of undoubtedly older
age than some of the gneisses. Although, for the greater part at least,
of undoubted sedimentary origin, the Dharwar strata are altogether
un^ossiliferous, a circumstance to be explained as much by their ex" 6 8
THE DHARWAR SYSTEM
69
J early age, when no organic beings peopled the earth, as by the
, AQOtee of metamorphism they have undergone. The complex
f Id "nas of the citist in -which these locks have been inYoWed have
ViVterated nearly all traces of their sedimentary nature, and have
• n to them a thoroughly crystalline and schistose structure, hardly
t be distinguished from the underlying gneisses and schists. They
besides extensively intruded by granitic bosses and veins and
i,pets and by an extensive system of dolerite dykes, thus rendering
these rock-masses still more difficult of identification.
AH these circumstances have led to the sedimentary nature of the
Dharwar rocks of several areas, notably of Mysore, being doubted by
some geologists who regard the bedded schists, limestones and conglomerates as of igneous origin, the conglomerates having resulted
from the autoclastic crushing of quartz-veins and plutonic dykes.
Field work in Mysore area has shown that many of the subjacent
gneisses have intrusive relations towards what were previously included among the Dharwars and are therefore younger than them.
But such is liot universally the case, and during the last few years the
sedimentary nature of many terraines of Dharwar rocks has been demonstrated beyond doubt, i
Of late there has been a tendency to discard the term Dharwar and
to designate this system by the name Archaean. The use of the term
Dharwar to embrace all the great sedimentary systems resting upon
the fundamental basement gneisses of India, and' separated from the
overlying Purana systems by a pronounced eparchaean unconformity,
seems appropriate and has the sanction of long usage. In one of the
best-studied Archaean provinces of India Dr. A. M. Heron has proved
at least two, and possibly three, great cycles of Archaean sedimentary
deposits, separated by important unconformities, denoting periods
of diastrophism, erosion and peneplanation, overlying the Bundelkhand gneiss. These clastic Archaean rock-formations of great thickness and extent, reposing over an older gneissic floor, need a distinguishing term to separate them from the igneous Archaeans.
Outcrops of the J)harwar rocks—One important peculiarity regarding the mode of occurrence of the Dharwar rocks—as of generally all
other occurrences of the oldest sediments that have survived up to the J
present—is that they occur in narrow elongated synclinal outcrops
among the gneissic Archaeans—as outliers in them. This tectonic
peculiarity is due to the fact that only those portions of the Dharwar
1B. Rama Rao, Records, Mysore Geol. Depl. vol. xxxiv., 1936.
70
GEOLOGY OF INDIA
beds that were involved in the troughs of synclinal folds and have,
consequently, received a great deal of compression, are preserved, the
limbs of the synclines, together with their connecting anticlinal tops,
having been planed down by the weathering of ages.
The lithology of the Dharwars—The rocks of this system possess
the most diverse Kthological characters, being a complex of all kinds
of rocks—plastic sediments, chemically precipitated rocks, volcanic
and plutonic rocks—all of which generally show an intense degree of
metamorphism. No other system furnishes such excellent njaterial
for the study of the various aspects of rock-metamorphism. The
rocks are often highly metalliferous, containing ores of iron and
manganese, occasionally also of copper, lead, and gold. The bulk of
the rocks of the system is formed of phyllites, schists, and slates.
These are hornblende-, chlorite-, haematite- an(l magnetite-schists,
felspathic schists ; quartzites and highly altered volcanic rocks, e.g.
rhyolites and andesites turned into hornblende-schists; abundant
and widespread granitic intrusions; crystalline Kmestones and
marbles ; serpentinous marbles ; steatite masses ; beds of brilliantly
coloiired and ribboned jaspers ; roofing slates ; and massive beds of
iron and manganese oxides.
»
Plutonic intrusions—The plutonic intrusions assumed to be of
Dharwar age have given rise to some interesting rock-types, some
of which have already been described in the last chapter, viz.
nepheline-syenites of Rajputana, differentiated into the elaeolitesyenite and sodalite-syenite of Kishengarh', which carry the beautiful
mineral, sodalite. Many of the granites of the Dharwar system are
tourmaline-granites ; among other intrusives are the quartz-porphyry
of Rajputana, and the dunites of Salem. The pegmatite-veins intersecting some of the plutonics are often very coarse, and, especially
when they cut through mica-schists, bear extremely large crystals of
muscovite, the cleavage sheets of which are of great commercial
value. Such is particularly the case with the mica-schists of Hazafibagh, Nellore, and parts of Rajputana, where a large quantity of mica
is quarried. Besides muscovite, the pegmatites carry several other
beautifully crystallised rare minerals, e.g. molybdenite, columbite,
pitch-blende, gadolinite, torbernite, beryl, tourmaline, etc.
Crystalline limestones originating by metasomatism of gneisses—
Here must also be considered the curious group of manganiferous crystalline limestones of Nagpur and Chhindwara districts of the Central
Provinces, containing such minerals as piedmontite (Mn-epidote),
spessartite (Mn-garnet), with Mn^pyroxene, -amphibole, -sphene, etc.,
THE DHARWAR SYSTEM
.
71
whici have given rise, on subsequent alteration, to some quantity of
manganese ores. As mentioned on p. 60, these crystalline limestones
aie attributed a curious mode of origin. Dr. Fermor has shown them
to be due to the metasomatic replacement of Archaean calc-gneisses
and calciphyres, which in turn were themselves the product of the
regional metomorphism of highly calcerous and manganiferous
sediments.^
Another peculiar rock is the flexible sandstone of Jind (Kaliana).
The rock was originally formed from the decomposition of the gneisses,
and had a certain proportion of felspar grains in it. On the subsequent decomposition of the felspar grains the rock became a mass of
loosely interlocking grains of quartz, with wide interspaces around
them, which allow a certain amount of flexibility in the stone.
Distribution of the Dharwaxs—The Dharwarian rocks are very
closely associated with' the Archaean gneisses and schists in many
parts of the Peninsula. The principal exposures in the Peninsula are
three : (1) Southern Deccan, including the type-area of Dharwar and
Bellary and the greater part of the Mysore State ; (2) the Dharwar
areas of Carnatic, Chota Nagpur, Jabalpur, Nagpur, etc.; with those
of Bihar, Eewah and Hazaribagh ; (3) the AravaUi region, extending
as far northwards as Jaipur, and in its southern extremity including
north Gujarat. In the extra-Peninsula the Dharwar system is well
represented in the Himalayas, both in the central and northern zones,
as well as in the Shillong plateau of the Assam ranges.
1. DHAEWAR {the Type-area). The rocks occur in a number of
narrow elongated bands, the bottoms of old synclines, extending from
the southern margin of the Deccan traps to the Cauvery. The general
dip of the strata is towards the middle of the bands. The constituent
rooks are hornblende-, chlorite-, talc-schists, together with slates,
quartzite, and conglomerates and very characteristic brilliantly
banded cherts ; these rocks are associated with various types of
ortho-gneisses and schists and lavas of dioritic composition. The
Dharwar slates exhibit all the intermediate stages of metamorphism
(anamorphism) into schists, viz. unaltered slates, chiastolite-slates,
phyllites and mica-schists. Numerous quartz-veins or reefs traverse
the Dharwar rocks of these areas. Some of those are auriferous and
contain enough of disseminated gold to support some goldfields.
The principal gold-mining centre in India, the Kolar fields in the
Mysore State, is situated on the outcrops of some of these quartzliJcc. O.S.I., vol. xxxiii, pt. 3, 1906.
72
GEOLOGY OF INDIA
v
veins or reefs. For a fuller account the student is referred to tlie
publications of the Mysore State Geological Department. ^
2. RAJPUTANA. Rocks which may be regarded as belonging to the
Dharwarian group occupy a wide surface extent of Rajputana, constituting the vast system of pre-Cambrian sediments, designated as
the Aravalli system. The results of a comprehensive study of this
ancient sedimentary system, which is separated from the oldest
Purana system by a hiatus, represented by one or two profound unconformities, are now made available.^ The relations of the Aravalli system in the different parts of Rajputana, as elucidated by
Dr. A. M. Heron, are shown in the annexed Table.
Aravalli mountains—The type rocks are exposed in a very large
outcrop in the Aravalli range of Rajputana. This, the most ancient
mountain-chain of India, came into existence at the closes of the
Dharwar era, when the sediments that were deposited in the seas of
that age were ridged up by an upheaval of orogenic nature. Since
then the Aravalli mountains remained the principal feature in the
geography of India for many ages, performing all the functions of a
great mountain-chain and contributing their sediments to many,
deposits of later ages. Evidence exists that this mountain-chain received renewed upheavals during early Palaeozoic and was of far
greater proportions in past times, and that it stretched from the
Deccan to perhaps beyond the limits of the Himalayas.
Aravalli system—The Dharwarian rocks of the Aravalli region form
a long and wide synclinorium in the basement schistose gneisses of
Rajputana, constricted in the middle. Heron has classified these
rock-groups into two great pre-Cambriah systems separated by a profound regional unconformity—the lower division forming the Aravalli
system and the upper forming the Raialo series.The lower, Aravalli system, is a vast formation, aggregating oyer
10,000 feet in vertical extent, composed of basal quartzites, conglomerates, shales, slates, phylhtes and composite gneisses. I t rests
with a great erosional unconformity on the finely schistose and
banded gneiss (Bundelkhand gneiss). Its metamorphism is variable
and there are exposures of almost unaltered Archaean shales in. one
part of the outcrop and such highly metamorphosed rocks as hornblende-schists and schistose conglomerates in another. The schists
1 Sampat Iyengar, Acid Rooks of Mysore, Seventh Indian Science Congress Proceedings, Calcutta, 1921.
' A. M. Heron, Synopsis of Pre-Vindhyan Geology of Rajputana, Trans. Nat. Inst,
Ss. Ind. vol. i. no. 2, 1935.
_
73
THE DHARWAR SYSTEM
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GEOLOGY OF INDIA
include numerous secondary aluminous and calcareous silicates, e.g.
andalusite, sillimanite, staurolite. Bind a great many garnets. At a
few localities the Aravallis include lodes of copper with traces of
nickel and cobalt. Granite and amphibolite have intruded at many
places into the slates and phyllites iri the form of veins, attended with
offshoots of quartz-veins and pegmatites. lAt-par-lit injections of
granite in slaty rocks have given rise to composite gneisses.
Eaialo series. Delhi system—The Eaialo series comes above theAravallis with a pronounced unconformity. JThis series is rich in
crystalline limestones, associated with quartzites, grits and schistose
rocks. The famous Makrana marbles, the source of the material for
the celebrated Mogul buildings of Delhi and Agra, are. a product of
this rock-series. The Eaialos are succeeded in the northern part of
the Aravallis, after another great unconformity, by the system of
quartzites, grits and schistose rocks constituting the famous Ridge of
the city of Delhi. These form the Delhi system. The Delhi system is
now regarded as of Cuddapah age and is described on p. 89, Chapter V.
On a possible prOlotigation of the Aravalli strike to the interior of the
plains of the Punjab, a few small straggling outhers of the same rockr
series are found, composed of ferruginous quartzite and slate,
together with a great development of rhyolitic lavas (Malani rhyolites, p . 96). These outliers constitute the low, deeply weathered, hills
known as Kirana and Sangla, lying between the Jhelum and the
Chenab.^
Features of great interest in the study of metamorphisin are brought to
light in the survey of the ancient sedimentary systems of Bajputana.
Schistose and banded gneisses in the Aravallis have been traced along the
strike into rocks still in the condition of practically unaltered shales and
slates. By the injection of granite, sedimentary rocks have been converted
into banded composite gneisses on a large scale, which may easily be giistaken for ortho-gneisses. Comparatively newer sediments, e.g., of the Delhi
system, occurring in the centre of the synclinorium of the Aravalli strata
evince a higher grade of metamorphism and tectonic deformation than the
Aravalhs on which they rest with a great hiatus. This anomalous metamorphism of a newer series is explained by Dr. Heron as due to the fact that
the Delhi strata have been buried more deeply in their synclinal roots and
therefore subjected to more intense pressures and intrusive action than the
underlying Aravallis which flank the Delhis.
Dr. Heron has observed that the Aravallis of Rajputana are analogous to, if not contemporaneous with, the Dharwars of South India,
and has suggested a very general correlation of these with the
1 Bee. 0.8.1. vol.^liii. pt. 3, 1913.
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76
GEOLOGY OF INDIA
Dharwars of the Central Provinces, Chhota Nagpur, and the Mergui
series of Burma.
Champaner series—One further outUer of the AravaUi series, but
this time to the south-west extremity of its strike, is found in the
vicinity of Baroda on the site of the, ancient city of Champaner. I t
overspreads a large area of northern [Gujarat and was known as the
Champaner series. The component rocks are quartzites, conglomerates, slates and limestones, all highly metamorphosed. A green
and mottled marble of exquisite beauty is quarried from these rocks
near Motipura.
'
SMUong series—The Shillong series of the Assam hills is-a widely'
developed group of' parallel deposits consisting of a thick series of
quartzites, slates and schists, with masses of granitic intrusions and
basic interbedded traps. The Shillong series is for the greater part of
its extent overlain by horizontally bedded Cretaceous sandstones.
3. THE NORTH-EAST AREA.
Central Provinces. Manganiferous deposits of Kodurite and Gondite
series—The Dharwarian system covers large connected areas in the
Central Provinces and Bihar, spreading over Balaghat, Nagpur and
Jabalpur districts, and over Hazaribagh and Rewah. In these areas it
possesses a highly characteristic metalliferous facies of deposits wLich
has attracted a great deal of attention lately on account of the ores of
manganeseand iron associated withit. The lithology of theDharwarsin
these exposures is very varying, but each outcrop possesses a sufficient
variety of its peculiar rock-types to reveal the identity of the system.
The Dharwar rocks of Nagpur, Chhindwara and Bhandara districts of
the Central Provinces have been named the Sausar series. They consist
of granulites, calciphyres, dolomitic marble in lenticular association
with mica-sillimanite-quartz-schists, diopsidites, hornblende-schist,
etc. These rocks carry important economic deposits of mangan^eores. The Sausar series has been sub-divided into stages which have
a wide geographical extent in the Provinces and can therefore be
correlated in distant outcrops of the series. The series is largely of
aqueous sedimentation, but subsequently it has been metamorphosed
and invaded by acid and basic plutonic rock-masses. The Sakoli
series of the southern parts of the Central Provinces, consisting of less .
altered slates, chlorite-schists, jaspilites and haematitic quartzites is
probably an upward extension of the Sausars. In the Balaghat
district, and probably some other parts of the Central Provinces, the
local representatives of the Dharwar are distinguished as the Chilpi
series, from the Chilpi Ghat; these_rocks include a great thickness of
THE DHARWAR SYSTEM
77
highly disturbed slates and phyllites, with quartzite and basic trj' ]pean intnisions. In Jabalpur the outcrop is distinguished by luj
occiifrences of perfectly crystaUine dolomitic limestones. The famous
" marble-rocks " ^ of Jabalpur in the Narbada gorge belong to this
system. In other parts of the Central Provinces and in Kewah, some
places in the Bombay Presidency (Panch Mahals ^), etc., the exposures
are distinguished by a richly manganiferous facies, containing large
deposits of workable manganese-ores. Sir L. Fernior has given the
name Gondite series to these rocks, because of their containing, as their
characteristic member, a spessartite-quartz-rock, to which he has.
given the name of Gondite (p. 59). . Besides spessartite, the rock contains many other manganese-sihcates ; it is the deco^aposition of these
manganese-sihcates that has given rise to the enormous deposits of
manganese-ores contained in these occurrences of the Dharwar
system.
GoaSiie series—The origis £-/ ihe &osdit& series is interes'^'.g.
According to Fermor these manganiferous rocks of the Gondite series
have resulted from the metamorphism of sediments deposited during
Dharwar times which were originally partly mechanical clays and
' sands, and partly chemical precipitates—chiefly of nianganese-oxides.
The same metamorphic agencies that have converted the former into
slates, phyllites and quartzites, have altered the latter into crystalline
manganese-oxides, when pure, and into a number of manganesesilicates where the original precipitates were mixed with clayey or
sandy impurities.
Outcrops of the Gondite series are typically developed in the Baiaghat, Chhindwara, and Nagpur districts of the Central Provinces and
a few localities in Bombay, Central India, and in iBanswara in Eajputana.
Kodurite series—The same authority regards the manganese
deposits of the Madras Presidency as due to the alteration of a series
of plutonic intrusions (belonging to the Kodurite series) which may be
of hybrid origin and due to the incorporation in ^cid intrusives of
manganese ore-bodies of the Gondite type. The Kodurite series is
typically developed in the Vizianagram State of the Vizagapatam
district of Madras.
4. SiNGHBHUM, ORISSA. This area contains the following sequence
of Archaean sediments. It consists essentially of a series of iron-bearing
' A series, of Dharwar marbles and Deccan traps dissected into a number of magnificent dazzling white steeps, through which the Narbada, after its fall (Dhurandhar),
runs for about two miles in a defile that is barely twenty yards iri width.
' The manganese-ores of the Panch Mahals occur in the south extension of the
Aravalli system (Champaner series).
78
GEOLOGY OF INDIA
sediments—phyllites, tuffs, lavas, quartzites, and limestones, designated as the Iron-ore series—resting unconformably on an older
metamorphic series. The age of the Iron-ore series is regarded as
Upper Dharwar:
Iron-ore
Series.
Shales, phyllites, tuSs with lava-flows.
Phyllites, quartzites, limestones with tuffs and lavas.
Banded haematite-quartzites and iron-ores.
Shales and phylhtes with sandstones and limestones.
.Sandstones—conglomerates.
? Sausar (Gangpur Series—schists, crystalhne limestones, phylhtes with
Series. \ Mn-ore bodies.
'
Older Metamorphics—hornhlende-schists, mica-schists and
quartzites.
^
The Iron-ore series is economically the most important (p. 346),
containing interbedded ore-bodies of large dimensions, estimated to
yield a total of nearly three thousand million tons of high grade ironore. In its petrogenesis the series is believed to be akin to the other
well-known pre-Cambrian iron-bearing formations of the world, e.g.^
the Lake Superior deposits, of the U.S.A. and those of Brazil. The
question of the ultimate source of iron oxides and the exact processes
which segregated them here on such an immense scale yet awaits solution. Indian geologists generally regard these ores as, in the main,
marine chemical precipitates in the form of oxides, carbonates and
silicates. Some secondary, changes and replacement have taken place
subsequent to their deposition, but it is not believed that organic
agencies such as algae or bacteria have helped in the precipitation of
iron. I t is possible, however, that no single mode of origin applies to all
the occurrences, \7hile the larger deposits of iron-ore, such as those
of Singhbhum or Keonjhar, may be sedimentary there are otli.er
deposits belonging to the series which have probably originated by a
process of metasomatic replacement under terrestrial conditions, in
a period of marked volcanic activity.
The ores occur as massive beds and lenses of ferric oxides, soft
powdery haematite, and as banded or ribboned haematite-quartzite
or jasper, from which the free ore is liberated by the leaching out of
the interlaminated silica. There is a considerable amount of igneous
volcanic action in this area witnessed by the bosses of Singhbhum and
Bonai granite, by masses of ultra-basic intrusives and by lava-flows
and tuffs. The basic intrusives have given origin to the chromite,
asbestos and steatite of Singhbhum.
THE DRARWAR
SYSTEM
79
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GEOLOGY OF INDIA
Overlying the' Iron-ore series are altered basalts and associated
sub-aerial volcanic products—Daln^a traps.''^
Manganese-ores of Dharwar system—Almost the whole of the Manganese-ores annually produced in India is derived directly or indirectly from the
Dharwar rocks. With regard to their geological relations Dr. Fermor has
divided the ore befdies into three classes.
(1) Deposits connected with the intrusive rock, Kodurite, a basic plutonio
rock, possessing an exceptional mineralogical composition, in being unusually rich in manganese-silicates like manganese-garnets, rhodonite, and
manganese-pyroxenes and -amphiboles. The orps of the Vizagapatam
district have resulted from the meteoric alteration of these manganesesilicates, while the felspar has altered into masses of lithomarge and chert;
the other products being wad, ochres, etc. The ore-bodies resulting in this
manner are of course of extremely irregular form and dimensions and the
grade of the ore is low.
(2) Deposits contained in the Gondite series are developed in the Central
Provinces, Central India, Panch Mahals, etc. As above described, the
Gondite rocks were originally clastic sediments, including precipitates of
manganese-oxides hke those of iron oxides enclosed in the sedimentary
rocks of various ages. Their dynamic or regional metamorphism has given
rise to crystallised ores of manganese, like braunite, hausmanite, hollandite,
etc. The resulting ore-bodies are large and well-bedded, foUqwing the
strike of the enclosing rocks;-indicating that they have had the same origin
as the latter. Sometimes, as in Chhindwara and Nagpur, the manganeseores are found in the crystalline limestone and calc-gneisses associated with
the other Dharwar rocks. In addition to the ores psilomelane, braunite,
hollandite, the crystalhne limestone contains usually piedmontite (the
manganese-epidote). The Gondite. deposits yield by far the largest part
of the economically important manganese-ores.
(3) Lateritio deposits are due to metasomatic surface replacement of
Dharwar slates and schists by manganese-bearing solutions. These ores
occur in Singhbhum, Jabalpur, Bellary, etc. They are irregular in distribution, occurring as a cap on the outcrops of the Dharwar rocks, as is evident
from their pecuHar nature of origin.
These ore-deposits have brought to light some new mineral speoies*and
beautiful crystallised varieties of already recognised manganese minerals.
They are : Vredenburgite, Sitaparite—riianganese and iron oxides ; Hollandite and Beldongrite are manganates; Winchite is a blue manganeseamphibole, and Blanfordite a pleochroic manganese-pyroxene ; Spandite is
a manganese-garnet, intermediate in composition between spessartite and
andradite ; Granditeis similarly a " hybrid " of grossularite and andradite;
Alurgite is a pink-coloured manganese-mica.^]
5. T H E HIMALAYAS. Rocks probably belonging to this, the oldest
sedimentary system, occur in a more or less continuous band between
' J. A. Dunn, Origin of Iron Ores in Singhbhum, Earn. Oeol. vol. xxx. p. 643 (1935)}
Mem. G.S.I. vol. Ixix. pt. 1,1937.
2F3rmor, Mem. G.SJ. vol. xxxvii., 1909.
THE DHARWAR SYSTEM
81
, J crystallifte axis of the higher Himalayas and the outer
"
They occupf tracts of North Hazara, Indus Kohistan, GiU'f'^^-r (jakh and the Zanskar range to beyond the Sutlej. They are
^1^ ' 1 associated with the Central gneiss and also at places with the
^°
Puranas, to which they are distinctly uiiconformable in the
[ess disturbed areas. They consist of slates, phyllites (often graphitic),
®,. , quartzites afii crystaYiine \iniestones a n i doiomites. T^iey
^
been named Sdkhala series in the Kashmir area and Jutogh
. • ^-^Q Simla aiea. The gneissification of these rocks at some
1 es and the wide prevalence of later intrusive granites, especially
the central axial r^nge of the Himalayas, make it difficult to separ, £j,j,jj^ ^his complex any remnants of the Archaean gneisses. The
Great Himalaya range, west of Ladakh, is largely composed of the
Salkhalas, converted into para-gneiss, the Nanga Parbat (26,620)
a<!«if being almost wholly built of this, with intrusive biotite-gneiss
of later age and hornblende-granite of still newer. Eocene or postEocene age. SoTitti o^ 't^^* laTigfc ttie 'Sa^kViala's skc.-^ a steadiiy decreasing grade bf metamorphism, clearly revealing their sedimentary
characters. Some of the rock-elements present in them show remarkable resemblance with the Dharwars of EajputaOa and Singhbhum ;
and it appears probable that the Great Himalaya range represents the
basement of the old Peninsular Archaeans on which the Tethyan
sediments were laid down in the Himalayan geosyncline. It thus
denotes the protaxis of the Himalayas.
There are no Archaean outcrops between the Aravallis and the
Punjab Himalayas, except perhaps in the few straggling hillocks of
"SLiTana and SangVa, "^V^^^i ^v^\>'&}ii\^ %\<b ttifc ^Ki\>^iswi ^taka <j.i ?>, fevapected ridge buried under the alluvium of the Punjab.
Himalayan DharWars—Different exposures of Himalayan Archaeans have received different names, according to the localities of
their distribution. On the north of the crystdline axis, in the district
of Spiti, the equivalents of the Dharwars are known as the Vaikrita
series. On the south of that axis there occur more extensive exposures of metamorphosed highly folded and unfossiliferous sedimentary rocks of distinctly older age than Cambrian. A part of these
may be regarded as Dharwar in age, but owing to the comphcated
folding and inversions of the strata, it is not easy to identify the representatives of the Dharwar from younger sediments, much less to
correlate and group together the widely-separated outcrops of these
formations in the different parts of the Himalayas. One of the most
important occurrences of these ancient sediments is in the neighbourW.O.I.
p
82
GEOLOGY OF INDIA
tood of Simla, covering large tracts to its east and west, which was
previously known under the general name of the Simla system. Recent investigations have enable(^ this comprehensive system to be
differentiated : the basal part, named the Jutogh series, being referred
to Dharwar age, while a newer sferies coming unconformably over it
is of Purana or still newer age—Simla slate series. The Jutoghs are a
series of carbonaceous spates, limestones and dolomites, quartzites'
and schists, possessing a high order of metamorphism. Intervening
between the Jutoghs and the Simla slates are a group of light grey
schistose slates and talcose quartzites which have been named the
Chail series. The Chails show thrust-fault relations to the series above
and below.
Simla—The tectonics of the Simla area are of great interest. Pilgrim
and West have proved that the highly metamorphosed Jutoghs now
resting on top of the practically unaltered Simla slates at Simla, are not
in their normal position, but have been inverted and thrust southward,
from their original position in the central axis of the Himalayas, along
a horizontal plane of thrust that has travelled for many miles. The
effects of denudation on this overthrust sheet of the Jutoghs is to
leave isolated outliers, " klippen ", of older rocks capping the sumrnits
of the Chaur and Chail mountains, while the main body of these
mountains is built of younger rocks.
Kaslunir—-The Dharwar rocks of Hazara and Kashmir have been
distinguished under the.name of Salkhala series. In composition, association of the lithological types and in degree of metamorphism the
Jutoghs and Salkhalas show a marked parallelism. The carbonaceous
element is locally very preponderant in the Salkhalas, associated at
some places with thick beds of white marble. From the Indus to GJ^rhwal a chain of massive porphyritic biotite-gneiss intrusions occur in
these ancient sediments. In the eastern Himalayas, a series of schists'
of the same formation near Darjeeling constitjites the Baling ieries.TThe Dahng series extends along the Tista valley into Sikkim and
thence to Bhutan, consisting of much-contorted slates and chloritic
and sericitic phyllites with hornblende-schists and quartzites. Some
lodes of copper are associated with these rocks at some places.
Among the constituent rocks of the foregoing Himalayan series there
are a few of the characteristic types of the Peninsular Dharwars, by
which they are distinguished as such.
Homotaxis of the Dharwar system—With regard to the age of the
Dharwar system, there is no doubt that they are far older than the
Cambrian, separated from them by an immense interval of geological
THE DHARWAR SYSTEM
83
.
j.gpresented by three or possibly four vast cycles of deposition,
oiintain-building and base-levelling. With regard to their lower
Tmit they are so'closely associated and intermixed with the Archaean
neisses at certain places that they leave no doubt that some of the
ffneisses are younger than some of the Dharwar schists. From their
field-relations, and from the circumstance of a widespread unconformity separating the Dharwars from all younger formations,
gir T. H. Holland has grouped them along with the Archaean.
There is no parallel system of deposits comparable to the Dharwars
in England or many parts of Europe, but the Dharwars show a degree
of affinity with the Huronian rocks of America in their stratigraphic
position and their'petrological constitution.
A very careful and detailed investigation has been made in the great
Archaean complex of South India by the Mysore State Geological Department. The Mysore geologists have unravelled a number of successive
(about Vqo natural size)
FIG. 6i—Diagram showing the relation of Dharwar schists
with the gneisses.
(After Sampat Iyengar, Bee. M.O.D. vol. xi.)
eruptive groups in what have been hitherto dfi&ribed as the Archaean
fundamental gneisses of the Peninsula, and as a result of these investigations they came to the conclusion that the Dharwar schists were all
decidedly older than the gneisses ; that they were not of sedimentary
origin as hitherto held, but were certainly in part and possibly entirely of
igneous volcanic derivation, being in fact strictly basic lava-flows metamorphosed into hornblende and chloritic schists. In theirfield-relationsthe
Dharwar schists have again and again been observed to show a distinct intrusive contact towards the invading gneisses, and have been penetrated
by the latter times without number. The characters of the schists also,
according to these observers, point to an igneous, and not a sedimentary
84
GEOLOGY OF INDIA
origin, for they have not been able to trace any passage of these schists into
phyllites or unaltered slates, within the territories of the Mysore State, which
encompass an area of nearly 30,000 pquare miles. On the other hand, they
show a gradual transition into epidiorites or hornblende-rocks. Many of
the Dharwar conglomerates, likewise, are believed to be of crushed, auioclaslic, origin. Fig. 6 gives an ide^ of the nature of the association of the
two rock-groups. These views have been to apQonsiderable extent modified
as the result of later work by the State geologists.
The subject is still one of the major controversies of Indian Geology, but
the prolonged study of the South Indian crystalline complex, by Sir Lewis
Fermor and his colleagues, extending from 1902, has helped to clear it
•considerably. Present opinion tends to support the Mysore view in so far
as the age of the main body of the Dharwars is concerned, though work in
extra-Mysore areas equally supports the older views as regards the sedimentary nature and origin of a portion of these rock-bodies, there being
little doubt about the detrital nature of the phyllites and quartzites.
The following general scheme of classification of the Archaeans of India
4. The Charnockite and Bundelkhand Gneisses, with intrusions-such as
Peridotites, Granites and Syenites;
3. Ee-melted masses of the Basement Gneiss, now constituting much of
the schistose and garnetiferous Bengal and Peninsular Gneissfes.
These include some para-gneisses and schists;
2. Dharwar sediments and contemporaneous lavas ; also Khondalitefs.
1. The oldest Basement*^Gneisses representing, in part at least, the
primitive crust of the Earth,
adopted by Sir Lewis Fermor in 1919, is now amplified by the sub-division
of the Archaean foundation of the Peninsula into 15 distinct .provinces,
based largely on their petrological characters. The Archaean terrain of
India is first broadly divided into two regions the CharnocJcitic and the
non-Charnockitic; these major regions are further sub-divided into a
number of provinces, grouped under (1) Iron-ore provinces, (2) Manganeseore-marble provinces and (3) Igneous provinces, based on their compositional differences. In establishing these divisions and their correlations in
different parts of the Indian Peninsula, Fermor uses the following criteria :
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
Stratigraphic sequence.
•*
Structural relationships—unconformities, periods of folding, etc.
Relationship to igneous intrusives. Associated ore-deposits of epigenetic origin.
Lithological composition.
Chemical composition.
Grade of metamorphism..
Lead and helium-ratios.^
Economics—The Dharwar system carries the principal ore-deposits
of t h e country, e.g. those of gold, manganese, iron, copper, tungsten,
lead, etc. These with their associated rocks are also rich in such
» Mtmmrs Q.S.I, vol. Ixx.pt. 1, 1936.
THE D H A B W A R S Y S T E M
. 85
• A trially useful products as mica, corundum, etc.; rare valuable
^ • rals like pitchblende and columbite, etc.; a few gems and semi"iecious stones like tbe ruby, beryl, cbrysoberyl, zircon, spinels,
ets tourmalines, amethyst, rock-crystal, etc. This system is also
h in its resources of building materials, e.g. granites, marbles,
mental building sltones, and roofing slates. The famous marbles
f which the best specimens of ancient Indian architecture are built
are a product of the Dharwar system.
EEFERENCES
T L Fermor, Mem. 0.8.1. vol. xxxvii., 1909 ; J.A.8.B. vol. xv. (New Series),
1919; Mem. O.S.I, vol. Ixx., 1936.
A M. Heron, Geology of Rajputana, Mem. O.S.I, vol. xlv., 1917 and 1922 ; and
Mem. vol. Ixviii. pt. 1., 1936 ; Bee. vol. liv. pt. 4, 1922.
Sir T. H. Holland and G. H.' Tipper, Mem. O.S.I. xliii. pt. 1, 1913, and (Second
Edition) Mem. li. pt. 1., 1926, The Dharwar System.
J. A. Dunn. Mineral Deposits of Eastern Singhbhum, Mem. O.S.I, vol. Ixix. pt. 1,
1937; GeologyofNorthSinghbhum, ife?7i. (?.(S./. vol. liv. 1929.
H. 0. Jones, Iron-Ore Deposits of Bihar and Orissa, Mem. O.S.I, vol. Ixiii. pt. 2,
1933.
G. E. Pilgrun»and W. D. West, Structure of the Simla Rooks, Mem. O.S.I, vol.
liii., 1928.
D. N. Wadia, Geology of Nanga Parbat and parts of Gilgit, Records O.S.I, vol.
Ixvi. pt. 2, 1932.
B. Rama Rao, Records, Mysore Oeol. Dept., vol. xxxiv., 1936.
M. S. Krishnan, Geology of the Gangpur State, Mem. O.S.I, vol. Ixxii., 1937.
References to the Dharwar system and its relation to the Archaean of the
Peninsula are most plentiful,in the Records of the Mysore State Oeological Department. See Smeeth, Bulletin III. M.O.D. 1910, also J.A.8.B. vol. xi. (New Series),
1916.
CHAPTER V
THE CUDDAPAH SYSTEM
General—The closing of the Dharwar era must have witnessed earthmovements on, a very extensive scale, which folded the Dharwar
sediments into complicated wrinkles, creating a number of mountainranges, the most prominent among them being the mountain-chain
of the Aravallis. No such powerful crystal deformation, of equal
degree of magnitude, seems to have taken place since then in the
Peninsula, since all the succeeding systems show less and less disturbance of the original lines of stratification and of their internal
structures, till, at the end of the Vindhyan era, all erogenic forces
almost disappeared from this part of the earth.
Cuddapah system—A vast interval of time elapsed before the next
rock-system began to,be deposited, during which a great extent of
Dharwar land, together with its mountains*and plateaus, was cut
down to the base-level by a cycle of erosion. For it is on the deeply
denuded edges of the Dharwar rocks that the basement strata of the
present formation rest. This formation is kn'own as the Cuddapah
system, from the occurrence of the most typical, and first-studied,
outcrops of these rocks in the district of Cuddapah in the middle of
the Madras Presidency. The Cuddapah is a series of formations or
systems, rather than a single system, it being composed of a number of
more or less parallel series or groups of ancient sedimentary strata,
each of the thickness and proportion of a geological system by ijself.
They rest with a great unconformity, at some places on the Dharwars
and at ot^er places on the gneisses and schists, and themselves underlie with another unconformity the immediately succeeding Vindhyan
system of Central India.
Lithology of the Cuddapahs—This system is mainly composed of
much indurated and compacted shales, slates, quartzites, and limestones. The shales have acquired a slaty cleavage, but beyond that
there is no further metamorphism into phyllites or schists ; such
secondary minerals as mica, chlorite, andalusite, staurolite, garnets,
etc., have not been developed in them; nor are the limestones recrystallizcd into marbles, as in the Dharwar rocks. Quartzites, which
- 86
THE CUDDAPAH SYSTEM
87
fjie most common rocks of tfie system, are metamorphosed sandtones the metamorphism consisting of the introduction and deposi,• of secondary silica, in crystalline continuity with the rolled
uartz-grains of the original sandstone. Contemporaneous volcanic
rtion prevailed on a large scale during the lower half of the system,
the records of which are left in a series of bedded traps (lava-flows)
and tuff-beds. (See Fig. 7.) Besides the above rocks, the Lower
Puddapahs contain brilhantly coloured and banded cherts and
iaspera and some interstratified iron- and.manganese-ores, very much
hke those of the Dharwar system. In these two peculiarities, most
,
S.byK.
FIG. 7.—Sketch section illustrating the relation of Cuddapah and ICurnool
rocks (marked K).
,
Afer King, Mem. G.S.I., vol. vui. 1872.
noticeable in the lower part, therefore, the Lower Cuddapahs resemble the Dharwar system ; while the upper half, in its unmetamorphosed shales and limestones, shows a close resemblance to the
overlying Vindhyan rocks.
On account of the absence of any violent tectonic disturbance of
the Peninsula during later ages, the Cuddapah rocks have in general
low angles of dip, except towards the Eastern coast, where they form
a part of the Eastern Ghats (the Y^Uaconda range of hills), and where
consequently they have been subjected to much plication and overthrust. To account for the enormous thickness of the Cuddapah
sedimentsj which amounts to more than 20,000 feet in the aggregate,
of slates and quartzites, it is necessary to suppose that a slow and quiet
submergence of the surface was in progress all through their deposition,
which lowered the basins of sedimentation as fast as they were filled.
Absence of fossils in the Cuddapalis—The entire series of Cuddapah
rocks is totally unfdssiliferous, no sign of life being met with in these
vast piles of marine sediments. This looks quite inexplicable, since
not • only are the rocks true clastic sediments and not chemical
. precipitates, laid down on the floor of the sea and very well fitted to
contain and preserve some relics of the life inhabiting the seas, but
also all mechanical disturbances and chemical changes, which usually
88
GEOLOGY OF INDIA
obliterate such relics, are abseni from them. I t cannot again' be
surmised that life had not originated in this part of the world, since
in formations immediately subsequent to the Cuddapahs, and in areas
not very remote from them, we find evidence of fossil organisms,
which, though the earliest animals to be discovered, are by no means
the simplest or the most primitive. The geological record is in many
respects imperfect, but in none more imperfect than this—its failure
to register the first^beginnings of life, by far the most important event'
in the history of the earth.
Classificalaon—The Cuddapah system is divided into two sections,
an upper and a lower, separated by a great unconformity. Each of
these divisions consists of several well-defined series, whose stratigraphic relations to each other, 4iowever, are not definitely established, and which may be quite parallel or homotaxial to each other
instead of successional. '
Kurnool series (Lr. Vindhyan)
(
(
Kistna series—slates and quartzites—Kaladgi series
2000 ft.
11,000 ft.
Nallamalai series (Gumbum slates.
3i00 ft^
XBairenkonda quartzites.
Cheyair series—shales and quartzites. Bijawar series.
10,500 ft.
Papaghani series fVaimpalli slates.
XGulcheru quartzites. Gwalior series.
Aiohaean and Dharwarian.
Distribution—A large development of these rocks occurs in the
type area of Cuddapah district. The outcrop is of an irregular crescent
shape, the concave part of which faces the coast, the opposite'side
abutting on the gneisses. Another large development of the same
system is in the Central Provinces and in Chhatisgarh. A few isolated
exposures occur in the intervening area, while to the north-west they
occur on the east border of the AravaUis. A part of the zone of
metamorphosed sediments lying to the south of the central crystaUine
axis of the Himalayas can be referred to the Cuddapah system of
rocks, but they cannot be certainly identified as such, as in the case of
the representatives of the Dharwar and the succeeding Vindhyan.
The Lower Cuddapah—The Papaghani series. The lowest member
of the Cuddapah system takes its name from the Papaghani river, a
tributary of the Penner, in the valley of which these rocks are exposed.
THE'CUDDAPAH SYSTEM
89
The bottom beds are sandstones followed by shales and slates, with a
few limestone layers in the shales. Contemporaneous lava-ilows, with
intrusions of the same magma in the form of dykes and sills, are
common ; in the latter case, where the invading rock comes in contact with limestones, these are found to be converted into marbles,
serpentines, and talc.
Economically the slate and limestone series (Vaimpali slates) are
of importance, because considerable deposits of barytes and asbesto"s
occur in these rocks and their associated basaltic sills. (See p. 374.) *
The Delhi system—The Delhi system of strata referred to in the last
chapter is probably of Lower Guddapah age, though in its intense
structural disturbance and degree of.folding it departs from the
general tectonic features of this system. I t appears to be a locally
specialised type of the Cuddapahs owing its structural disturbance to
local orogenic flexures and also to the intrusion of large bodies of
granite and amphibolite. The Delhi system occupies a large extent
of E. Kajputana country extending from Delhi to Idar (Central India)
in constricted, sorely eroded bands in the centre of .the Aravalli
synclinorium. The Alwar quartzites, which constitute a prominent
part of the system", are quartzites, grits and flagstones. The Delhi
system is intruded by a varied series of basic rocks and by a series of
granite bosses and laccoliteSi—with their related group of pegmatites
and aplites, {Erinpura granite), covering a large area to the west of
the Aravalli range. -The Idar granite (granite, microgranite and
granophyre) occurs in a number of scattered masses at the south
extremity of the outcrop of the Delhi system. Over the whole of this
area the Delhi system exhibits violent unconformity with the Aravallis
at its base, while towards the newer Vindhyan terrain to the east its
relations are those of a great boundary fault, with a throw of over 5000
ft. Dr. A. M. Heron has classified the Delhi system as follows i
Semri series (Lr. Vindhyan) of Chitor
'AjabgarJi series : biotite-schist, phyllites, quartz-]
it^s and impure biotitic limestones and calci- j-5000 ft.
phyres - J
Delhi
Hornstone
breccia
:
of
variable
thickness.
,.
System
Kushalgarh limestone
1500 ft.
Alwar series : quartzites, arkose, conglomerates 110,000l
and mica-schists with bedded lavas - J 13,000 ft.
VrKonformity. ^ . - ^ _ ^ w - . . ^ ^ . - ^
--^—..Jlaialo
/Raialo hmestones and marble.
-Series \Raialo quartzites.
'
^
»A. L. Coulaon, Mem. 0.8J. vol. xliv. 1934.
90
GEOLOGY OP INDIA
The Bijawar series—The upper division of the Lower Cuddapah is
more widely developed, and occurs extensively at Bijawar, Cheyair,
GwaHor, etc. The Bijawar series'is composed of cherty limestones,
siliceous hornstones and ferruginous sandstones, haematite beds, and
quartzites, resting unconformably on the gneisses. But the most'
distinctive character of the Bijawar series is the presence in it of'
abundant products of contemporaneous volcanic action—ash-beds,
lava-flows and sills of a basic augite-andesite or basalt, now resting as
a number of interbedded green traps. The dykes of these lavas that
have penetrated the older formations are supposed to be the parentrock of the diamonds of India. The reputed " Golconda " diamonds
were mostly derived from a conglomerate mainly composed of the
rolled pebbles of these dykes. Wherever the andesitic lava of the
Bijawar series is subjected to folding and compression, it has altered
into an epidiorite.
An exposure of very similar character, occurring in the valley of
the Cheyair river, is known as the Cheyair series, while the one at
Gwahor, on which the town of Gwalior stands, forms the Gwalior
series. In the latter series there is a very conspicuous development.of
ferruginous shales, jaspers, porcellanites, and hornstones, associated
with the andesitic or basaltic lavas of Bijawar type. The porcellanite
and lydite-like rocks appear to have originated from the effects of
contact-metamorphism on argillaceous strata, while the preponderance of hornstones, cherts and other siliceous rocks points 'to the
presence of solfataric action, connected with the volcanic activity of
the period. Solfataras or hot siliceous springs come into existence
during the dechning stages of volcanoes; they precipitate large
quantities of silica on the surface, likewise bringing about a good deal
of silicification of the previously existing rocks by chemical replace- j
ment (metasomatism) in the underlying rocks. The lower division of i
the Gwalior series, resting upon the basement gneiss, is known as the
Par, and the upper is designated the Morar series. Dr. Heron regal-ds
the Gwalior series as an isolated outcrop of unmetamorphosed
Aravalli series which owe their horizontality and absence of riietamorphism to their distance from the main axes of folding of the
Aravalli range and their protection by the resistant mass of Bundelkhand gneiss upon which they rest.^
An outUer formed of identical rocks is seen in the valley of the
Pranhita, and is named Penganga beds. It must be understood that
the reason for giving these different local names to the different
Wem. G.8.L vol. Ixvjii. pt. 1, 1936.
THE CUDDAPAH SYSTEM
91
occurrences of wliat might ultimately prove to be t t e same division
of the Lower Cuddapah is the uncertainty, which is always present
in the case of unfossiliferous strata, of correlating them with one another
in the absence of any positive evidence. Such an arrangement is,
however, only provisional, and is adopted by the Geological Survey in
their explorations of new districts till the homotaxis of the different
exposures ds clearly established. The local names are then dropped,
and all the occurrences designated by a common name.
The Upper Cuddapahs—The Upper Cuddapahs rest unconformably over the rocks last described at a number of places. The most
important development is in the type area of the Cuddapah basin,
where it has received the name of the Nallamalai series, froni the
Nallamalai range of hills in which it is found. The component rocks
of the Nallamalai series are quartzites (Bairankonda quartzites) in the
lower part, and indurated shales and slates (Cumbhum slates) in the
upper. In the limestone beds that occur intercalated with the shales
there is found an ore of lead, galena.
The Kaladgi series—The Kaladgi series, another member of the
same system, is several thousand feet of quartzites, limestones, shales,
conglomerates and breccias, occupying the country between Belgaum
and Kaladgi in the Bijapur district. Towards the west they disappear
under the basalts of Deccan Trap age. The upper part includes
some haematite-schists, which include sometimes so much of haematite as to constitute a workable ore of iron. Besides the above
there are other localities where rocks of the Upper Cuddapah horizon
occur, viz. in the Kistna valley (the Kistna series); in the Godavari
valley (the PaTchal series, of 7500 feet of quartzites, slates and flinty
_ hmestone), and in Kewah.
Economics—The economic importance of the Cuddapah rocks lies
in some iron and manganese ores, ~interbedded with the shales and
slates. Numerous workable deposits of barytes and asbestos occur
among the Papaghanis in the Ceded Districts of the Madras Presidency (p. 374). Other products of some use are the bright-coloured
jaspers and cherts, which are used, when polished, in interior decoration and inlaid work; as in the old Mogul buildings. The Delhi system
contains some lodes of metalUc compounds. Most of the copper-ores '
and all the cobalt and nickel ores known in Rajputana are associated
with rocks of the Delhi system.
Stratigraphic position—The stratigraphic relations of the Cuddapahs
prove that they are fat younger than the Dharwar. On the other
hand, their thoroughly azoic nature, and the moderate degree of meta-
92
GEOLOGY OF INDIA
morphism they have undergone, show that the Cuddapahs are older
than the Vindhyan. In their lithblogical characters they show much
resemblance to the pre-Cambrian Algonkian system of North America.
In Holland's scheme of classification, as we shall see later on, the
Cuddapahs are grouped with the overlying Vindhyans as the Purana
group.
REFERENCES
W. King, Kadapah and Kamul Formations in Madras Presidency, Mem. Q.S.I.
vol. viii. pt. 1, 1872.
R. B. Eoote, Geology of Madras, Mem. Q.S.I, vol. x. pt. 1, 1873.
A. M. Heron, Geology of Eastern Rajputana;, Mem. O.S.I, vol. xlv., 1917-22, and
Geology of South-Eastem Mewar, Mem. G.S.I, vol. Ixviii. pt. 1, 1936,
CHAPTEE VI
THE VINDHYAN SYSTEM
Extent and thickness—The Vindhyan system is a vast stratified formation of sandstones, shales and limestones encompassing a thickness
of over 14,000 feet, developed principally in the Central Indian highlands which form the dividing ridge between Hindustan proper and
the Deccan, known as the Vindhyan mountains. They occupy a
large extent of the country—a stretch of over 40,000 square miles—
from Sasaram and Rohtas in Western Bihar to Chitorgarh on the
Aravalhs, with the exception of a central tract in Bundelkhand.
The outcrop has its maximum breadth in the country between Agra
and Neemuch.
Rocks. Structural features—The Vindhyan system is composed of
two distinct facies of deposits, one marine, calcareous and argillaceous, characteristically developed in the lower part, and the other
almost exclusively arenaceous, of fluviatile or estuarine deposition,
forming the upper system. The shale, limestone and sandstone strata
show very little structural displacement or disturbance of their
primeval characters ; they have preserved almost their original horizontality of deposition over wide areas ; the rocks show no evidence
of metamorphism, as one is led to expect from their extreme age, beyond induration or compacting. The shales have not developed
cleavage nor have the limestones undergone any degree of crystallisation. The only locality where the Vindhyan strata show any marked
structural disturbance is along the south-east edge of the AravalU
country, where they have been aifected by folding and overthrust due
to the crust-movements which succeeded their deposition, and their
internal mineral structure considerably altered, especially in the.case
of the freestones which have beconie quartzites. The epeirogenic upheaval which lifted up the Vindhyan deposits from the floor of the sea
to form a continental land-area was the last serious earth-movement
recorded in the history of the Peninsula, no other disturbance of a
similar nature having ever affected its stability as a land-mass
93
94
GEOLOGY OF INDIA
during the long series of geological ages that we have yet to
review. The Peninsula has remained an impassive solid block of the
lithosphere, unsusceptible to any folding or plication, and only
affected at its fringes by sHght movements of secular upheaval and •
depression.
1
Xhe Vindhyan sandstones throughout their thickness give evidence
of shallow-water deposition in their oft-recurring ripple-marked and
sun-cracked surfaces, and in their conspicuous current-bedding or
diagonal lamination, characters which point to the shallow Agitated
water of the coast, near- the mouths of rivers, and the constantly
changing velocity and direction of its currents.
Life—Except for a few obscure traces of animal and vegetable life
occasionally discernible in the Vindhyan system, and such plausible
evidences of the existence of life as are furnished by the presence of
thick Hmestone strata and beds of carbonaceous shales, glauconitic
sandstones, and some lenticles of bright coaly raatter (vitrain), occurring at the base of the Kaimurs at Japla, this vast pile of sandstones,
shales and hmestones is characterised by an almost total absence of
recognisable organic remains. The only fossils that have been hitherto discovered in these rocks are small carbonised, horny disCs,
1-3 mm., which are believed to-belong definitely to some fossil
organism; these have been found embedded in black shales at the
base of the Kaimur series (Suket shales) by Mr. H. C. Jones, near
Rampura, Central India. But the specimens are too imperfectly
preserved for specific or even generic determination and have been
variously identified by palaeontologists as minute horny valves of
primitive brachiopods, possessing aflinities with AcrotJiele or Neobolus and also as algal plant remains. These impressions or casts, •
while abundant at Rampura have not been observed elsewhere in the
same or overlying beds. Fucoid markings, belonging to indistinguishable thallophytic plants, are usually seen on the ripple-marked* and
sun-cracked surfaces of sandstones and shales.
Classification—The Vindhyan system has been divided into the
Lower and Upper divisions of very unequal proportion, but
justified by an unconformity between the two parts, quite apparent
at some places and non-existent at others, and also by a sharp
lithological contrast between the lower and upper portions of the
system.
The Lower Vindhyans show tectonic deformation by folding movements, while the Upper Vindhyans are generally lying in undisturbed horizontal strata.
h
D
THE VINDHYAN SYSTEM"
9S
Stages.
Series.
Upper Bhander sandstone
Sirbu shales.
Lower Bhander sandstone.
Bhander limestone.
Conglomerate-bed.
Upper Rewah sandstone.
Jhiri shales.
Upper
Lower Rewah sandstone.
Yindhyan
Panna shales.
Conglomerate-bed.
/-Upper Kaimur sandstone.
Kaimur conglomerate.
-; Bijaigarh shales.
Kaimur.
Lower Kaimur sandstone.
Suket shales.
Lower Vindhyan—
Semri Series • Kurnool Series • Bhima Series.
Malani Series of rhyolites and tuffs.
Granite bosses of Jalor and Siwana.
(
(
' Distribution of the Lower Vindhyan—The most typical, and at the
same time the most conspicuous, development of the system is along
the great series of escarpments of the Vindhyan range, from which the
system takes its name. The lower division is well displayed in the Son
valley, in Chhatisgarh and in the valley of the Bhima. The Lower
Vindhyans of theSon valley have been the subject of a, detailed study
by J. B. Auden, which throws light on conditions of sedimentation,
palaeogeography, climate and the question of the prevalence of life
at the time. He groups together 3000 feet of limestones, shales and
sandstones with interbedded porcellanites (silicified ash and tuffs),
glauconitic sandstones, and intrusive dolerites into the Semri series,
which conformably underlies the Kaimur series of the UpperVindhyan.
There are conglomerates, epiclastic breccias, and pebble-beds in the
Semris, which show the great variability and instability of physical
conditions of the period, in contrast with the striking uniformity of
deposition which persisted all through the Upper Vindhyan. In the
Bhima valley they constitute the Bhima series, composed of quartzites
and grits in the lower part and shales and limestones of varying
colours in the upper. Besting unconformably over the Cuddapah
system, in the district of Kurnool, there is a large outcrop of contemporaneous rocks, about 1200 feet in thickness, known under the name
of the Kurnool series (Fig, 7). The Kurnool series is interesting, as it
contains at the base a group of sandstones, some bands of which are
96
*
GEOLOGY OF INDIA
diamondiferous. These beds, known as the Banaganapalli beds, consist of coarse, earthy felspathic or ferruginous sandstones of a dark
colour. North of the Narbadq., the Lower Vindhyans are very well
exposed in the Dhar forest area. The Sullavai sandstones of the Godavari valley are a group of Lower Vindhyan sandstones and quartzites
resting unconformably on the PaJchal quartzites. The composition of
all these occurrences shows local variations in the rock-iypes, but in
the main conforms to the argillaceous and calcareous nature of the
system. Some of the Hmestones show a concretionary structure, the '
concentric layers exhibiting different colours and giving to the polished
rock a beautiful marble-like appearance. The limestones of the Lower
Vindhyan formation are extensively drawn upon for burning as well
as for building purposes. The Eohtas limestone of the Shahabadk
district is especially valuable for lime and cement manufacture, and
is largely quarried.
/
The Malani series—The Lower Vindhyan rocks of Western Eajputana deserve special notice. Eocks which may be correlated to this
system show there a very much altered facies, being- composed of a
group of rhyolitic lavas with abundant pryoclastic material, resting
unconformably on the Aravalli schists. This volcanic series is k'nown
as the Malani series, from the district of that name (near Jodhpur in
Marwar). The Malani rhyelites cover some thousands of square miles
around Jodhpur. They are partly glassy, much devitrified, amygdaloidal lavas largely interstratified with tuffs and volcanic breccia. «
The lavas vary in acidity from rhyolites to quartz-andesites. In the
majority of cases they have undergone such an amount of devitrification that they appear almost as felsite, the glassy ground-mass having
completely disappeared. An outcrop of the Malani series composed of
felsitic rhyolites and tuffs occurs, remote from the AravalUs, in the
plains of Northern India, in the Sangla hill in the Punjab, a sniall
highly eroded outlier of the Aravalli chain. ^ - In the Vindhyan terrain
of S.E. Mewar the Malani volcanics and the Semri series are,,represented by a group of limestones, shales and sandstones with breccias
and conglomerates.
Connected with these lava-flows, as their subterranean plutonic
roots or magma-reservoirs which supplied the materials of the eruptions, are bosses of granite, la.id bare by denudation, in some parts of
Rajputana. Two varieties of granite are recognised in them—one,
hornblende-biotite-granite (Jalor granite), and the other, hornblendegranite {Siwana granite). The latter boss 'shows distinctly intrusive
» Esc. G.S.L vol xliii. pt. 3, 1913.
THE VINDHYAN SYSTEM
97
relations to both the Malani series and the Aravalh schists ; it rises to
a height of nearly 3000 feet above sea-level.
'
Meaning of " Lower " and " Upper " System—The Lower Vindhyan
is separated from the Upper by an unconformity that is very apparent
in the north but which tends to disappear in the south areas of
Mewar, Chitor and the Son valley. This signifies that earth-movements supervened after the deposition of the Lower Vindhyan sediments which elevated them into land in the Aravalli sirea of the north
and put a stop to further sedimentation in these aresis. When, after
re-submergence, deposition was renewed, an interval of time had
elapsed, during which the former set of conditions disappeared, and
the mountains and highlands which yielded the detritus changed
completely. Such earth-movements, causing cessation of deposition
in a particular area, with a change in the physical conditions, are at
the root of stratigraphic divisions. Smaller and more local breaks in
the continuity of a stratified succession have led to its further subdOTsion. into series and stages. "While •profouQ.det changes, accompanied by more pronounced alterations of land and sea, affecting the
inter-continental and inter-sea migrations of life inhabiting them,
determine the limit between system and system.
Upper Vindhyan—In their type-area, north of the Narbada, the
Upper Vindhyan sandstones consist of three well-marked divisions
(^®™^) •
rUpper Bhander sandstone.
Sirbu shales.
Bhander series - \ Lower Bhander sandstone.
Bhander limestone.
.Ganurgarh shales.
Diamondiferous beds.
Upper Rewah sandstone.
Jhiri shales.
Lower Rewah sandstone.
Panna shales.
Diamondiferous beds.
Upper Kaimur sandstone.
Kaimur conglomerate.
Bijaigarh shales.
Kaimur series Lower Kaimur sandstone.
Suket shales.
The East India Railway from Katni to Allahabad runs through the
heart of the Vindhyan country and thence up to Dehri-on-Son,
passes along its north-eastern margin, without ever leaving sight of the
outcrops of horizontally bedded red or buff sandstones. Another
(
W.Q.I.
Q
98
GEOLOGY OF INDIA
Vindhyan province lies in Central InSia, and on the eastern borders of
the AravaUi chain. This country is also crossed by the railway from
Jhalra Patan to Bharatpur, -which almost constantly keeps within
sight of, or.^ctually meets, a series of illustrative outcrops of the
system. Prevalence of arid, continental conditions in the Upper
Vindhyan times is suggested by the perfect,rounding of quartzgrains in the majority of the sandstones and also by the prevailing
red and brown colours of the sediments and by the occasional pres-,
ence of gypsum in the Bhander shales.
The junction of the Upper Vindhyans with the older rocks of the
Aravallis, at their north-west extremity, reveals an extremely long
fault of great throw, which has brought the undisturbed, almost horizontal strata of the Vindhyan sandstone in contact with the highly
FIG. 8.—Section showing relation between Gwalior series and rocks
of the Vindhyan system (after Oldham).
4. Vindhyan (Kaimur) sandstone.
3. Kaimiir conglomerate.
2. Gwalior series (Par sandstone),
1. Bundelkhand gneiss.
folded and foHated schists of the Aravallis. This great fault is roughly,
parallel with the course of the river Chambal and can be traced from
the western limit of the outcrop as far north as Agra. I t is probable
that this junction is not of the nature of an ordinary fracture or dislocation, but marks the approximate limit of deposition of the jFoung^
Vindhyan sandstone against the foot of the Aravallis, which was modified subsequently by faulting and thrusting. The fault, therefore, is
of the nature of a " Boundary Eault", which recalls the much better
known case of the junction of the younger with the older Tertiaries of
the Himalayas. (See Siwalik System, Chapter XX. p. 264.)
Vindhyan sandstones—Sandstones are by far the most common
rocks throughout this division with the exception of the lower Bhander
stage, which is for the greater part calcareous. The sandstones are of
a uniformly fine grain, preserving their uniformity of texture and
composition unchanged for long distances. The colours are variegated shades of red, yellow or buff, or grey, while they are often
THE VINDHYAN SYSTEM
99
mottled or speckled, owing to the variable dissemination of the
colouring matter, or to its removal by deoxidation. The Kaimnr as
well as the Bhander sandstone is a fine-textured, soft, easily workable
stone of a deep red tint, passing now and then into softer shades of
great beauty. These sandstones are available for easy quarrying in
any quantity in all the localities mentioned. No other rock-formation
of India possesses such an assemblage of characters, rendering it so
eminently suitable for building or architectural works. When thinly
stratified, the rock yields flags and slabs for paving and roofing purposes ; when the bedding is coarse, the rock is of the nature of freestone, and large blocks and columns can be cut out of it for use in a
number of building,and architectural appliances.^
Shales are sparsely developed in the Upper Vindhyan division, and
are of local occurrence only. They are often carbonaceous. At other
times they are siliceous or calcareous. They are distinguished under
various names, such as Bijaigarh shale, Panna shale, Jhiri shale, etc.,
from their localities.
Economics—The Upper Vindhyans are remarkable for their .enclosing two diamond-bearing hojiMns of strata, one lying between the
Kaimur and the Rewah s e r i ^ the other between the latter and the
Bhander series. The historically famous Panna and Golconda diamonds were mined froni these beds, from one or two small productive
patches. The country-rock is a conglomerate containing water-worn
pebbles of older rocks,' aWong which are pebbles of the Bijawar
andesite already alluded to, which is conjectured to be the original
matrix in which the> diamonds had crystallised. The Vindhyan
system is not possessed of any metalliferous deposits, but is rich in
resources of building materials, which furnish an unlimited measure
of excellent and durable freestones, flagstones, ornamental stones, and
large quantities of limestones for the manufacture of lime and cements.
The Bhander stage has yielded materials for the building of some of the
finest specimens of Indian architecture. The economic aspects of the
Yindhyan rocks are dealt with in the chapter on Economic Geology.
Himalayan Vindhyans—The extra-Peninsular representatives of the
Vindhyans, and probably also of the Cuddapahs, are surmised to be
largely present in the belt of unfossiliferous sedimentary rocks that
hes between the crystalline rocks of the central and the younger
rocks of the outer Himalayas. It is a question how far they are
homotaxial with the Vindhyans, or with the Raialos or the Delhis of
Rajputana. They are designated by various names in the different
» See Chapter XXVI.—Building Stones.
100
GEOLOGY OF INDIA
parts of the mountains. Near Peshawar they form a large outcrop
of dark slates (the Attack slates), with a few limestones and sandstones
here and there permeated with 'trappean intrusions ;. in Hazara also
there is a large outcrop of black unfossiliferous slates. A prominent
belt of slates and associated rocks occurs in the south-west flank of
the Pir Panjal and Dhauladhar ranges of the Kashmir Himalaya.
This series has been named the Dogra slates. In the Simla area the
Vindhyan is probably recognised in a thick series of dark unaltered '
slates and micaceous sandstones under the name of Simla slates.
The Simla slates are succeeded after a pronounced hiatus, indicating
either an unconformity or a thrust-plane, by a group of banded slates,
sandstones and pebbly quartzites, named the Jaunsar series. North
of Chakrata, rocks of this age, forming the peak of Deoban, are known
as the Deoban series. They consist of extremely compact grey dolomite and limestones with cherty concretions. Near Darjeeling, the
Western Duars and the foot-hills of Bhutan, they constitute the Baxa
series of quartzites, slates and dolomites occurring in bands between
the Daling outcrop and the Gondwana strips of eastern sub-Him-,
alayas. All these Vindhyan rocks of the Himalayas are distinguished
from the Vindhyan of the Peninsula by the scanty development in
them of the arenaceous facies and the predominance of argillaceous
elements ; also, as is quite obvious, they are much folded, compressed
and inverted by being involved in the severe flexures of the mountains. As a rule these older rocks overhe the younger members of the
sub-Himalayan zone along a plane of overthrust—this being the most
persistent feature of the structure of the Outer Himalayas from the
Punjab to Assam (see p. 310).
The relation of the Himalayan unfossiliferous systems to the Peniasular Puranas—It is the beUef of the Indian Geological Survey, first
promulgated by Sir T. H. Holland, that these old unfossiliferous
formations developed on the south of the central Himalayan axS^
representing the Dharwar, Cuddapah and Vindhyan systems pf the
Peninsula, are only the northern outHers or prolongations of the respective Peninsular systems, which were once continuous and connected before the Himalayan area became demarcated from the
Peninsula by the upheaval of the Himalayan chain and the concomitant formation of the deep Indo-Gangetic depression. During these
movements the extra-Peninsular extensions of the Dharwar, Cuddapah and Vindhyan systems were caught up in the Himalayan system
of flexures, while their " Peninsular congeners " were left undisturbed.
The behef receives strong confirmation from the fact that on the
THE VINDHYAN SYSTEM
101
northern side of the central axis, viz. the Tibetan, there is an altogether different sequence of strata from that occurring on the Indian
side, being composed of marine fossilifeious sediments of almost every
geological age from the Cambrian to the Eocene. This total difference
in the facies of the deposits of the two sides of the chain suggests the
prevalence of altogether different physical and geographical conditions in them, and indicates that the two areas (Tibet and India) were
from the earliest times separate and underwent an altogether different
geological history.
Homotaxis—With regard to the homotaxis of the Vindhyan system
there exists some difference of opinion. From its lithological agreement with the fossiliferous Cambrian of the Salt-Range, Vredenburg
has considered it to be Cambrian in age, while Sir T. H. Holland
regards all the unfossiliferous Peninsular formations resting above the
Archaean-Dharwar complex as pre-Cambrian, occupying much the
same position as the Torridon sandstone of Scotland, overlying the
Lewisian gneisses, and groups them in his Purana group. The Puiana
group of this eminent author includes the unmetamorphosed but
more or less disturbed and folded rock-system that intervenes between the crystalline Archaean and the fossiliferous younger systems
of the Peninsula. The Purana group thus forms a sort of transition
between the foliated and the highly metamorphosed Dharwar and
Archaean gneisses and the fossili|efous Palaeozoic strata. They include the major part of whatj-itfthe early days of Indian geology, was
called the Transition System. ' The discovery of the few undoubted
organic remains and rock-aggregates suggestive of the action of life,
both in the Lower and Upper Vindhyan now lifts this rock-system
from the pre-Cambrian to an indefinite horizon in the Cambrian.
Future discoveries of fossils may prove that the upper part of the
hitherto barren Puranas of parts of the Himalayas are really Lower
Palaeozoic and owe their generally unfossiliferous character to accidental circumstances.
We have seen in Chapter IV that the same author has linked the
Dharwar with the Archaean system, recognising, in the unconformity
that separates the former from the Puranas, a far wider significance
and more extensive lapse of time than in that which separates the
Archaean from the Dharwars.
The following table shows in outline the scheme of classification of
the Indian formations adopted by the Geological Survey of India.
The classification of the post-Purana systems is based upon the recognition of the two_ most profound breaks in the continiiity of that
102
GEOLOGY OF INDIA
series of deposits. These breaks or " lost intervals " have a fundamental meaning in the geological history of India ; they denote
periods of great crust-movements and erosion, and m a r k t h e commencement of new eras of life a n d Sedimentation. The firgt break
was subsequent t o the Vindhyans, and is universally observed in both
the Peninsula and t h e extra-Peninsula. The other is a soniew'hat less
pronounced break a t t h e base of the Permian in the extra-Peninsula.
I n all t h e other areas of India, t h e post-Vindhyan break is t h e most
momentous a n d universal, a n d comprehends a long cycle of unchronicled ages from t h e Vindhyan t o t h e Permo-Carboniferous.
Eecent
t
Productus Series and Talchir
Series {Permian).
Aryan.
Palaeozoic unconformity.
Fossiliferous.
Po Series
t
(Lower to MidCarboniferous).
Dravidian.
Haimanta System (Cambrian).
Post-Vindhyan break.
t
Vindhyan System
t
Cuddapah System.
Purana.
Eparchaean
Unconformity.
Unfossiliferous.
Dharwar System
and
Archaean System.
Archaean.
REFERENCES
R. D. Oldham, Geology of Son Valley, Jabalpur, etc., Mem. G.S.I, vol. xxxi.
pt. 1, 1900.
T. H. D. La Touohe, Geology of Western Rajputana, Mem. O.S.I, vol. xxxv. pt. 1,
1902.
A. M. Heron, Oeography and Oeology of the Himalaya, pt. 4, (Second Edition), 1934.
Sir T. H. Holland and G. H. Tipper, Mem. O.S.I, vol. xliii. pt. 1, 1913 and
(Second Edition) vol. li. pt. 1, 1926, Archaean,—Dharwar—Purana.
A. M. Heron, Geology of S.E. Rajputana, Mem. O.S.I, vol. xlv. pt. 2, 1922;
Mem. vol. Ixviii. pt. 1, 1936.
J. B. Auden, Vindhyans of the Son Valley, Mem. G.S.I, vol. Ixii. pt. 2, 1933.
C ^ A P T E E VII
THE CAMBRIAN SYSTEM
The Cambrian of India—Marine fossiliferous rocks of Cambrian age
are found in a thick series of strata a t three places in the extraPeninsula, each of -s^hich deserves a separate description. The first
and the most easily accessible locality is the Salt-Raiige in the northwest Punjab ; the other is the remote district of S ^ t i in t h e northern
Himalayas, in t h e province of Kumaon, beypad the crystalline axis
of the Himalayas. The third area is t h e Baramula district of Kashmir. These rocks contain well-preserved fossils, and hence their age
is no longer a m a t t e r of conjecture or hypothesis, as was the case with
the Peninsular formation last dealt with.
[ The Salt-Range—The Salt-Range is the most important locality in India,
for the study of physical as well as stratigraphical geology. Since very
early times it has attracted the attention of geologists, not only because it
contains a very large portion of the fossiliferous stratified record of the
Indian region, but because of the easily accessible nature of the deposits
and the clearness with which the'various geological formations are exposed
in its hills. Besides the stratigraphical and palaeontologioal interest, there
is inscribed in its barren cliffs and dried guUies such a wealth of geodynamical and tectonic illustrations, that 'this imposing Hue of hills can
fitly be called a field-museum of geology. The Salt-Range is a continuous
range of low, flat-topped mountains rising abruptly out of the flat Punjab
plains. The range extends, from long. 71° E. to 74° with an approximately
east-west strike, from the Jhelum westwards, through the Indus, to a long
distance beyond it, undergoing where it crosses the Indus a deep bend of
the strike to the south-west. In all essential structiiral, stratigraphical as
well as physiographic features the Salt-Range o'lfers p, striking contrast to
the north-western portion of the Himalayas, which rise hardly fifty miles to
north of it. The two mountain-ranges thus belong to a different orographic
system altogether. The prominent structural pecuharity of the Salt-Range
is the more or less level plateau-top, ending abruptly on the one side in a
long line of steep escarpments and chffs overlooking the Punjab, and on the
other northern side inclining gently towards and merging into the high
Potwar plains, which represent a synclinal trough between the Salt-Range
and the Rawalpindi foot-hills, filled up by Tertiary deposits. The general
dip of the strata is to the north direction, from one end of the range to the
other. Thus, it is on the north border that the youngest Tertiary rocks of
103
104
GEOLOGY OF INDIA
the mountains are seen, inclining away from the steep escarpment, while it
is in these steep escarpments that the oldest Palaeozoic formations are
exposed. The line of high precipitous chffs is intersected by a number of
deep gullies and ravines, some of them deserving the name of canons,
affording sections which distinctly ireveal the inner architecture of the'
range, as well as the details of its stratigraphy. There is little vegetation,
or covering of decomposed rock or soil to hide the details of these sec-tions. Extensive heaps of talus or scree-deposits are seen all along the
southern foot of the range at the base of the bold bare cliffs.
The entire length of the range is faulted in a most characteristic fashion
by a number of. transverse dip-faults into well-marked blocks (blockstructure). (Fig. 9.) These clean-cut faulted blocks are so conspicuous to.
Chambal Hill Stn.
Hills towards Darapur
13
Fla. 9.—Section illustrating the general structure of the Salt-Eange
(Block-faults). Section over Chambal Hill (East).
12-13. Siwahk sandstones and clays (Upper Tertiary).
1. Salt-marl and gypsum (Eocene)i
a. Dolomite bed in Salt-marl.
4. Magnesian sandstone"!
3. Neobolus beds
WCambrian).
2. Purple sandstone J
Wynne, Mem., G.S.I., vol. xiv.
one who looks at the range from the plains, that they can be separated out,
and the main elements of their composition recognised, from great distances.
At many places the faults are of the reversed type, sometimes intensified into
thrust-planes, which have introduced a great deal of compUcation into the
structure and stratigraphy of the area. (See Figs. 9,10, 14 and 23.)
The name Salt-Range is aptly derived from the circumstance that its
lowest, bottom rock contains large beds or lenses of pure common s^t, alW
throughout its extent. In this way an immense-quantity of rock-salt is
embedded and available for extraction in all parts of these mountain^.]
The Salt-Range Cambrian—At t h e eastern extremity of the SaltE a n g e a thick stratified series of rocks occurs in a conformable
sequence. They are sub-divided into the following groups in the
order of super-position (Fig. 1 0 ) :
„ J,
J
7 7,
[Bright red or green flaggy argillaceous
Salt^seudomorph shales : J ^eds, with cubic clay pseudomorphs
*^0 tt.
(^ j,f salt-crystals.
Magnesian-sandsfone:
jLaminated white or cream-coloured
250 ft.
\ sandstones, often dolomitic.
M • cn «n (o
z
z
Oh
1- 0
\0-l
•a
ik
o
-2
1 1
l\
11
5 *g
-^
~o
E
1
li
111
" f
ll!i
';;/.'^
-i-
lOG
GEOLOGY OF INDIA
("Grey or dark-coloured shales containJ jjjg braohiopods, trilohites, gastro[ pods, etc.
Neobolus shales :
100 f*„ ,
,,
Purp^^andstone.
•
f Dark red or purplist-brown wellI ^^^^^^ sandstones with maroon{ coloured shales at the base.
Stiff' clay or marl, mainly dark-red
and vermiHon, with abundant gypsum and salt, and thin beds of dolomite.
i
The Saline Series—The age of the lowest group, composed of saltmarl, gypseous marl, salt, gypsum, and dolomite presents a difficult
problem which has long been one of the major controversies of Indian
geology. The boundary between the Saline series and the overlying
Purple sandstone is much disturbed and is undoubtedly not a regular
one. This fact has been interpreted in different ways; one view is
that this disturbed boundary is merely the result of differential movement between two very different types of rock—the very " competent " Purple sandstones, and the soft, plastic, and " incompetent "
beds of the Saline series ; another interpretation stresses the effects
of solution of saline inaterial and suggests that this has led to the
severe disturbance and brecciation noticeable wherever the Saline
series is in contact with other rocks. A widely different interpretation has been put forward by several geologists and is supported by
the recent work of E., R. Gee. It is that the apparent infra-Cambrian
position of the Saline series is due to a large overthrust and that the
salt-marl and associated beds are really of Eocene age. Gee has
established beyond all doubt that the large masses of gypsum in the
western part of the main Salt-Range—where it borders on the Indus
valley—are of Laki (Eocene) age, and although the age of the gypsum
and salt of the central part of the range cannot be directly established
in the same way, it seems a reasonaljle assumption that it is of.the
same age as the gypsum and associated beds^a-short distance further
north-west. We shall therefore discuss the salt-marl in Chapter
xyii.
The purple sandstone—Overljdng the salt-marl, but in a most
irregular and mechanically disturbed manner, is a series of purple oi
red-coloured sandstones. The junction-plane between the two series
of strata is so discordant that the marl appears to have intruded itseli
into the lower beds of the Purple sandstone. The Purple sandstone is
a red or purple-coloured series of sandstone-beds. I t is a shallow-
THE CAMBRIAN SYSTEM
107
water deposit, as can be seea from the frequency of oblique lamination,
ripple-marks and sun-cracks, and such surface-marks as rain-prints,
wdrm-burrows, fucoid impressions, etc. The lower beds are argillaceous, being known as the " Maroon " shales, gradually becoming
more arenaceous at the top. Worm-tracks and fucoid marks are the
only signs of life in these rocks.
Neobolus beds^This stage is succeeded by the most important beds
of the system, a group of dark micaceous shales with white dolomitic
layers, known as the Neobolus beds, from their containing the fossil
brachiopod Neobolus. Other fossils are Discinolepis, SchizophoUs,
Lahhmina, Lingula, Orthis, Conocephalites, Redlichia (a trilobite resembling Olenellus) and the doubtful mollusc, Hyolithes. The
brachiopods and trilobites resemble those of the Cambrian of Europe,
and hence the Neobolus beds stamp the whole connected series of
deposits as Cambrian. This division of the Cambrian of the SaltRange is well displayed in the hill surmounted by the old Khusak
fortress in the neighbourhood of Khewra.
Ma'gnesian sandstone stage—Overlying the Neobolus beds is the
magnesian sandstone stage, a sandstone whose matrix is dolomitic,
and imparts to the rock its white or cream colour. There are also
some beds of dolomite, among which are a few oolitic or pisolitic
bands. Some of the beds in this group are very finely laminated.
Sometimes a hundred laminae can be counted in the thickness of an
inch. When showing oblique lamination and minor faulting in handspecimens, they form prize specimens in a student's collection. The
only fossil contained in these rocks is Stenotheca, H lower Cambrian
mollusc, besides a few unrecognisable fucoid and annelid -markings.
Salt-pseudomorph shales—The Salt-pseudomorph shales are bright
red and variegated shales with thin-bedded sandstones. The name of
the group is derived from the numerous pseudomorphic casts of large
perfect crystals of rock-salt very prominently seen on the shalepartings. I t is evident that these strata were lormed on a gently
shelving shore which was laid bare at each retreating tide. In the
pools of saltwater left on the bare beach crystals of salt would be
formed by evaporation, which would be covered up by the sediments
brought by the next tide. The cavities left by their subsequent dissolution would be filled up by infiltrated clay.
Trans-Indus Cambrian—In the west of the Salt-Range, in the transIndus area, the Cambrian beds are seen near Saiduwali in the KirriKhasor range. The lowest beds are the Purple ^sandstones of the
Salt-Range succession but higher in the sequence there are massive
108
GEOLOGY OF INDIA
gypsum, dolomite, and bituminous shale; the facies thus differs
somewhat in lithology from the corresponding beds in the upper part
of the Cambrian sequence of the Salt-Eange.
THE CAMBRIAN OF SPITI
In the Spiti valley ^ lying amid the north-eastern ranges of the
Kangra district, and in some adjoining parts of the central Himalayas,
a very complete sequence of fossiliferous Palaeozoic and Mesozoic
strata is laid bare, in which representatives of all the geological
systems, from Cambrian to Eocene, have been worked out in detail
by a number of geologists since the middle of the last century.
The Spiti area, the classic ground of Indian geology, which will
recur often in the following pages, is in general a broad synclinal basin
(a Geosyndine) which contains the stratified deposits of the old Himalayan sea representative of the ages during which it occupied the
northern Himalayas and. Tibet.
The axis of the syncline is north-west-south-east, in conformity
with the trend of the Himalayas. The youngest Mesozoic formations
are, obviously, exposed in the central part of the basin, while the
successively older ones are laid bare on the flanks, the oldest, Cambrian, being the outermost, i.e. towards the Punjab. The dip of the
latter formations is northerly in the main, i.e. towards the interior.
All these formations are fossiliferous, the fossils being the means of a
very precise correlation of these systems with those of Europe. The
student should consult Dr. Hayden's memoir on the geology of Spiti.^
Hayden's researches have contributed a great deal in elucidating
the Palaeozoic geology of this region.
The Cambrian of Spiti. Cambrian fossils—The Cambrian of Spiti
rests over the highly metamorphosed pre-Cambrian series of schists
(the Vaikrita series), which in turn are underlain by what have bepn
regarded as the Archaean gneisses. They are- a great thickness of
highly folded and disturbed sedimentary strata comprising the whole
of the Cambrian system—Lower, Middle and Upper. The system has
been named Haimanta, from its occurrence in high snow-capped
peaks. The component rocks are principally siliceous and argillaceous rocks such as slates and quartzites; the latter occupy the base,
' The Spiti river is a tributary of the river Sutlej, running N.W.-S.E. in a tract of
mountains which form the boundary between N.E. Punjab and Tibet. (Lat. 32° 10' N.,
Long. 78° E.)
^Mem. O.S.I., vol. xxxvi. pt. 1, 1909. »
THE CAMBRIAN SYSTEM
109
followed by red and black slates, with much enclosed haematite in the
former and carbonaceous matter in the latter. At the top are again
siliceous slates and shales interbedded with dolomite. The upper
portion of the group, constituting a thickness of some 1200 feet, is
fossiliferous. A fairly abundant Cambrian fauna has been discovered
in them, of which trilobites form the chief element. The following are
the leadii^g genera: Olenus, Agndstus, Microdiscus, Ptychoparia
(many species) and Dicellocephalus. Among the other fossils are the
brachiopods Lingulella, Obolus and Obolella, and a few crinoids and
gastropods (Bellerophon). The species of the above-named genera
of fossils show clear affinities with the European Cambrian forms.
The most complete development of these strata is exposed in the
valley of the Parahio, a tributary of the Spiti river. (See Fig. 11, p. 113.)
Autoclastic conglomerates—Some conglomerate layers among the
slates are of interest because of their uncommon mode of origin.
They are not ordinary clastic conglomerates of sedimentary deriva-,
tion, but, according to Dr. Hayden, they are of "autoclastic" origin/
i.e. they are produced by the crushing of veins of quartz into more^or
less rounded fragments or lenticles scattered in a fine-grained micaceous matrix, representing the original material of the veins.
CAMBRIAN OF KASHMIR
Fossiliferous Cambrian rocks are developed on a large scale in the
mountains of the Baramula district of Kashmir to the north of the
Jhelum, forming a broad irregular band on the north limb of the
Palaeozoic basin of Hundawar. Several thousand feet of clays,
greywackes and shales with quartzite-partings, full of annelid tracks
and pipes, conformably succeed the Dogra slates and in turn pass
upwards into an equally thick series of massive clays of bright blue
colour and grey and green sandy shales with limestone lenses and
intercalations. Fossil brachiopods and trilobites occur sporadically
in the upper series, which on palaeontological grounds is determined
to be of Middle and Upper Cambrian age, while the lower group with
indeterminate annelid and Vermes is probably Lower Cambrian.
Sixteen genera of trilobites, almost all the species of which are new
to India, have been determined by Dr. Cowper Reed. The principal
fossil genera are :
(Trilobites) Agnostus, Microdiscus, Conocoryphe, TonJcinella, Anomocare, Chaungia, Hundwarella; (Brachiopods) Obolus, Lingulella,
Acrothele ; (Pteropod) Hyolithes ; (Cystoid) Eooystites.
110
GEOLOGY OF INDIA
This fauna is strictly provincial in character, showing no similarities
at all with the adjacent Cambrian life-provinces of the Salt-Range,
Spiti district, or Persia.^
REFERENCES
A. B. Wynne, Mem. 0.8.1. vol. liv., Geology of the Salt-Range, 1878.
C. S. Middlemiss, Rec. O.S.I, vol. xxiv. pt. 1, 1891.
H. H. Hayden, Geology of Spiti, Mem. 0.8.1. vol, xxxvi. pt. 1, 1904.
F. B. C. Reed, The Cambrian Fossils of Spiti, Palaemitologid Indica, Series XV.
vol. ii. mem. 1, 1910; Cambrian and Ordovioian Fossils of Kashmir, Pal.
Ind. New Series, vol. xxi. mem. 2, 1934.
' D. N. Wadia, Cambrian Trias Sequence of N. W. Kashmir, See. 0.8.1. vol. Ixviii.
pt. 2, 1934,
CHAPTEE VIII
>
THE SILURIAN, DEVONIAN AND LOWER CARBONIFEROUS
SYSTEMS
General—These great groups of Palaeozoic strata do not occur at all in
the Peninsular part of India, while their occurrence in the extra-Peninsular area also, with onp exception, is outside the geographicaFUmits
proper of India, and confined to the northernmost b o r d ^ of the
Himalayas and to Upper Burma. In the Peninsula there exists, between the Vindhyan and the next overlying (Upper Carboniferous)
deposits, a great hiatus arising from a persistent epeirogenic uplift of
the country during the ages that followed the deposition of the
Vindhyan sediments. The absence from India of these formations,
constituting nearly three-fourths of the Palaeozoic history of the
earth, is quite noteworthy, as it imparts to the Indian geological
record, especially of the Peninsula, a very imperfect and fragmentary
character. The Himalayan occurrences of these rock-groups, referred
to above, are restricted also to the northernmost or Tibetan zone of
the Himalayas, where a broad belt of marine fossihferous sedimentary
rocks extends from the western extremity, Hazara and Kashmir,
through Spiti, Garhwal and Kumaon, to Nepal and even beyond, and
in which representatives of almost all the rock-systems from Cambrian
to Eocene are recognised.
1. SPITI AEEA.
(Eig.
11.)
Silurian—Overlying the beds of the Haimanta system in all parts of
Spiti there are a thick series of red quartzites and grits underlain by
conglomerates, and passing upwards into shales with bands of limestone and dolomite. The accompanying table shows the relations of
the Silurian system of Spiti with the overlying and underlying formations (see Fig. 11) :
111
112
GEOLOGY OP INDIA
Devonian.
Upper Silurian.
Lower Silurian
or Ordovician.
Cambrian:
Muth Quai'tzite.
Grey coloured siliceous limestones.
Coral limestone.
Shaly limestones with brachiopodSj
corals and gastropods.
Hard-grey dolomitic limestones.
Dark and grey limestones with cystidea,
braohiopods and trilobites.
Shales and flaggy sandstones and quartzites.
Thick mass of pink or red quartzite, gritty
unfossiliferous coarse conglomerates.
2000 ft.
Haimanta black shales and slates.
The lower, arenaceous, beds are unfossiliferous, but the upper shaly
and calcareous portion has yielded numerous fossil brachiopods,
cystidea, crinoids, corals and trilobites. Of these the most important
genera are : (Trilobites) Cheirurus, Illaenus, Asaphus, Calymene and
Bronteus; (Brachiopods) Orthis,. Strophomena, Leptaena, Atrypa,
Pentamerus (?); (Corals) Favosites, Holysites, CyatJiophyllum,
Syringopora and Chaetetes ; (Hydrozoa) Stromatopora ; (Gastropods)
Bellerophon and Pleurotomaria ; (Cystoids) Pyrocistites and Craterina.
The above-named genera bear close zoological relations to those obtained from the Silurian of England and Europe, a relationship which
extends also to many of their species, a certain number of them being
common.
Devonian—Resting over the Silurian beds is a thick series of white
hard quartzites, which are quite unfossiliferous, whose age therefore,
whether Upper Silurian or Devonian, is a matter of uncertainty.
Since it rests directly over distinctly fossiliferous Silurian beds and
underlies fossiliferous strata of undoubted Lower Carboniferous
horizon, its age is inferred with a high degree of probability to^be
Devonian, in part at least. This quartzite is known as the Muth
quartzite from its occurrence very conspicuously on the pass of that
name in Spiti. Dr. Hayden is inclined to consider the Muth quartzite
as partly Silurian and partly Devonian. "The beds immediately
underlying the Muth quartzite contain Pentamerus oblongus, and are,
therefore, of Llandovery age. As there is no unconformity here, the
overlying beds, at least in part, must, therefore, belong to the Silurian.
As the Muth quartzite merely represents an old sandstone, and is
therefore probably deposited fairly rapidly, the odds were in favour
THE SILURIAN AND DEVONIAN SYSTEMS
of tlie whole of the Muth quaitzite being Silurian. I t is, however,
usually regarded as partly Silurian *
and partly Devonian." K The
Muth quartzites, together with an
overlying group of hard siUceous
limestone, some 300 feet in thickness in the neighbouring locality
of Bashahr, may be taken to
represent in part at least the
Devonian Age in the Himalayas.
Carboniferous. Lipak series—
The Muth quartzite is overlain
by a thick series of limestones"
and quartzites more than 2000
feet in thickness. The limestones
are hard," dark-coloured and
splintery. They are, however,
very proHfic in fossils, the fossiliferous bands alternating with
white and grey barren quartzites.
This series is known as the Lipak
series, from a typical outcrop 4n
the Lipak valley in the eastern
part of Spiti. The fossils are
characteristic Lower Carboniferous organisms belonging to such
brachiopod genera as Produdus
(sp. cora and semi-reticulatus),
Chonetes, Alhyris (sp. roysii),
Syringothyris
(sp. cuspidata),
Spirifer, Reticularia; (Lamellibranchs) Conocardium, Aviculopecten, the Carboniferous trilobite
PhilUpsia; (Cephalopods) OrthocerasundPlatyceras; (Gastropods)
Euomphalus, Conularia, Pleurotomaria; (Crustacea) Estheria; fishteeth, etc.
The Po series—The Lipak series
is succeeded, in the same coritinuW.o.L
' Sir H. H. Hayden in a personal note,
113
114
GEOLOGY OF INDIA
ous sequence, by a group of dark-coloured shales and quartzites constituting what is known a__s the Po series. (See Pig. 19.) The low^er
division is for the most part composed of black shales, traversed by
intrusive dykes and,sheets of dolerite. The intruded rock has induced much contac^-metamorphism in the shales, some of which are
converted into pyritous slates and ^ even into garnetiferous micaschists in the immediate neighbourhood of the igneous rock.. The
unaltered shales contain impressions of the leaves of ferns and allied
plants, of Lower or Middle Carboniferous affinities, such as Rhacopteris, Sphenopteridium, Sphenopteris, etc. The upper division of the
Po series is composed of shales and quartzites, the higher part of
which contains marine organisms in'which the polyzoan genus Fenestella preponderates, and gives the name Fenestella shales to that
sub-division. The other fossils are species of Productus, Dielasma,
Spirigera, Reticularia, Spirifer, Nautilus, Orthoceras, Protoretepora
(sp. ampla), etc. From the preponderance, of polyzoa and the species
of brachiopods characteristic of the Middle Carboniferous, the latter
age is ascribed to the Po series.
The Upper Carboniferous unconformity—The Po series is overlain by
Upper or Permo-Carboniferous strata beginning with a conglomerate.
This complete development of the Palaeozoic systems, up to and including the Mid-Carboniferous, which we have seen in Spiti, is an
exceptional circumstance and confined to some parts only, for in
Hazara, N.W. Kashmir and several other areas of the central Himalaya, the Upper Carboniferous conglomerate is seen to overlie unconformably- formations of far lower horizons, whether Haimanta,'
Silurian or Muth, all the intervening stages being missing. This
conglomerate, which will be referred to later in our description of the
Upper Carboniferous and Permian system, is a most important
horizon, a datum-line, in the geology of India. I t covers an unconformity universal in all parts of India where the Permian system
is seen. In this particular area of Spiti this unconformity is not
apparent, because this area remained undisturbed by the criistal
readjustments of the rest of the continent, permitting an uninterrupted sedimentation to proceed in this locality, bridging over
the gap.
This break in the contiinuity of the deposits at the top of the
Middle Carboniferous is utilised by Sir T. H. Holland as the basis for
the separation of all the systems below it (collectively forming the
Dravidian group), from the remaining systems of later ages which
come above it, constituting the great Aryan group.
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THE SILURIAN AND DEVONIAN SYSTEMS
115
The following table gives a general view of the Palaeozoic sequence
in Spiti:
• Permian to Tertiary. *
Aryan
Upper Carboni- (Basement conglomerate,
Group.
ferous.
I
Slight unconformity.
^Middle Carboniferous.
Lower Carboniferous.
Dravidian
Grouj).
Devonian.
Silurian.
Cambrian.
/Pre-Cambrian.
Purana
Group.
f
Penestella shales.
/Po Series,
Shales and quartzite
I 2000 ft.
with plants (Culm).
jLipak Series, f Shales and limestones
I 2000 ft. -1. -svith Syringothyris,
[ Spirifera, etc.
/Muth quartzite and hmestone,
I 800 ft.
Quartzites,. shales and coral hmestone, etc.,
2000 ft.
("Haimanta, slates and quartzites with
•I
dolomite,
[ 4000-5000 ft.
(
Vaikrita series of schists and phylhtes.
2. KASHMIR.
A stratified series, in manJK^espects identical with the above
sequence in Spiti, is developed in Kashmir in a " basin " of sediments
which lies on a direct north-west continuation of the strike of the
Spiti basin, the only instance within the limits of India of a continuous
and conformable well-developed Palaeozoic succession. In these there
is a very perfect succession of the five primary stratigraphical systems
—Cambrian, Ordovician and Silurian, Devonian, Carboniferous and
Permian—conformably overlying the unfossiliferous slate series
(Dogra slates) of basal Cambrian or late Purana age. In the Lidar
Valley of Kashmir, Middlemiss has proved a continuous succession
of fossiliferous Palaeozoic strata from Ordovician to Permian (see
pp. 402-418).
116
. GEOLOGY OF INDIA
The following table shows the section up'to Middle Carboniferous :
Fenestella Series
2000 ft.
Syringothyris limestone
1000 feet.
Mitth quartzites
3000 ft.
Silurian and Ordovician
100 feet.
^
Middle Carboniferous.
<
Lower Carboniferous.
? Devonian.
.
.
.
•
In North-West Kashmir later work has shown a very pronounced
stratigraphic break involving the whole time-interval between the
Muth quartzites and Upper Carboniferous.- At many localities the
Ordovician and Silurian also are not developed and the Cambrian
comes to be covered by the basal beds of the Upper Carboniferous"
volcanic series of deposits.
Unfossiliferous representatives, however, of what are believed to
be continental types of the older Palaeozoic systems are observed in
parts of Hazara, Kashmir and the Simla Himalayas. In the two
former areas they have been grouped under the name of Tanawal
system and in the latter under Nagthat system.
The detailed stratigraphy of Kashmir is treated in Chapter XXVII.
3. CHITRAL.
In the valley of the Chitral river, at the north-west frontier,
Devonian strata are found containing some of the characteristic
brachiopods and corals of the period, Favosites, Cyathophyllum,
Orthis, Athyris, Atrypa, Spirifer. Mr. G. H. Tipper has found sections showing conformable sequence from Lower Devonian to the
Fusulina Uinestone of Upper Carboniferous age. The structure in
these mountains is highly complicated and the Devonian is as a r u ^
thrown against a Cretaceous or Lower Tertiary conglomerate (Eeshun
conglomerate) by a great fault. The Carboniferous occurs in wellmarked bands and embodies the Chitral slates and Sarikolshaleshesides
Fusulina limestone and some BelleropJion beds. Lithologically the
Devonian of Chitral is a thick series of limestone overlying a series of
older Palaeozoic strata, quartzites, red sandstones and conglomerates,
in which are to be recognised the probable equivalents of the Muth
quartzite and the Upper Silurian horizons of the better-known
areas. ^
1 H . H. Hayden, Rec. 0.8.1. vol. xlv. pt. 4, 1915 ; 6 . H. Tipper, See. O.S.I. vol. \r.
p. 38, and vol. Ivi. pp. 44-48, 1924.
THE SILURIAN AND DEVONIAN SYSTEMS
117
i. BuEMA (Northern Shan States).
But a much more perfect development of marine Palaeozoic rocks is
found in the eastern extremity of
the extra-Peninsula, in the Shan
States of Upper Burma, in which
the Indian Geological Survey have
worked out a succession of faunas,
revealing a continuous history of the
life a,nd deposits of the Palaeozoic
group from Ordovician to Permian.
The Shan States of Burma are a
solitary instance, with the exception
of Spiti and Kashmir, within the confines of the Indian Empire, which
possesses a complete geological
record of the Palaeozoic era. The
extreme rarity of fossiliferous Palaeozoic rock-systems in the Indian
Peninsula compels the attention of
the Indian student to this distant,
though by no means geologically
alien, province for study. We can
here give but the barest outline of
this very interesting development.
For fuller details the student should
consult the original Memoir by
Dr. La Touche, vol. xxxix. part 2,
1913.
Ordovician—In the Northern
Shan States, Lower Silurian (Ordovician) rocks are exposed, resting
t* fe'C
over a broad outcrop of unfossiliferous Cambrian quartzites and
C o
greywackes. These in turn overlie
=3 ^
still older Archaean or Dharwar
gneisses (the Mogok gneiss), with
which is interbedded the well-knowil
crystalline limestone (the rubymarble of Burma), the carrier of a number of precious stones, such as
rubies, sapphires and spinels. The Ordovician rocks are variously
118
GEOLOGY OF INDIA
coloured shales and limestones containing the characteristic trilobites,
cystideaus and brachiopods of that age. The characteristic Ordovician genus of stemmed cystoid, Aristocystis, is noteworthy. Also the
cystoids Caryocrinus and Heliocrinus. T t e brachiopods are Lingula,
Orthis; Strophomena, Plectambonites and Leptaena. The pteropod
genus Hyolithis is present, together with some gastropods. The
trilobites are" Am-pyx, Asaphus, Illaenus, Oalymene, Phacops, etc.
Namshim series. Zebingyi series—The Ordovician beds are overlain by Silurian strata composed of a series of quartzite and felspathic
sandstones, the lower beds of which contain many trilobites'and^
graptolites. - The graptoUtes include characteristic forms Uke Diplograptus, Climacograptus, Monograptus, Cyrtograptus, Rastrites, etc.
The graptolite-bearing beds are succeeded by what are known as the
Namshim series, containing trilobites of the genera Illaenus, Encrinurus, Calymene, Phacpp^, Cheirurus, and numerous brachiopods.
The Namshim sandstones are in turn overlain >by a newer series of
calcareous, fossiliferous, soft yellow and grey limestones and sandstones, constituting the Zebingyi series of the Northern Shan States.
The fossils of the Zebingyi series include a few species of graptolites
of the type-genus Monograptus, together with cephalopods and trilobites (Phacops and Dalmanites), possessing ai&nities somewhat newer
than the Wenlock limestone of England. These fossils indicate" an .
uppermost Silurian age of the enclosing strata. The Zebingyi stage
is, thus to be regarded as forming the passage-beds between the
Silurian and the overlying Devonian.
Silurian fauna of Burma—The Silurian fossils obtained from both
the Namshim and Zebingyi horizons of the Shan States are :
Brachiopods—Lingula, Leptaena, Orthothetis, Strophomena, Orthis,
Pentamerus, Atrypa, Spirifer, Meristina.
^
LamelKbranchs—Pterinea, Modiblopsis, Glassia, 'Dualina, Conocardium.
Gastropods—Tentaculites.
Cephalopods—Many species of Orthoeeras.
Numerous broken stems of crinoids.
Rugose coral—Lindstroemia.
Worm borings and tubes.
Trilobites—Illaenus, Proetus,^ Encrinurus, Calymene, Cheirurus,
Phacops, Dalmanites, and fragments of many other trilobites.
During the last few years geological work in Burma has established
the existence of a more or less parallel series of fossiliferous Ordo-
THE SILURIAN AND DEVONIAN SYSTEMS
119
vician, and Silurian in tlie Southerp Shan States comparable with
those of the Northern Shan States through the help of a rich graptoHte
and brachiopod fauna. ^ The graptoKtes have established the Valentian
and Salopiah horizons of the Silurian.
Devonian—The Devonian is rep'resented by a series of crystalline
dolomites and limestones of Padaukpin, which have yielded a very
rich assemblage of Devonian fossils, the only undoubted occurrpnce
of Devonian fauna that has been met with hitherto in the Indian
jegion. The fossils are very numerous and belong to all kinds of life
of the period—corals, branchiopods, lamellibranchs, gastropods,
cystoids, crinoids, polyzoa, Crustacea, etc.
Devonian fauna—The Devonian fauna of Burma :
Corals—Calceola (sp. sandalina, the characteristic Devonian coral),
, Cyathofhyllum, Cystiphyllum, Alveolites, Zaphrentis, Heliolites,
Pachypora„ etc.
Polyzoa—Fenestrapora, Hemitrypa, Polypora.
Brachiopods—Orthis, Atrypa,' Pentamerus, Ghonetes, Spirifer,
Cyrtina, Merista, Meristella, etc.
Lamellibranchs—Conocardium, Avicula.
Gastropods—Loxonema, Pleurotomaria, Murchisonia, Euomphalus,
BeUerophon.
Cephalopods—Anarcestes.
Trilobites—Phacops, etc.
Gimoida—Cupressocrinus, Taxocrinus, Hexacrinus.
The Wetwinslates—The limestone and dolomite are followed by an
argillaceous series of yellow-coloured shales and slates of Upper
Devonian age, known as the Wetwin slates, also fossiUferous, and containing Lingula, Athyris, Chonetes, Janeia, Nucula and BeUerophon
as the commonest fossils. With the Wetwin slates are-associated fine
crystalline dolomites and limestones with remains of corals and
foraminifera.
Carboniferous and Permo-Carboniferous~The Devonian is succeeded, in the same locality and in one continuous succession, by a
great development of .limestones and dolomites belonging to the
Lower and Upper Carboniferous and Permian systems, which on
account of their forming (together with the Devonian limestones) the"
plateau country of the Northern Shan States, have been collectively
known as the Plateau limestone. The limestones, which are extensively crushed and brecciated, vary from pure limestones through
' V. P. Sondhi and J. Coggin Brown; Bee, 0.8.1. vols. Ixvi. pt. 2, 1932, and Ixvii.
pt. 2, 1933.
120
GEOLOGY OF INDIA
dolomitic limestones to pure dolomites. There'are foraminiferal limestones (Fusulina limestone), from the preponderance of Fusulinae in
it (a rock-building foraminifer highly peculiar to this age in many
parts of the world).- The fossils of the upper portion of the Plateau
limestone very closely correspond in facies with those of the Productus
limestone of the Salt-Range (Chapter XI.) of Permian age. (See Figs.
12 and 20.) In the Southern Shan State, where the Plateau Kmestone covers vast expanses of the plateau country, it has been divided
into Lower (Devonian and Lower Carboniferous) and Upper (Carboniferous and Permian) on hthological differences, supported by some
measure of palaeontological evidence. The supposed Devonian part
of the limestone is generally a white or grey dolomite, extensively
brecciated, and in the main unfossiliferous ; while the upper part is
more calcareous and contains a fauna showing af&nities with the
Productus fauna of India.
The faunas throughout the whole series of strata following the
-Wetwin shales are closely related and are stamped with the same
general facies. The Lower Carboniferous forms are not separable
from the Upper, nor are these from the Permian. Por this reason the
two groups of Carboniferous and Permian rooks are described under
the name of Anthracolithic group, a grouping which was applicable to
the Permo-Carboniferous rocks of some other parts of India as well,
before their fossil faunas were differentiated..
The foregoing facts are summarised in the following table of geological formations of the Shan States, Upper Burma :
Burma.
Other parts.
Ehaetic.
Napeng beds.
Permo-Carboni• ferous
(AnthracoUthic)
Systems.
Devonian System.
Upper plateau limestone.
Productus limestone
of the Salt-Range.
Fusulina and Productus limestones. Partly dolomitic Productus shales oi
Spiti and Zewan
and brecciated. In the
beds of Kashmir.
main unfossiliferous.
'Crystalline dolomites and
limestones,
much
crushed, with Calceola
sandalina,
Pfiacops,
Pentamerus, etc. (of Padaukpin), forming the
plateau country.
Wetwin shales with Chonetes Muth Series and Deand a very rich Devonian
vonian of Chitral.
fauna (Eifelian).
THE SILUBIAN AND DEVONIAN SYSTEMS
Silurian System.
Ordovician
System.
Cambrian System.
Archaean
System.
Burma.
Zebingji beds, blue and
grey flaggy limestones
with GraptoUtes, Tentaculites, Orthoceras.
Namshim
sandstones,
quartzose and felspathio
sandstones, soft marls;
and limestones with
Orthoceras, Trilobites,
\ etc.
Nyaungbaw beds—brown
limestones with shales
containing Upper Ordovician fossils.
Naungkangyi beds, yellow
or purple shales with
. thick limestones. Cystoids, Orthis, Stro^homena, Trilobites.
Chaung Magyi beds, thick
quartzites, slaty shales
and greywackes: unfossiliferous.
Mogok gneiss, gneiss and
interbanded crystalline
Hmestones with intrusive
granites.
121
Other parts.
Silurian of Spiti and
Kashmir.
Ordovician of
Kashmir.
Haimanta of Spiti
and Cambrian of
N.W. Kashmir and
the Salt-Range.
peninsular gneisses.
Physical changes at the end of the Dravidian era^With the advent
of the Upper Carbordfeious, the second great era of the geological
time-sca,le in India ended. Before we pass on to the description of the
succeeding rock-groups we have to consider a great revolution in the
physical geography of India at this epoch, whereby profound changes
were brought about in the relative distribution of land and sea. The
readjustments that followed these crust-movemeJits brought large
areas of India under sedimentation which were hitherto exposed
land-masses. An immense tract of India, now forjning the northern
zone of the Himalayas, was covered by the waters of a sea which
invaded it from the west, and overspread North India, Tibet and a
great part of China. This sea, the great Tethys of geologists, was the
ancient central or mediterranean ocean which encircled almost the
whole earth at this period in its history, and divided the continents
of the northern hemisphere from the southern hemisphere. It
retained its hold over the Himalayas for the whole length of the
122
GEOLOGY OF INDIA
Mesozoic era, and gave rise, in the geosynclinal trough that was forming
at its floor, to a system of deposits which recorded a continuous history
of the ages between Permian and Edcene. This long cycle of sedimentation constitutes the second and last marine period of the
Himalayan area.
j
During this interval the Peninsula of India underwent a different
cycle of geological events. The Upper Carboniferous movements'
interrupted its long unbroken quiescence since the Vindhyan. Al-'
though the circumstances of its being a horst-Uke segment of the crust
gave it immunity from deformations of compressional or erogenic '
kind, yet it was susceptible to another class of crust-movements,
.characteiristic of such land-masses. These manifested themselves in
tensional cracks and in the subsidence of large Unear tracts in various
parts of the country between more or less vertical fissures of dislocation in the earth (block-type of earth-naovements), which eventually
resulted in the formation of chains of basin-shaped depressions on the
old gneissic land. These basins received the drainage of the surrounding country and began to be filled by their fluviatile and lacustrine
debris. As the sediments accumulated, the loaded basins subsided
more and more, and subsidence and sedimentation going on pari
passu, there resulted thick deposits of fresh-water and subaerial sediments several thousand feet in vertical extent and entombing among
them many relics of the terrestrial plants and animals of the time.
These records, therefore, have preserved to us the history of the landsurface of the Indian continent, as the zone of marine sediments,
accumulated in the geosynclinal of the Northern Himalayas, has of
the oceans. Thus a double facies is to be recognised in the two
deposition-areas of India in the systems that follow—a marine type
in the extra-Peninsula and a fresh-water and subaerial type in the
Peninsula.
REFERENCES
H. H. Hayden, Geology of Spiti, Mem. G.S.I, vol. xxxvi. pt. 1, 1904.
T. H. D. La Touche, Geology of the Northern Shan States, Mem. O.S.I, vol.
xxxix. pt. 2, 1913.
F. R. C. Reed, Palaeantologia Indica, New Series, vol. ii. mem. 3 and mem. 6,
1906-8 and vol. xxi. mem. 3, 1936 ; Series XV. vol. vii. mem. 2, 1912, and
Pal. Ind., New Series, vol. vi. mem. 2, 1922.
H. L. Chhibber, Geology o/ Burma (MacmHlan), 1935.
CHAPTER I X
THE GONDWANA SYSTEM
General. The Ancient Gondwanaland—Rocks of later age thaa
Vindhyan in the Peninsula of India, belong to a most characteristic
system of land-deposits, which range in age from the Upper Carboniferous, through the greater part of the Mesozoic era, up to the end of
the Jurassic. As mentioned in the last chapter, their deposition on
the surface of the ancient continent commenced with the new era, the
Aryan era. This enormous system of continental deposits, in spite of
some local unconformities, forms one vast conformable and connected
sequence from the bottom to' the top. It is distinguished in the geology of India as the Gondwana system, from the ancient Gond kingdoma south of the Narbada, where the formation was first known.
Investigations in other parts of the world, viz. in South Africa, Madagascar, Australia and even South America, have brought to light a
parallel group of continental formations, exhibiting much the same
' physical as well as organic characters. From the above circumstance,
which in itself is competent evidence, as well as from the additional
proofs that are furnished by important palaeontological discoveries in
the Jurassic and Cretaceous systems of India,' Africa and Patagonia, it
is argued by many eminent geologists that land-connection existed
between these distant regions across what is now the Indian Ocean,
either through one continuous southern continent, or through a series of
land-bridges or isthmian links, which extended from South America to
India, and united within the same borders the Malay Archipelago and
AustraUa. The presence of land connections in the southern world for
a long succession of ages, which permitted an unrestricted migra- '
tion of its animal and plant inhabitants within its confines, is indicated
by another very telUng circumstance. I t is the effect of such a continent on the character and distribution of the hving fauna and flora
of India and Africa of the present day. Zoologists have traced unmistakable affinities between the living lower vertebrate fauna of
India and that of Central Africa and Madagascar, relationships which
oould never have subsisted if.the two regions had always been apart,
123
124
GEOLOGY OF INDIA
and each pursued its own independent course of evolution. From
data obtained from the distribution of fossil Cretaceous reptiles,
especially the Sauropods, Prof. Von Huene suggests a distinct landconnection through Lemuria (the name given to the Indo-Madagascar continent) to South America. According to this authority, the
Cretaceous dinosaurs of the Central Provinces of India belonged to the
same faunistic province as Madagascar, and there is a great similarity
in the fauna of the latter with that of Patagonia, Brazil, and Uruguay.
The northern frontier of this continent was approximately co-extensive with the central chain of the Himalayas and was washed by the
waters of the Tethys.
The evidence from which the above conclusion regarding an IndoAfrican land connection is drawn, is so weighty and so many-sidedthat the differences of opinion that exist among geologists appertain
only to the mode of continuity of the land and the details of its geography, the main conclusion being accepted as one of the settled facts
in the geology of this part of the world. The subaerial deposits
formed by the rivers of this continent during the long series of ages are
preserved in a number of isolated basins throughout its area, indicatr
ing a general uniformity and kinship of hfe and conditions on its
surface. The term Gondwana system has been consequently extended to include all these formations, while the name of Gondwanaland is given to this Mesozoic Indo-African-American continent or
archipelago. The Gondwanaland, called into existence by the great
crust-movements at the beginning of this epoch, persisted as a very
prominent feature in ancient geography till the commencement of the
Cainozoic age, when, collaterally with other physical revolutions in
India, large segments of it drifted away, or subsided, permanently,
under the ocean, to form what are now the Bay of Bengal, the Arabian
Sea, etc., thus isolating the Peninsula of India.
The Gondwana system is in many respects a unique formation, its
homogeneity from top to bottom, the fidelity with which it has preserved the history of the land-suriace of a large segment of the earth
for such a vast measure of time, the peculiar mode of its deposition in
slowly sinking faulted troughs in which the rivers of the Gondwana
country poured their detritus,, and the preservation of valuable coalmeasures lying undisturbed among them, stamp these rocks with a
striking individuality among the geological systenis of India.
The geotectpnic relations of the Gondwana rocks—The most important fact regarding the Gondwana system is its mode of origin.
The formation of thousands of feet of river and stream deposits in
0
T H E CONDWANA SYSTEM
125
definite liiilsar tracts cannot be explained on any other supposition
than the one already briefly alluded to. I t is suggested that the
niountain-building and other crustal movements of an earlier date
had their reaction now in th'e subsidence of large blocks of the country
to the equilibrium-plane, between vertical or slightly inclined fissures
in the crust. IThese depressions naturally became the gatheringgrounds for the detritus of the land, for the drainage system must
soon have betaken itself to the new configuration. The continually
increasing thickness of the sediments that were poured into the
basins caused them to sink relatively to the surrounding Archaean or
Vindhyan country, from which the sediments were derived, and thus
gave rise to a continuation of the same conditions without interruption.
Although in a general way the Gondwanas were deposited in faulted
depressions' which have a general correspondence to the present disposition of their outcrops, it should not be supposed that in every case these
outcrops imply "the original fault-bound basin. Some of the boundary
faults may be of post-Gondwana age. The original limits of deposition
of the individual beds now found in these basins may not correspond in
every case to the present outcrops.
I t is this sinking of the loaded troughs among the Archaean crystalline^ rocks that has tended to preserve the Gondwana rocks from removal by surface denudation, to which they would certainly have
*' been otherwise subject. The more or less vertical faulting did not
disturb the original horizontal stratification of the deposits beyond
• imparting to them a slight tilt now to one direction, now to the other,
while it made for their preservation during all the subsequent ages.
As almost all the coal of India is derived from the coal-seams enclosed in the Gondwana rocks, this circumstance is of great economic
'importance to India, since to it we owe not only their preservation but
their immunity from all crushing or folding which would have destroyed their commercial value by making the extraction of the coal
difficult and costly.
Their fluviatile origin—The fluviatile nature of the Gondwana deposits is proved not only by the large number of the enclosed terrestrial plants, crustaceans, insects, fishes, amphibians, reptiles, etc.,
and by the total absence of the marine molluscs, corals and crinoids,.
but also by the character and nature of the very detritus itself,
which gives conclusive evidence of the deposition in broad rivervalleys and basins. The rapid alternations of coarse- and fine-grained
sandstones, and the numerous local variations met with in the rocks.
126
GEOLOGY OF INDIA
point to a depositing agency which was liable to constant fluctuations
in its velocity and current. Such an agency is river water. Further
evidence is supplied by the other charao'ters commonly observed in the
alluvial deposits of river valleys, such as the frequency of false-bedding,
the existence of several local unconformities due to what is known as
" contemporaneous erosion " by a current of unusual velocity renioving the previously deposited sediment, the intercalations of finely
laminated clays among coarsely stratified sandstones, etc.
It is probable that in a few instances the deposits were laid down
in lakes and not in river-basins, e.g. the fine silty shales of the Talchir
stage at the bottom of- the system. The distinctive character of the
lacustrine deposits is that the coarser deposits are confined to the
margin of the lake or basin, from which there is a gradation towards
the centre where only the finest silts are precipitated. Breccias,
conglomerates and grits mark the boundary of ancient lakes, while
finely laminated sandstones and clays are found in the middle of the
basins. This is frequently observed in deposits belonging to the
Talchir series.
Climatic vicissitudes—The Gondwana system is of interest in bearing the marks of several changes of climate in its rocks. The boulderbed at its base tells us of the cold of a Glacial Age at the commencement of the period, an inference that is corroborated, and at the same
time much extended in its application, by the presence of boulderbeds at the same horizon in such widely separated sites as Hazara,
Simla, Salt-Kange, Eajputana, Central Provinces and Orissa. This
Upper Carboniferous glacial epoch is a well-established fact not only
in -India, but in other parts of Gbndwanaland, e.g. in Australia and
South Affica. The thick coal-seams in the strata of the succeeding
epoch, pointing to a superabundance of vegetation, suggest a much
•warmer climate. This is followed by another cold cycle in the next
series (the Panchet), the evidence for which is contained in the presence of undecoiAposed felspar grains among, the clastic sediments..
The last-mentioned fact proves the existence of ice among the agents
of denudation, by which the crystalline rocks of the surface were
disintegrated by frost-action, and not decomposed as in normal climates.
•The thick red Middle Gondwana sandstones succeeding the Panchet
epoch denote arid desertic conditions during a somewhat later period,
a conclusion warranted by the prevalence in them of so much ferruginous matter coupled with almost the total absence of vegetation.
Life of the period—The organic remains entombed in the sediments
are numerous and of great biological interest, as furnishing the natural
THE GONDWANA SYSTEM
127
history of the large continent; but they do not help us in fixing the
homotaxis of the different divisions of the system, in terms of the
standard stratigraphi,cal scale, with other parts of the world. The
palaeontological value of terrestrial and fresh-water fossil organisms is
limited, as they do not furnish a continuous and connected history of
their evolution, nor is the geographical distribution of their species
wide enough, as is the case with the marine molluscs, echinoderms,
etc. Plant fossils, however, are abundant, and are of service in enabling the different groups of exposures to be sub-divided and correlated among themselves with some degree of minuteness. The lower
wondwanas contain numerous pteridosperms, ferns and equisetums ;
t
FIG. 13.—Sketch map of typical Gondwana outcrop.
the middle' part of the system contains a fairly well-differentiated
invertebrate as well as vertebrate fauna of Crustacea, insects, fish,
amphibia; and crocodilian and dinosaurian reptiles, besides plants,
while in the upper division there is again a rich assemblage of fossil
plants, now chiefly of the higher vegetable sub-kingdom (spermaphyta), cycads and conifers, with fish and other vertebrate remains.
• A succession of distinct J?oras has been worked out from the shale
and sandstone beds of the various Gondwana divisions by palaeobotanists, and distinguished as the Talchir, Damuda, Raniganj,^
Rajmahal, Jabalpur flora, etc., each possessing some individual
characteristic of its own.
Distribution of the Gondwana rocks—Outcrops of the Gondwana
system are scg-ttered in a number of more or less isolated basins (see
Figs. 13 and 14) lying in the older rocks of the Peninsula along certain
very definite lines, which follow approximately (thougtt not always)
the courses of some of the existing rivers of the Peninsula. Three large
tracts in the Peninsula can be marked oiit as prominent Gondwana
128
GEOLOGY OF INDIA
areas : (1) a large linear tract in Bengal along the valley of the
Damodar river, with a considerable area in the Kajmahal hills;
(2) an expansive outcrop in the Central Provinces prolonged to the
south-east in a belt approximately following the Mahanadi valley;
(3) a series of more or less connected troughs forming an elongated
band along the Godavari river from near Nagpur to the head of its
delta. Besides these main areas, outliers of the Upper Gondwana
rocks occur in Kathiawar, Cutch, Western Rajputana and, the most
important of all, along the East Coast. The Gondwana system, however, is not confined to the Peninsular part of India only, since we
find outliers of the same system to the north of the Peninsula on the
other side of the Indo-Gangetic alluvium, at such distant centres as
Afghanistan, Kashmir, Nepal, Sikkim, Bhutan, i and the Abor
country.^
From what has been said regarding their mode of origin and their
geotectonic relations with the older rocks into which they have been
faulted, the above manner of disposition of the Gondwana outcrops
Fr^'lGneiss
^^3Gondwana
roCka with coal seams
^ ^ S Vindhyan sandslanet
Fio. 14.—^Tectonic relations of the Gondwana rocks. Vertical
scale exaggerated.
will easily be apparent. I t also follows that the boundaries of the
outcrops are sharply marked off on all sides, and that there is a zone
of somewhat disturbed and fractured rock along the boundary while
the main body of the rocks is undisturbed. These are actually observed facts, since 'the Gondwana strata never show any folding or
plication, the only disturbance being a gentle inclination or dipping,
usually to the south but sometimes to the north'. The extra-Peninsular occurrences, on the other hand, have been much folded and
compressed, along with the other rocks, and as a consequence the
sandstones, shales and coal-seams have been metamorphosed into
quartzites, slates and carbonaceous (graphitic) schists. These
extra-Peninsular occurrences are of interest as indicating the limit of
the northern extension of the Gondwana continent and the spread
of its peculiar flora and fauna.
• Sec. G.S.I. vol. xxxjv. pt. 1, 1908.
» Rec. O.S.I. vol. xlii. pt. 4,1912.
T H E GONDWANA SYSTEM
129
Classification—The system is classified into tjiree principal divisions,
tlie Lower, Middle, and Upper, corresponding in £t, general way respectively to the Permian, Triassic and Jurassic of Europe. The
following tables show the division of the principal sections into
series and stages, their distribution in the different Gondwana areas
and the names by which they are recognised in these areas :
I. Broad Correlation of the Gondwana System of India with equivalent
deposits of other parts of the Southei-n Hemisphere. \G. S. Fox.]
INDIA.
SOUTH ABRICA.
S . E . AUSTRALIA
S . AMEMCA,
Jabalpur group.
. Rajmahal group.
Jurassic.
ce Panchet group.
Stonnberg
Series.
Beaufort Series.
•o Damuda group.
^
(Coal raeasJ5
ures)
Ecoa Series.
(Coal measures)
Talchir Series.
(Glacial)
AGE.
Hawkesbury
Triassic.
Series.
Santa
Maitland
Catharina Permian.
Series.
System.
(Upper Coal
measures)
Murree Series Rio Tubaro
Upper
(Lower Coal
Series
Carbonif
measures
(Glacial)
and Glacial)
Dwyka Series.
(Glacial)
1. LOWER GONDWANA SYSTEM
Talchir series—The lowest beds of the Lower Gondwana are known
as the Talchir series, from their first recognition in the Talchir district
of Orissa. The series is divided into two stages, of which the lower,
the Talchir stage, has a wide geographical prevalence, and is present in
all the localities where Gondwana rocks are found, from the Rajmahal
hills to the Godavari and from Raniganj to Nagpur. The group is
quite homogeneous and uniform in composition over all these areas,
and thus constitutes a valuable stratigraphical horizon. The component rocks (300-400 feet thick) are green laminated shales and soft
fine sandstones. The sandstones contain undecomposed felspar grains,
a fact which suggests the prevalence of land-ice and thai disruptive
action of frost. Glacial conditions are, however, more clearly indicated by a boulder-bed also of very^ide prevalence in all the Gondwana areas, containing the characteristically glaciated, striated and
facetted blocks of rock brought from afar and embedded in a fine
silt-like matrix. The presence of fine silty matrix suggests fluvioglacial agency of transport and deposition rather than glacial. The
boulders and blocks were transported in floating blocks of ice, and
W.G.I.
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130
GEOLOGY OF INDIA
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LOWER GONDWANA SYSTEM
131
dropped in the Talchir basins, in which the depomtion of fine silt was
going on. Proofs of similar glacial conditions at this stage exist in
many other parts of India, viz. the Aravallis, Eajputana, Salt-Range,
Hazara and Simla. The Aravallis, it appears, were the chief gathering-grounds for the snow-fields at this time, from which the glaciers
radiated out in all directions. Many parts of the Southern Hemisphere,
as shown on Table on page 130, experienced glacial conditions at this
period. Boulder-conglomerates (tillites) homotaxial with the Talchir
stage occur in South Africa (Dwyka series), South-East Australia
(Murree Series) and in South America (Itarara boulder-beds).
Talchir fossils—Fossils are few in the Talchir stage, the lower beds
being quite unfossiliferous, while only a few remains of terrestrial
organisms are contained in the upper sandstones ; there are impressions of the fronds of the most typical of the Lower Gondwana seed
ferns Gangamopteris and Glossopteris with its characteristic stem,
\iamed Vertebraria ; also spores of various shapes have been foimd on
some fertile fronds; wings of insects, worm-tracks, etq,,, are the only
signs of animal life. The Talchir stage is succeeded by a group of coalbearing strata known as the Karharbari stage, 500-600 feet in thickness, also of wide geographical prevalence. The rocks are grits,
conglomerates, felspathic sandstones and a few shales, containing
seams of coal. Plant fossils are numerous, the majority of them belonging to genera of unknown affinity, provisionally referred to the
class of seed-ferns (Pteridosperms). The chief genera are :,
(Pteridosperms) Gangamopteris—several species—this genus being
represented at its best in the Karharbari stage ; Glossopteris and its
stem Vertebraria, Gondwanidium (formerly known as Neuropteridium);
(Cordaitales) Noeggerathiopsis, Euryphyllum.
(Equisetales) Schizoneura.
(Incertae) Buriadia, Ottoharia, Arberia.
-^
Besides there occur the seed-like bodies Samaropsis and Cordaicarpus,
as well as scales with an entire or lacerated margin.
Damuda series—The Talchir series is succeeded by the second division of the Lower Gondwanas, the Damuda series, the most important
portion of the Gondwana system. Where fully developed, as in the
Damuda area of Bengal, the series is divided into three stages, in the
descending order:
Raniganj—5000 feet.
Ironstone shale—1400 feet.
Barakar—2000 feet.
132
GEOLOGY OF INDIA
Of these the Barakar stage, named from the Barakar branch of the
Damodar river, alone is of wide distribution among the Gondwana
basins outside Bengal, viz. in the Sat|)ura and the Mahanadi and
Godavari valleys ; the middle and upper members are missing from
most of them, being restricted chiefly to the type-area of the Damodar
valley. The Barakar stage rests conformably upon the Talchir series, and
consists of coarse, soft, usually white, massive sandstones and shales
with coal-seams. The Barakars contain a large quantity of coal in
thick coal-seams, though the quality of the coal is variable. The percentage of the carbon is sometimes so low that the coal passes, into
mere carbonaceous shale by the large admixture of clay. It is usually
comp9sed of alternating bright and dull layers. ^ The coal is often
spheroidal, i.e. it breaks up into ball-like masses. The Ironstone
shales are a great thickness of carbonaceous shales with concretions
(Sphaerosiderites) of impure iron-carbonate and oxides. They have
yielded much ore of iron. But this group is of a most inconstant
thickness and appears only at a few localities in the Damuda area,
being altogether missing from the rest of the Gondwa,na areas. This
is succeeded by the Raniganj stage of the Damuda series, named from
the important mining town of Bengal. The Raniganj stage is composed of massive, false-bedded, coarse and fine sandstones and red,
brown and black shales, vith numerous interbedded coal-seams.
The sandstones are felspathic, but the felspar in it is all decomposed,
i.e. kaolinised. The coal is abundant and of good quality as a fuel
with a percentage of fixed carbon generally above 55.
Igneous rocks of Damuda coal-measures—Many of the coalfields
of the Damodar valley, especially those of the eastern part, are invaded by dykes and sills of an ultra-basic rock which has wrought
much destruction in the coal-seams by the contact-metamorphism it
has induced. The invading rock is a' mica-peridotite, containing a
large quantity of apatite. The peridotite has intruded in the form of
dykes and then spread itself out in wide horizontal sheets or sills.
Another intrusive rock is a dolerite, whose dykes are thicker, but they
are fewer and are attended with less widespread destruction of coal
than the former.
Effects of contact-metamorphism—The coal is converted into coke,
and its economic utility destroyed. The reciprocal effects of contactmetamorphism on the peridotite as well as the coal are very instructive to observe. The peridotite has turned into a pale earthy and
friable mass with bronze-coloured scales of mica in it, but without any
^C. S. Fox, Natural History of Indian Coal, Mem. O.S.I. Ivii, 1931,
LOWER GONDWANA SYSTEM
133
other trace o^its former crystalline structure. On^the other hand,
the coal has coked or even burnt' out, becoming light and cindery, and
at placed it has developed prismatic structure.
The Damuda flora—The Damuda fossils are nearly all plants.
The'flora is chiefly cryptogamic, associated with only a few spermaphytes. It is exceedingly rich in Pteridosperm leaves of the net-veined
type,- the genus Glossopteris here attaining its maximum development, while Gangamopteris is on the decline. The following are the
mpst important genera :
(Pteridosperms)—Glossopteris with Vertebraria, at least nine species,
several of them confined to the Haniganj stage, Gangamopteris, Belemnopteris, Merianopteris, Sphenopterjs, Pecopteris, Palaeovittaria.
(? Ginkgoales)—Rhipidopsis.
(Cordaitales)—Noeggerathiopsis, Dadoxylon.
(Cycadophyta)—Taeniopteris, Pseudoctenis.
(Filicales)—Cladophlebis.
(Equisetales)—Schizoneura, Phyllotheca.
(Sphenophyllales)—Sphenophyllum.
(Lycopodiales)—? Bothrodendron.
(Incertae)—Barakaria, Bictyopteridium, scales, seeds including
Samaropsis and Cordaicarpus.
The animals include Estheria, Labyrinthodonts and some Pishes.
The Damuda series of other areas—In the Satpura area the Damuda series is represented, in its Barakar and Eaniganj stages, by
aboiit 10,000 feet of sandstone and shale, constituting what are
known as the Barakar, Motur and Bijori stages respectively of this
province. The Mohpani and the Bench valley coalfields of the
Satpura region belong to the Barakar stage of this series. In the
strata of the last-named stage, at Bijori, there occur bones and
other remains of a Labyrinthodont (Gondwanosaurus), OtherHfossils
include scales and teeth of ganoid fishes, and seed-ferns and equisetums identical with those of Bihar. It is quite probable that large
expanses of the Lower Gondwana rocks are buried under the basalts
of the Satpuras, which must have contained, and possibly still contain,
some valuable coal-seams.
Another area of the Peninsula where the Damuda series is recognised, though greatly reduced and with a somewhat altered facies, is
in the Godavari valley, where a long but narrow band of Lower
Gondwana rocks stretches from the old coalfield of Warora to the
134
GEOLOGY OF INDIA
neighbourhood of Kajahmundri. The Barakar stage of the Damuda
series prevails in these outcrops which bear the coal-fields of Warora,
Singareni, Bellarpur, etc.
One more outcrop of the Damuda group is seen in the Rewah State,
Central India, which at one or two places contains workable coalseams, e.g. in the Umaria field. The division of the Lower Gondwana
exposed in this field also is the Barakar.
Homotaxis of the Damuda and Talchir series—Few problems in the
geology of India have aroused greater controversy than the problem
of the lower age limit of the Gondwana system. The Talchir series has
been referred, by different authors, to almost every stratigraphic
position from Lower Carboniferous to Trias. The discovery, however,
of a Lower Gondwana horizon in Kashmir, bearing the eminently
characteristic genera Gangamopteris and Glossopteris overlying the
Upper Carboniferous and underlying marine fossiliferous strata of
undoubtedly Permian age, has settled the question beyond doubt. A
similar occurrence of Lower Gondwana plants has been noted in the
. Lower and Middle Productus limestone of the Salt-Range,,the marine
fossils of which point to Lower and Middle Permian afl&nities. The
Upper Carboniferous, or Permo-Carboniferous age, attributed to the
Talchir glacial horizon by this circumstance is quite in keeping with
the internal evidence that is furnished by the Talchir and Damuda
floras, as well as by the fish and labyrinthodont remains of Bijori. The
eminent American palaeontologist. Professor Charles Schuchert, has,
however, ascribed a definitely Permian (Lower to Middle) age to the
Talchir glacial epoch.
Further positive evidence leading to the same inference is supplied
by the Lower Gondwanas of Victoria and New South Wales, Australia.
Here, Gangamopteris and other plant-bearing beds of fundoubted
Gondwana facies, underlain by a glacial deposit, identical with th#
Talchir boulder-bed, are found interstratified with marine beds which
contain an Upper Carboniferous fauna with Eurydesma, resembling
that of the Speckled sandstone group of the Salt-Range.
Economics—The Damuda series contains a great store of mineral
wealth in its coal-measures, and forms, economically, one of the most
productive horizons in the geology of India. I t contains the most
valuable and best worked coal-fields of the country. The mining
operations required for the extraction of coal from these rocks are
comparatively simple and easy because of the immunity of the
Gondwana rocks from all folding or plication. Also, mining in India
is not so dangerous on account of the less common association of
LOWER GONDWANA SYSTEM
135
highly explosive gases (marsh-gas or " firedamp ") with the coal as
compared with E u r o p e a n coal fields. There are, however, special
difficulties associated with the working of thick seams, and fires and
subsidences have proved very troublesome.
[Although coal occurs in India in some later geological formations also—
e.g. in the Eocene of Assam, the Punjab, Eajputana and Baluchistan, and
in the Jurassic rocks in Cutch—the Damuda series is the principal source of
Indian coal, contributing nearly 98 per cent, of the total coal production.
The principal fields are those of Bihar—Eaniganj, Jharia, Giridih and
Bokaro. The Eaniganj coalfield covers an area of 500 square miles, containing many seams of good coal with interbedded ironstones. The thickness
of the individual seams of coal is great, often reaching to forty or fifty feet,
while a thickness of eighty or more feet is not rare. The annual output of
coal from the Eaniganj mines is more than six miUion tons. The Jharia
field has at present the largest output, 10,000,000 tons per annum. The
coal of the Jharia fields belongs in geological age to the Barakar stage. It
has less moisture and greater proportion of fixed carbon than that of the
Eaniganj stage. T i e coal-fields of Bokaro, to t i e west of Jiaria, contain
thick seams of valuable coal. Their total resources are estimated at 1500
million tons. Besides the foregoing there are smaller fields in the Damodar
valley. The coal-fields of the other Gondwana areas are not so productive,
the more important of them being the Umaria field of Central India in
Eewah, the Bench valley and Korea and Bellarpur fields of the Central
Provinces, and the Singareni of Hyderabad. But the aggregate yield of
these extra-Bihar fields is a little over two milhon tons per annum.]
Besides coal, i r o n ' i s the chief product mined from the D a m u d a
rocks, while beds of fire-clay, china-clay or kaolin, terra-cotta clays
for the manufacture of fire-bricks, earthenware a n d porcelain, etc.,
occur in considerable quantities in Bihar and the Central Provinces.
The Barakar sandstones and grits furnish excellent material for millstones.
Classification—During recent years Dr. G. de P . Cotter, in an att e m p t t o subdivide the Gondwana system on palaeobotanical basis,
has found it more appropriate, on the evidence of an interesting
suite of plant fossils obtained from the* Parsora beds of South Rewa,
to include among t h e Lower Gondwanas t h e thick zone of strata
which overlies t h e D a m u d a series and underlies t h e Rajmahal, embodying in fact t h e group t h a t has been here treated as Middle Gondwana. Dr. Cotter names these strata in question Panchet series
(divided into three stages—Panchet, Maleri amd Parsora) and groups
t h e m along with t h e Talchir and D a m u d a series in the Lower Gondwana. Dr. C. S. F o x in his comprehensive Memoir on the Gondwana
system has adopted a different grouping of this middle series. In
136
GEOLOGY OF INDIA
his scheme of classification the Maleri and Parsora series are included
in t h e Upper Gondwanas while t h e Panchets are grouped with the
Lower.
The flora of t h e beds placed in t h e Parsora stage b y Cotter still
needs a critical examination. Possibly t h e fossils belong to two distinct horizons, t h e older (containing a typical Glossopteris flora) definitely belonging to the Lower Gondwanas, the younger (with
Thinnfeldia
as the dominant genus) belonging to the Middle or
Upper Gondwanas. According to Seward and Sahni the affinities of
t h e latter flora are also distinctly with t h e Lower rather t h a n with the
Upper Gondwana (see page 141). Sahni holds the view t h a t on the
palaeobotanical evidence the Parsora beds cannot possibly be
classed as Jurassic. The classification t h a t is here adopted was
originally based on the views of Feistmantel and Vredenburg, b u t
chiefly on lithological considerations and t h e physical conditions of
the period embracing the Middle Gondwanas, which were strikingly
different from those prevailing in t h e D a m u d a and Rajmahal eras.
The presence of red beds, indicating arid or semi-desert conditions supervening on the damp forest climate of the Damuda period, the Triassic affinities
of the fossil reptiles and stegpcephaUan amphibia and the coincidence of the
Palago-Mesozoic boundary at the base of the Panchets with the unconformity at the top of the Raniganj series are features distinguishing the
Middle Gondwana group. The total extinction of Gangamopteris and the
SpJienophyllales after the Damuda epoch is widespread and denotes a
datum-line of some importance. The Middle Gondwana was also the
epoch of most extensive land-conditions in India. During the Upper
Gondwana epeiric seas began to encroach on its borders from the northwest and south-east.
CHAPTER X
T H E GONDWANA SYSTEM {continued)
2. MIDDLE GONDWANAS
the upper beds of the Damuda series and the next overlying
group of strata, distinguished as the Panchet, Mahadev, Maleri and
Parsora series, there is an unconformable junction ; in'addition there
exists a marked discordance in the hthological composition and in the
fossil contents of these groups. For these reasons the series overlying
BETWEEN
+
+
++•*•
•' +
i
+ + +
+ + + +^ +
TTO. 15.—Sketch map of the Gondwana rocks of the Satpura area.
1. Archaean.
4. Pachmarhi (Kamthi).
6. Jabalpur.
2. Talchir.
5. Denwa (Maleri) and Bagra.
7. Deccan Trap.
3. Damuda.
Medlicott, Mem. O.S.I, vol. x (1873).
the coal-bearing Damudas have been separately grouped together
under the name of Middle Gondwanas by Mr. E. W. Vredenburg.i
Usually it is the practice to regard a portion of the latter group as
' Summary of the Geology of India, Calcutta, 1910.
137
138
GEOLOGY OF INDIA
forming the upper portion of the Lower Gondwanas, and the remaining part as belonging to the bottom part of the Upper Gondwanas, but,
in view of the above dissimilarities, as well as of the very pronounced
Uthological resemblance of what are so distinguished as the Middle
Gondwanas with the Triassic system of Europe, it is convenient, for
the purpose of the student at any rate, to regard the middle division
as a separate section of the Gondwana system.
Rocks—The rocks which constitute the Middle Gondwanas are a
great thickness of massive red and yellow coarse sandstones, conglomerates, grits and shales, altogether devoid of coal-seams or of
carbonaceous matter in any'shape. Vegetation, which flourished in
such profusion in the Lower Gondwanas, became scanty, or entirely
disappeared, for the basins in which coarse red sandstone were deposited must have furnished very inhospitable environments for any
luxuriant growth of plant life. The type area for the development of
this formation is not Bihar but the Mahadev hills in the Satpura
Range, where they form a continuous line of immense escarpments
which are wholly composed of unfossilLferous red sandstone. (See
J i g . 15, sketch map of the Mid-Gondwanas of the Satpura area, and
Fig. 16, generalised section across it.) On this account the Middle
Gondwanas have also received the name of the Mahadev series. The
railway from Bombay to Jabalpur, just east of Asirgarh, gives a fine
view of these massive steep scarps looking northwards. The other
localities where the strata are well developed, though not in equal
proportions, are the Damuda valley of Bengal and the chain of basins
of the Godavari area. The whole group of the Middle Gondwanas is
sub-divided into three series, of which the middle alone is of wide
extension, the other two being confined to one or two local'^evelopments:
Maleri (and Parsora) series—variable thickness.
Mahadev (or Pachmarhi) series—3000 feet to 8000 feet.
Panchet series—1500 feet.
Panchet series—The Panchet series rests with a slight unconformity
on the denuded surface of the Raniganj stage and at some places on
the Barakars through overlapping of the former. The beds consist of
alternations of fine red clays and coarse, micaceous and felspathic sandstones, occasionally containing rolled fragments of Damuda rocks.
The felspar in the sandstones is in undecomposed grains. Characteristic Panchet plant fossils are : Schizoneura gondwanensis, Glossopteris, Vertebraria indica, Pecopteris^ concinna, Cyclopteris, Thinn-
MIDDLE GONDWANAS
feldia. The group is of importance, as
containing many well-preserved remains of "
vertebrate animals, affording us a glimpse
of the higher land-lue that inhabited the
Gondwana continent. These vertebrate
fossils consist of >the teeth, scales, scutes,
jaws, vertebrae and other bones of terrestrial and fresh-water fishes, amphibians
and reptiles. Three or four genera of
labyrinthodonts (belonging to the extinct
order Stegocephala of the amphibians)
have been. discovered, besides several
genera of primitive and -less differentiated
reptiles.
Panchet fossils :
(Amphibia) Gonioglyptus, Glyptognathus, ;
and Pachygonia; (Fish) Amhly- |
pterus ; (Eeptiles) Dicynodon and '^
Ptychosiagum and the dinosaur
Epicampodon.
The fresh-water
crustacean Estheria is very abundant at places.
139
X
H?fi
o
•£1
Mahadev series—The Mfihcidev series, II
locally also named Pachmarhi, is the most | ;
conspicuous and the best-developed member
of the Middle Gondwana in the Central Provinces. Near Nagpur it consists of some
4000 feet of variously coloured massive
sandstones, with ferruginous and micaceous
clays, grits and conglomerates.
The most typical development of the
series is, however, in the Mahadeva and
Pachmarhi hills of the Satpura range,
where it is exposed in the gigantic escarpments of these hills. It unconformably
overlies the Bijori stage there {Raniganj
stage of Damodar valley area). Here
the series is composed essentially of thickbedded massive sandstones, locally called
Pachmarhi sandstones, variously coloured
<5H
140
GEOLOGY OF INDIA
by ferruginous matter ; in addition to sandstone there are a few shale
beds which also contain a great deal of ferruginous matter, with
sometimes such a concentration of the iron oxides in them locally that
the deposits are fit to be worked as ores of the metal. The sandstones
as well as shales are frequently micaceous. The shales contain beau-'
tifully preserved leaves of seed-ferns and equisetaoeous plants along
their planes of lamination. Some animal remains are also obtained,'
including parts of the skeletons of vertebrates similar to those occurring in the Panchet beds. The most important is an amphibian:—
Brachyops. This labyrihthodont was obtained from a quarry of fine
red sandstone which lies at the bottom of the series forming a group
known as the Mangli beds near the village of Mangli. The fiora of the
Pachmarhi series consists of seed-ferns and eqmsetums, several species
of Vertebraria and Phyllotheca being found with the ferns Glossopteris,
Gangamopteris, with Pecopteris, Angiopteridium, and Thinnfeldia;
the species T. hughesi being very characteristic of the Pachmarhi.
This flora resem.b\e8 that oi the Damuda series in many oi its ioims,
being for the most part, the survivors of the latter flora.
Maleri series—The Maleri (or Denwa) series comes generally conformably on the top of the last. Its'development is restricted to the
Satpura and Godavari regions. Lithologically it is composed of a
thick series of clays with a few beds of sandstones. Animal remains
are' abundant. The shales are full of coprolitic remains of reptiles.
Teeth of the Dipnoid fish Gemtodus, similar to the mud-fish living in
the fresh waters of the present day, and bones of labyrinthodonts like
Mastodonsaurus, Gondwanosaurus, Capitosaurus and Metopias are
met with in the Maleri rocks of Satpura, recognised there under the
name of Denwa beds. Three reptiles, identical in their zoological relations with those of the Trias of Europe, are also found in the rocks ;
they are referred to the genevaHyperodapedon (order Rhynchocephala)^
Belodon, and Parasuchus (order Crocodilia). The Maleri group is well
represented in the Godavari valley in the Hyderabad State also, and
it is from the discovery of reptilian remains at Maleri, a village near
Sironcha, that the group has taken its name. I t here rests with an
unconformity on the underlying Mangli, or Panchet beds, and consists
of bright red clays with pale-coloured sandston§,beds. The shales are
full of coprolite remains of reptiles together with their teeth, vertebrae
and limb-bones, the above three fossil genera having been met with
here also. Other fossils from the same locality include Ceratodus and
the reptiles of the genus Hyperodapedon and Parasuchus. While the
animal fossils clearly indicate a Triassic age, some plant-remains re-
MIDDLE GONDWANAS
141
corded by Feistmantel^ from Naogaoii west of Maleri are cliaraoteristic Upper Gondwana fossils common in the Kota and Jabalpur
stages, and would point definitely to a Jurassic horizon.' These species
are Araucarites cutcJie'^sis and Elatocladus jabalpurensis.^
The Maleri group is succeeded by the Kota stage. Its affinities,
however, are" with'the Upper Gondwanas, and will be described in
connection with them. The combined groups were sometimes designated as the Kota-Maleri stage. Reptilian fossils have also been
collected from the Tiki beds of South Rewah, representing approximately the Maleri horizon of other Gondwana centres. The Tiki
sandstones and shales have yielded some fragmentary bones among
which are maxillae and vertebrae of Hyperodapedon, teeth and other
relics of Dinosaurs, together with shells of the fresh-water lamellibranch Unio.
The Parsora stage.: This name is given by Dr. Cotter to a group of
beds in South Eewah, stratigraphically denoting a horizon corresponding roughly with the Rhaetic stage of Trias. These beds constitute the typical Middle Gondwanas of Feistmantel. The Parsoras
have yielded a flora of somewhat uncertain affinities containing elements of both Lower and Upper Gondwana type which still await a
critical examination. Among the fossils collected from the villages of
Parsora and Chicharia the dominant genus is Thinnfeldia (Dicroidium). This is represented by T. (D.) hughesi and several species allied
to those known from other parts of Gondwanaland, where the introduction of the Thinnfeldia element marks the later (Permo-Triassic)
phases of the Glossopteris flora. From localities further south a flora
apparently somewhat older, with Glossopteris as the chief genus, has
been collected. I t is possible that the latter is a typical Lower Gondwana flora, distinct from the northern set characterised by Thinnfeldia. In that case only the beds round Parsora should be included
in the Middle Gondwanas.
Triassic age of the Middle Gondwanas—Froni the foregoing account
of the Middle Gondwanas it must have been clear that they agree
in their lithology with the continental facies of the Triassic (the
New Red Sandstone) system of Europe. At the same time the
terrestrial forms of life, like the crustaceans, fish, amphibia and reptiles that are preserved in them, indicate that they are as akin biologically as they are physically to the English Trias. There are, how1 See Feistmantel, Pal. Indica, Fossil Flora of the Gondwana System (1877), vol. ii.,
pt. 2, p. 16 ; - (1879) vol. i., pt. 4, pp. 198-208.
•Sahni, Pal. Indica, vol. xi (1931), pp. 115-116.
142
GEOLOGY OF INDIA
ever, no indications in tlieso roclcs of tliat wonderful differentiation of
reptilian life which began in the Triassic epoch in Europe and America,
and gave rise, in the succeeding Jurassic period, to the numerous
highly specialised races of reptiles that adapted themselves to life in
the sea and in the air as much as on the land, and performed in that
geological age much the same office in the economy of nature as is now
performed by the class of Mammals.
<^
3, THE UPPER GONDWANA SYSTEM
Distribution—^Upper Gondwana rocks are developed in a, number of
distant places in the Peninsula, from the Eajmahal hills in Bengal to
the neighbourhood of Madras. The outcrops of the Upper Gondwanas, as developed in their several areas, viz. Eajmahal hills,^Damuda valley, the Satpura hills, the Mahanadi and Godavari valleys,
Cutch and along the Eastern coast, are designated by different names,
because of the difficulty of precisely correlating these isolated outcrops
with each other. I t is probable that future work will reveal their
mutual relations with one another more clearly, and will render possible their grouping under one common, name. In Cutch and along
the Coromandel coast, beds belonging to the upper horizon of the
Gondwanas are found interstratified with marine fossiliferous sediments, a circumstance of great help to geologists in fixing the timelimit of the Upper Gondwanas, and determining the homotaxis of the
system in the stratigraphical scale.
Lithology—Lithologically the Upper Gondwana group is composed of the usual massive sandstones and shales closely resembling
those of the Middle Gondwanas, but is distinguished from the latter
by the presence of some coal-seams and layers of lignitised vegetable
matter, and a considerable development of limestones in some of its
outcrops ; while one outcrop of the Upper Gondwanas, viz. that at thft
Rajmahal hills, is quite distinct from the rest by reason of its being
constituted principally of volcanic rocks. This volcanic formation is
composed of horizontally bedded basalts contemporaneously erupted,
which attain a great thickness.
Rajmahal series—^Upper Gondwana rocks are found in Bengal and
Bihar at two localities, the Damodar valley and the Rajmahal hills,
some 30 miles N.E. of the Raniganj coal-field, the latter being the
more typical locality. The Upper Gondwanas in the Rajmahal hills
rest unconformably on the underlying Barakar stage. The lowest
beds above the break are known under the name of the Dubrajpur sand-
.
THE UPPER GONDWANA SYSTEM
143
stone ; the Rajniahal series consists of 2000 feet of bedded basalts or
dolerites, with about 100 feet of interstratified sedimentary beds (intertrappean beds) of siliceous and carbonaceous clays and sandstones.
Almost the whole mass of the Eajmahal hills is made up of the volcanic flows, together with these inter-trappean sedimentary beds.
The shales have turned porcellanoid and lydite-like on account of the
contact-effects of the basalts. The basalt is a dark-coloured, porphyritic and amygdaloidal rock, commonly fine-grained in texture.
When somewhat more coarsely crystalline it resembles a dolerite.
The amygdales are filled with beautiful chalcedonic varieties of silica,
calcite, zeoUtes or other secondary minerals. A radiating columnar
structure due to " prismatic " jointing is produced in the fine-grained
traps at many places. It is probable that these superficial basaltflows of the Eajmahal series are connected internally with the dykes
and sills that have so copiously permeated the Raniganj and other
coal-fields of the Damuda region, as their underground roots. The
latter are hence the hypabyssal representatives of the subaerial
Eajmahal eruptions. Among these dykes mica-peridotites, lamprophyre, minette and ketsantite types have been found.
The andesitic trap of Sylhet, in the Khasi hills of Assam, unconformably underlying the Upper Cretaceous, is probably an eastward
continuation of the Eajmahal trap.
Eajmahal flora—The sihcified shales of the Eajmahal beds have
yielded a very rich flora in which the fossil Cycads (Bennettitales) are
the predominant group. Next in order of abundance are the Ferns
and Conifers. The cycad genera comprise many types of leaves
(e.g. Ptilophyllum, Pterophyllum, Dictyozamites, Otozamites, Nilssonia, Taeniopteris), also a few flowers {Williamsonia) and stems
[Bucklandia). The stem known as BucMandia indica bore leaves of
the Ptilophyllum type and Williamsonia flowers ; the connections of
the other leaf genera are still unknown. The most important Fern
genera are Marattiopsis, Cladophlebis, Coniopteris, GleicJienites and
Sphenopteris. The Coniferales include several kinds of vegetative
shoots (Elatocladus, Brachyphyllum, Retinosporites), detached cones
and scales (Gonites, Qntheodendron, Araucarites) and wood (Araucarioxylon). The Equisetales are represented by Equisetites and the
Lycopodiales by Lycopodites.'^ Among the Incertae are some genera
(Rajmahalia, Homoxylon, Pentoxylon, etc.) of much palaeobotanical
interest. Homoxylon rajmahalense is a type of fossil wood which
closely resembles the wood of some Jurassic Cycads as well as that of
some primitive modern angiosperms. It therefore supports the
144
GEOLOGY OF INDIA
well-known theory of the Bennettitalean origin of angiosperms.
The Rajmahal flora was till recently known almost exclusively from
impressions. Recent anatomical studies by Professor Sahni and his
pupils have considerably advanced our knowledge of this classical
flora.
The Rajmahal stage can fitly be called an age of fossil cycads, from
the predominance of the Bennettitales. The flora presents a sharp
contrast with those of the Lower and Middle Gondwanas. It wears a
distinctly more familiar aspect, the affinities of the great majority of
the genera being known. The Pteridosperms and the Cordaitales have
disappeared. The Equisetales have dwindled into insignificance.
The Ferns now claim an important place, and most of them can be
assigned to recent families. The conifers, formerly a small group, are
now on the increase ; in the collateral Kota and Jabalpur stages of
the Upper Gondwana they are as important an element in the flora as
the cycads, while in the succeeding Umia stage they actually dominate
the flora.
Satpura and Central Provinces
Jabalpur stage—^Upper Gondwana rocks, of an altogether different
facies of composition from that at Rajmahal, are developed on a very
large scale in these areas. The base of the series rests unconformably
on the underlying Maleri beds locally known under the *name of
Denwa and Bagra beds, and successively covers, by overlapping, all
the older members of the Middle and Lower Gondwanas exposed in
the neighbourhood. The rocks include two stages: the lower
Chaugan and the upper Jabalpur stage. The Chaugan stage consists
of limestones, clays and sandstones, with boulder conglomerates. I t
is succeeded unconformably by the next stage, named after the town
of Jabalpur. The rock components of the Jabalpur stage are chiefly
soft massive sandstones and white or yellow shales, with some lignite
and coal seams, and in addition a few limestone bands. The Jabalpur
stage is of palaeontological interest because of its having yielded a rich
Jurassic flora, rather distinct from that of the preceding series and of
somewhat newer age, viz. Lower Oolite. I t differs from the Rajmahal
flora mainly in its containing a greater proportion of conifers, viz.
Elatocladus (several species), Retinosporites, Bracliyphyllum, Pagiophyllum, Desmiophyllum, Araucarites, Strobilites, and in the much
reduced number of cycads.
At Jabalpur this stage is overlain by the Lameta group of Cretaceous strata, remarkable for their containing many fossil remains
of dinosaurs.
THE UPPER GONDWANA SYSTEM
145
Godavari Basin
Kota stage—A narrow triangular patch, of Upper Gondwana rocks
occurs in the Godavari valley south of Chanda. The rocks are of
the same type as those of the Satpuras, with the exception of the top
member, which is highly ferruginous in its constitution. At places the
oxides of iron are present to such an extent as "to be of economic value.
Here also two stages are recognised : the ],ower Kota stage, some 2000
feet in thickness, and the upper Chikiala stage, about 500 feet, composed of highly ferruginous sandstones and conglomerates. The Kota
stage is fossiliferous, both plant and animal remains being present in
its rocks in large numbers. The Kota stage, which overlies the Maleri
stage described above, consists of loosely consolidated sandstone, with
a few shale beds and with some limestones. From the last beds
numerous fossils of reptiles, fish, and Crustacea have been obtained,
e.g. several species of Lepidotus, Tetragonolepis, Dapedius, Ceratodits ;
and the reptiles Hyperodapedon, Pachygonia, Belodon, Parasuchus,
Massospondylus, etc. The plants include the conifers Palissya,
Araucarites and CJieirolepis, and numerous species of cycads belonging
to Cycadites, Ptilophyllum, Taxites, etc., resembling the Jabalpur
forms. The Chikiala stage is unfossiliferous, being often strongly
ferruginous (haematitic) and conglomeratic.
Gondwanas of the East Coast
The Coastal system—Along the Coromandel coast, between Vizagapatam and Tanjor, there occur a few small isolated outcrops of the
Upper Gondwanas along a narrow strip of country between the,gneissic
country and thecoast-line. These patches are composed, for the most
part, of marine deposits formed not very far from the coast, during
temporary transgressions of the sea, containing a mingling of marine,
littoral organisms with a few relics of the plants and animals that lived
near the shore. Near the Peninsular mainland there are consequently
to be seen in these outcrops both fossil plants of Gondwana facies and
the marine or estuarine molluscs including ammonites. In geological
horizon the different outliers correspond to all stages from the Eajmahal to the uppermost stage (Umia).
Rajahmmidri outcrop—The principal of these outcrops is the one
near the town of Eajahmundri on the Godavari delta. It includes
three divisions :
Tripetty sandstone—150 feet.
Raghavapuram shales—150 feet.
Golapili sandstones—300 feet.
W.O.I,
K
146
GEOLOGY OF INDIA
This succession of beds rests unconformably over strata of Eaniganj horizon, termed Chintalpudi sandstones. Lithologically they are
composed of littoral sandstones, gravel and conglomerate rock, with
a few shale-beds. The latter contain some marine lamellibranchs
{e.g. species of Trigonia, including T; ventricosa) and a few species
of ammonites. Intercalated with these are some beds containing
impressions of the leaves of cycads and conifers.
Ongole outcrop—Another outcrop of the same series of beds is found
near the town of Ongole, on the south of the Kistna. I t also consists
of three sub-divisions, all named after the localities :
Pavaloor beds—red sandstone.
Vemavaram beds—shales.
Budavada beds—yellow sandstone.
The Vemavaram shales contain a very rich assemblage of Gondwana plants, related in their botanical affinities to the Kota and
Jabalpur plants.
Madras group—A third group of small exposures of the same rocks
occurs near Madras, in which two stages are recognised. The lower
beds form a group which is known as the Sripermahir beds, consisting
of whitish shales with sandy micaceous beds containing a few cephalopod and lamellibranch shells in an imperfect state of preservation ;
the plant fossils obtained from beds associated in the same horizon
correspond in facies to the Kota and Jabalpur flora. The Sripermatur
beds are overlain by a series of coarser deposits, consisting of coarse
conglomerates interbedded with sandstones and grits, which contain
but few organic remains. This upper division is known as the Sattavadu beds.
One more exposure of the same nature, occurring far to the north
on the Mahanadi delta, is seen at Cuttack. I t is composed of grits,
sandstones and conglomerates with white and r e i . clays. The sandstone strata of this group are distinguished as the Athgarh sandstones._
They possess excellent qualities as building stones, and have furnished
large quantities of building material to numerous old edifices and
temples, of which the temple of Jagan Nath Puri is the most famous.
A middle Jurassic age was ascribed to these coastal Gondwanas but
of late the discovery of a suite of better preserved ammonites from
. Budavada and Kaghavapuram proves a considerably newer horizon
for these beds. Lower Cretaceous (Barremian). The ammonites are :
Holcodiscus, Lytoceras, Gymnoplites and Hemihoplites.
The identification of angiospermous fossil wood Homoxylon, a
T H E U P P E R GONDWANA SYSTEM
147
masnoliaceous dicotyledon and the flower of Williamsonia sewardi
from the Rajmalial series (the flora of which is essentially identical
with that of the coastal Gondwanas) by Sahni lends support to the
inference that both the series are probably of Neocomian or still later
age.
Umia Series
Upper Gondwanas of Cutch—The highest beds of the Upper Gondwanas are found in Cutch, at a village named Umia. They rest on the
top of a thick series of marine Jurassic beds (to be described with the
Jurassic rocks of Cutch in a later chapter). The Umia series, as the
whole formation is called, is a very thick series of marine conglomerates, sandstones and shales, in all about 3000 feet in thickness. The
special interest of this group lies in the fact that with the topmost
beds of this series, containing the relics of various cephalopods and
lamellibranchs, there occur interstratified a number of beds containing plants of Upper Gondwana facies, pointing unmistakably to the
prevalence of Gondwana conditions at the period of deposition of this
series of strata. The marine fossils are of uppermost Jurassic to lower
Cretaceous aSinities, and hence serve to define the upward stratigraphic limit of the great Gondwana system of India within very precise bounds. The Umia plant-remains are thought to be the newest
fossil flora of the Gondwana system. The following is the list of the
important forms:
(Conifers) Elatocladus, Retinosporites, Brachyphyllum,
phyllum, Araucarites.
(Cycads) Ptilophyllum, Williamsonia, Taeniopteris.
(Ferns) Cladophlebis.
Pagio-
Some of the species of these genera are allied to the Jabalpur species,
others are distinctly newer, more highly evolved types.
The Umia beds have also pelded the remains of a reptile, a species
belonging to the famous long-necked Plesiosaurus of the European
Jurassic. I t is named P. indica.
In Northern Kathiawar there is a large patch of Jurassic rocks
occupying the country near Dhrangadhra and Wadhwan which
correspohds to the Umia group of Cutch in geological horizon. It has
yielded conifers and cycads resembling the Umia plants.
Economics—The Upper Gondwana rocks include several coalseams, but they are not worked. Some of its fine-grained sandstones,
e.g. those of Cuttack, are much used for building purposes, while the
148
GEOLOGY OF INDIA
clays obtained from some localities are utilised for a variety of^ceramic manufactures. The soil yielded by the weathering of the Upper
Gondwanas, as of nearly all Gondwana rocks, is a sandy shallow soil
of poor quality for agricultural uses. Hence outcrops of the Gondwaiia rocks are marked generally by barren landscapes or else they .
are covered with a thin jungle. The few Umestone beds are of value
for lime-burning, while the richly haematitic or limonitic shales of
some places are quarried for smelting purposes. The coarser grits and
sandstones are cut for millstones.
REFERENCES
W. T. Blanford, The Ancient Geography of Gondwanaland, Rcc. O.S.I, vol.
xxix. pt. 2, 1896.
Charles Schuohert and Bailey Willis, Gondwana Land Bridges and Isthmian Links,
Bulletin of the Geological Society of America, vol. xliii., 1932.
0. Feistmantel, The Fossil Flora of the Gondwana System, vols, i.-iv. Pal. Indica,
1879-1886.
The Coal-Fields of India, Mem. O.S.I, vol. xli. pt. 1, 1913.
T. H. Huxley, R. D. Lydekker, etc., PossU Vertebrata of Gondwana System, Pal.
Indica, Series IV. pts. 1-5 (1865-1885).
G. de P. Cotter, Revised Classification of the Gondwana System, Bee, G.S.I, vol.
xlviii. pt. 1, 1917.
A. C. Seward and B. Sahni, Indian Gondwana Plants: A Revision, Pal. Indica,
vol. vii. mem. 1, 1920.
B. Sahni, Revisions of Indian Fossil Plants, Pal. Indica, N.S. vol. ix., 1928-1931
and vol. xx, mems. 2 and 3, 1932.
C. S. Fox, The Gondwana System and Coal Deposits of India, Mems. O.S.I, vols.
Ivii-lix., 1931-1934.
H. Crookshank, Gondwanas of North Satpura, Mem. O.S.I, vol. Ixvi. pt. 2, 1936.
CHAPTER XI
UPPER CARBONIFEROUS AND PERMIAN SYSTEMS
The commencement of the Aryan era—In the last two chapters we
have followed the geological history of the Peninsula up to the end of
the Jurassic period. Now let us turn back to the other provinces of
the Indian region where a different order of geological events was in
progress during this long cycle of ages.
As referred to before, the era following the Middle Carboniferous
was an era of great earth-movements in the extra-Peninsular parts of
India, by which sedimentation was interrupted in the various areas
of deposition, the distribution of land and sea was readjusted, and
numerous other changes of physical geography profoundly altered the
face of the continent. As a consequence of these physical revolutions
there is, almost everywhere in India, a very marked break in the
continuity of deposits, represented by an unconformity at the base
of the Permo-Carboniferous system of strata. Before sedimentation
was resumed, these earth-movements and crustal re-adjustments had
resulted in the easterly extension over the whole of Northern India,
Tibet and China of the great Mediterranean sea of Europe, whioh in
fact at this epoch girdled almost the whole earth as a true mediterranean sea, separating the great Gondwana continent of the south
from the Eurasian continent of the northern hemisphere. The southern shores of this great sea, which has played such an important part
in the Mesozoic geology of the whole Indian region—^the Tethys—
coincided with what is now the central chain of snow-peaks of the
Himalayas, beyond which it did not transgress to any extent; but,
to the east and west of the Himalayan chain, bays of the sea spread
over areas of Upper Burma and Baluchistan, a great distance to the
south of this line, while an arm of the same sea extended towards the
Salt-Eange and occupied that region, with but shght interruptions,
almost up to the end of the Eocene period. It is in the zone of deepwater deposits that began to be formed on the floor of this Central sea
at this time that the materials for the geological history of those
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CARBONIFEROUS AND PERMIAN SYSTEMS
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regions are preserved for the long succession of ages, from the beginning of the Permian t o the middle of the Eocene period, constituting
the great Aryan era of Indian geology.
jj
The nature of geosyndines—Portions
of t h e sea-floor subsiding i n t h e
form of long narrow troughs concurrently with the deposition of sediments,
and thus permitting an immense thickness of deep-water deposits to be laid
down over them without any intermission, are called Geosyndines. I t is
the behef of some geologists that the slow continual submergence of the
ocean bottom, which renders possible the deposition of enormously thick
sediments in the geosynclinal tracts, arises, in the first instance, from a
disturbance of the isostatic conditions of that part of the crust, further
accentuated and enhanced by the constantly increasing load of sediments
over localised tracts. The adjacent areas, on the other hand, which yield
these sediments, have a tendency to rise above their former level, by reason
of the constant, unloading of their surface due to the continued exposure to
the denuding agencies. They thus remain the feeding-grounds for the
sedimentation-basins. This state of things will continue till gravity has
restored the isostatic equilibrium of the region by a sufiicient amount of
deposition in one area and denudation in the other. At the end of this
cycle of processes, after prolonged intervals of time, a reverse kind of
movement will follow in this flexible and comparatively weak zone of the
crust, rendered more plastic by the rise of the isogeotherms, compressing
and elevating these vast piles of sediments into a mountain-chain, on the
site of the former geosyncline.
Geosynclinfis_are thus long narrow portions of the earth's outer shell
which are relatively the weaker parts of the earth's circumference, and are
liable to periodic alternate movements of depression and elevation. I t is
such areas of the earth which give rise to the mountain-chains when they
are, by any reason, subjected to great lateral or tangential compression.
Such a compression occurs, for instance, when two large adjacent blocks of
the earth's crust—horsts—are sinking towards the earth's centre during the
secular contraction of our planet, consequent upon its continual loss of
internal heat. The bearing of these conceptions on the elevation of the
Himalayas, subsequent to the great cycle of Permo-Eocene deposits on the
northern border of India, is plausible enough. The Himalayan zone is,
according to this view, a geosynclinal tract squeezed between the two large
continental masses of Eurasia and Gondwanaland. This subject is, however, one of the unsettled problems of modern geology, and one which is yet
subjudice, and is, therefore, beyond the scope of this book.
The records of t h e Himalayan area which we h a v e now to study
reveal an altogether different geological history from what we have
known of the Gondwana sequence. I t is essentially a history of the
oceanic area of the earth and of the evolution of t h e marine forms of
life, as the latter is a history of the continental area of the earth and
of the land plants and animals that inhabited it. This difference
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CARBONIFEROUS AKD PERMIAN SYSTEMS
153
emphasises the distinction'between the stable mass of the Peninsula
and the flexible, relatively much weaker extra-Peninsular area subject
to the periodic movements of the crust. In contrast to the Peninsular
horst, the latter is called the geosynclinal area.
The Upper Carboniferous and Permian—The Upper Carboniferous
and Permian systems are found perfectly developed in two localities
of extra-Peninsular India, one in the western part of the SaltRange and the other in Kashmir and the northern ranges of the
Himalayas.
I. UPPER CARBONIFEROUS AND PERMIAN OF THE
SALT-RANGE
After the Salt-pseudomorph shale of the Cambrian age, the next
series of deposits that was laid down in the Salt-Range area belongs to
this system. Since the Cambrian, the Salt-Range, in common with the
Peninsula, remained a bare land area exposed to denudational
agencies, but, unlike the Peninsula, it was brought again within the
area of sedimentation by the late Carboniferous movements. From
this period to the close of the Eocene, a branch of the great central
sea to the north spread over this region, and laid down the deposits
of the succeeding geological periods, with a few slight interruptions.
These deposits are confined to the western part of the Range,
beyond longitude 72° E., where they are exposed in a series of
more or less parallel and continuous outcrops running along the
strike of the range. In the eastern part of these mountains, PermoCarboniferous rocks are not met with at all, the Cambrian group
being there abruptly terminated by a fault of great throw, which
has thrust the Nummulitic limestone of Eocene age in contact
with the Cambrian.
The Permo-Carboniferous rocks of the western Salt-Range are a
thick series of highly fossiliferous strata. A two-fold division is discernible in them : a lower one composed of sandstones, and an upper
one mainly of limestones, characterised by an abundance of the
braohiopods Productus, and hence known as the Productus limestone.
The Productus limestone constitutes one of the best developed geological formations of India, and, on account of its perfect development, is a type of reference for the Permian system of the other parts
of the world.
154
" GEOLOGY OF INDIA
The table below shows the chief elements of the Permo-Carboniferous system of the Salt-Eange :
Chideru Stage. Marls and sandstones.
Upper Kundghat
Sandstones with Bel- Thuringian.
200 ft.
lerophons.
Sandy limestones.
Jabi
Produclus
limestone
700 ft.
Middle
300 ft.
Kalahagh
Virgal
Katta
Lower
dmb
200 ft.
Crinoidal limestones
with marls and dolo- Punjabian.
mites.
Cherty limestones.
Brown sandy limestones.
Calcareous sandstones. PermoFusulina limestone.
Carboniferous.
Clays, grey and blue. Upper
CarboniMottled sandstones.
ferous.
Olive shales and sandstones.
Speckled
Conularia and Eurysandstones
desma.
700 ft.
Boulder'
Urahan.
bed,
Glaciated boulders in
Talchir
Stage
10-200
a fine matrix.
ft.
Speckled sandstones,
300 ft.
Conularia beds,
200 ft.
Boulder beds—The basement bed of the series is a boulder-conglomerate of undoubted glacial origin, which from its wide geographical
occurrence in strata of the same horizon, in such widely separated
parts of India as Hazara, Simla^ the Salt-Kange, Rajputana, Orissa
and various other localities wherever the Lower Gondwana rocks have
been found, has been made the basis of an inference of a Glacial Age
at the commencement of the Upper Carboniferous period throughout
India. The evidence for this Ice Age in India lies in the existence of
the characteristic marks of glacial action in all these' areas, viz. beds
of compacted " boulder-clay " or glacial drift, resting upon an under
surface which is often sharply defined by being planed and striated by
the glaciers. The most striking character of a boulder-clay is its
heterogeneity, both in its component materials, which have been
transported, from distant sources, and in the absence of any assortment and stratification of these materials. Many of the boulders in
the boulder-bed of the Salt-Eange are striafted and polished blocks of
CARBONIFEROUS AND PERMIAN SYSTEMS
155
the Malani rhyolites, felsites and granites of Vindhyan age—an important formation of Rajputana. These are intermixed with smaller
pebbles from various other crystalline rocks of the same area, and
embedded in a fine dense matrix of clay. Besides striations and
polishing, a certain percentage of the pebbles and boulders shows
distinct " facetting ". The AravalU region must have been the home
of snow-fields nourishing powerful glaciers at this time, as the size of
the boulders as well as the distances to which they have been trans.ported from their source clearly testify to the magnitude of the
glaciers radiating from it.
Boulder-beds similar to that of the Salt-Range, and also hke them
composed of ice-borne boulders of Malani rhyolites and other crystalline rocks, are found in Rajputana in Marwar (Jodhpur'State) and are
known as the Bap and Pokaran beds, from places of that name.. At
the latter place there occur typical roches moutonnees. The Talchir
boulder-bed is homotaxial with the glacial beds associated with the
Eurydesma beds of South East Australia.
The Speckled sandstones—The boulder-bed is overlain by a group
of olive shales and sandstones forming the lower part of the Speckled
sandstone series designated as the Conularia beds, because of their
containing the fossil Conularia enclosed in calcareous concretions.
The genus Conularia is of doubtful systematic position and, like
Hyolithes, is referred to the Pteropoda, or at times to some other suborder of the Gastropoda, or even to some primitive order of the
Cephalopoda. Associated fossils are, Pleurotomaria, Eurydesma,
Bucania, Nucula, Psevdomonotis, Chonetes, Aviculopecten, etc.
These fossils are of interest because of their close similarity to the
fauna of the Permo-Carboniferous of Australia, which also contains,
intercalated at its base, a glacial formation in' every respect identical
to that of the Talchir series. The Conularia beds are succeeded by a
series of mottled or speckled red sandstones, from 300 to 500 feet in
thickness, interbedded with red shales. The whole group is currentbedded, and gives evidence of deposition in shallow water. From the
mottled or speckled appearance of the sandstone, due to a variable
distribution of the colouring peroxide of iron, the group is designated
the Speckled sandstones.
The Productus limestone—This group is conformably overlain by
the Productus hmestone, one of the most important formations of
India, and one which has received a great deal of attention from
Indian geologists, being the earliest fossiliferous rock-system discovered in India. I t is ftiUy developed in the central and western
156
GEOLOGY OF INDIA
part of the range, but thins out at its eastern end. About 700 feet of
Umestones are exposed in a series of fine cliifs near the Nilawan valley,
and thence continue westwards along Ithe Salt-Kange right up to the
Indus gorge, beyond which the group disappears gradually. The best
and the most accessible outcrops of the rocks are in the Warcha
valley ^ and Chideru hills in the neighbourhood of Musa Khel, -yest
of the Son Sakesar phtean. The greaher part of the Prodactus limestone is a compact, crirxoidal magnesian limestone sometimes passing
into pure crystalUne dolomite, associated with beds of marl and sandstones. It contains a rich and varied assemblage of fossil brachiopods,
corals, crinoids, gastropods, lamellibranchs,cephalopods,fusuKnae and
plants, constituting the richest Upper Palaeozoic fauna anywhere dis- i
covered in India, to which the faunas of the other homotaxial deposits;
are. referred. The abundance and variety of the Productus fauna has
thus led to the name of Punjahian being given to the series of Middle
Permian strata coming between the Artinskian and Thuringian. The
stage name of Punjabian has also been used in the past to include the
strata from the Boulder-bed to the top of the Speckled sandstone
(Uralian to Artinskian). On a palaeontological basis the Productus
Umestone is divided into three sections: the Lower, Middle and
Upper.
With the lower beds of the Lower Productus limestone there comes
a sudden change in the character of the sediments, accompanied by a
more striking change in the facies of the fauna, almost all the species
of the Speckled sandstone group disappearing from the overlying
group. The lower 200 feet carry many beds of Fusulina liipestone
with ParafusuUna. It is composed of soft calcareous sandstones, fuU
of fossils, with coal-partings at the base. Productus cora, P. semireticplatus and P. spiralis are the characteristic species of this division.
Associated with these, in the coal-partings, are the genera Glossopteris and Gangamopteris, of Damuda affinities. - I t includes two
stages : the lower, more arenaceous stage is well seen at the Amb
village, and is known as the Amb beds, and the upper calcareous stage
is known as the Katta beds.
The Middle is the thickest and most characteristic part of the Productus limestone, consisting of from 200 to 300 feet of blue or grey
limestone, which forms the high precipitous escarpments of the
mountains near Musa K.hel. Dolomite layers, which are frequent, are
white or cream-coloured, and from the greater tendency of dolomite
to occur in crystalline form they are much less fossiUferous owing to
' Records, O.S.I, vol. Ixii, pt' 4, 1930.
CARBONIFEROUS AND PERMIAN SYSTEMS
157
the obliteration of the fossils attending the recrystallisation process.
Marly beds are common, and are the best repositories of fossils, yielding them readily to the hammer. The limestones are equally fossili' ferous, but the fossils are very difhcult to extract, being only visible
in the weathered outcrops at the surfaces. Many of the fossils are
silicified, especially the corals. There' is also an intercalation of plantbearing Lower Gondwana shales and sandstones. P. lineatus is a
common brachiopod species in the Middle Productus. Elint and chert
concretions are abundantly distributed in the limestones. This
division also includes two stages, Virgal and Kalabagli, the latter
containing the ammonoids Xenaspis and Foordoceras.
The Upper Productus group is' much less thick, hardly reaching
100-200 feet at places. The group is more arenaceous, being composed
of sandstones with carbonaceous shales, with subordinate bands of
limestone and dolomite. Silica is the chief petrifying agent here also.
P. indicus is a common species. Fossils are numerous, but they reveal
a striking change in the fauna, which separates this group from the
preceding group. The most noteworthy feature of this change is the
advent of cephalopods of the order Ammonoidea, represented by a
number of its primitive genera. The topmost stage of the Upper
Productus forms a separate stage by itseK, known as the Chideru beds.
They show a marked palaeontological departure from the underlying
ones in the greatly diminished number of brachiopods and the increase
of lamellibranchs and cephalopods. They are thus to be regarded,
from these peculiarities, as a sort of transition, or "passage beds", between the Permian and the Triassic. The Chideru beds pass conformably and without any notable change into a series of Ceratitebearing beds of Lower Triassic age.
Productus fauna—The following is a list of the more characteristic
genera of fossils belonging to the Productus limestone. Many of the
genera are represented by a large number of species :
Upper Productus : (Ammonites) Xenodiscus, Cyclolobus, Medlicottia,
'Arcestes, Sageceras, Popanoceras, Taenioceras ; (Brachiopods)
Productus, Oldhamina, Berhya, Chonetes, Martinia, Aulostegia;
(Gastropods) Bellerophon, Euphemus, etc.; (Lamellibranchs)
Schizodus, Lima, Gervillia; (Polyzoa) Entolis, Synocladia,
etc.
Middle Productus : (Brachiopods) Productus, Spirifer, Spiriferina,
Athyris, Lyttonia, Oldhamina, Richthofenia,
Reticularia,
Hemyptycliina; (Lammellibranchs) Oxytoma, Pseudbmonotis,
Marginifera, Notothyris;
(Polyzoa) Fenestella, Stenopora,
158
GEOLOGY OF INDIA
Thamniscus,
AcantJiocladia;
(Worm) Spirorbis;
(Corals)
Zaphrentis, Lonsdaleia; (Gastropods) Macrocheilus; (Cephalopods) Xenaspis, Nautilus,
Orthoceras.
Lower Productus : Productus ( P . cora, P. semireticulatus, P. spiralis)
Spirifer,
Spiriferina,
Aihyris
royssi, Orthis,
Reticularia,
Richthofenia, Martinia, Dielasma, Streptorhynchus,
Strophalosia ; (Foraminifers) Fusulina,
Parafusilina.
[Besides these mentioned above, the following fossils also are characteristic of the Salt-Range Productus limesttine :
Gastropods : Euomphalus, Macrocheilus, Naticopsis, Phaseonella, Pleurotomaria, Murchisonia, Bellerophon {Bucania, Stachella, Euphemus,
and several other genera of the family Bellerophontidae), Hyolithes
and Entalis.
Lamellibranchs : Cardiomorpha, Lucina, Cardinia, Schizodus, Aviculopecten, Pecten (two species).
/
Brachiopods : These are the most abxmdant, both as regards species
and individuals. Didasma is represented by ten species, Notothyris (eight species), Lyttonia (three species), Camarophoria (five
species), Spirigerilla (ten species), Aihyris (ten species), Spirifer
(eight species), Martiniopsis, Martinia, Reticukeria, Orthis, Strophomena, Streptorhynchus, Derbya (eight species), Leptaena,
Chonetes (fourteen species), Strophalosia, Productus (fifteen species),
and Marginijera.
Polyzoa : Polypora, Goniocladia, Thamniscus, Synocladia.
Crinoids : Poteriocrinus, Philocrinus, Cyathocrinus, etc.
Corals: Pachypora, Michelinia, Stenopora, Lonsdaleia,
Amplexus,
Zaphrentis, Glisiophyllum.
Ganoid and other fishes. Plants, etc.]
The P r o d u c t u s fauna shows several interesting peculiarities.
While the fauna as a whole is decidedly Permian, the presence in it
of several genera of true Ammonites and of a lamelUbranch like
Oxytoma and a Nautilus species, which in other p a r t s of the world are
not m e t with in rocks older t h a n the-Trias, giveg. t o it a somewh'lt
newer' aspect. The most noteworthy peculiarity, however, is the
association of such eminently Palaeozoic forms as Productus', Spirifer,
Athyris, Bellerophon, etc., with cephalopods of the order AmmonoideU.
All forms which can be regarded as transitional between the goniatites
and the Triassic ceratites are found, including true ammonites like
Cyclolobus, Medlicottia,
Popanoceras,
Xenodiscus,
Arcestes, etc.
Some of these possess a simple p a t t e r n of sutures resembling those of
the Goniatites (sharply folded) or Clymenia (simple zig-zag lobes and
saddles), while others show an advance in the complexity of the sutures
approaching those of some Mesozoic genera.
CARBONIFEROUS AND PERMIAN SYSTEMS
159
The Anthracolithic systems of India—The lo^Ycr part of the SaltRange Productus limestone group is, from fossil evidence, the homotaxial equivalent of the Permo-Carboniferous of Kashmir, Spiti and
Northern Himalayas generally. The term "anthracolithic", used by
some authors as a convenient term to express the closely connected
Carboniferous and Permian .systems of rocks and fossils in those
areas, e.g. the Shan States of Burma, which exhibit an intimate
stratigraphic as well as palaeontological connection with one another,
and where it is difficult to separate the Carboniferous from the
Pernjian, is to be distinguished from the term " Permo-Carboniferous ", which refers to the zone of strata lying between the topmost Carboniferous and the base of the Permian.
11. THE UPPER CARBOinFEROUS AMD PERMIAN SYSTEMS
OF THE HIMALAYAS
The Himalayan representatives of the Productus limestone are
developed in the northern or Tibetan zone of the Himalayas along
their whole length from Kashmir to Kumaon and beyond to the
Everest region. They are displayed typically at two localities, Spiti
and Kashmir, where they have been studied in great detail by the
Geological Survey of India.
Spiti
In Chapter VIII we have followed the Palaeozoic sequence of the
area up to the Eenestella shales of the Po series. Resting on the top
of the Fenestella shales, in our type sections, but at other places lying
over beds of varying horizons from the Silurian to the Carboniferous,
is a conglomerate layer of variable thickness, belonging in age to the
Upper Carboniferous or Permian. This conglomerate, as has been
stated before, is an important datum-line in India, for it is made the
basis of the division of the fossiliferous rock-systems of India into two
major divisions, the Dravidian and Aryan. The Aryan era, therefore,
commences in the Himalayas, with a basement conglomerate, as it
commenced in the Salt-Range a5d in the Peninsula with the glacial
boulder-bed.
The Productus shales—The conglomerate is succeeded by a group
of calcareous sandstones, containing fossil brachiopods of the genera
Spirifer, Productus, Spiriferina, Dielasma and Streptorhynchus, representing the Lower Productus horizon of the Salt-Range. These are
160
GKOLOGY OF INDIA
overlain by a thin group of dark carbonaceous shales, the characteristic Permian formation of
the Himalayas, known as the
Productus shales, corresponding to the Upper Productus
horizon. (See Figs. 11 and 19.)
The Productus shales are a
group of black siliceous, mica"*- V^7M
w\§ s •" S • ceous and friable shales. They'
are only 100 t(^ 200 feet in
thickness, but are disBnguished
by a remarkable constancy in
their lithological composition
•s
over the enormous extent of
mountains
from Kashmir to
p.
Nepal. The Productus shales
constitute one of the most
conspicuous and readily distinguished horizons in the
\
.Palaeozoic geology of the*^
a
5a
Himalayas. Being a soft,
earthy deposit, it has yielded
a
most to the severe flexures and
compression of this part of
CI
the
mountains and suffered a
/
a
sO
o
greater degree of crushing than
ea
the more rigid strata above
,/ /
and below. (See Plate VIII.»
facing p. 114, also Plate XII
y^»
facing p. 166.) The fossil^,^
organisms entombed in
shales include characteristic
Permian brachiopod species
of Productus (P. purdoni),
Spirifer {S. musakheylensis, S.
fill!
(D
T/i
jeaiy ijids,.
5*5^
rajah, and five other species),
Spirigera, Dielasma, Martinia,
Marginifera {M. himalayensis)
and Chonetes. Of these the
species Spirifer rajah and
Marginifera himalayensis are highly characteristic of the Permian
X
CARBONIFEROUS AND PERMIAN SYSTEMS
IGI
of the Central Himalaya. In- some concretions contained in tlie
black stales are enclosed ammonites like Xenaspis and Cydolobus.
The Permian rocks of the Central Himalaya have been also designated
as the Kuling system from a locality of that name in the Spiti valley.
Dr. Hayden gives the following sequence of Permian strata in the
Spiti area :
Lower Trias.
Otoceras zone of Lower Trias.
Productus shales : black or brown siHceous shale
with Xenaspis, Cydolobus, Marginifera himalayensis, etc.
Permian,
Calcareous sandstone with Spirifer.
Grits and qnartzites.
Conglomerates (varying in thickness).
SUght unconformity
Upper Carboniferous,
Fenestella shales of Po series.
The Productus shales are succeeded by a group of beds character- ,
ised by the prevalence of the Triassic ammonite Otoceras, which denotes the lower boundary of the Trias of the Himalayas, one of the
most important and conspicuous rock-systems of the Himalayas from
the Pamirs to Nepal.
The strata above described mark the beginning of the geosynclinal facies of deposits constituting the northern or Tibetan zone of
the Himalayas. As yet the strata are composed of shales and sandstones, indicating proximity of the coast and comparatively shallow
waters, but the overlying thick series of Triassic and Jurassic systems
are wholly constituted of limestones, dolomites and calcareous shales
of great thickness, giving evidence of the gradual deepening of the
ocean bottom.
Kashmir
In keeping with the rest oi the Palaeozoic systems, the Upper
Carboniferous and Permian is developed on a large scale in Kashmir.
The Upper Carboniferous consists of a thick (over 8000 feet) volcanic
series—Panjal Volcanic series—of bedded tuffs, slates, ash-beds and
andesitic to basaltic lava-flows {Panjal Trap). The slaty tuffs contain at places marine fossils allied to-the fauna of the Productus limestone.
In the Tertiary zone of the Kashmir Outer Himalaya there
occur a number of large masses of an unfossiliferous dolomitic limestone, laid bare as cores of denuded anticlines, in the Upper Tertiaries of Murree age. This limestone (the " Great limestone " of
162
GEOLOGY OJ? INDIA
Medlicott) is markedly similar in, its litliological characters and
stratigraphic relations to the " Infra-Trias " limestone of Sirban,
Hazara, and is now referred to it. This limestone is of considerable
economic value from some workable lodes of zinc, copper and nickel
occurring in it (p. 352). A most interesting circumstance in connection with the Permian of Kashmir is the association of both the Gondwana facies of fluviatile deposits containing seed-ferns hke Gangamofteris and Glossopteris and the marine facies containing the characteristic fossils of the age. The Gondwana beds (known as the Gangamopteris beds), which are the local representatives of the TaichirDamuda series of the Peninsula, are overlain by the marine Permian
beds {Zewan series), containing a brachiopod fauna identical in many
respects with that of the Productus limeston'e. (Chap. XXVII,
p. 416).
Hazara
As in the western parts of Kashmir, the Palaeozoic record of Hazara
is confined to representatives of the Upper Carboniferous and the
Permian. On the upturned truncated edges of Purana slates, the
contemporaries of Attock and Dogra slates, there comes a boulderconglomerate composed''of facetted and striated boulders set in a fine
silty matrix. This boulder-bed (tillite), regarded as the contemporary
of the Talchir and Salt-Range glacial conglomerate, is followed by a
series of purple and speckled sandstones and shales, the whole overlain by dolomitic limestones, over 2000 feet in thickness. The limestone is compact and well bedded, of purple, grey and cream colours ;
its weathering is very pecuhar, giving rise to blocks with deeply incised cuts and grooves.. The rock is wholly unfossiliferous, but from
its intimate association in Kaghan with the Panjal Volcanic series
and the occurrence of the glacial boulder-bed at its base there is now
little room for doubting its Upper Carboniferous or Permo-Carboniferous age. The above Hazara sequence was formerly regarded as
probably Devonian and named " Infra'-Trias " from its immediately
underlying the more conspicuous Trias limestone of the Sirban mountain, a prominent mountain near Abbottabad. (Fig. 22.)
Simla HiUs Area
With the exception of some intervening limestones and slates ol
uncertain position (Shall limestone), the system of deposits which
comes next above the Simla slates is referred to the Upper Carboniferous and Permian with a high degree of probability. As in Hazara.
CABBONIFBROUS AND PERMIAN SYSTEMS
163
flip bottom bed is a glacial boulder-bed—the Blaini conglomerate—
mconformably reposing on the Simla slates or the Jaunsars, succeeded by pink-coloured dolomitic limestones. Over these comes a
thick series of carbonaceous shaly slates, with brown quartzite partjjjgg ^;.iie Infra-Krol series—which have been provisionally correlated with the Lower Gondwanas of the Peninsula. The succeeding
series consists of a thick group of massive blue limestones and shales,
underlain by partly-consolidated, coarse sandstones, referred to as the
Krol series, from their building the conspicuous mountain of that name
near Solon. As with the rest of the formations of the Simla area, the
Krol limestones, so eminently adapted to preserve any entombed
organisms, are entirely barren of fossils. The inference that it is homotaxial with the Sirban limestone of Hazara and with the Productus
group of the Salt-Range is based on the probable parallelism of the
sequence commencing with a glacial boulder-bed (? Talchir) in these
areas.
The most prominent development of the Krol series is in what is
known as the Krol belt of the Outer Himalaya of Simla, extending
from near Subathu to Naini Tal, a distance of 180 miles. A very
perfect stratigraphic sequence has been worked out in this area by
J. B. Auden, which has revealed the presence of a number of thrusts
causing overriding of Tertiary rocks by the much older rocks we are
considering here.. In the neighbourhood of Solon and Subathu,
Eocene and Oligocene rocks are exposed as inliers (" windows ") by
the erosion of the superjacent overthrust masses of these presumed
Fermo-Carbonifeious rocks.^
Burma
We have seen in Chapter VIII that there is in Upper Burma
(Northern Shan States) a conformable passage of the Devonian and
Carboniferous to strata of the Permian age in the great limestone
formation constituting the upper part of what is known there as the
Plateau limestone. (See also Pig, 12, p. 117.) In the upper beds of
these limestones there is present a fauna ^ of brachiopods, corals,
polyzoa, etc., which show on the whole fairly close relations to the
Productus limestone of the Salt-Eange and the Productus shales of
the Spiti Himalayas and the Zew'an series of Kashmir. From these
affinities between the homotaxial faunas of the Indo-Burma region,
Dr. Diener, the author of many memoirs on the faunas, considers all
1 Mec. a.S.I. vol. Ixvii. pt. 4, 1934.
^ Anthraoolithic Faunas of the Southern Shan States, Hec. G.S.I, vol. U™. pt. I,
1933.
164
GEOLOGY OF INDIA
these regions as belonging to the same zoo-geographical province,
their differences being ascribed to the accidents of environment, isolation through temporary barriers and differences in the depth and
salinity of waters, etc.
The Permo-Carboniferous rocks of Burma contain two foraminiferal limestones : the Fusulimk^mestone and the Schimgerina limestone, from the preponderance of these two genera of Carboniferous
and Permian foraminifers.
4
3
2
1 *
- 5
Fio. 20.—Palaeozoic rocks of the N. SJian States.
i. Chaung-Magyi series (Cambrian).
2 and 3. Naungkangyi series (Ordovician).
4. Namshim beds (Silurian).
5. Plateau limestone (Devonian and Permo-Carboniferous).
6. Napeng beds (Upper Triassic).
La Touche, Mem. Q.8.I. xxxix. pt. 2, 1913.
III. MAHINE PERMO-CARBONIFEROUS OF THE
PENINSULA
An extraordinary occurrence has been recorded ^ at Umaria
(Central India) of a thin and solitary band of marine Productus limestone in the midst of fresh-water coal-bearing beds belonging to the
Barakar stage of the Damuda series (Lower Gondwana system).
The marine intercalation is only ten feet thick and conformably
underlies the sandstone and grit strata of normal Barakar facies,
exposed in a cutting in the Umaria coal-field. I t unconformably overlies the Talchir boulder-bed. The limestone bed is made up entirely
of the fossil shells of Productus, the only other fossils present being
Spiriferina, and Reticularia.
Cowper Keed considers the Umaria fauna is quite local and unique,
showing no clear affinities with the nearby Salt-Range province, but
rather with the Himalayan and Russian Permo-Carboniferous province.
This bed must be regarded as a solitary record of an evanescent
transgression of the sea-waters into the heart of the Peninsula, either
from the North through Rajputana, or from the West Coast, induced
' Sinor. K- P.. Mineral Resources of Eewa Slate, p. 21, 1923.
CARBONIFEROUS AND PERMIAN__SYSTEMS
165
bv some diastrophic modification of tlie surface of the land, which,
however must have been of a transient nature and must have soon
ceased to operate.
REFERENCES
H H Hayden, Geology of Spiti, Mem. O.S.I, vol. xxxvi. pt. 1, 1904.
Karl Diener, Pal. Indica, Series XV. vol. i. pts. 2, 3, 4 and 5 (1897-1903) ; Pal.
Indica, New Series, vol. iii. mem. iv. (1911) ; vol. v. mem. ii. (1915).
W Waagen, Pal. Indica, Series XIII. vol. i. pts. 1-7 (1879-1887), (Salt-Range
Fossils); and vol. iv. pts. 1 and 2 (1889-1891).
CHAPTER X I I
THE TEIASSIC SYSTEM
General—Tlie Productus shales (Ruling system) of the Himalayas
and the Chideru stage of the Productus limestone of the Salt-Range
are succeeded by a more or less complete development of the Triassic .
system. The passage in both cases is quite conformable and even
transitional, no physical break in the continuity of deposits being
observable in the sequence. The Triassic system of the Himalayas,
both by reason of its enormous development in the northern geosynclinal zone as well as the wealth of its contained faunas, makes a conspicuous landmark in the history of the Himalayas. The abundance
of its cephalopodan fauna is such that it has been the means of a zonal
classification of the system {zones are groups o£ strata of variable
thickness, but distinguished by the exclusive occurrence, or predominance, of a particular species, the zone being designated by ^he name
of the species). In Spiti, Garhwal and Kumaon, and on the northwest extension of the same axis in Kashmir, the Trias attains a development of more than 3000 feet, containing three well-marked subdivisions, corresponding respectively to the Bunter, Muschelkalk and
Keuper of Europe.
Other regions where the Trias occurs, either completely developed
or in some of its divisions, are the Salt-Range, Baluchistan and Burma.
In the Salt-Range the Triassic system is confined to the Lower Trias
and the lower part of the Middle Trias, while in Baluchistan and
Burma it is confined to the Upper Triassic stages^ only. In the t ^ o
latter areas it assumes an argillaceous facies of shales and slates,
whereas in the Himalayan region the system is entirely composed of
Umestone, dolomites and calcareous shales.
Principles of classification of the geological record—With the Trias we
enter the Mesozoic era of geology, and before we proceed further we might
at this stage enquire into the basis for the classification of the geological
record into systems and series, and consider whether the interruptions or
" blanks " in the course of the earth's history, which have led to the creation of the chief divisions, in the first instance, in some parts of the world,
were necessarily world-wide in their effects and applicable to all parts of
the world.
166.
THE TEIASSIC SYSTEM
167
In Europe the geological record is divided into three broad sections or
groups : the Palaeozoic, Mesozoic and Cainozoic, representing three great
eras in the history of the development of life on the earth, each of which is
separated from the one overlying it by an easily perceptible and comparatively wide-spread physical break or " unconformity ". Whether these
divisions, so well marked and natural in Europe, where they were first recognised, are as well marked and natural in the other parts of the world,
and whether these three, with their sub-divisions, should be the fundamental periods of eaith-history for the whole world is a subject over which
the opinion of geologists is sharply divided. In the geological systems of
India, as in the other regions of the earth, although the distinctive features
of the organic history of the Palaeozoic, Mesozoic and Cainozoic are clearly
evident, as we ascend in the stratigraphic scale, we cannot detect the sharp
breaks in the continuity of that history at which one great time-interval
ends and the other begins. Just at these parts the geological record
appears to be quite continuous in India, and any attempt at setting a Umit
would be as arbitrary as it would be unnatural. On the other hand, there
are great interruptions or " lost intervals " in the Indian record at other
stages (where the European record is quite continuous) at which it is much
more natural to draw the dividing lines of its principal divisions—the groups.
As we have already seen, Sir T. H. Holland has accomplished this in Ms
scheme of the classification of the Indian formations. Though generally
adopted in India, and best suited to the rather imperfect character of the
geological record as preserved in India, such a classification and nomenclature may not be acceptable to those geologists who hold that the grand
divisions of geology are universal and applicable to the whole world. The
subject is difficult to decide one way or the other' but for the information of
: the student the following view, which summarises the arguments of the
latter class of geologists with admirable lucidity, is given verbatim from
the work of Professors T. C. ChamberHn and R. T>. Salisbury : ^
" We believe that there is a natural basis of time-division, that it is
recorded dynamically in the profounder changes of the earth's history, and
that its basis is world-wide in its applicability. I t is expressed in interruptions of the course of the earth's history. It can hardly take account of all
local details, and cannot be applied with minuteness to all localities, since
geological history is necessarily continuous. But even a continuous history
has its times and seasons, and the pulsations of history are the natural basis
for its divisions.
" In our view, the fundamental basis for geologic time-divisions hap. its
seat in the heart of the earth. Whenever the accumulated stresses within
the body of the earth overmatch its effective rigidity, a readjustment takes
place. The deformative movements begin, for reasons previously set forth,
with a depression of the bottoms of the oceanic basins, by which their
capacity is increased. The epicontinental waters are correspondingly
withdrawn into them. The effect of this is practically universal, and all
continents are affected in a similar way and simultaneously. This is the
reason why the classification of one continent is also applicable, in its larger
features, to another, though the configuration of each individual coatiueat
' Advanced Geology, vol. iii.. Earth History,
168
GEOLOGY OF INDIA
modifies the result of the change, so far as that continent is concerned.
The far-reaching effects of such a withdrawal of the sea have been indicated
repeatedly in preceding pages. Foremost aqiong these effects is the profound influence exerted on the evolution of the shallow-water marine life,
the most constant and reliable of the means of intercontinental correlation.
Second only to this in importance is the influence on terrestrial life through
the connections and disconnections that control migration. Springing from
the same deformative movements are geographic and topographic changes,
affecting not only the land, but also the sea currents. These changes affect
the climate directly, and by accelerating or retarding the chemical reactions
between the atmosphere, hydrosphere, and lithosphere, affect the constitution of both air and sea, and thus indirectly influence the environment of
life, and through it, its evolution. In these deformative movements, therefore, there .seems to us to be a universal, simultaneous, and fundamental
basis for the sub-division of the .earth's history. I t is all the more effective
and applicable, because it controls the progress of life, which furnisheJ the
most available criteria for its application in detail to the varied rock formations in all quarters of the globe.
" The main outstanding question relative to this classification is whether
the great deformative movements are periodic rather than continuous, and
co-operative rather than compensatory. This can only be settled by comprehensive investigation the world over; but the rapidly accumulating
evidence of great base-levelling periods, »which require essential freedom
from serious body deformation^ as a necessary condition, has a trenchant
bearing on the question. So do_the more familiar evidences of great sea
transgressions, which may best be interpreted as consequence of general
base-levelling and concurrent sea-fiUing, abetted by continental creep during a long stage of body quiescence. It is too early to affirm, dogmatically,
the dominance in the history of the earth of great deformative movements,
separated by long intervals of essential quiet, attended by (1) base-levelling,
(2) sea-fiUing, (3) continental creep, and (4) sea-transgression; but it requires little prophetic vision to see a probable demonstration of it in the
near future. Subordinate to these grander features of historical progress,
there are innumerable minor ones, some of which appear to be rhythmical
and systematic, and some irregular and irreducible to order. These give
rise to the local epochs and episodes of earth-history, for which strict
intercontinental correlation cannot be hoped, and which must be neglected
in the general history as but the individuahties of the various provinces.
" The periods which have been recognized in the Palaeozoic and Mesozoic, chiefly on the basis of European and American phenomena, seem to us
likely to stand for the whole world, with such emendations as shall come
with widening knowledge."
Trias of Spiti
The Triassic system of Spiti—Triassic rocks are developed
whole nothern boundary of the Himalayas, constituting
scarps of the plateau of Tibet, but nowhere on such a scale
tion as in Spiti and the adjoining provinces of Garhwal and
along the
the great
of perfecKumaon.
(See Figs. 11, 19 and 21.) A perfect section of these rocks, showing
THE TRIASSIC SYSTEM
169
the relations of the Trias to the system below and above it, is exposed
at Lilang in Spiti. From this circumstance the term Lilang system
is used as a synonym for the Triassic system of Spiti,
The component members of the system are principally darkcoloured limestones and dolomites, with intercalations of bluecoloured shales. The colour, texture, as well as the whole aspect of
the limestone, remain uniform over enormous distances without showing local variations. This is a proof of their origin in the clear deep
waters of the sea free from all terrigenous sediments. The rocks are
richly fossiliferous at all horizons, a circumstance which permits of
the detailed classification of the system into stages and zones. The
primary division of the Himalayan Trias is into three series, of very
unequal dimensions, which, so far as they denote intervals of time,
are the hom(:)^axial equivalents of the Bunter, Muschelkalk, and
Keuper series of the European (Alpine) Trias. The following section
from Dr. Hayden's Memoir gives a clear idea of the classification of
the'system: ^
Jurassic : (Ehaetic ?) Massive Megalodon limestone.
EJeuper
' 2800 ft.
'1 Muschelkalk,
400 ft,
Bunter,
50 ft.
Quartzites with shales and limestones: Lima,
Spirigera.
" Monotis shale " : sandy and shaly limestone.
Coral limestone.
Juvavkes beds : sandstones, shales and limestones.
Tropites beds : dolomitic limestone, and shales.
Grey shales: shaly limestone and shales with
Spiriferina, Rhynchonella, Trachyceras, etc.
Halobia beds: hard dark Umestone with Halobia,
Arcestes, etc.
Daondla Hmestone: thin black limestone with
shales, Daonella, Ptychites.
Limestone with concretions.
Grey limestone with Ceratites, Sibirites, etc.
Nodular limestone (Niti Umestone).
/ Nodular limestone.
Limestone and shale with Aviculopecten.
Hedenstroemia zone.
Meekoceras zone, M. varahaa.
Pphiceras zone, 0. sakuntala.
Otoceras zone, 0. woodwardi.
"
I
Fermian:
Productus shales.
> Geology of Spiti, Mem. O.S.I, vol, :5sxvi. pt. 1, p. 90.
]70
GEOLOGY OF INDIA
Triassic favina—The Lower Trias is thin in comparison with the
other two divisions of the system, and rests conformably on the top
of the Productus stales. The rocks are composed of dark-coloured
shales and limestone, with an abundant ammonite fauna. Besides
those mentioned in the section above, the following genera are important :
Tirolites, Ceratites, Danubites, Flemingites, Stephanites, with
Pseudomonotis, Rhynchonella, Spiriferind and Retzia.
The middle division is thicker, and largely made up of concretionary limestones. This division is also widespread and capable of
detailed subdivision into stages and zones, which preserve a uniform
\Daonella limestone
Meekocefas zone
Ophiceras zone
Otocerad zone
Fio. 21.—Section of tfio Trias of Spiti.
1. Productus shales (Permian).
3. Muschellialls.
2. Lower Trias.
4. Upper Trias (lower part only).
Hayden, Mem. 0.8.1., vol. xxxvi. pi. i.
character, both faunistic and lithological, over Spiti, Painkhanda,
Byans, and Johar. This division possesses a great palaeontological
interest because of the rich Muschelkalk fauna it contains, resembling
in many respects the Muschelkalk of the Alps. The Upper Muschelkalk is especially noted for the number and variety of its cephalopod
fossils ; it forms indeed the richest and most widely spread fossil
horizon in the central and N,W, Himalaya. The most typical fossil
THE TRIASSIC SYSTEM
171
belongs to the genus Ceratites; besides it there are : (Ammonites)
Ptychites, Trachyceras, Xenaspis, MonophylUtes, Gymnites, Sturia,
Proarcestes, Isculites, Hollandites, Dalmanites, Haydenites, Pinacoceras, Buddhaites with Nautilus (sp. spitiensis), Pleuronautilus,
Syringonautilus and Orthoceras. The brachiopods are Spiriferina and
Spirigera ; Daonella and Halobia are the leading bivalves.
The uppermost division of the Trias is by far the thickest, and is
composed of two well-marked divisions—dark shales and marl beds
at the lower part, and of thick grey-coloured limestone and dolomite
in the upper, with an abundant cephalopodan fauna, whose distribution often characterises well-marked zones. The lower of the two
divisions corresponds to the Carnic and Noric stages of the Alpine
Trias,'while the uniform mass of limestones overlying it probably
represents the Khaetic of the Alps (cf. Kioto Umestone, p. 178).
The faunistic resemblance between the Triassic rocks of the
Himalayas and Alps suggests open sea communication maintained by
the Tethys between these two areas since the beginning of the Permian. This sea provided a free channel of migration and intercommunication between the marine inhabitants of the central zone of the
earth from the Mediterranean shores of France to the eastern borders
of China, and maintained this waterway up to the beginning of the
Eocene period. The commonest fossils are again: (Ammonites)
Joannites, Halorites, Trachyceras^ Tropites, Juvavites, Sagenites,
Sirinites, Hungarites, Gymnites Ptychites, Griesba'chites. Lamellibranchs are also numerous, the most commonly occurring forms are
Lima, Daonella, Halobia, Megalodon, Monotis, Pecten, Avicula, Corbis,
Modiola, Mytilus, Homomya, Pleuromya, with the addition of the
aberrant genera Radiolites and Sphaerulites of the Rudistae family of
the lamellibranchs. The brachiopods are very few, both as regards
number and their generic,distribution, being confined to Spirigera,
Spiriferina, Rhynchonella, and their allied forms.
The Triassic fauna shows a, marked advance on the fauna of the
Productus limestone. The most predominant element of the former
is cephalopods, while that of the latter was brachiopods. This is the
most noteworthy difference, and signalises the extinction of large
numbers of brachiopod families during the interval. This class, of the
MoUuscoidea entered on their decline after the end of the Palaeozoic
era, a decline which has steadily persisted up to the present. During
the Mesozoio era the brachiopods were represented by three or four
genera like Terebratula, Rhynchonella,, Spirigerina. etc. The place of
the brachiopods is taken by the lamellibranchs, which have greatly
172
GEOLOGY OF INDIA
increased in genera and species. The cephalopods, the most highly
organised members of the Invertebrata, will henceforth occupy a place
of leading importance among the fauna of the succeeding Mesozoic
systems.
'
» Hazara (the Sirban Mountain)
The Trias is found in Hazara occupying a fairly large area in the
south a"nd south-east districts of this province, resting on the presumed Permo-Carboniferous series of sediments underlain by a glacial
conglomerate, which was previously referred to as the Infra-Trias.
The Triassic system of Hazara consists, at the base, of about 100 feet
of felsitic or devitrified acid lavas of rliyolitic composition, succeeded
by a thick formation of rather poorly fossiliferous limestone, in which
the characteristic Upper Triassic fossils of the other Himalayan areas
are present. The Lower and Middle Trias are absent from Hazara. >
The limestone is thickly bedded, of a grey colour, sometimes with an
oolitic structure. Its thickness varies from 500 to 1200 feet. These
rocks form the base of a very complete Mesozoic sequence in Hazara,
which though considerably thinner, is similar in most respects to that
of the geosynclinal zone of the Northern Himalayas, so tjrpically displayed in the sections in the Spiti Valley and in Hundes.
Mt. Sirban—A locality famous for geological sections in Hazara is
Mt. Sirban, a lofty hiU lying to the south of Abbotabad. Most of the
formations of Hazara are exposed with wonderful clearness of detail,
in a number of sections along its sides (see Figs. 22 and 23), in which
N.W.
FIG. 22.—Diagrammatic section of Mt. Sirban, Hazara.
1. Slate series.
3. Trias.
2. Permo-Carboniferous.
4. .Jura, Cretaceous.
After Middlemiss, Memoir, Geological Survey of India, vol. xxvi.
#
one can trace the whole stratigraphic sequence from the base of the
Permo-Carboniferous to the Nummulitic limestone. The sections
revealed in this hill epitomise in fact the geology of a large part of the
North-West Himalaya. ^
" On'the south border of Hazara, in the Kala Chitta hills of Attock
district, some strips of Trias limestone are laid bare in a series of
> Mem. G.8.I. vol, ix. pt. 2, 1872, and Mem. Q.S.J. vol. xxvi. 1896.
THE TRIASSIC SYSTEM
173
denuded isoclinal folds of the Nummulitic limestones which constitute
these hill-masses.
The Trias of the Salt-Range
The Ceratite beds—The Trias is
developed, though greatly reduced
in its proportion, in the western part
of the Salt-Eange. The outcrop of
the system commences from the
neighbourhood of the Chideru hills,
and thence continues westward up
to a great distance beyond the
Indus. I t caps the underlying Productus limestone^ and accompanies
it along a great length of the Eange
until the disappearance of the latter
beyond Kalabagh and. Shekh Budin
hills. The Triassic development of
the Salt-Range comprises only the
Lower Trias and a small part of the
Middle Trias in actual stratigraphic
range, but these horizons are completely developed, and they include
all the cephalopod-zones worked out
in, the corresponding divisions of
the Spiti section. On account of the
abundance of the fossil ammonite
genus Ceratites the Lower Trias of
the Salt-Range is known as the
Ceratite beds. The rocks comprising them are about a hundred feet
of thin flaggy limestone, which
overlie the Chideru stage quite conformably, from which also they
are undistinguishable lithologically.
Overlying beds are grey limestones
and marls, nodular at places.
Besides Ceratites, which are the
leading fossils, the other ammonites
are Ptychites, Gyronites, Flemingites,
Koninckites, Prionoldbus, etc. Eossil
174
GEOLOGY OF INDIA
shells are found in large numbers in the marl^ strata, of which the
common genera are Cardinia, Gennllia, Rhynchonella and Terebratula. A very -curious fossil in the Oeratite beds is ^a Bdlero-phon
of the genus Stachella, the last survivor of the well-known Palaeozoic
gastropod. The Ceratite beds are succeeded by about 100 to 200 feet •
of Middle Trias (Muschelkalk), composed of sandstones, crinoidal
limestone and dolomites full of cephalopods, whose distribution characterises zones corresponding to the lower portion of the Middle Trias
of Spiti and Kashmir. Some of the clearest sections of these and
younger Mesozoic formations are to be seen in the gullies and nullahs
of the Chideru hills of the range. There is a deep ravine near Musa
Khel, the Nammal gorge, which has dissected the whole breadth of the
Mouth of Ravine
Permo-Carbonlferoua
Bakh
j^-^^
Jur'asii^^
Upper waters of the
ITahi River'
'
Ravine
Nummulitic
,
SiwaliU
FIG. 24.—Section through the Bakh Ravine from Musa Khel to Nammal.
About natural scale, 3 inches = 1 mile.
Wynne, Salt-Range, Memoir, G.S.I. vol. xiv.
mountain from Nammal to Musa Khel, and the section laid bare in its
precipices comprehends the stratified record from the Permian to the
Pliocene, with but few interruptions or gaps. As one walks along the
section to the head of the gorge, one passes in review the rock-records
of every succeeding age from the Productus limestone, through the
representatives of the Trias, Juras, Eocene and Mioeene, with at the
very top the Upper Siwalik boulder-conglomerates.
After the Middle Trias there comes a gap in the continuance of the
Salt-Range deposits, indicating a temporary withdrawal of the gea
from this area. This cessation of marine conditions has produced a
blank in its geological history covering the "Upper Trias and the early
part of the Jurassic period.
Baluchistan
to
In the Quetta and Zhob districts of North Baluchistan outcrops of
Triassio rocks appear as inliers in the anticlines of the more widespread
Lias development, which are marked by the exclusive prevalence of
the uppermost Triassio or Ehaetic stage, no strata referable to the
Lower and Middle Trias being found in this province. The rocks are
THE TRIASSIC SYSTEM
175
several thoasand feet of shales and slates, with a few intercalations of
limestone. They contain the Upper Trias species of Monotis and a few
ammonites like Didymites, Halorites, Rhacophyllites.
The Trias of Baluchistan rests unconformably on an older Produdusbearing limeptone, enclosing a foraminiferal limestone, Fusulina limestone, of Permo-Carboniferous age.
Burma
A very similar development of the Triassic system, also restricted
to the uppermost (Ehaetic or Noric) horizon, occurs in the Arakan
Yoma of Burma. The fossils are a few ammonites and lamellibranchs, of which Halobia and Monotis are the most common.
The only known occurrence of Lower Triassic rocks and fossils inBurma was recorded by M. R. Sahni at Na-hkam in the Northern
Shan States. Among the genera represented are Ophiceras, Juveniles,
Hemiprionites, Naticopsis, Platyceras, Lingula, etc.
The fauna is of shallow water facies, ammonites forming the domiuant element, while the calcareous brachiopods are entirely absent.
It therefore presents a striking contrast to the Burmese anthracolithic
faunas in which calcareous bmchiopods predominate and ammonites
are absent. With the exception of a few fragments of Upper Trias
ammonites from the Burmo-Siamese frontier and a Turonian species
from Ramri Island, the Na-hkam fauna contains the only ammonites so far known from Burma.
Napeng series—Also, what are known as the Napeng beds occur in a
number of scattered small outcrops in the Northern Shan States.
(See Fig. 20, p. 164.) The beds are composed of highly argillaceous,
yellow-coloured shales and marls, with a few nodular limestone strata.
The fossils are Avicula contorta, Myophoria, Gervillia praecursor,
Pecten, Modiohpsis, 'Conocardium, etc. Although some of these are
survivals of Palaeozoic genera, the other fossils leave no doubt of the
Triassic age of the strata, while the specific relations of the latter
genera suggest a Rhaetic age.*
Kashmir
As is generally the case with the other rock systems, the development of the Trias in Kashmir is on much the same scale as in Spiti, if
indeed not on a larger scale. A thick series of compact blue limestone,
^Mem. 0.8.1. vol. xxxix. pt. 2, 1913.
176
'
GEOLOGY OF INDIA
slates and dolomites is conspicuously displayed in m^ny of the hills
bordering the valley to the noEth, while t h e y have entered largely into
the structure of t h e higher p a r t s of the Sind, Lidar, (jurais and Tilel
valleys and of the north-east flanks of the Pir Panjal (P- 420),
REFERENCES
Karl Diener, Trias of the Himalayas, Mem. O.S.I, vol. xxxvi- P*- 3, 1912, and
Triassio Faun* of the Himalayas, Pal. Indica, Series XV. "^oi- ii- pts- 1 and 2
(1897).
E. Mojsisovics, Cephalopoda of the Upper Trias, Pal. Indica, Series XV. vol. iii,
pt. 1 (1899).
W. Waagen, Fossils of the Ceratite Beds, Pal. Indica, Series XlH- vol. u. (1895).
CHAPTER XIII
THE JURASSIC SYSTEM
Instances of Jurassic development in India—In the geosynclinal zone
of the Northern Himalayas, Jurassic strata conformably overlie the
Triassio in a great thickness of limestone and shales. The succession
is quite normal and transitional, the junction-plane between the two
systems of deposits being not clearly determinable in the type section
at Lilang. Marine Jurassic strata are also found in the Salt-Eange,
representing the middle and upper divisions of the system (Oolite).
The system is developed on a much more extensive scale in Baluchistan, both as regards its vertical range and its geographical extent.
A temporary invasion of the sea (marine transgression), over a large
part of Rajputana, in the latter part of the Jura gave rise to a thick
series of shallow-water deposits in Rajputana and in Cutch. A fifth
instance of Jurassic development in India is also the result of a marine
transgression on the east coasts of the Peninsula, where an oscillation
between marine and terrestrial conditions has given rise to the interesting development of marine Upper Jurassic strata intercalated with
the Upper Gondwana formation.
Life during the Jurassic—Cephalopods, especially the ammonites,
were the dominant members of the life of the Jurassic in all the abovenoted areas. Although perhaps they reached the climax of their development at the end of the Trias in the Himalayan province, they
yet occupied a place of prominent importance among the marine
forms of life of this period, and are represented by many large and
diversified forms with highly complex-sutured shells. Nearly 1000
species and over 150 genera have been found in the Jurassic rocks of
Cutch ; the majority of the species are new and restricted to the West
Indian province. LamelUbranchs were also very numerous in the
Jurassic seas, and held an important position among the invertebrate
fauna of the period. A rich Jurassic flora of cycads and conifers
peopled the land regions of India. The lower classes of phafierogams
had already appeared and taken the place of the seed-fern
(pteridosperm) and the horsetail of the Permo-Carboniferous periods.
W.Q.I.
177
M
178
GEOLOGY OF INDIA
The land was also inhabited by a varied population of fish, amphibia
and several orders of reptiles, besides the terrestrial invertebrates.
We have already dealt with the relics of the latter class of organisms
in the description of the Gondwana system.
JURASSIC OF THE CENTRAL HIMALAYAS
Spiti
Kioto limestone—In the Zanskar range of Spiti, Garhwal and
Kumaon, as far as the west frontier of Nepal, the Upper Trias (Noric
stage) is succeeded by a series of limestones and dolomites of great
thickness, the lower part of which recalls the Rhaetic of the Alps, while
^
Fia. 25.—Saotion of the Jurassic and Cretaceous rocks Bf Hundes.
1. Kioto limestone.
4. Cretaceous fiysch.
2. Spiti shales.
6. Basic fgneous rocks.
3. Giumal sandstone.
After Von Krafift, Mem. G.S.I, xxxii. pt. 3.
the upper is the equal of the Lias and part of the Oolite. The bottom
, beds of the series, containing shells of Megalodon, pass up into a massive limestone, some 2000 to 3000 feet thick, called the Great limestone, from its forming lofty precipitous cliffs facing the Punjab
Himalayas. They are better known under the name of the Kioto
limestone. The lithological characters of this limestone indicate the
existence of a constant depth of clear water of .the sea during ils
formation. The passage of time represented by this limestone is from
Rhaetic to Middle Oolite, as evidenced by the changes in its fauna.
The highest beds of the Kioto limestone are fossiliferous, containing
a rich assemblage of belemnites and lamellibranchs, and are known
as the Sulcacutus beds from the preponderance of the species Belemnites sulcacutus. The greater part of the Kioto limestone—the middle .
" —is unfossiliferous. A fossiliferous horizon—the Megalodon limestone—occma again at the base, containing numerous fossil shells of
Megalodon and Dicerocardium. Other fossils are Spirigera, Lima,
Ammonites, Belemnites, with gastropods of Triassic afShities. This
THE JURASSIC SYSTEM
179
lower part of the Kioto limestone is also sometimes designated as tlie
Para stage, while the part above the Megalodon limestone is known as
the Tagling stage.
Spiti shales—The Kioto limestone is overlain conformably by the
most characteristic Jurassic forjnation of the inner Himalayas, known
as the Spiti shales. (See Fig. 25.) These are a group of splintery black,
almost sooty, micaceous shales, about 300 to 500 feet thick, containing numerous calcareous concretions, many of which enclose a wellpreserved animonite shell or some other fossil as its nucleus {Saligram).
The shales enclose pyritous nodules and ferruginous partings and, towards the top, impure limestone intercalations. The whole group is
very soft and friable, and has received a great amount of crushing and
compression. These black or grey shales show a singular lithological
persistence from one end of the Himalayas to the other, and can be
traced without any variation in composition from Hazara on the west
and the northern confines of the Karakoram range to as far as Sikkim
on the east. These Upper Jurassic shales, therefore, are a valuable
stratigraphic unit, or " reference horizon ", in the geology of the
Himalayas, of great help in unravelling a confused or compUcated mass of strata, so usual in mountainous regions where the
natural order of superposition is obscured by repeated folding and
faulting.
Fauna of the Spiti shales—The Spiti shales are famous for their
.great faunal wealth, which has rnade great contributions to the
Jurassic geology of the world. The ammonites are the preponderant
forms of life preserved in the shales. The enumeration of the following genera gives but an imperfect idea of the great diversity of
cephalopodan life : Phylloceras, Lytoceras, Hoploceras, Hecticoceras,
Oppelia, Aspidoceras, HolcostepJianus (Spiticeras), the most common
fossil, Hoplites, PerispJiinctes and Macrocephalites. Belemnites are
very numerous in individuals, but they belong to only two genera,
Belemnites (B. gerardi) and Belemnopsis. The principal lamellibranch
genera a t e : Avicula (A. spitiensis), Pseudomonotis, Aucella, Inoceramus gracilis, Lima, Pecten, Ostrea, Nucula, Leda, Area (Cuculhea),
Trigonia, Astarte, Pleuromya, Cosmomya, Homomya, Pholadomya;
gastropod species belong to Pleurotomaria and Cerithium.
The fauna of the Spiti shales indicates an uppermost Jurassic
age—Portlandian and Argovian.
They pass conformably into
the overlying Cretaceous sandstone of Neocomian horizon (Giumal
sandstone).
Upper Jurassic deposits of Spiti shales facies cover large areas of
180
GEOLOGY OF INDIA
central and southern Tibet, according to the accounts of Sven Hedin,
overlain by an enormous spread of the Cretaceous. The Jurassic is
folded into long isoclinal belts, carrying outlier strips of the Cretaceous
and Eocene.
The following table shows in a generalised manner the Jurassic
succession of the Central Himalaya :
Giumal sandstone.
Spiti shales
(500 ft.).
Kioto limestone
(3000 ft.).
fLochambel beds.
beds.
[Belenmites beds.
Sulcacutus beds.
Great thickness of massive limestones,
unfossiliferous (Tagling stage).
Megalodon Umestone (Para stage).
Neooomian
(Wealden).
J. (Chidamu
Portlandian.
(
Callovian.
Monotis shale.
Lias
(Rhaetic in
part).
Noric.
Eastern Himalayas—Mt. Everest Region
Vast tracts of the Himalayas east of the Ganges—the Nepal and
Assam Himalayas—are yet geologically unknown, but the successive
Mt. Everest Expeditions have elucidated the geology of the neighbouring tracts north of Darjeeling and Sikkim. Hayden, Heron,
Odell, and Wager have geologically surveyed large areas of Sikkim"
and Southern Tibet.
Immediately to the north of the crystalline axis of the high range
culminating in the peak of Mt. Everest there lies a broad expansive
zone of much folded and disturbed Jurassic strata, composed of
monotonous black shales and argillaceous sandstones, probably the
easterly representatives of the Spiti shales. The, Jurassic shales t r e
unfossiliferous for the most part, but a few obscure ammonites,
belemnites and crinoids have been obtained from them. In the tightly
compressed and inverted folds of the Jurassic rocks are outliers of
Cretaceous and Eocene (Kampa system) rocks, the latter containing
Alveolina limestone; while underlying the Jurassic shales, and
adpressed against the crystalline rocks at the foot of Mt. Everest on
its north slopes, is a thick series of metamorphosed fossiliferous limestones, quartzites and shales (Lachi series) which has yielded some
well-preserved brachiopods, Productus and Spirifer, of probably
Permo-Carboniferous affinities. Immediately underlying these is a
THE JURASSIC, SYSTEM
181
dark grey limestone, about 1000 feet tliick, followed by a yellow,
slabby, schistose limestone, which together build the actual summit of
Mt. Everest—the Mt. Everest limestone series. Their age is believed
to be Upper Carboniferous or somewhat newer. The thick zone of
rocks which come below the Mt. Everest Hmestqne, consists of metamorphosed foliated slates and schists referable to the DaUng series.
This zone is extensively injected by granite of Tertiary age.
The prevalent tectonic strike of the mountains here is due east to
west, the regional dip being to the north. To the east of the river
Arun the strike undergoes a sharp bend to the south.
South of the Everest-Kanchenjunga group, to as far as the Dafjeeling Duars, the geology is more complicated, the rocks being a
complex of crystalline metamorphic schists, gneisses, and Tertiary
injection-granites, with here and there patches of the Dalings. The
latter series ends abruptly to the south of Kurseong, by a mechanical
thrust contact in a narrow belt of coal-bearing Gondwana rocks of
Damuda age. These in turn are inverted and thrust over the Upper
Tertiary Siwalik belt of the foot-hills, the structural relations being
here similar to those observed all along the south foot of the Himalayas
west of the Ganges.
Tal series—^In the Lesser Himalayas east of the Ganges, in the zone
lying between the outer Tertiary zone and the inner crystalline zone
of the main snow-covered range, and* distinguished by the exclusive
occurrence in it of highly metamorphosed old (Purana) sediments
only, there is noted an exceptional development of patches of fossiliferous Jurassic (1) beds underlying the Eocene Nummulitic limestone.
This is one of the rare instances of fossiliferous pre-Tertiary rocks
being met with south of the central axis of the Himalayas, and is
therefore interesting as indicating a slight trespass of the shores of the
Tethys beyond its usual south border (see p. 149). The fossils are few
and undeterminable specifically ; they are fragments of belemnites,
corals and gastropods. These beds, known as the Tal series, overhe
with a great unconformity older hmestones belonging to the Deoban
or Krol series of indeterminate Palaeozoic age.
Lithologically the Tal series consists of sandstones and black shales
with fossil plant-impressions in the lower part of the series and
arenaceous blue limestones containing comminuted shells in the
upper. The principal outcrops of the series are in the Tal tributary of
the Ganges, covering large areas in western Garhwal. The fossils are
not very helpful in indicating the exact age of the rocks, but they
approximately indicate Jurassic affinities.
182
GEOLOGY OF INDIA
Baluchistan
Jurassic of Baluchistan—Marine Jurassic rocks, of tlie geosynclinal
facies, and corresponding homotaxially to the Lias and Oolite of
Europe, are developed on a vast scale in Baluchistan, and play a
prominent part in its geology. The liassio beds are composed of
massive blue or black, crinoidal, oohtic or flaggy limestone, interbedded
with richly fossiliferous shales, attaining a thickness of more than
3000 feet, in which the principal stages of the European Lias can be
recognised by means of the cephalopods and other molluscs entombed
in them. The Liassic limestones are overlain by an equally thick series
of massive grey, thick-bedded limestone of Oolitic age, which is seen
in the mountains near Quetta and the ranges running to the south.
The top beds of the last-described hmestone contain numerous
ammonites, among which the genus Macrocephalites, represented by
gigantic specimens of the species M. polyphemus, attains very large
dimensions.
[The rock-systems of Baluchistan are capable of classification into two
broad divisions, comprising two entirely different types of deposits. One
of these, the Eastern, is mainly characterised by a calcareous constitution
and comprises a varied geological sequence, ranging in age from the PermoCarboniferous upwards. This facies is prominently displayed in the mountain ranges of E. Baluchistan, constituting the Sind frontier. The other
facies is almost entirely argillaceous or arenaceous, comprising a great
thickness of shallow-water sandstones and shales, chiefly of Ohgocene* Miocene age. The latter type prevails in the broad upland regions of W.
Baluchistan, stretching from the Mekran coast northwards up to the southward confines of the Helmand desert. These differences of geological
structure and composition in the two divisions of Baluchistan have determined in a great measure its principal physical features.] ^
All the Mesozoic systems are well represented in East Baluchistan,
and are very prominently displayed in the high .ground extending
meridionally from the Takht-i-Suleman mountain to the Mekran
coast. In the broad arm or guK of the Tethys which, as we have
already stated, occupied Baluchistan, almost since the commencement of its existence, a series of deposits was formed, representative
of the ages that followed this occupation. Hence the main Mesozoic
formations of the Northern Himalayas find their parallels in Baluchistan along a tract of country folded in a series of parallel anticlines and
synclines of the Jura type, stretching in a north to south direction.^
i E. W. Vredenburg: Eec. 6.8.1. vol. xxxviii. pt. 3, 1910.
' See Vredenburg's Map of Baluchistan, Bee. G.S.I, vol. xxsviii. pt. 3, 1910, and
Fal. Ind. New Series, vol. iii. mem. 1, 1909.-^ntroduction.
THE JURASSIC SYSTEM
183
Hazara
Spiti shales of Hazara—The Jurassic system is developed in Hazara,
both in the north and south of the province. The two developments,
however, are quite distinct from one another, and exhibit a different
facies of deposits. The northern exposure is similar both in its lithological and palaeontological characters to the J.ura of Spiti, and conforms in general to the geosynclinal facies of the Northern Himalaya.
The Spiti shales are conspicuous at the top, containing some of the
characteristic fauna. But the Jurassics of south Hazara differ
abruptly from the above, both in their composition and their fossils ;
they show greater affinity to the Jurassic outcrops of the Salt-Range,
which are characterised by a coastal, more arenaceous facies of
deposits. The Spiti shales of the Northern zone have yielded these
fossils : Oppelia, Perisphinctes, Belemnites, Inoceramus, Cucullaea,
Pecten, Corbula, Gryphaea, Trigonia.
To the south of Hazara the Jurassics outcrop in a few inhers in the
tightly squeezed isoclinal folds of the Kala Chitta range of hills of the
Attock district. The horizons present are the top beds of the Kioto
(Lias) Kmestone, Middle Jurassic and the Argovian (Spiti shales),
closely associated with the Giumal series of limestones and sandstones
(Albanian or Gault). The fossils present in these rooks are : Velata,
Lima, Plicatula, Gryphaea, Chlamys, Mayaites and Perisphinctes.
Burma
Namyau beds—Jurassic strata are met with in the Northern Shan
States, and are referred to as the Namyau beds, also sometimes designated the Hsipau series. (See Fig. 12, p. 117.) The rocks are red
or purple sandstones and shales, unfossiliferous in the main, but the
few limestone bands have yielded a rich brachiopod fauna with some
lamellibranchs of Upper Jurassic age. There are no ammonites
present. This group of strata is underlain by shales and concretionarj'
limestones, which have already been referred to as the equivalents of
the Rhaetic or Napeng series of Burma.
Rocks belonging to the Lias horizon occur at Loi-an, near
Kalaw, in the Southern Shan States, enclosing a few coalmeasures, the plant-bearing beds of which have yielded, among fossil
conifers and cycads, the characteristic species Ginkgoites digitata.
The Loi-an coal-measures support a small coal-field.
184
GEOLOGY OF INDIA
Salt-Range
Jurassic of the Salt-Range—The middlte and upper divisions of the
Jurassic are represented in the Salt-Eange. To the east of about
longitude 72° the Jurassic is missing owing to the pre-Tertiary denudation, which was progressively more pronounced from west to east in
the Salt-Range. In the north-western part of the Salt-Range, near
Nammal and Khairabad, the Jurassic beds thicken to at least 1200
feet and form prominent strike ridges. Still further west in the transIndus Salt-Range the gap iii the sequence below the Tertiary becomes
much less marked and the Jurassic system attains a thickness of
1500 feet. The Surghar range, north-west of Isa Khel, is composed
almost wholly of Jurassic and Eocene (Nummulitio) rocks.
The Jurassic strata of the trans-Indus ranges may be summarised
in the following table :
Cretaceous.
White sandstones with dark shales, 60 ft.
Neocomian fossils.
' Upper Jurassic—•Kght-coloured, thinbedded highly fossiUferous limestones,
and blackish arenaceous shales. Fossils :
Pecten, Lima, Ostrea, Homomya, Pholadomya, with several ammonites, belemnites and gastropods.
Middle Jurassic—white and variously tint- Mid. and
Upper
Jurassic strata
ed soft sandstones and clays with Ugnite
Jurassic,
(500-1500 ft.).
and coal-partings; pyritous (alum)
shales with subordinate bands of limestone and haematite. Fossils : obscure
plant remains—Ptilophyllum ; Belemnites, Pleurotomaria, Natica, Mytillus,
Andllaria, Pecten, Myacites, Nerinea,
Cerithium, Ehynchonella, etc.
Ceratite beds, 370 feet.
Triassic.
• A section of the above type is seen near Kalabagh on the Indus;
a fuller section is visible in the Shekh Budin hills and in the Surghar
range.
A few coal or lignite seams occur irregularly distributed in the lower
part, and are worked near Kalabagh, which yield on an average about
1000 tons of coal per year ; some haematite layers also occur. Fossil
plants of Jabalpur aihnities, e/iclosed in these beds, point to the
vicinity of land. A few beds of a peculiar oolitic limestone, known as
the " golden oolite ", are found among these rocks. The rock is a
T H E JURASSIC SYSTEM
185
coarse-grained limestone, the grains of which are coated with a thin
ferruginous layer. Fossil organisms preserved in these rocks, besides
those named in the section above, are : Ostrea, Exogyra, species of
Terebratula, numerous gastropods,
many ammonites and belemnites.
The spines of numerous large
species of echinoids, like Cidaris,
and fragments of the tests of
irregular echinoids, are frequent in
the limestones.
A rapidly varying" lithological
composition of a series of strata,
such as that of the Jurassic of the
Salt-Range, is suggestive of many
minor changes during the course
of sedimentation in that area;
such, for instance, as changes in
the depth of the sea, or of the
height of the lands which contribute the sediments, of alterations
in the courses of rivers, and of the
currents in the sea.
, [It is in the west and trans-Indus
part of the Salt-range that the Mesozoic group is developed in some
degree of completeness.
In the
eastern, cis-Indus part, the Mesozoic
group is, on the whole, rather incompletely developed and irregularly
distributed.
The structure of this part of the
Salt-Eange is one of colossal disturbance, by which the stratigraphy of
the mountains is completely obscured.
The strata by repeated folding and
faulting have acquired such a confused disposition that the natural order of superposition is often subverted, while the faulted and tilted blocks lie against one another in the
most intricate disorder imaginable.]
Marine Transgressions dining the Jurassic period
After the emergence of the Peninsula at the end of the Vindhyan
system of deposits, this part of India has generally remained a land
186
GEOLOGY OF INDIA
area, a continental tableland exposed to the denuding agencies. No
extensive marine deposits of any subsequent age have been formed on
the surface of the Peninsula since that early date.
Nature of marine transgressions—In the Jurassic period, however,
several parts of the Peninsula, viz. the coasts and tKe low-lying flat
regions in the interior, like Eajputana, were temporarily covered by the
seas which invaded the lands. These temporary encroachments of the
sea over what was.previously dry land are not uncommon in the records
of several geological periods, and are caused by the sudden decrease in
the capacity of the ocean basin by some deformation of the crust, such
as the sinking of a large land-mass, or the elevation of a submarine
tract. Such invasions of the sea on land, known as " marine transgressions ", are of comparatively short duration and invade only low
level areas, converting them for the time into epicontinental seas.
These temporary epicontinental seas should be distinguished from the
gecsjmclinal or mediterranean seas. The series of deposits which
result from these transgressions are clays, sands or limestones of
a littoral type, and constitute a well-marked group of deposits,
sometimes designated by a special name—the Coastal system.
One example of the coastal system we have already seen in connection with the Upper Gondwana deposits of the East Coast.
The remaining instances of marine transgressional deposits in the
geology of India are the Upper Jurassic of Cutch and Eajputana;
the Upper Cretaceous of Tiichinopoly, of the Narbada valley and of
the Assam hills, the Eocene and Oligocene of Gujarat and Kathiawar,
and the 'Somewhat newer deposits of a number of places on the
Coromandel coast.
Deposits which have originated in this manner possess a welldefined set of characters, by which they are distinguishable from the
other normal marine shallow-water deposits. (1) Their thickness is
moderate compared to the thickness of the ordinary marine deposits,
or of the enormous thickness of the geosynclinal formations ; (2) they,
as a rule, cover a narrow strip of the coast only, unless low-lands extend farther inland, admitting the sea to the interior ; (3) the dip of
the strata is irregular and sometimes deceptive, owing to currentbedding and deposition on shelving banks. Generally the dip is seaward, away from the main land ; consequently the oldest beds are
farthest inland while the newest are near the sea. In some cases,
howevef, a great depth of deposition is possible during marine transgressions, as when tracts of the coast, or the continental shelf, undergo
sinking, of the nature of trough-faulting, cojicurrently with deposition.
T H E JURASSIC SYSTEM
187
Such was tlie case, for instance, with the basins in which the Jurassics
of Cutch were laid down, in which the sinking of the basins admitted
of a continuous deposition of thousands of feet of coastal detritus.
Such block-faulting is quite in keeping with the horst-like nature of
the Indian Peninsula, and belongs to the same system of movements
as that which characterised the Gondwana period.
• Cutch
The Jurassics of Cutch—Jurassic rocks occupy a large area of the
Cutch State. It is the most important formation of Cutch both in
respect of the lateral extent it covers and in thickness. With the
exception of a few small patches of ancient crystalline rocks, no older
system of deposits is met with in this area. I t is quite probable, however, that large parts of the country which at the present day are long,
dreary wastes of black saline mud and silt (which form the Rann of
Cutch) are underlain by a substratujn of the Peninsular gneisses together with the Puranas. A broad band of Jurassic rocks extends in an
east-west direction along the whole length of Cutch, and they also
appear farther north in the islands in the Rann of Cutch. Structurally
the Jurassic is thrown into three wide anticlinal folds, separated by
synclinal depressions, with a longitudinal strike-fault at the foot of the
•squthernmost anticline. The main outcrop attenuates in the middle,
owing to the overlap of the younger deposits. The aggregate thickness of the formation is over 6000 feet, a depth quite incompatible
with deposits of this nature, but for the explanation given above.
The large patch of Jurassic rocks in East Kathiawar around
Dhrangadhra belongs to the same formation, and is an outlier of the
latter on the eastern continuation of the same strike.
The Jurassics of Cutch include four series—Patcham, Chari, Katrol
and Umia, in ascending order, ranging in age from Lower Oolite to
Wealden. The base of the system is not exposed and the top is unconformably covered either by the basalts of the Deccan Trap formation
or by Nummulitic beds (Eocene).
The following table, adapted from Dr. Oldham, gives an idea of the
stratigraphic succession:
'Marine sandstones with Crioceras, etc.,
sandstone and shale with cycads,
Umia
conifers, and ferns (Gondwana facias).
(3000 ft.). Marine sandstone and conglomerate with
Peri'sphincfes and Trigonia.
Wealden.
188
GEOLOGY OF INDIA
Sanflstone and shale with PerispMnctes
Upper
and Offelia.
Ferruginous red and yellow sandstone
Oolite.
{Kantkote sandstones) with Stephanoceras, Aspidoceras.
Dhosa oolite, oolite limestone ; Peltoceras,
Aspidoceras, PerispMnctes.
White limestones; Peltoceras, Oppelia. Middle
Chari
Oolite.
Shales with ferruginous nodules; Peri(1100 ft.).
spMnctes, Harpoceras.
Shales with " golden oolite " ; Macrocephalites, Oppelia.
I Grey limestones and marls with Oppelia,
I corals, brachiopods, etc.
Lower
j Yellow sandstones and limestones with
Oolite.
Fatcham
(1000 ft.). > Irigonia, Corhula, Cucullaea, etc.
Eatrol
(1000 ft.).
Base not seen.
Patcham series—The lowest member, Patcham series, occurs in the
Patcham island of the Kann, as well as in the main outcrop in Cutch
proper. The lower beds are exposed towards the north, and are visible
in many of the islands. . The strata show a low dip to the south, i.e.
seawards. The constituent rocks are yellow-coloured sandstones, and
limestones, overlain by limestones and marls. The fossils are principally ammonites and lamellibranchs, but not so numerous as in the
two upper groups, the leading genera being Trigonia, Lima, Corhula,
Gervillaea, Exogyra, and Oppelia, PerispMnctes, MacrocepJialites
triangularis, Sivajiceras, Stephanoceras ; some species of Nautilus.
Chari series—The Chari series takes its name from a village near
Bhuj, from where an abundant fauna corresponding with that of the
Callovian stage of the European Jura has been obtained. I t is composed of shales and limestones, with a peculiar red or brown, fe^uginous, oolite limestone, known as the Dhosa oolite, at the top. There
also occur, at the base, a fejv bands of what is known as the golden
oolite, a limestone composed of rounded calcareous grains coated with
iron and set in a matrix. The chief element of the fauna is cephalopods, some hundred species of ammonites being recognisable in them.
The principal genera a r e : PerispMnctes, Phylloceras, Oppelia,
MacrocepJialites (many spdcies), Harpoceras, Peltoceras, Aspidoceras,
ReinecMa, Mayaites, Ghoffatia, IndospMnctes, Aptychus, Grossouvria, Stephanoceras. In addition there are three or four species of
Belemnites, several of Nautilus, and a large number of lamellibranchs.
I h e Chari group is palaeontologically the most important group of the
THE JURASSIC SYSTEM
189
Jurassic of Cutch, because it has furnished the greatest number of
fossil species identical with known European types ; it is divided into
the following zones : macrocephalus beds, rehmanni beds, anceps beds,
and athleta beds, underlying the Dhos.a oolite; the Dhosa oolite,
coming at the top of the Chari series, is the richest in ammonites,
being divided into three well-defined zones.
The Katrol series—The Chari series is overlain by the Katrol group
of shales and sandstones. The shales are the preponderant rocks of
this series, forming more than half its thickness. The sandstones are
more prevalent towards the top. The shales are variously tinted by
iron oxides, which at places prevail to such an extent as to build small
concretions of haematite or limonite. The Katrol series forms two
long wide bands in the main outcrop in Cutch ; the exposure where
broadest is ten miles wide. Besides forms which are common to the
whole system the Katrol series has, as its special fossils, Harpoceras,
Phylloceras, Lytoceras, and Aptychus. The other Katrol cephalopods
are: %Hibolites, Aspidoceras, Waagenia, Streblites, PachyspMnctes,
Katroliceras (many species). The group is divided into lower, middle
and upper, capped by the Zamia shales, containing fossil cycads and
other plants. A few plants are preserved in the sandstone and shale
beds belonging to the Zamia stage, but in such an imperfect state of
fossilisation that they cannot be identified and named.
The Umia series—Over the Katrol group comes the uppermost division of the Cutch Jura, the Umia series, comprising a thickness of
3000 feet of soft and variously coloured sandstones and sandy shales.
The lower part of the group is conglomeratic, followed by a series of
marine sandstone strata in which the-fossils are rare except two species
of Trigonia, T. ventricosa and T. smeei, which are, however, very typical.
Over this there comes an intervening series of strata of sandstones
and shales, which, both in their lithological as well as palaeontological
relations, are akin to the Upper Gondwana rocks of the more easterly
parts of the Peninsula. The interstratification of these beds with the
marine Jurassic should be ascribed to the same circumstances as that
which gave rise to the marine intercalations in the Upper Gondwana
of the east coast. After this slight interruption the marine conditions
once more established themselves, because the higher beds of the
Umia series contain many remains of ammonites and belemnites.
The Umia group has wide lateral extent in Cutch, its outcrop being
much the broadest of all the other series. Its breadth, however, is
considerably reduced by the overlapping of a large part of its surface
by the Deccan Traps and still younger beds. The fossils yielded by
190
GEOLOGY OF INDIA
fclie Umia series are : species of Williamsonia, PtilopJiyllum, Elatocladus, Araucarites, Brachyphyllum, Cycads and Conifers, which have
been enumerated in the chapter relating to the Upper Gondwana.
The niarine fossils include the genera Crioceras, Acanthoceras, HapIqceras, Umiaites, Virgatosphindes, Aulacosphinctes, Belemnites, with
Trigonia smeei and Trigonia ventricosa.
The Cutch Jurassic rocks are very rich in fossil cephalopoda. Out
of the material lately collected L. P. Spath has distinguished 114
genera, fifty-one of which are new to India, and nearly 600 species, a
large percentage of which is of local or provincial type, unknown elsewhere. No resemblances are detected with the Mediterranean or with
the North-West European province, nor is there seen any affinity with
the Boreal province, but there exists a close faunal relationship between the Jura of Cutch and Madagascar.
The rocks above described are traversed by an extensive system of
trap dykes and sills and other irregular intrusive massgs of large dimen-"
sions. In the north they become very complex, surrounding and ramifying through the sedimentary beds in an intricate net-work. The
intrusions form part of the Deccan Trap series and are its hypogene
roots and branches.
-The Jurassic outcrop of North-East Kathiawar, already referred to,
is composed of soft white or ferruginous sandstones and pebble-beds
or conglomerates. In this respect, as well as in its containing a few
plant fossils, it is regarded to be of Umia horizon. The sandstone is a
hght-coloured freestone, largely quarried at Dhrangadhra for supplying various parts of Gujarat with a much-needed building material.
Rajputana
Jurassic of Eajputana—The inroads of the Jurassic sea penetrated
much farther than Cutch in a north-east direction,' and overspread a.
great extent of what is now Rajputana. "Large areas of Eajputana.
received the deposits of this sea, only a few patches of which are exposed to-day, from underneath the sands of the Thar desert. It is
quite probable that a large extent of fossihferous rocks, connecting
these isolated inUers, is buried under the desert sands.
Fairly large outcrops of Jurassic rocks occur in Jaisalmer and
Bikaner. They have received much attention on accoimt of their
fossiliferous nature. A number of divisions have been recognised in
them, of which the lowest is known as the Balmir sandstone ; it is.
coinposed of coarse sediments—grits, sandstones and conglomerates.
THE JUEASSIC SYSTEM
191
with a few badly preserved remains of dicotyledonous wood and
leaves. The next group is distinguished as the Jaisalmer limestone,
composed of highly fossiliferous limestones with dark-coloured sandstones. The limestones have yielded a number of fossils, among which
the more typical are Pholadomya, Corhula, Trigonia costata, Nucula,
Pecten, Nautilus and some Ammonites. This stage is regarded as
homotaxial in position with the Chari series of Cutch.
The Jaisalmer limestone is overlain by a series of rocks which are
referred to three distinct stages in succession: Abur beds, Parihar
sandsto7ies and Badasar beds. The rocks are red ferruginous sandstones, suci'.eeded by a soft felspathic sandstone, which in tuxn is succeeded by a group of shales and limestones, some of which are fossiliferous.
Dr. La Touche, of the Geological Survey of India, has assigned a
younger age- to the Balmir beds (Cretaceous), mainly from the evidence of the dicotyledonous plant fossils which they contain.
Jurassic rocks are also exposed in the southern part of Eajputana,
where a series of strata bearing resemblance to the above underlie
directly Nummulitic shale beds of Eocene age,
*
REFERENCES
F. Stoliczka, Mem. O.S.I, vol. v. pt. 1, 1865.
T. H. D. La Touche, Geology of W. Rajputana, Mem. 0.8.1. '/ol. xxxv. pt. 1,1902.
A. B. Wynne, Geology of the Salt^Range, Mem. 0.8.1. vol. xiv. 1878.
C. S. Middlemiss, Geology of Hazara, Mem. O.S.I, vol. xxvi. 1896.
,
V. Uhlig, etc., Fauna of the Spiti Shales, Pal. Indica, Sers. XV. vol. iv. pts. 1, •
and 2.
J. W. Gregory, etc., Jurassic Fauna of Cutch, Pal. Indica, Sers. IX. vols. i. to iii.
A. B. Wynne, Geology of Cutch, Mem. O.S.I, vol. ix. pt. i. 1872.
A. M. Heron, Geology of Mt. Everest, Bee. O.S.I, vol. liv. pt. 2, 1922.
L. F. Spath, Revision of the Jurassic Cephalopod Fauna of Cutch, Pal. Ind., N.S.,
vol. ix., 1927-1933.
L. R. Wager in Everest 1933 (Hodder & Stoughton), 1934
CHAPTER XIV
THE CRETACEOUS SYSTEM
Varied facies of the Cretaceous. The geography of India in the Cretaceous period—No other> geological system shows a more widely divergent facies of deposits in the different areas of India than the Cretaceous, and there are few which cover so extensive an area of the.
country as the present system does in its varied forms. The marine
geosynchnal type prevails in the Northern Himalayas and in Baluchistan ; parts of the Coromandel.coast bear the records of a great'marine
transgression during the Cenomanian Age, while right in the heart of
the Peninsula there exists a chain of outcrops of marine Cretaceous
strata along the valley of the Narbada. An estuarine or fluviatile
facies is exhibited in a series of wide distribution in the Central Provinces and the Deccan. An igneous facies is represented, in both its
intrusive and extrusive phases, by the records of a gigantic volcanic
outburst in the Peninsula, and by numerous intrusions of granites,
gabbros and other plutonic rocks in many parts of the Himalayas,
Burma and Baluchistan. This heterogeneous constitution of the
Cretaceous'is proof of the prevalence of very diversified physical conditions in India at the time of their formation, and the existence of
quite a different order of geographical features. The Indian Peninsula yet formed an integralj!arlLnfJilie_^sgJi43flildwana' continent,
which was still a more or less continuous land-mass stretching from
Africa to Australia. This mainland divided the seas of the south
and east from the great central ocean, the Tethys, which kept its
hold over the entire Himalayan region and Tibet, cutting off the
northern continents from the southern hemisphere. A deep gulf of
this sea occupied the Salt-Range, Western Sind and Baluchistan and
overspread Cutch, and at one time it penetrated to the very centre of
the Peninsula by a narrow inlet through the present valley of the
Narbada.
The southern sea at the same time encroached on the
Coromandel coast, and extended much further north, over-spreading
Assam and probably flooding a part of the Indo-Gangetic depression.
It is a noteworthy fact that no communication existed between
192
THE CRETACEOUS SYSTEM
193
these two seas—of Assam and the Narbada valley—although
separated by only a small distance of intervening land.
While such was the geography of the rest of India the north-west
part of the Peninsula was converted into a great centre of vulcanicity
of a type which has no parallel among the volcanic phenomena of the
modern world. Hundreds of thousands of square miles of the country
between Southern Rajputana and Dharwar, and in breadth almost
from coast to coast were inundated by basic lavas which covered,
under thousands of feet of basalts, all the previous topography of
the country, and converted it into an immense volcanic plateau.
We shall consider the Cretaceous system of India in the following
order:
(i) Cretaceous of the Extra-Peninsula :
N. Himalayas—^piti, Kashmir, Hazara, Chitral.
Igneous Action during Cretaceous.
Sind and Baluchistan.
Assam.
Burma.
(ii) Cretaceous of the Peninsula:
Trichinopoly Cretaceous.
Narbada Valley Cretaceous.
Lameta series.
(iii) Deccan Traps.
CRETACEOUS OF THE EXTRA-PENINSULA
Northern Himalayas
Spiti: Giumal sandstone—^That prominent Upper Jurassic formation,
the Spiti shales, of the Northern ranges of the Himalayas constituting
the Tibetan zone of Himalayan stratigraphy is overlain at a number of
places by yellow-coloured siliceous sandstones and quartzites known
as the Giumal sandstone. (See Fig. 25.) In the Spiti area the Giumal
series has a thickness of about 300 feet. The deep and clear waters of
the Jurassic sea, in which the great thickness of the Kioto limestone
was formed, had shallowed perceptibly during the deposition of the
Spiti shales. . The shallowing became more marked with the deposits
of the next group. These changes in the depth of the sea are discernible as much by a change in the characters of the sediments as by
changes in the fauna that are preserved in them. The deeper-wL' - '
194
GEOLOGY OF INDIA
organisms have disappeared from the Giumal faunas, except for a few
colonies where deep local basins persisted. The fossil organisms entombed in the Giumal satidstone include : (Lamellibranchs) Gardium,
Ostrea, Gryphaea, Pecten, Tellina, Pseudomonotis, Area, Oj)is, Corbis,
Cucullaea, Tapes ; (Ammonites) HolcosiepJianus, Hoplites.
Chikkim series. Flysch—The Giumal series is succeeded in the area
we are considering at present by a group of about 250 feet of white
limestones and shales. Fossils are found only in the limestones which
underlie the shales. This group is known as the Chikkim series, from a
hill of that name in Spiti. The Chikkim series is also one of wide horizontal prevalence, like the Spiti shales, outcrops of it being found in
Kashmir, Hazara, Afghanistan and Persia. The fossils that are preserved in the Hmestone are fragments of the guards of Belemnites,
shells of the peculiar lamellibranch genus Hippurites (belonging to the
family Rudistae) and a number of foraminifers, e.g. Nodosaria, Cristellaria, Textularia, Dentallina, etc., congeners of the foraminifers whose
tiny shell-cases have built up the chalk of Europe. In the areas
adjacent to Spiti the Chikkim series is overlain by a younger series of
Cretaceous rocks, composed of a great thickness of unfossiliferous
sandstones and sandy shales of the type to which the name of Flysch ^
is apphed. (See Fig. 25.) The Cretaceous flysch gives further evidence of the shallowing of the Tethys and its rapid filUng up- by the
coarser littoral detritus. With the flysch deposits the long and uninterrupted geosynclinal conditions approached their end,- and the
Chikkim series may be regarded as the last legible chapter in the long
history of the Himalayan marine period. The flysch deposits that
followed mark the gradual emergence of land, and the receding of the
shore-line fuithei and further north. The Himalayan continental
period had already begun and the first phase of its uphft into the
loftiest mountain-chain of the world commenced, or was about to^
commence.
In the general retreat of the. Tethys from the Himalayan province
at this period, a few scattered basins were left at a few localities, e.g.
in Central Tibet, at Hundes and Ladakh. In these areas the sea retained its hold for a time, and laid down its characteristic deposits till
about the middle of the Eocene, when further crustal deformations
drove back the last traces of the sea from this part of the earth.
* The typical Flysch is a Tertiary formation of.Switzerland, and is composed mainly
of soft sandstones, marls, and sandy shales covering a -wide extent of the country. Its
age is Eocene or Oligocene. Fossils are rare or absent altogether. The term is, however, applicable to. similar deposits in other countries also and of other ages than
Eocene or Oligocene.
THE CRETACEOUS SYSTEM
195
The geological composition of a large area of Central Tibet, lying
between Ladakh and Shigatse, is now, known from the rock and fossil
collections brought by Sven Hedin. An extensive spread of Cenomanian Kmestones covers thousands of square miles of the surface,
underlain by Giumal sandstones (of Neocomian and Gault age) and
the shales and sandstones of Spiti shales facies. The important Cretaceous fossils occurring in these limestones are Praeradiolites, several
species of Orbitolina and the ammonite CJioffatella. This vast cover of
Cretaceous rocks supports in the south a wide extent of Eocene rocks
(Kampa system) and post-Eocene sediments, extending from Gartok,
to the north-west of the Manasarovar lake, to the vicinity of Gyantse.
In the north of this area the Cretaceous cover supports patches of
newer Tertiary and Pleistocene sediments containing mammalian
bones and other remains.
Chitral
In the Chitral area the Middle Cretaceous is represented by Hippurites limestone and Orbitolites limestone in narrow faulted bands
which run along the general strike of the country (N.E.-S.W.). These
pass upwards into the Eeshun conglomerate of Upper Cretaceous or
Lower Tertiary age.^
Further evidence of the distinctly intrusive nature of extensive belts
of granitoid gneiss of the Central Himalayan Gneiss facies has been re'cbrded by Tipper in Chitral. Numerous bosses of granite are found
to have invaded Mesozoic strata in, some cases inferred, on fossil evidence, to be of Jurassic age.
Igneous action during Gretaceous
Plutonic and volcanic action—The history of the latter part of the
Cretaceous age, and the ages that followed it immediately, is full of
the proofs of widespread igneous action on a large scale, both in its
plutonic as well as in its volcanic phase. An immense quantity of
magma was intruded in the pre-existing strata, as well as ejected at
the surface over wide areas in B aluchistan, the North-West Himalayas,
Kumaon Himalayas and Burma. Masses of granites, gabbros and
peridotites cut through, the older rocks in bosses and veins, laccolites
and sills, while the products of volcanic action (lava-flows and ashbeds) are found interstratified in the form of rhyolitic, andesitic and
basaltic lava sheets and tuffs. The ultrabasic, peridotitic intrusions
iQ. H. Tipper, Rec. G.S.I, vol. IF. p. 38, and vol. Ivi. pp. 44-48, 1924.
196
GEOLOGY OF INDIA •
of these and slightly subsequent ages are at the present day found
altered into serpentine-masses bearing some useful accessory products
that have been separated from them by the process of magmatic
segregation. Of these the most important .are the chromite masses in
Baluchistan, the semi-precious mineral jadeite in Burma, and serpentine in Ladakh.
,
A great proportion of the granite which forms such a prominent
part of the crystalline core of the Himalayas, forming the broad
central belt between the outer Tertiary zone and the inner Tibetan
zone, is also tentatively referred, in a great measure, to the igneous
activity of this age. Three kinds of granites, as stated before, are
recognised in the Himalayan central ranges, viz. Biotite-granite,
which is the most widely prevalent. Hornblende-granite and Tourmaline-granite, but it is quite probable that all the three have been
derived by the differentiation of one originally homogeneous magma.
As will be alluded to later, this outburst of igneous forces is connected with the great physico-geographical revolutions of the eaily
Tertiary period, revolutions which culminated in obliterating the
Tethys from the Indian region and the severing of the Indian Peninsula from the Indo-African Gondwana continent.
" Exotic " Blocks of Johax—According to Von Krafft, the records
of an extraordinary volcanic phenomenon-are witnessed in connection
with the Cretaceous rocks of the Kumaon Himalayas. Lying over th^^
Spiti shales and Cretaceous rocks of Johar, on the Tibetan frontier of
Kumaon, are a number of detached blocks of sedimentary rocks of all
sizes from ordinary boulders to blocks of the dimensions of an entire
hill-mass. These lie in a confused pell-mell manner, in all sorts of
stratigraphic discordance on the underlying beds. From the evidence
of their contained fossils these blocks are found to belong to almost
every age from early Perin,ian to the newest Cretaceous. But the
fossils reveal another, more curious, fact that these reok-inasses do not
belong to the Spiti facies of deposits, but are of an entirly foreign facies
of Permian, Triassic and Jurassic, prevaibng in a distant northern
locaUty in Upper Tibet. Such a group of " exotic " or foreign blocks
of rocks, out of all harmony with their present environments, were at
first believed to be the remnants of denuded recumbent folds, or were
ascribed to faulting, and were considered as identical with the
" Klippen " of the Alps. But from the circumstance of the close
association, and sometimes even intermixing of these blocks with great
masses of early Tertiary volcanic products like basalts and andesites,
.an altogether novel method of origin has been suggested, viz. that
T H E CBETACEOUS SYSTEM
197
ttese blocks were torn by a gigantic volcanic explosion in North Tibet
(such as is connected with the production of volcanic agglomerates
and breccias), and subsequently transported in the lava inundation
to the positions in which they are now found. The mode in which
these blocks are scattered in the most confused disorder imaginable,
is not in disagreement with the above view of their origin. These
foreign, transported blocks on the Kumaon frontier are known in
Himalayan geology as the exotic blocks of Johar. Similar phenomena
are recorded in some other parts of the Himalayas as well.
In view of the nappe structures lately observed and mapped in the
Kashmir, Simla and Garhwal Himalayas, it appears highly probable
that the Mala Johar blocks, some of which are found building the
tops of prominent mountains, may after all prove to be a tectonic
phenomena and have to be regarded as the " klippen " they were once
conjectured to be, the severed frontal ends of nappes or horizontal
recumbent folds, whose main body has been denuded away. According to Arnold Heim, these exotic blocks of Johar not only occur as
•isolated masses but also form sheet-like expanses covering several
square miles of mountainous country.^
Kashmir
A thick pile of volcanic ejectamenta, bright green and purple,
• laminated ash-beds, tuffs, agglomerates, and basaltic lava flows, with
intercalated sedimentary layers and lenses of limestone, containing
Orbitolina and other foraminifera, corals, fragmentary ammonites,
echinoids, etc., occupies a long and wide synclinal belt stretching
from south-east of Astor to beyond Dras in Ladak. This is the northwest extension of the basal part of the much more extensive zone of
Eocene volcanic and marine sediments of the upper Indus valley from
Kargil to Hanle in S.E. Ladak (p. 428). The vertical extent of this
clastic volcanic series reaches several thousand feet and in its width
the belt is over 12 miles across the strike where it is traversed by
the Burzil valley. Dolerite, gabbro and pyroxenite masses and
stocks, together with bathyliths of hornblende-granite are injected
into these rocks and have, given rise to a varied suite of alteration
products.
Hazara
Eepresentatives of the Giumal sandstone are found in Hazara
capping the Spiti shales, in a group of dark-coloured, close-grained,
' Arnold Heim, Himalayan Journal, ix. p. 41, 1937.
%
198
GEOLOGY OF INDIA
massive sandstones, calcareous shales and shelly limestones containing Ostrea and Trigonia. The Giumal sandstone passes up into a very
thin arenaceous limestone only some 10 to 20 feet thick, but containing a suite of fossils possessing affinities with the English Gault. The
leading fossils are ammonites, of typically Cretaceous genera, Uke
Acanthoceras (in great numbers), Ancyloceras, Anisoceras, Baculites,
etc., the latter forms being characterised by possessing an uncoiled
shell. There are also many Belemnite remains. The Cretaceous limestone is overlain by a great development of the Eocene system—the
Nummulitic Kmestone—much the most conspicuous rock-group in all
parts of the Hazara province.
The Giumal series also occurs in the Kala Chitta and Margala hills,
near Rawalpindi, overlying the Spiti shales in about 100 feet of
ochreous limestones, green sandstones, and 'marls, containing ammonites of Albian age. They occur i a vividly coloured sharply
defined bands and the outcrops serve to define the compressed anticlinal flexures of the Nummulitic limestones of these ranges.The Gault, or Giumal series, has also been observed with identical
fossil ammonites, in the Kohat district. I t is there underlain by a
lower Cretaceous stage with OlcostephanuSi
Sind and Baluchistan
Cretaceous of Sind. Cardita beaumonti beds—Upper Cretaceous"^
rocks indicating the Campanian and Maestrichtian horizons (Upper
Chalk) are developed in Sind in one locality only, the Laki range.
The bottom beds are about 300 feet of whitish limestones, containing
echinoids hke Hemipneustes, Pyrina, Clypeolampas, and a number of
molluscs. Among the latter is the genus Hippurites, so characteristic
of the Cretaceous period in all parts ofi the world. This hippurite
limestone is a local representative of the much more.widely developed
hippurite limestone of Persia, which is prolonged into south-eastern
Europe through Asia Minor. I t is succeeded by a group of sandstones
and shales, often highly ferruginous, some beds of which contain ammonites like Indoceras, Pachydiscus, Baculites, Sphenodiscus, etc.
These are in turn overlain by fine, green arenaceous shales and sandstones, imfossiliferous and of a flysch type, attaining a great thickness.
An overlying group of sandstone is known as the Pab sandstone. The
top beds of this sandstone consist of olive-coloured shales and soft
sandstones, the former of which are highly fossiliferous, the commonest fossil being Cardita beaumonti, a lamellibranch with a highly
THE CRETACEOUS SYSTEM
199
globose shell. This group is designated the Cardita heaumonti beds.
Other fossils include Ostrea, Corbula, Turritella, Natica, Lytharea,
Caryophyllia, Smilotrochus, and o t h ^ corals; echinoderms, gastropods
and some vertebrae belonging to a species of crocodiles. The Cardita
beds are both interstratified with as well as overlain by sheets of
Deccan Trap basalts, one band of which is nearly 100 feet thick,
of amygdaloidal basalt. The age of the Cardita beds, from the
affinities of their contained fossils, is regarded as uppermost
Cretaceous (Danian).
Cretaceous of Baluchistan—The Cretaceous system as found developed in Baluchistan is on a much more perfect scale than in Sind,
covering a far wider extent of the country and attaining a greater
thickness. In this area, moreover, the Lower Cretaceous horizons of
Wealden and Greensand ages are also represented, having been recognised in a series of shales and limestones resting upon the Jurassic
rocks of Baluchistan, known respectively as the Belemnite shales and
the Park limestone. The lower, belemnite beds are a series of black
shales crowded with the guards of belemnites. They are overlain by a
conspicuous thick mass of variously coloured siliceous limestones,
1500 feet in thickness, extending from the neighbourhood of Karachi
to beyond Quetta in one almost continuous outcrop. This division is
known as the Parh limestone^ The Parh limestone is in the main unfossiUferous except for a few shells, e.g. Inoceramus, Hippurites, and
some corals.
The Upper Cretaceous sequence of Baluchistan rests with a slight
unconformability on the eroded surface of the Parh limestone. This
sequence is broadly alike in Sind and Baluchistan, and the account
given above applies to both. In Baluchistan, however, the flysch deposits are found developed on a larger scale than in Sind, and form a
wider expanse of the country. They are distinguished as the Pab
sandstone from the Pab range in Baluchistan. The upper beds of the
Pab Sandstone are the equivalents of the Cardita beaumonti beds of
Sind.
The Upper Cretaceous of both Sind and.Baluchistan, especially the
Cardita beaumonti beds, is largely associated with volcanic tuffs and
basalts, the local representatives of the Deccan Traps of the Peninsula.
In Baluchistan there are also large bosses and dykes of gabbros and
other basic plutonio rooks piercing through strata of this age.
It should be noticed that the upper parts of the Umia beds described with the Jurassic rocks of Cutch are of Lower Cretaceous age—
Wealden.
200
GEOL(yGY"0B' INDIA
Salt-Range
The Cretaceous system is rather inconspicuously developed in the
cis-Indus Salt-Eange, the principal fossiliferous outcrops being confined to the Chichali hills, Makerwal and the vicinity of Kalabagh.
Only the lower Cretaceous is present; the rocks, consisting of v/hite
and yellow sandstones and shales with a basal stage of Pl^ck shales and
glauconitic sandy marls, Belemnite shale, rest upon t'te Jurassic and
are overlain by the Eocene. A rich neocomian fauna of cephalopods
characterises the belemnite beds. The principal genera are : OlcostepJianus (very common), Spiticeras, Neocomites, Blanfordiceras,
Belemnopsis and HiboUtes. Some reptilian and fish r^niains together
with Exogyra, Pecten, Pholadomya and a few other moUnscs are associated with these.
Assam
With the exception of a narrow belt of interrupted Lower Gondwana outcrops stretching from Darjeeling to the Abor country, the
oldest fossiliferous sediments of the Assam region belong to the Cretaceous system of deposits prominently seen in the ^hillong plateau
region. In this area, Cretaceous sandstones lie on an irregular surface
of SKillong quartzites and other metamorphic rocks, ^ t e basal bed is
usually an irregular conglomerate interbedded with s^^ndstone. This
is followed by glauconitic sands and a pale-coloured carbonaceous®
sandstone which contains plant remains. There is much lateral
variation and most of the sandstones are unfossilifefous, but below
Cherrapunji there has been found a large fauna indicating a Cenomanian horizon. The leading geVera a r e : BacuUtes, Gryphaea,
Pecten, Nerita, .Spondylus, Inoceramus, Rostellaria, Turritella, etc.,
together with many plant remains. The orgaijic remains of
this group of beds prove their identity with, the * much better
known and more perfectly studied Cretaceous of the south-east
coast of Trichinopoly.
The Cherra sandstone, formerly regarded as t^e upper part
of the Cretaceous is now thought to be the lowest member of the
Eocene.
On the Shillong plateau (which includes a lar^e part of the
Garo hills and of the Khasi and Jaintia hills) the Cretaceous
and overlying beds are nearly horizontal, but along the southern
edge of the plateau the Cretaceous and Tertiary l?eds dip southwards at steep angles.
THE CRETACEOUS SYSTEM
201
Burma
In the Arakan Yoma of Burma, and in the southward continuation
of the same strike in the Andaman Islands, is found a large thickness
of beds which are at least in part Cretaceous. Owing to the paucity of
fossils and our lack of knowledge of the complex Arakan Yoma
country, the classification of these lyeds is uncertain. The Mai-i series
is largely sandstone and dark shale but it includes an argillaceous
limestone with ScJiloenbachia inflatus. The Negrais series includes
sandstones and shales, somewhat metamorphosed, evidently a flysch
deposit recalling that of Sind and Baluchistan. The uppermost
Cretaceous contains Cardita beaumonti, also characteristic of beds in
Sind and Baluchistan.
Among the intrusive Cretaceous rocks of Burma are masses of
serpentines traversed by veins of jadeite,. which yield the jadeite of
commerce for which Burma is famous (p. 358).
Cretaceous rocks have lately been found in the Irrawaddy river defile
near Yanbo' in Upper Burma, containing species of Orbitolina, allied
to those occurring in the Cretaceous of Eastern Tibet. This suggests
an extension of the Cretaceous sea of the Tibetan zone of the
Himalayas into Burma.^
REFERENCES
W. T. Blanford, Ancient Geography of Gondwanaland, Bee. O.S.I, vol. xxix.
pt. 2, 1896.
A. von Krafft, Exotic Blocks of Mala Johar, Mem. O.S.I, vol. xxxii. pt. 3, 1902.
H. B. Medlicott, Shillong Plateau, Mem. O.S.I, vol. vii. pt. 1, 1869.
H. H. Hayden, Geology of Spiti, Mem. O.S.I, vol. xxxvi. pt. 1, 1904.
E. Spengler, Pal. Indica, N.S., voL viii. mem. 1, 1923.
H. L. Chhibber, Oeohgy of Burma (Chapter on " Igneous Activity in Burma "),
(Macmillan), 1934.
^Rec. Q:8.I. vol. Ixxi. pp. 350-375, 1937.
CHAPTER XV
THE CRETACEOUS SYSTEM (Continued)
PENINSULA
Upper Cretaceous of theCoromandel coast—Upper Cretaceous rocks of
the south-east coast of the Peninsula form one of the most interesting
formations of South India, and have been studied in great detail by
many geologists and palaeontologists. They are a relic of the great
marine transgression of the Cenomanian age, whose records are seen
in many other parts of the world, besides the coasts of the Gondwana
continent in India as well as Africa. Three small inliers of these rocks
occur among the younger Tertiary and Post-Tertiary formations
which cover the east coast of the Peninsula. Their bottom beds rest
either upon a basement of the ancient Archaean gneisses or upon the
denuded surface of some division of the Upper Gondwana. As is usual
with deposits formed during transitory inroads of the sea, as mentioned in a previous chapter, the dip of the strata is towards the easi,
hence the outcrops of the youngest stage occur towa,rds the sea, while
the older beds are seen more towards the interior of the mainland.
Interest of the south-east Cretaceous—South of Madras these rocks
are exposed in three disconnected patches, in which all the divisionsof the Cretaceous from Cenomanian (Lower Chalk) to Danian (uppermost Cretaceous) are present. The most southerly outcrop, viz. that
in the vicinity of Trichinopoly, has an area of from two to three hundred square miles, while the other two are much smaller. But the
fauna preserved in these outcrops is of remarkable interest and of
inestimable value ahke on account of the multitude of genera and
species of an old-world creation that are preserved, and for the perfect
state of their preservation. Sir T. H. Holland speaks of these three
small patches of rocks as forming a little museum of palaeozoology,
containing more than 1000 species of extinct animals, including forms
which throw much light on the problem connected with the distribution of land and sea during the Cretaceous. Their distribution and
their relations to the Cretaceous fauna of the other Indian and_African
2D3- '
;
THE CRETACEOUS SYSTEM
203
regions from Madras to Madagascar and Natal, have much to tell
about the geography of the Gondwana continent at this epoch, and of
the barriers to inter-oceanic relations of life which it interposed.
The Cretaceous rocks of South India are classified into three stages
in the order of superposition :
Ariyalur,
Trichinopoly,
Utatur.
Utatur stage—The lowest Utatur stage rests upon an ancient landsurface of the Archaean gneisses or Upper Gondwanas. I t is mostly
an argillaceous group about 1000 feet in thickness. At the base it
contains as its principal member a coral limestone (an old coral reef)
succeeded by fine silts, clays, and gritty sandstones. The Utatur outcrop is the westernmost, and is continuous through the whole Cretaceous area along its western border. At places its width is greatly
reduced by the overlapping of the next stage, the Trichinopoly. The
Utatur fossils are all, or mostly, littoral organisms, such as wood-boring
molluscs, fragments of cycadaceous wood, and numerous ammonites.
The preponderance of the latter at particular horizons enables the
series to be minutely sub-divided into sub-stages and zones. The
genus Schloeribachia occurs largely at the base, and gives its name to
'the lowest subdivision of the Utaturs, followed by the Acanthoceras
zone, etc.
Trichinopoly stage—The next group is distinguished as the Trichinopoly stage, and comes somewhat unconformably on the last. This
group is also 1000 feet in thickness, but in lateral extent is confined
to the outcrop in the vicinity of Trichinopoly only. Both the composition of this group, as well as the manner of its stratification, show
it to be a littoral deposit from top to bottom. The rocks are conspicuously false-bedded coarse grits and sands, clays and shelly limestones,
with shingle and gravel beds. Granite or gneiss pebbles are abundantly
dispersed throughout the deposits. The proximity of the coasts is
further evidenced by the large pieces of cycad wood, sometimes entire
trunks of trees, enclosed in the coarser sandstone and grits. The
shell-limestone has compacted into a beautiful hard fine-grained,
translucent stone which is much prized as an ornamental stone, and
used in building work under the name of Trichinopoly marble. Fossils
are many, though not so numerous as in the Utatur division. They
indicate a slight change in the fauna.
204
GEOLOGY OF DSTDIA
AriyaluT stage. Ninijmr stage—The Trichinopoly is conformably
overlain by the Ariyalur stage, named from the town of Ariyalur in
the Trichinopoly district. I t consists of about one thousand feet of
regularly bedded sands and argillaceous strata, with, towards the top,
calcareous and concretionary beds full of fossils. The Ariyalur stage
occupies by far the largest part of the Cretaceous area, the breadth of
its outcrop exceeding fifteen miles. The Ariyalur fauna exceeds in
richness that of the two preceding stages, the gastropods alone being
represented by no less than one hundred and forty species. Besides
these, cephalopods, lamellibranchs, echinoderms, worms, etc., are
present in a large number of species. The uppermost beds of this stage
are sharply marked off from those below and form a distinct subdivision, known as the Niniyur stage, and distinguished from the remainder on palaeontological grounds, though there is no stratigraphic
break visible. The ammonites have disappeared from this division,
and with them also many lamellibranch genera, while the proportion
of gastropod species shows a marked increase. Numerous beds of
algal ^ and foraminiferal hmestones are enclosed among argillaceous
and gritty sediments. The following genera of fossil marine algae are
common: Dissocladelld, Indopolia, Acicularia arcd several lAthothamnia. MiUoline foraminifers are associated with these. The fossils
.of the Niniyur beds reveal a Danian affinity, and, according to Mr.
Vredeuburg, they are equivalent to the Cardita heaumonti beds of
Sind and Baluchistan. The decUne of the ammonites and the increase
in the families and orders of the gastropods are a very significant index
of the change of times : the Mesozoic era of the earth's history has
well-nigh ended,, and the third great era, the Cainozoic, is about to
commence.
Fauna of the south-east Cretaceous—The following list shows the
distribution of the more common genera in the three stages :
j>'
Utatur Stage:
Brachiopods: Kingena, Terebratula (many species), Rhynchonella (many species).
Corals: Trochosmilia, Stylina, CaryophylUa, Isastrea, Thamnastrea.
Gastropods : Fusus, Patella, Turritella.
Ammonites; Schloenbachia, Acanthoceras, Hamites, Mannitps,
• Turrilites, Nautilus neocomiensis.
• L. R. Rao and Julius Pia, Pal. Indica N.S., vol. xxi. mem. 4, 1936.
THE CRETACEOUS SYSTEM
205
Lamellibranclis: Exogyra, Gryphaea, Inoceramus, Tellina, Opis,
Nuculana, Nucula, Area, Aucella, Radula, Pecten, Spondylus,
Lima, Pinna, Trigonoarca.
Trichinopoly Stage; "
Ammonites : Placenticeras, Pachydiscus, Heteroceras, Scaphites.
Lamellibranchs : Pholadomya, Modiola, Ostrea, Gorbula, Mactra,
Cyprina, Cytherea, Irigonia, Trigonoarca, Pinna, Cardium,
Pecten.
Eeptiles : Ichthyosaurus, Megalosaurus (Dinosaur).
Ariyalur Stage:
Ammonites : Pachydiscus, Baculites, Sphenodiscus, Desmoceras,
Puzosia, Anisoceras.
Lamellibranchs : Cytherea, Cardium, Cardita, Lucina, Yoldia,
Nucula, Axinea, Modiola, Radula, Gryphaea, Radiolites,
Trigonoarca, Exogyra, Plicatula, Anomia.
Gastropods: Voluta, Cypraea, Aporrhais, Alaria, Cytherea,
Pseudoliva, Cancellaria, Cerithium, Turritella, Solarium,
Patella, Nerita, Nerinea, Phasianella, Rostellaria.
Reptiles : Ichthyosaurus, 1 Titanosaurus, Megalosaurus and other
theropod and sauropod dinosaurs.^
Corals : Stylina, Caryophyllia, Thamnastrea, Cyclolites.
Echinoids : Epiaster, Cardiastar, Holaster, Catopygus, Holectypus, Salenia, Pseudodiadema, Cyrtoma.
Crinoids: Marsupites, Pentacrinus.
Polyzoa : Discopora, Membranopora, Lunulites, Cellepora, Entalophora.
Niniyur Stage : Nautilus danicus, large specimens of Nerinea and
Nautilus with Orbitoloides, Cyclolites. Many gastropods,
foraminifera, algae, and other plant remains.
The above list gives but an imperfect idea of the richness of the
fauna and of its specific relations. All the groups of the Invertebrata
are represented by a large number of genera, each genus containing
sometimes ten or even more species. The mollusca are the most
largely represented group, and of these the cephalopods form the most
dominant part of the fauna. There are one hundred and fifty species
of cephalopods, including three species of Belemnites, twenty-two of
Nautilus, ninety-three of the common species of Ammonites, and three
species of Scaphites, two of Hamites, three of Baculites, eight of
' Sec. O.S.I. vol. Ixi. pt. 4, 1929.
206
GEOLOGY OF INDIA
Turrilites, eleven of Anisoceras, and three of Ptyc)ioceras. The gastropods and lameUibranchs number about two hund);ed and forty specie's
\ a c h . The next group is corals, represented by about sixty species,
echinoids by forty-two species, polyzoa twenty-five and brachiopods
twenty.
Of Vertebrata there occur seventeen species of fishes, and two or
three of reptiles, one of Megalosaurus and one of Ichthyosaurus and
? Titanosaurus, relatives of the giant reptiles of the European and
American Cretaceous. No fossil mammals belonging to the Cretaceous
age have yet been discovered in any part of India.
Marine Cretaceous of the Narbada Valley; Bagh Beds
The Narbada valley Cretaceous^A number of small detached outcrops occur along the Narbada valley, extending along an east-west
line from the town of Bagh in the GwaUor State^ to beyond Baroda,
stretching as far west as Wadhwan in Kathiawar> They cover an extensive area of Panch Mahals district of N. Gujarat, generally underlying the Deccan Traps. The rocks are charactbrised bv an heterogeneous composition including cherts, impure shelly Umestones,
quartzitic sandstones arid shales. In most case^ they occur around
inliers of older rocks in the Deccan Trap, by the cjenudation of which
these beds are laid bare. They are the much worix relics of another of
the incursions of the sea (this time it is the se% to the north—the
Tethys) during the Cenomanian transgression ar^j, therefore, of the
same age as the Utatur beds described above. Tj^e fossiliferous portion of the Bagh Cretaceous comprises only a v^j-y small thickness,
60-70 feet of limestone and marls, which are (jlassified into three
sections :
Deccan Traps.
Bagh beds.
I Coralline limestones : red polyzoon Kmestone.
Deola marls :' 10 feet fossiliferous inarls.
Nodular limestone (argillaceous limestone)
underlain by unfossiliferous sandgtone
and conglomerates (Nimar sandstone). Cenomanian.
Unconformity.
Gneisses ; Middle Gondwana rocks, etc.
The lower beds are nodular argillaceous limestones, of a wide extension horizontally, met with in the majority of the outcrops between
Bagh and Baroda, followed by richly fossiliferous marls—the Deola
T H E CRETACEOUS SYSTEM
207
and Chirakhan marls—and by a coralline limestone formed of the remains of polyzoa. The last two zones do not extend much westwards.
The fossils are numerous, the chief genera being : Placenticeras and
Namadoceras (Ammonites), Ostrea, Inoceramus, Pecten, Pinna, Crassinella, Grotriana, Protocardium, Gardium-; (Echinoids) Salenia,
Cidaris, Echinobrissus, Hemiaster, Opisaster, Cyphosoma ; (Polyzoa)
Escharina, Eschara; (Coral) Thamnastrea; (Gastropods) Triton,
Turritella, Natica, Cerithium.
The unfossiliferous sandstones underlying the Bagh beds of the
western inliers, particularly near Baroda, have furnished to this region
large quantities of an excellent building stone of very handsome appearance and great durability. ^ The stone (known locally as Songir sandstone ^) has been largely quarried in former years, and besides supplying building stones it affords good millstones.
Conclusions from the Bagh fauna—^The main interest of the Bagh
faima is the contrast which it offers to the fauna of the Trichinopoly
Cretaceous, feom wliich. it differs as widely as it is possible for two
formations of the same age to differ. The Bagh fauna, as a whole, bears
much closer affinities to the European Cretaceous than the former.
This is a very significant fact, and denotes isolation of the two seas in
which they were deposited by an intervening land-barrier of great
width, which prevented the inter-sea migrations of the animals inhabiting the two seas. The one was a distant colony of the far European sea, connected through the Tethys, the other was a branch of the
main Southern Ocean. The two areas, though so adjacent to each
other, were in fact two distinct marine zoological provinces, each having its own population.^ This barrier was no other than the Gondwana continent, which interposed its entire width between the two
seas, viz. that which occupied the-Narbada valley and that which
covered the south-east coast.
While the diiference between these two Cretaceous provinces is of
such a pronounced nature, it is interesting to note that there exists a
very close agreement, both lithological as well as faunal, between the
Trichinopoly Cretaceous and the Assam Cretaceous described in the
last chapter. This agreement extends much further, and both these
• The appearanoe of the stone is greatly improved by the abundant diagonal bedding,
made conspicuous by the inclusion of red and purple laminae in the white or creamcoloured general massof the rock.
' The Songir sandstone of Gujarat is probably the same as the Ahmednagar sandstone of the Idar State.
' Recent discovery of some fossil forms related to the Uppef Cretaceous species from
Trichinopoly area has somewhat reduced this distinctness of the Bagh fauna from the
Coromandel fauna.
208
GEOLOGY OF INDIA
outcrops show close relations to the Cretaceous of Central and South
Africa. These facts point to the inference that it was the same sea
which covered parts of Africa, the Coromandel coast and Assam, in
which the conditions of life were similar and in which the free
intercourse and migrations of species were unimpeded. These
series of beds must therefore show very wide faunal discrepancies
from the deposits that were laid down in an arm of the great
northern sea, Tethys, which was continuous from West Europe to
China, and was peopled by species belonging to a different marine
zoological province.
Lameta Series: Infra-Trappean Beds
Metasomatic limestones. Age of the Lameta series—Lameta series
is the name given to a fairly widely distributed series of estuarine or
fluviatile deposits of the same or shghtly newer stratigraphic position
than the Bagh beds of the Narbada. Outcrops of the series are found
scattered in Central India, the Central Provinces, and in many parts
of the Deccan, underlying directly the Deccan Traps. They generally
appear as thin narrow discontinuous bands round the borders of the
trap country, particularly the north-east and east borders. The name
is derived from the Lameta ghat near Jabalpur, where they were first
noticed. The Lameta group is not of any great vertical extent in comparison to its wide horizontahty. The constituent rocks of the series
are cherty or siUceous limestones, earthy sandstones, grits and clays
attaining in all from 20 to 100 feet in total thickness. The limestones
form the most characteristic part of the series, and in some parts are
of interest as offering an instructive mode of rock-genesis. These limestones, though of ordinary sedimentary origin near Jabalpur and in
the Kewah area, have been found at Chhindwara and at some other
locahties to have largely originated by the chemical replacement of a
former series of igneous and metamorphic rocks. Investigations by
Dr. Fermor have revealed that many of these limestones are metasomatic in origin, and have resulted from the calcification of the underlying Archaean gneisses and schists through the process of molecular
transformation, effected by the agency of percolating waters. The
metasomatic changes are seen in all stages of progress, from unaltered
gneisses through partly calcified rock to the typical siUceous limestone
of the Lameta series. The calcification and silicification have affected
all kinds of underlying rocks, gneisses, granites and hornblende and
other schists. There are, however, beds of true sedimentary or organic
THE CRETACEOUS SYSTEM
209
origia as well, e.g. at Jabalpur and Lameta G h a t / as is evident
from tlie few badly preserved fossil shells and other organic remains
preserved in them. The sandstones and clay beds of the Lameta series
have yielded a few land or fresh-water shells and the remains of
numerous reptiles ; among the former are species of BulUnus, Melania, Corhicula, Paludina, etc., which are readily recognised as freshwater, or at the most estuarine, species. The vertebrate fossils include Dinosaurian reptiles, turtles (Chelonia) and some fish remains.
The latter are valuable as having yielded conclusive evidence with
regard to the stratigraphy of the Lameta series. The fishes were obtained from Dongargaon in the Central Provinces. They include
species of Eoserranus, Lepidosteus, and Pycnodus. The first of these
belong to the order Teleostea of bony fishes, the latter belong to the less
highly organised order of Ganoidea. Sir Arthur Smith Woodward has,
from the evidence of these fish remains, determined the age of the
Lameta series to be between Danian and Lower Eocene. Von Huene
places the Jabalpur Lametas in,the Turonian.
The recent discovery of remains of Cretaceous dinosaurs from Jabalpur and Pisdura (Chanda district) has greatly increased our knowledge of the fossil Dinosauria of India. Twelve new genera have been
added to the known Indian fossil dinosaurs ; these include the first
records of the stegosauria and the coelurosauria. The dinosaurs
reached their highest development in India during the Lameta epoch.
The twelve genera have been identified from the vertebrae, skull and
limb-bones, armour-plates, teeth and coprolites. The following are
the principal genera : Titanosaurus, three species ; Antarctosaurus,
two species; Indosuchus, two species; Lameiosaurus; Laplatasaurus ; Jubbulporia. Prof. Von Huene states that the Central
Provinces fossil dinosaurs are closely allied to those occurring in the
Cretaceous of Madagascar and also with those found in Patagonia and
Brazil. This would suggest land-bridges in the existing Indian and
Atlantic oceans, or the persistence of large remnants of the old
Gondwana continent. (See p. 123.)
The Lameta series everywhere rests with a great unconformity over
the older rocks, whether they are Archaean gneisses or some member of
the Gondwana, or the Bagh beds. As a rule they are conformably
overlain by the earliest lava-flows of the Deccan Traps series of volcanic eruptions which began at this point, and the geology of which
now claims our attention. At a few places, however, the lowest Traps
iDr.C. A. Matley, Bee. G.S.I. vol. liii. pt. 2, 1921.
210
GEOLOGY OF INDIA
exhibit discordant relations t o the Lametas, denoting t h a t a considerable interval of time elapsed before t h e volcanic cycle began. I t is
quite probable, however, t h a t the discordant relations m a y be only
apparent and rnay be due t o the fact t h a t in these particular cases the
supposed L a m e t a limestone is only t h e altered calc-gneiss ^ which
Fermor and others have foujid so commonly between t h e Traps and
the Archaeans a n d which has in the past been so often mistaken for
Lameta limestone.
Western India
The H i m m a t n a g a r sandstone in I d a r State h a s recently yielded a
small b u t interesting flora including Weichselia and
Matonidium,
two extinct genera of ferns which are of considerable stratigraphical
value. The former genus is represented by W. reticulata, a very characteristic Wealden species. The Matonidium ( M . indicum) is closely
allied t o t h e well-known European species M. goepperti. This genus
reached its m a x i m u m development in t h e Lower Cretaceous though it
also occurs in t h e Jurassic.^
,
REFERENCES
F. Kossmatt, Cretaceous Deposits of Pondicherry, Bee. O.S.I, vol. xxviii. pt. 2,
and XXX. pt. 2, 1895 and 1897.
F. Stoliczka and H. F. Blanford, Cretaceous Fauna of Southern India, Pal. Ind.
Sers. I., III., v., VI. and VIIL, 1861-1873.
F. von Huene and C. A. Maltey, Pal. Ind., N.S., vol. xxi. mem. 1, 1933.
L. L. Fermor, Rec. 0.8.1. vol. xlvii. pt. 2, 1916.
W.- T. Blanford, Geology of the Taptee and Narbada Valleys, Mem. O.S.I, vol.
vi. pt. 3, 1869.
» See Chapter III. p. 60 ant.
» Sec. G.8.I. vol. Ixxi. pt. 2, 1936.
CHAPTBE XVI
DECCAN TRAP
The great volcanic formation of India—Towards the close of the Cretaceous subsequent to the deposition of the Bagh and the Lameta beds,
a large part of the Peninsula was affected by a stupendous outburst of
volcanic energy, resulting in the eruption of a thick series of lava and
associated pyroclastic materials. This series of eruptions proceeded
from fissures and cracks in the surface of the earth from which highly
hquid lavas welled out intermittently, till a thickness of some thousands of feet of horizontally bedded sheets of. basalts had resulted,
obliterating all the previously existing topography of the country and
converting it into an immense volcanic plateau. That the eruptions
took place from fissures such as those which arise when the surface of
the earth is in a state of tension, and not from the more localised vents
of volcanic craters, is evident from a number of circumstances, of
which the entire absence of any traces, even the most vestigial, of
volcanoes of the usual cone-and-crater type, and the almost perfect
horizontahty of the lava-sheets, in the immense basaltic region, are
the most significant.
This great volcanic formation is known in Indian geology under the
name of the Deccan Traps. The term " trap " is a vague, general
term, which denotes many igneous rocks of widely different nature,
but here it is used not in this sense but as a Swedish word meaning
" stairs" or " steps ", in allusion to the usual step-Uke aspect of the
weathered flat-topped hills of basalts which are so common a feature
in the scenery of the Deccan.
Area—The Deccan Traps encompass to-day an area of 200,000
square miles, covering a. large part of Cutch, Kathiawar, Gujarat,
Deccan, Central India, Central Provinces, Hyderabad, etc., but their
present distributi6n is no measure of their past extension, since denudation has been at work for ages, cutting through the basalts and
detaching a number of outUers, separated from the main area by wide
211
212
GEOLOGY OF INDIA
distances. These outliers, which are scattered over the whole ground
from .W. Sind to Rajahmundri on the East Coast, therefore, must
testify to the original extent of the formation, which at the time of its
completion could not have been much less than half a million square
miles.
Thickness—The maximum thickness of the Deccan Traps reaches
to nearly 10,000 feet along the coast of Bombay, but it rapidly becomes less farther east, and varies much at different places. Towards
FIG. 27.—View of Deccan Trap country (Oldham).
its southern limit it is between, 2000 and 2500 feet"; at Amarkantak,
the eastern limit, the thickness is 500 feet, while in Sind, i.e. the
northern limit, it dwindles down to a band of only 100 or 200 feet. In
Cutch the Traps are about 2500 feet in thicknegs. The individual
lava-flows are about 15 feet on an average, but occasionally some
flows are seen reaching 50 to 100 feet in thickness. The successive
sheets of lava are often separated by thinner partings of ashes, scoriae
and green earth, and in very many cases by true sedimentary beds,
which are hence called inter-trappean beds. The ash and tuff beds are
pretty uniformly distributed throughout, but they are scarcer towards
the lower part.
The presence of volcanic ashes and tuffs suggests explosive action of
some intensity. This might have been the case at certain local vents
along the main fissures, where a few subsidiary cones may have been
DECCAN TRAP
_
213
raised. The eruption of the main mass of the lava was, however, of a
quiet, non-explosive kind, as is the case with fissure-eruptions.
Horizontality of the-lavas—A very remarkable character of the lavas
of the Deccan Trap, having an important bearing on the question of
their mode of origin, is their persistent horizontality throughout their
wide area. It is only in the neighbourhood of Bombay that a marked
departure from horizontality appears and a gentle dip is perceptible,
of about 5°, towards the sea. Other localities, where a slight but
appreciable inclination and even gentle folding of the lava-sheets is
noticeable, are the Western Satpuras, Kandesh and the Rajpipla hills,
near Broach, but these dips are believed to be due to the effects of late
disturbances of level due to tectonic causes rather than to an original
inchnation of the flows. ^
Petrology—In petrological composition the Deccan basalts are
singularly uniform. The most common rock is a normal augite-basalt,
of mean specific gravity 2-9. This rock persists, quite undifferentiated
in composition, from one extremity of the trap area to the other. The
only variation is in the colour and texture of the rock; the most
prevalent colour is a greyish-green tint, but a perfectly black colour
or lighter shades are not uncommon. A few, especially those of
trachytic ojr more acid composition, are even of a rich brown or buff
colour ; less common are red and purple tints. The texture varies
from a homogeneous crypto-crystalline, almost vitreous basalt, through
all gradations of coarseness, to a coarsely crystalline dolerite. The
rock is often vesicular and scoriaceous, the amygdaloidal cavities being filled up by numerous secondary minerals like calcite, quartz, and
zeolites. Porphyritic close-grained varieties, with phenocrysts of
glassy felspar (a medium labradorite) have an almost semi-vitreous
lustre, a dark lustrous colour, and conchoidal fracture. Owing to the
high basicity, and consequent fluidity of the lavas, crystallisation was
a comparatively rapid process, for which reason basalt-glass or tachylite is quite rare, except in some " chilled edges ", where a vitreous
glaze appear^.
Over enormous extents of the trap area there is no evidence at all of
any magmatic differentiation or variation indicated by the presence
of acidic or intermediate varieties of lavas. Some very notable exceptions, however, have been observed in Cutch, parts of Gujarat,
e.g. the Pawagarh hills near Baroda, and Girnar hills of Kathiawar,
where rocks of more acid or basic composition (rhyohtes, granophyres
1 Bee. G.S.I. vol. xlvii. pt. 2, X916.
214
_
GEOLOGY OF INDIA
and gabbros) are found associated with tbe basalts. Their occurrence
in close association with the ordinary basalts suggests that they were
local differentiation products of the same magma. The most common
of these acid lavas are rhyolites, approaching dacites and quartzandesites, pitcJistones and pumice found at Pawagarh.^ The gabbroid
complex of Girnar hills is much more noteworthy. Here are masses of
gabbros and aUied basic intrusives occupying a large tract of hilly
country rising abruptly from the level trap-built plains of Kathiawar.
The relations of the plutonic masses with one another and with the
surrounding country-rocks, which are Deccan Trap flows of usual
composition, suggest some post-trappean intrusion, or series of intrusions, proceeding from the same magma reservoir as that of the
basalts. Subsequent differentiation of the intruded magma by prolonged segregative processes appears to have given rise to several interesting tjrpes ranging in basicity from gabbro, lamprophyre, limburgite,
diorite, and syenite to granophyre, which are so well exposed in the
various temple-crowned hill-masses in the vicinity of Junagadh town.
In Kathiawar, R. B. Foote found a large number of acid and basic
trap-dykes intruded into the main trap-flows. The basic varieties are
of dioritic or doleritic composition, while acidic dykes are composed of
trachytes or rocks of allied composition and character. Other types
from the Kathiawar peninsula are: moncJiiquite, nepheline-syenite,
rhyolite, monzonite, oceanite, anharamite. Acid differentiates of -the
Deccan Traps, trachytes, granophyres and rhyolites are found on the
Bombay coast associated with normal basalts, dolerites and glassy
gabbros.
Of these rocks, the ultrabasic types occur in dykes and small stocks
along the west edge of the trap outcrop from Cutch to Bombay, in all
three phases, volcanic, hypabyssal and plutonic. The acidic types
show a more extensive distribution, but individual occurrences are
small and their total volume is insignificant in proportion to the vast
bulk of the plateau basalts.
'~'
As we have seen in the last chapter, there is a much greater
diversity of petrological composition among the eruptive and intrusive products of the extra-Peninsula, which are in all probability the
representatives of the Deccan. Trap of the. Peninsula.
Microscopic character of the Deccaa basalts—In microscopical
characters, the basalts are hemi-crystaUine, augite-basalts, generally
free from olivine. The mineral olivine is locally abundant in some
» Fermor, Bee. O.S.Lsol. xxxiv. pt. 3, 1906.
DECCAlSr T R A P
215
places. The bulk of the rock is composed of a fine-grained mixture or
ground-mass of plagioclase and augite. Besides abundant plagioclase
(labradorite or anorthite) prisms, which are often corroded at the
edges, there occur sometimes large tabular crystals of clear glassy
labradorite of medium composition as phenocrysts in the groundmass. But porphyritic structure is not common. The augite, often
enstatitic, the next important constituent, is present in small grains,
very rarely with any crystalline outline. Magnetite is abundantly
disseininated through the ground-mass either as idiomorphic crystals
or grains, or as secondary dendritic aggregates. In the ordinary grey
or green basalts there is very little glass, or isotropic residue, left, it
being all devitrified ; but in the black dense specimens there is a large
quantity of glass present, of a green or brown colour. I n some cases
the peculiar amorphous isotropic product palagonite ^ is seen infilling
cavities and interstices of the rock.
The relation of the plagioclase to augite crystals, when apparent, is
of a modified ophitic type, the latter having a tendency to partially
enclose the former. Primary accessory minerals are few, like apatite,
but secondary niinerals, produced by the wide-spread meteoric and
chemical changes that the basalt has undergone, are many, viz. calcite,
quartz, chalcedony, glauconite, prehnite, zeoUtes, etc., filling up the
steam-cavities as well as the interstices of the rock. A host of other
secondary minerals have been described from the basalts of different
localities—chlorophaeite, delessite, celadonite, serpentine, chlorites,
iddingsite and lussatite. By the discoloration attending these changes
the original black colour of the basalts is altered to a grey or greenish
tint (glauconitisation). Glauconite is a very widely distributed product in the basalts of the Deccan Trap, both in the body of the rock
as well as coating the amygdaloidal secretions. The basalt-tuffs are
composed of the usual comminuted lava-particles, with fragments of
pumice, crystals of hornblende, augite, felspar, etc. They are usually
finely bedded, and have a shaly aspect.
[CHEMICAL COMPOSITION : Eleven specimens of Deccan traps, collected
from widely scattered localities, have been chemically analysed in detail by
H. S. Washington. The most striking feature of these analyses is the uniformity of composition of the majority of the basalts, with variation in silica
from 48-6 to 50 per cent.
^ Palagonite is the name given to a peculiar green or brown amorphous alterationproduct met with in basic volcanic rocks, resulting from change of its ferro-magnesian
constituents as well as from residual glass. Much of it is analogous to chlorophaeite.
Its exact origin is not known with certainty. See Bee. O.S.I, vol. Iviii. pt. 3, 1925.
16
GEOLOGY OF INDIA
The following table gives the average of the eleven analyses by
f^ashington:
SiOa
50-61 •
AI2O3
13-58
FeaOs - - - - 3-19
FeO
9-92
MgO
- - - - 5-46
CaO
9-45
NajO
2-60
K2O
0-72
H2O+
l'-70
H2O0-43
TiOa
1-91
P2O5
0-39
CrgOg
none
MnO .
- ,0-16
100-12 Sp. Gr., 2-916.
This chemical constitution of the traps, expressed in terms of standard
normative minerals calculated from the composition gives the following
result as the norm of the Deccan Traps : ^
Quartz Orthoclase'
Albite Anorthite
Diopside
Hypersthene
Olivine Magnetite
Ilmenite /
Apatite -
-
-
-
-
-
. -
4-14
4-45
22-01
23-07
17-41
17-78
4-64
3-65
1-01.]
The basalts exhibit a tendency to spheroidal weathering by the '
exfoliation of roughly concentric shells, hence rounded weathered
masses are everywhere to be seen in the exposed outerops, whether in
the field and in stream-courses or on the sea-coasts. Prismatic jointing, or columnar structure, is also observed in the step-like series of
perpendicular escarpments which the sheets of basalt so often present
on the hill-side or slope. At some places beautiful symmetrical prismatic columns are to be seen; this is especially observed in some
dykes, e.g. those of Cutch. It is the tendency of this kind of jointing,
giving rise to the la,nding-stair-like or " ghat "-like aspect to the basalt
hills of the Deccan, that has given the name of the-Deccan Trap to the
formation.
. ' H, S, Washington, Bulletin, Oeological Society of America, vol. xxxiii, 1922.
DECCAN TRAP
217
Among the abundant secondary minerals that are found as kernels
in the amygdaloidal cavities, the hiost common are the zeolites, stilbite, apophyltite, heulandite, scolecite, ptilolite, laumontite; also
thomsonite and chabazite ; calcite, crystalline quartz, or rock-crystal
and its cryptocrystalhne varieties, chalcedony, agates, carnelian,
heliotrope, bloodstone, jasper, etc. Glauconite is abundant as a coating round the kernels. A quantity of bitumen and asphalt, filling
large cavities in the lavas near Bombay, was found in 1919.
StratigraphTy of the Deccan Trap—The following table shows the
stratigraphic relations of the Deccan Traps among themselves, and
also with the overlying and underlying rocks :
Nummulitics of Surat and Broach ; Eocene of Cutch ; Laterite.
Upper Traps
1500 ft.
Middle Traps
4000 ft,
Lower Traps
500 ft. .
Of Bombay and Kathiawar. Lava flows with
numerous ash-beds ; sedimentary inter-trappean
beds of Bombay with large number of fossils, vertebrata and moUuscan shells.
Of Malwa and Central India. Lavas and ash-beds
forming the thickest part of the series. No fossiliferous inter-trappean beds.
Of Central Provinces, Narbada, Berar, etc. Lavas
with few ash-beds. Fossiliferous inter-trappeans
numerous.
Lameta or Infra-trappean series; Bagh beds; Jabalpur beds and
Older rocks.
Inter-trappeaii beds—-At short intervals the lava-flows are separated
by sedimentary beds of small vertical as well as horizontal extent, of
lacustrine or fiuviatile deposition formed on the irregularities of the
surface during the eruptive intervals. These sedimentary beds,
known as Inter-trappean beds, are fossiliferous, and are valuable as
furnishing the history of the periods of eruptive quiescence that intervened between the successive outbursts, and of the animals and plants
that again and again migrated to the quiet centres. Usually they are
only 3 to 10 feet in thickness, and are not more than three to four miles
in lateral extent, but they are fairly regularly distributed throughout
the lower and upper traps, being rarely absent for any distance in them.
The rocks comprising these beds are a black, cherty rock, resembling
lydite, stratified volcanic detritus, impure limestones and clays. Many
•plant-remains and fresh-water moUuscan shells are entombed in these,
218
GEOLOGY OF INDIA
together with insects, Crustacea, and the rehcs of fishes, frogs, tortoises, etc. The most common shell, whiph is also the most characteristic fossil of the inter-trappean beds, wherever they have been discovered, is Physa (Bullinus) prinsepii—a species of fresh-water
gastropod; other fossils are Limnaea, TJnio, Paludina, Valvata,
Melania, Natica, Vicarya, Cerithium, Turritella, Pupa : the crustacean Gypris, some insects, bones, scales, scutes and teeth of vertebrate animals, e.g. fish, frogs (Rana and Oxyglossus) and tortoises
{Hydraspis, Testudo, etc.). The flora is very rich in palms, of which
numerous stems have been found as well as leaves and fruits ; several
species of dicotyledonous trees are also present. In places a rich
aquatic flora including the fresh-water alga Ghara, the water-fern
Azolla and other aquatic plants have been found beautifully preserved
in a cherty rock which is probably the silicified mud of lakes.
A type-section through a portion of the basalts will show the relations of the traps to these sedimentary intercalations as well as to the
inffa-trappean Lametas.
1. Bedded basalts, thick. Individual flows often marked on upper
and lower surfaces by steam-holes.
2. Cherty beds, lydites, with TJnio, Paludina, Cypris, fossil wood,
5 feet.
3. Bedded basalts, very thick.
4. Impure limestone, stratified tuffs, etc., with Cypris, Physa (Bullinus), and broken shells, 7 feet.
5. Bedded basalts, thick.
6. Siliceous limestones with sandstone (Lametas), with a few shell
fragments, 20 feet.
The mode of eruption of the Deccan Trap—The lowermost trappean
beds rest upon an uneven floor of older rocks, showing that the eruptions were subaerial and not,subaqueous. In the latter case, i.e. if the
eruptions had taken place on the floor of the sea or lake, the junctionplane between the two wovild have been quite even, from the depositing action of water. As already alluded to, the actual mode of the
eruptions was discharge through linear fissures, from which a highly
liquid magma welled out and spread itself out in wide horizontal
sheets. This view is abundantly borne out by the monotonous horizontality of the traps everywhere, and the absence of any cone or
crater of the usual type as the foci of the eruptions; whether within
the trap region, or on its periphery. The most gigantic outpourings of
lavas in the past, in other parts of the world, the " Plateau Basalts ",
have all taken place through fissures, viz. the great basaltic plateau of
DECCAJSr TRAP
219
Idaho in the U.S.A., the Abyssinian plateau and the sheet-basalts of
Antrim, etc. A recent analogy, though on a very much smaller scale,
is furnished by the Icelandic type of eruptions, i.e. eruptions from a
chain of craters situated along fissure-lines. (Cf. the Laki eruption of
1783.)
Fissure-dykes in the traps—For any proof of the existence of the
original fissures which served as the channels of these eruptions we
should look to the peripheral tracts of the Deccan Traps, as it- is not
easy to detect dykes and intrusions, however large, in the main mass
of the lavas, unless the fornier differ in petrological characters from
the latter, which is never the case actually. Looked at in this way,
some evidence is forthcoming as to the original direction and distribution of the fissures. Dykes of large size, massive irregular intrusions,
and ash-beds are observed at a number of places in the neighbourhood
of the trap area around its boundary.^ The most notable of these is
the Rajpipla hill tract near Broach. In Cutch likewise there are
numerous large dykes and complex ramifications of intrusive masses
visible, along the edge of the trap country, among the Jurassic rocks.
The trap area of Kathiawar is traversed by a large number of dykes
intruded into the main mass of the lavas. They are of all sizes, from
thin veins to masses hundreds of yards wide and some miles in length,
and follow different directions. The dykes of Kathiawar are composed either of an acid, trachytic rock, or of a coarse-grained dark
doleritic or dioritio mass. Similar fissure-dykes occur in the Narbada
valley and Satpura area among the Gondwana rocks ; they are likewise seen in the Konkan, while ash-beds are of very frequent occurrence near Poona ; all these are evidences of the vicinity of an eruptive focus. It is clear that the foregoing instances of dykes, etc., are
only the starting-points of the linear fissures which extended a great
way into the interior.
Age of the Deccan Traps—There is no conclusive internal evidence
in the Deccan Traps with regard to their age. The inter-trappean
fossils do not throw any certain light on the age of the beds in which
they are entombed. To estabUsh an accurate correlation of the great
volcanic series in terms of the standard stratigraphic sequence, we must
look to external evidence furnished by the underlying and overlying
marine and estuarine beds. The eruptions were certainly subsequent
to the Bagh beds (Cenomanian) which they overlie at some places, and
' These dykes, intrusions and ash-beds must naturally abound in the vicinity of an
eruptive site, and thus help to indicate the location of the fissure and its probable
direction in the interior.
220
GEOLOGY OF INDIA
to the Lameta series wMch they overlie at others. The upward
limit of the series is fixed by the interstratification of a few flows of the
traps with the Gardita beaumonti beds of Sind, whose horizon is fixed
as Danian and somewhat newer. At jOne or two places on the west
coast the traps are seemingly unconformably overlain by small outliers of Nummulitic beds, as at Surat and Broach. Here the apparent
unconformable junction, denoting an appreciable lapse of time between the last eruptions and the submergence of the area is quite
marked. At Rajahmundri, on the Godavari delta, a distant outlier
of the traps occurs resting on the top of a small thickness of marine
Cretaceous sandstone of Ariyalur age. In the midst of the trap series
in the last-named locality are found sedimentary beds of estuarine and
marine deposition containing fossils such as Physa (BulUnus) prinsepii, Turritella, Nautilus, Cerithium, Morgania, Potamides, Corbula,
Hemitonia, Tympanotomus. These fossils, however, do not lead to any
definite inference, as the affinities of the species and genera are not
very pronounced. Recent examination by Prof. Sahni of the rich
fossil flora from the base of the trappean series of the NagpurChhindwara area, containing an abundance of fossil palms, the occurrence among them of Nipadites, a characteristic Eocene genus, and
the presence of numerous fertile specimens of Azolla (a modern genus
of floating water-ferns of which all the previous fossil records are postCretaceous) leads him to infer an early Tertiary age for the traps.
According to Sahni, the inter-trappean flora finds its clearest aSinities
with the London clay flora. This conclusion seems to find support
from recent finds by L. R. Rao and others of foraminifers of the family
Rotalidae, Lagenidae, and Miliolidae, of charopJiytic remains from
marl beds, and of Acicularia and other algae from an 'inter-trappean
limestone occurring in the small trap outcrop near Rajahmundry.
If Sir A. Woodward's inference of the age of the fish fossils from the
Lameta series (which is distinctly iw/m-trappetfn in position) is
accepted (p. 209) the base of the trap would be positively Eocene. An
Eocene age is also supported by the study of some fossil fish-scales
from the iwter-trappean beds of Betul district. Central Provinces.
Dr. S. L; Hora recognises in the^e scales representatives of an osteoglossid genus Musperia and several species of genus Clupeus with
some percoid fishes, the fossil members of which family carry it only
as far back as the Eocene.^
The present position may be thus summarised: from external
» Bee. O.S.I, vol. Ixxii. pt. 4, 1937.
DECCAN TRAP
-
221
evidence it is quite apparent tliat the Deccan Traps cannot be older
than the Danian stage of the Upper Cretaceous, while from the
internal evidence of fossil fishes, palms and foraminiferSj etc., they
could not be much younger than the Eocene.
With the trifling exceptions of Surat and Broach Tertiaries' noted
above, together with the alluvial deposits of river-valleys, by far the
largest area of the traps is uncovered by any later formation. The
peculiar subaerial alteration-product, known as laterite, surmounts the
highest flow of the traps everywhere as a cap, having been produced
by a slow meteoric alteration of the basalts.
Economics—The basalts are largely employed as road-metal, in
public works, and also to a certain extent as a building stone in
private dwelhngs. From their prevailing dark colour and their generally sombre aspect, however, the rock is not a favourite building
material, except some light-coloured varieties, e.g. the buff trachytes
of Malad, near Bombay. The large kernels of chalcedony often yield
beautiful agates, carnelians, etc., worked into various ornamental
articles by the lapidaries, for which there was once a large market at
Cambay. These are obtained from a Tertiary conglomerate, in which
pebbles of chalcedony, derived from the weathering of the traps, were
sealed up. The sands of some of the rivers and some parts of the seacoast are magnetitic, and when sufficiently concentrated (as on some
sea-beaches) are smelted for iron. Conditions of underground water
storage and supply in the Deccan Trap fireas are of interest. The
vesicular parts of the bedded lavas make good aquifers and yield fair
supplies of underground water. These together with the numerous
joints and fissures are the only means of water storage in this otherwise impervious and massive formation, containing but few stratification-planes or porous layers. The soil produced by the decomposition of the basalts is a rich agricultural soil, being a highly argillaceous dark loam, containing calcium and magnesium carbonates,
potash, phosphates, etc. Much of the well-known " cotton-soil",
known as the "black-soil", or regur, is due to the subaerial weathering
of the basalts in situ, and a subsequent admixture of the weathered
products with iron and organic matter.
REFERENCES
C. A. M'Mahon, Rec. O.S.I, vols. xvi. pt. 1, 1887, and xx. pt. 2, 1887.
W. T. Blanford, Mem. G.S.I, vol. vi. 1867-1869.
P. N. Bose, Mem. O.S.I, vol. xxi. pt. 1, 1884.
222
GEOLOGY OF INDIA
L. L. Fermor and C. Fox, Deccan Trap Flows of Chhindwara District, Bee. 0.8.1.
vol. xlvii. pt. 2, 1916.
L. L. Fermor, Rec. G.S.I, vol. Iviii. pt. 2, 1925.
J. W. Evans, A Monctiiquite from Girnar, Q.J.G.S., Ivii. pp. 38-54, 1900.
H. S. Washington, Deccan Traps and other Plateau Basalts, Bull. Oeol. Society
America, 1922.
K. K. Mathur and others, Magmatic Differentiation in the Gimar HUls, Journ.
of Geology, vol. 34, 1926.
H. Crookshank, Mem. G.S.I, vol. Ixvi. pt. 2, 1936.
B. Sahni, Proc. 21st and 24th Ind. Sc. Congr., 1934 and 1937.
CHAPTER XVII
THE TERTIARY SYSTEAIS
mTRODUCTORY
General—In Europe the upper limit of the Cretaceous is marked by an
abrupt hiatus between it and the overlying Eocene group of deposits.
A sudden and striking change of fauna takes place in the latter
system of deposits, whole families and orders of animals die out, and
new and more advanced types of creatures make their appearance.
The class of reptiles, the pre-eminent vertebrates of the Cretaceous
period, undergo a serious decline by the widespread extinction of many
of the orders of the class, and mammals begin to take precedence.
The earliest mammals are of a simple or generalised type of organisation, but they soon increase in complexity, and are differentiated into
a large number of genera, families and orders. Among the invertebrata the cephalopod class suffers widespread extinction of its species
with the advent of the new era ; the ammonites and belemnites are
swept away altogether. They are now only the items of geological
history hke the trilobites of the Palaeozoic era. The place of the
cephalopods is taken by the gastropods, which enter on the period of
their maximum development.
In India these changes in the history of life are as well marked as in
the other parts of the world, although there is not any sh^arply marked
stratigraphical break perceptible as in Europe.
Physical changes—The Tertiary era is the most important in the
physical history of the whole Indian region, the Himalayas as well as
the Peninsula. I t was during these ages that the most important
surface-features of the area were acquired, and the present configuration of the country was outlined. With the middle of the Eocene, an
era of earth-movements set in which materially altered the old
geography of the Indian region. Two great events of geodynamics
stand out prominently in these readjustments : one the breaking
up of the old Gondwana continent by, the submergence of large
223
224
GEOLOGY OF INDIA
segments- of it underneath the sea/ the other the uphft of the
Tethyan geosynclinal tract of sea deposits to the north into the
lofty chain of the Himalayas.
The prodigious outburst of igneous forces towards the end of
the Cretaceous seems explicable when viewed in connection with these
powerful crust-movements and deformations. The close association
of periods of earth-movements with phenomena of vulcanicity in the
records of the past lends support to the inference that the late Cretaceous igneous activity was in some way antecedent to these earthmovements.
The transfer of such masses of magmatic matter, as we have seen in
the last chapters, from the inner to the outer zone of the earth's sphere
could not but be accompanied by marked eifects on the surface,
chiefly of the nature of subsidence of crust-blocks and, secondly,
wrinkles and folds of the superficial crust, and vice versa, the dislocations and deep corrugations of the surface which marked the early
part of the Tertiary must have produced material effects on the deeper
zone. The exact nature of this interaction between the exterior and
interior of the earth is not understood, but there is no doubt regarding
the collateral and consequential nature of the two phenomena of
eruptivity'and earth-movements.
The elevation of the Himalayas—The pile of marine sedii^ents that
was accumulating on the border of the Himalayas and in Tibet since
the Permian period, began to be upheaved by a slow secular rise of the
ocean-bottom. From Mid-Eocene to the end of the Tertiary this upheaval continued, in several intermittent phases, each separated by
• long periods of time, till on the site of the Mesozoic sea was reared the
greatest and loftiest chain of mountains of the earth. The last signs
of the Tethys, after its evacuiation of the Tibetan area, remained in
the form of a few straggling basins. One of these basins occupied a
large tract in Ladakh, to the north of the Zanskar range, and another
in the Hundes province of Kumaon ; on their floors were laid down
the characteristic deposits of the age, including among them the
NummuHtic Umestone—that indubitable and unfailing landmark of
Tertiary geological history: These sedimentary basins are of high
value, therefore, in fixing the date of commencement of the' uplift of
the Himalayas in the time-scale of geology.
3- It is probable that the disruption of Gondwanaland was not a single event but t h a t '
it proceeded in stages. The first part to separate was Australia and the Malay Archipelago ; the next severence took place between South Africa and South America ; and
the last act was the foundering of Lemuria (the lan4-bridge between India and Madagascar), which brought into existence the Arabian Sea.
THE TERTIARY SYSTEMS
225
Three phases of upheaval of the Himalayas—There appear to have
been three important phases of the upheaval of this mountain system.
The first of these was post-Nummulitic, i.e. towards the end of the
Eocene, culminating in the Oligocene ; this ridged up the central axis
of ancient sedimentary and crystalline rocks. I t was apparently followed by a movement of greater intensity about the middle of the
Miocene. The most important phase elevated the central part of the
range together with the outlying zone of Siwalik deposits into the vast
range of mountains which have since been reduced by denudation to
form the present Himalayas. This last stage was mainly of postPhocene age, posterior to the deposition of the greater part of the
Siwaliks, and did not cease till after middle of the Pleistocene.^
There is some proof that the elevatory movement has not entirely
disappeared even within recent times.
After the final breaking up of Gondwanaland, the most prominent
feature of the earth's Mesozoic geography, the Peninsula of India
acquired its present restricted form. Incidental to this change, a profound .redistribution of land and sea must have taken place in the
southern hemisphere. Few geographical changes of any magnitude
have occurred since these events, and the triangular outline of South
India acquired then has not been altered to any material extent.
Distribution of the Tertiary systems in India—Tertiary rocks, from
the Eocene upwards td the Pliocene, cover very large areas of India,
but in a most unequal proportion in the Peninsula and the extraPeninsula. In the Peninsula a few insignificant outcrops of small
lateral as well as vertical extent are exposed in the near vicinity of
the west coast of Travancore, Gujarat and Kathiawar. A somewhat
larger area is covered on the east coast of these rocks, where a belt of
marine coastal deposits of variable horizon, from Eocene to Miocene
and Pliocene, is developed, and recognised as the Cuddalore sandstone.
A third and more connected sequence of Tertiary deposits is in Cutch,
where a band, of these rocks overlies the south border of the Deccan
Trap.
Tertiary systems of the extra-Peninsula—The Tertiary rocks of the
extra-Peninsula are much more impprtant, and occupy an enormous
superficial extent of the country. They are most prominently displayed in a belt running along the foot of the mountainous country on
^ In the Potwar geosyncline 5000 feet of Up. Siwalik boulder-conglomerates (Lower
Pleistocene) have been tilted up to a vertical position for many miles. In the upper
valley of the Sutlej in Ngari Khorsum, Pleistocene ossiferous aUuviltoi rests unconformably on tilted Pliocene strata. The Upper Karewa deposits of Kashmir show
considerable amount of tilting.
W.Q.I.
P
226
GEOLOGY OF INDIA
the western, northern, and eastern borders of the country. The Tertiary rocks are essentially connected with these mountain-ranges,
and enter largely into their architecture. The geological map of
India depicts an unbroken band of Tertiary development running
from the southernmost limit of Sind and Baluchistan, along the whole
of the west frontier of India, through the trans-Indus ranges, to the
north-west Himalayas, where it attains its greatest width ; from there
the Tertiary band continues eastward, though with a diminished
breadth of outcrop, flanking the foof of the Punjab, Kumaon, Nepal
and Assam Himalayas, up to their termination at the gorge of the
Brahmaputra. Thence the outcrop continues southward with an
acute bend of the strike. It is here that the Tertiary system attains its
greatest and widest superficial extent, expanding over eastern Assam,
Upp^r and Lower Burma to the extreme south of Bjirma.
Dual facies of Tertiary deposits—In all these areas the Tertiary
system exhibits a double facies of deposits—a lower marine facies and
in upper fresh-water or subaerial. The exact horizon where the change
from marine conditions to fresh-water takes place cannot be located
with certainty at all parts, but from Sind to Burma, everywhere the
Eocene is marine and the^Pliocene fluviatile or even subaerial. The
seas in which the early Tertiary strata were laid down were gradually
driven back by an uprise of their bottom, and retreated southward
from-the two extremities of the extra-Peninsula, one towards the Bay
of Bengal and the other towards Sind and the Rann of Cutch, giving
place, in their slow regression, to gulf, estuarine and then to fluviatile
conditions.
The back-bone of Tertiary India—its main water-shed—was the
Vindhyan mountains and the Kaimur ridge, continued north-easl by
the Hazaribagh-Rajmahal hills and the Assam ranges. This divide
separated the northerly drainage, flowing into the remnant of the
Tethys (left after the first, mid-Eocene uplift of the Himalayas) from
the southward flowing drainage into the Indian Ocean. There were
then two principal gulfs, the Sind gulf extending through Cutch,
Western Rajputana, Punjab, Simla and Nepal; and the Eastern gulf,
subdivided into two by the ridge of the Arakan Yoma into the Assam
gulf and the Burma gulf. The Gangetic plains then were a featureless
expanse of rocky country sloping northwards from the central highlands towards the narrow eastward extension of the Sind gulf.
The whole Tertiary history of India is exhaustively recorded in the
deposits filling up these two gulfs. As the seas dwindled and receded,
they were replaced by the broad estuaries of the rivers succeeding
THE TERTIARY SYSTEMS
227
them, e.g. the Indus in Sind, the Ganges-Brahmaputra system in the
case of the Assam gulf (p. 40), and the Irrawaddy in Burma ; their
earHer marine deposits were steadily replaced as the heads of the gulfs
were pushed outwards by the growing estuarine and deltaic sediments
of the rivers superseding them.
In the present chapter we shall take a brief general review of the
Tertiary sequence in India as a whole, leaving the more detailed
notice of these systems to the three'following chapters.
i
TERTIARY SYSTEMS OF PENINSULAR INDIA
In the Peninsula the following occurrences of the Tertiary strata
are observed:
Gujarat
Tertiaries of Surat and Broach—Two small exposures of Eocene
rocks, also underlying the laterite cap, are seen as inHers in the alluvial
country between Surat and Broach. ^ The component rocks are thick
beds of ferruginous clay, with gravel beds, sandstones, and limestones,
from 500 to 1000 feet in thickness, resting with a distinct unconformity on the underlying traps. These beds are well exposed at
Bodhan, near Surat,- on the Tapti. The gravels are wholly composed •
of rolled basalt-pebbles and some agates derived from the disintegration of the traps. Limestone strata are found in the lower part of the
exposure, and are full of foraminifers belonging to several species of
the genus Nummulites, and Ostrea, Rostellaria, Natica, etc., from the
evidenae of which the Gujarat Tertiaries are correlated to the Kirthar
series of Sind. Above these beds comes a great thickness, 4000-5000
feet, of gravel beds and clayey and ferruginous sandstones well exposed at Eatanpur, near Broach. The gravel and shingle beds con-,
tain many waterworn pebbles of chalcedony. The latter pebbles are
. extracted, by means of pits dug into the conglomerate, for working
them for agates. The age of the upper group is estimated as equivalent to the Gaj series of Sind.
Extensive areas of northern Gujarat are covered under a rich postTertiary alluvium or black soil. It is probable that the alluvial
country from Surat to Ahmedabad is mainly of estuarine and partly
of marine origin, filling up a broad arm of the sea which connected the
Gulf of Cambay with the Eann of Cutch—an inland sea in early
IW. T. Blanford, Mem. 6.S.I. vol. vi. pt. 3, 1869.
228
GEOLOGY OF INDIA
Pleistocene times (p. 292). Between Kathiawar peninsula and
Alimedabad there is a long depressed tract containing a large shallow
brackish water lake {Nal), which confirms the probability of this tract
being an old marine inlet.
Kathiawar
Perim island Tertiary—At the extreme east and west points of the
Kathiawar Peninsula, Tertiary strata, ranging from Oligocene to
Pliocene age are found overlying the traps. The western outcrop is
known as the Dwarka beds, and consists of soft gypsiferous clays overlain by sandy hmestone containing many foraminifera. The other
occurrence is near Bhavnagar, a detached outlier of which crops out in
the Gulf of Cambay as the island of Perim. The Perim island was a
famous locality for the collection of Tertiary mammalian fossils, and
has yielded in past years many perfect fossil specimens of several
varieties of extinct quadrupeds. The rock is a hard ossiferous conglomerate, enclosing many skulls, limb-bones, jaws, teeth, etc., of mammals like goats (Gapra), pigs (Sus), Binotherium, Rhinoceros, Mastodon, etc., of Middle and even Upper Tertiary affinities (Miocene to
Pliocene). Many of these relics were found among the beach-shingles
produced by wave-action on the conglomerate coastg_.
NummuUtic and later strata of Eocene-Miocene age (Nummulitic
to Gaj horizon) probably exist on both sides of the Gulf of Cambay,
buried under post-Tertiary alluvia; this fact is presumed from the
existence of sporadic reservoirs of natural hydrocarbon gas underground in parts round Baroda and the East Coast of Kathiawar.^
The fact that the chief petroUferous horizons of the Punjab, Assam
and Burma are restricted to rocks of this system (Eo-Miocene), lends
colour to the supposition that the Gulf of Cambay was a subsidiary
branch of the Sind gulf and locally afforded conditions suitable for the
deposition of small quantities of oil-forming, material.
[With the exception of*the rather large Jurassic inUer around Dhrangadhra, a few small Cretaceous outcrops near Wadhwan, and the Tertiary
development described above, by far the largest surface-extent of the
Kathiawar peninsula is occupied by the basaltic traps. It is only in the
peripheral parts of the province, in the immediate vicinity of the coast, that
rocks of different composition are met with, composed of marine coastal
accumulations of later ages. Of these the deposits known as the Porbander
sandstones (Miliolite) are the most important, and will be described later.]
1 P. K. Ghosh, Rec. G.S.I.^ol
Ixix'. pt. 4, 1936.
THE TERTIARY SYSTEMS
229
dutch
Tertiaries of Cutch—The Tertiary area of Cutch is on a larger scale
than those last described. I t is seen bordering the Trap and the
Jurassic area of Cutch proper, in two long bands parallel with the
coast. The older, inner, band abuts upon the traps directly, while the
outer," newer, band runs parallel with the latter, but approaches the
traps by overlapping successively the different members of the older
Tertiaries. To the east it encroaches still further north, and comes to
rest unconformably on the Jurassic beds by overlapping the traps in
turn.^
The bottom beds are argillaceous, with bituminous gypseous and
pyritous shales, which by their constitution recall the Laki series of
the much more perfectly studied Tertiary sequence of Siiid. This is
succeeded by about 700 feet of impure, sandy limestones with Nummulites, Alveolina, corals, echinoderms, etc., representing the massive
Nummulitic limestone of the Kirthar horizon. Above this comes a
thick succession of clays, marls, and calcareous shales, crowded, with
fossils of gastropods, corals and echinoderms, e.g. Turritella, Venus, •
Corbula, Breynia, etc. This part of the sequence corresponds to the
Gaj (Miocene) horizon of Sind. It is succeeded by a large development of Upper Tertiary strata representing the Manchar series of Sind
and the Siwalik of the Himalayas. The greater part of the latter
formation, however, is concealed under recent alluvium, blown sand,
etc.
The accompanying table gives a general idea of the Tertiary system
of Cutch, correlated with the European Tertiary :
Eecent alluvium : blown sand, etc.
Ferruginous conglomerates, sandstones and\ -„„ ,,
clays (Manchar of Sind).
I
Richly fossiliferous'shales, clays, and marlsl-it,^^ t,
with sandstone beds {Gaj series).
I
Impure Nummulitic hmestone (Kirtkar) „ ^ ,,
series).
j
Bituminous and pyritous shales, etc. (Laki\ nr^ ri.
series).
J
Pleistocene and
Recent.
Pliocene.
Lower Miocene.
Upper and Middle
Eocene.
Middle Eocene.
Basalts of the Deccan Trap.
1 Wynne's Map of Cutch, Mem. O.S.I. vol. ix. pt. 1, 1872 ; also Geological Map of
India (1925), scale 1 in..= 32 milea.
230
GEOLOGY OF INDIA
Rajputana
Rocks of the Tertiary system occur in connection witTi the Jurassic
and Cretaceous inliers of Bikaner and Jaisalmer in t t e desert tract of
Rajputana, west of the Aravallis. The characteristic Nummulitic
limestone is readily recognised in them by means of its foraminifera
and other fossils. The nummuhtic strata are underlain by a group of
shaly beds, the shales enclosing some seams of bituminous coal and
lignite. These reveal the Laki facies of Sind Tertiary. Some beds of
yellow and brown earthy shale belonging to this series are quarried for
the use of the material as fuller's earth. The Palana coal-field of the
Bikaner State is situated ou an outcrop of this same series.
The Coromandel Coast
Cuddalore series—A fairly widely developed series of Tertiary
fossiliferous rocks is found along the east coast, underlying the postTertiary or Quaternary formations and overlying the various Mesozoic coastal deposits. These formations are grouped under the general
title of the Cuddalore series, from a town of that name. Outcrops of
the Cuddalore series commence as far north as Orissa and Midnapur,
yfrom whence they extend in a number of more or less disconnected
inhers through the whole length of the coast to the extremity
of the Peninsula. A closely related formation is also met with on
the west coast, extending as far north as Ratnagiri. Throughout
this extent the deposits are of irregular distribution and of variable
composition. A variously coloured and mottled, loose-textured sandstone is the principal component of the series. I t is often ferruginous,
argillaceous and gritty. I t rests everywhere unconformably on the
older deposits of various ages, in one instance ovejlying the Ariyaliir
stage of the Trichinopoly Cretaceous. At, some places it is covered by
a laterite cap, at others by later alluvium. Some patches of the Cuddalore sandstones abound in fossils, principally gastropods, e.g. Terehra,
Conus, Cancellaria, Oliva, Mitra, Fusus, Buccinum, Nassa, Murex,
Triton, etc. Ostrea and Foraminifera of several species are also
present. A great part of the Cuddalore sandstones is believed to be of
Pliocene age, but some parts of it may be of older horizons.
A somewhat similar series of beds composed of sands, clays and
hgnite, capped by laterite, occurs on the Travancore coast, and is
designated as the WarJcalU beds. The Warkalli beds are in part
regarded as of fresh-water origin^ "*
T H E TERTIARY SYSTEMS
231
Travancore
A small outcrop of Middle Tertiary limestone • is found in the
vicinity of Quilon beneath the superficial cover of laterite [Quilon
beds). A few bright-coloured sands and clays, enclosing bands of
lignite -with lumps of fossil resin (amber), and pyritous clays occur
with the limestones. The limestone strata are full of fossil molluscs,
coral and foraminifers. The most abundant are gastropods, e.g.
Conus, Strombus, Valuta, Cerithium, Natica, Rimella, Murex, Terebra,
Turritella, etc. A species of foraminifer, Orbitolites, is also present in
the limestone. The fauna of the Quilon beds indicates approximately
Upper Gaj horizon (Mid. Miocene); it shows close aiEnities with the
fossils of the Warkali and Karikal beds.
A very similarly constituted outcrop of Tertiary rocks is seen at
Ratnagiri, on the Malabar coast, underneath the laterite.
TERTIARY SYSTEMS OF EXTRA-PENINSULAR INDIA
The Tertiary development of the extra-Peninsula is far more extensive, in which all the stages of the European Cainozoio from
Eocene to Pliocene are developed on a scale of great magnitude. I t
has again been more closely studied, and its stratigraphy as well as
palaeontology form the subject of several voluminous memoirs pubKshed by the Geological Survey of India. The palaeontological evidence available enables us to make a correlation of the different exposures with one another in the immense region which they cover, and
also to determine approximately the correspondence of the Indian
divisions with the stages of the standard Tertiary scale.
Until very much'more workTias been done on the Tertiary palaeontology of India it is hardly possible to put forward a completely
satisfactory classification and no scheme has yet been devised to
which all Indian palaeontologists agree. The classifications here
adopted are from the writings of Vredenburg, Pilgrim, and other
recent authors as "best suited to the purposes of the student.
Thq following are the principal localities where the system is well
developed : Sind, the Salt-Range and Potwar, the outer Himalayas,
Assam, and Burma.
Sind
The great series of Tertiary deposits of Sind are typically exposed
in the hill-ranges, Kirthar, Laki, Bugti, Sulaiman, etc., which separate
Sind from Baluchistan. The Tertiary sequence of Sind is, by reason
GEOLOGY OF INDIA
232
of its exceptional development, taken as a t y p e for the rest of India,
for systematic purposes. The following table gives an idea of the chief
elements of the sequence :
Lower and upper beds, grey sandstones with conglomerates ; middle part, brown and orange shales
Maacliar Series
and clays, unfossiliferous.
(10,000 ft.)
Lower Manchar conglomerates containing teeth of Mastodon, Dinoiherium, Rhinoceros.
Marine yellow limestones and
Gaj Series
shales, fossiliferous.
(1500 ft.)
Bugti beds of Baluchistan, freshwater, with mammalian fossils.
Upper Nari, thick sandstones, unfossiliferous and partly of fluviaNari Series
•i tile origin.
(6000 ft.)
Lower Nari, fossiliferous, marine
limestone,
Kirthar Series r Massive nummulitio limestones
(3000-9000 -! forming all the higher ranges in
[ Sind, richly fossihferous. .
ft.)
f Argillaceous and calcareous shales
Laki Series
-; with coal-measures. Alveolina
(500-800 ft.) [ limestones. Thickness varying.
Upper, fossiliferous brown Ume-
(
Ranikot Series
(2000 ft.)
Lower Pleistocene.
or
Upper Phocene.
to
Middle Miocene.
Lower Miocene.
Oligooene.
Upper and
Middle Eocene.
Middle Eocene.
Lower Eocene.
stone and shales.
Lower, variegated shales and sandstones, gypseous and carbonaceous, fluviatile.
Cardita beaumonti beds.
Danian,
Salt-Range and Potwar
The noftil-western p a r t of the Punjab contains, in t h e Salt-Eange
and the plateau country to the north, a very i m p o r t a n t development
of Tertiary rocks, and one which has received much attention. The
uppermost scarp of t h e Salt-Eange is a prominent cliff of limestone
which has often been termed the nummulitic hmestone. This has developed along the whole length of the range from the eastern spurs
near J h e l u m almost to the Indus near Kalabagh. Although a t the
eastern end of t h e Salt-Range the limestone lies wholly within the
Laki stage, towards the western end of the range a lower limestone of
Ranikot age develops and reaches a considerable thickness. Above
^
THE TERTIARY SYSTEMS
233
the Laki series there is a pronounced unconformity, the whole of the
Oligocene being absent. The limestones and associated marls are
overlain b y Upper Tertiary rocks, the unconformity being clearly
visible in sections at the head of the Nilawahan. I n t h e eastern p a r t
of the range the lowest beds above the unconformity belong to the
Murree series, b u t further west t h e overlying Kamlial stage rests upon
t h e Eocene. Above the Kamlials, there is developed a complete
sequence of the Siwalik s y s t e m ; this is seen not only in t h e SaltRange itself, but also in the large plateau to the north known as the
Potwar. This comprehensive development of t h e Siwalik system
constitutes t h e type area for India. The abundance and wide distribution of its mammalian fauna have enabled a very careful and
detailed zoning to be established b y Dr. Pilgrim and this affords a
basis for t h e correlation of the SiwaHk deposits of the various different
areas in India.
The succession in t h e Salt-Range is as follows :
Boulder conglomerate zone: con- Lower Pleistocene
to
Upper Siwalik
glomerates, sands and clays.
Pliocene
(6000 ft.)
Pinjor zone : pebbly sandstones.
Tatrot zone : sandstones and conglomerates.
Dhoh PatJian zone : light grey and Upper to
Middle Miocene.
white sandstones and pale-colMiddle Siwalik
oured shales, containing a rich
' (6000 ft.)
Pontian (Pikermi) fauna.
Nagri zone: grey sandstones and
red and pale-coloured shales.
Chinji stage : bright red nodular Middle Miocene.
shales and clays with grey soft
Lower Siwalik
sandstones and pseudo-conglomerates.
(5000 ft.)
Kamlial stage : hard dark-coloured
sandstones, red shales, and
pseudo-conglomerates.
Murree Series r Light-coloured and purple sand- Lower Miocene.
pseudo-conglomerates,
(up to 2000 -{ stones,
ft.)
[ red and purple shales.
Unconfornuty
Laki Series
(400 ft.)
Bhadrar beds: marls and hmestones, Sakesar limestone ; massive limestone' forming the summit of the Salt-Range scarp.
Nammal limestone-shale : bedded
hmestone, marls, and thin shales.
Middle Eocene.
234
GEOLOGY OF INDIA
Patala stage : shale with thin lime- Lower Eocene.
stones and impersistent sandstone ; coal seam at the base.
Eanikot Series Khairabad limestone : brown niim(50-1000 ft.) ] mulitiolimestone of very variable
thickness with calcareous shale.
Dhak Pass beds : Shale with pisolitic ferruginous beds at the base.^
The succession in the Potwar differs somewhat; the gap between
the Eocene and the Miocene is reduced both by the development of
the lower beds of the Kirthar series and by a great increase in the
thickness of the Murree rocks. The succession here merges into that
of the Kashmir Himalayas and is given in the table in p. 235.
Himalayas
Tertiary rocks enter preponderatingly into the composition of the
outer, lower, ranges of the Himalayas, i.e. the ranges lying outside
(south of) the central zone of crystalline and metamorphosed sedimentary rocks. In fact, ,the whole of the outer stratigraphic zone,
which is known as the sub-Himalayan zone,^ is almost exclusively
constituted of Lower and Upper Tertiary rocks. With the exceptions
noted below, Tertiary rocks are absent from the ranges to,the north of
the sub-Himalayas. In the Punjab and Simla Himalayas, where these
rocks have been studied, they are disposed in two broad belts, an
outer belt and an inner, formed respectively of the Upper Tertiary
and the Lower Tertiary. These strata in all likelihood continue eastwards with much the same disposition, but greatly reduced in width
of outcrop along the Kumaon, Sikkim and still more eastern Himalayas, forming the outermost foothills of the mountains, separating
them from the plains of the United Provinces, Bangal, and northern
Assam.
»L. M. Davies and E, S. Pinfold: Eocene Beds of the Punjab Salt Range,
Pal. Ind. N.S. xxiv. mem. 1, 1937.
• Chapter I.—The Geological Classification of Himalayas, pp. 9, 10.
T H E TERTIARY SYSTEMS
235
The succession is given in t h e following table :
Punjab and Kashmir HimKumaon and Simla Himalayas and northern part
alayas.
of the Potwar.
Upper Siwalik: Boulder-T
conglomerates,
clays,
sands and grit, 6000 ft.
Middle Siwalik : Massive
grey sandstone with pale
or drab shales, 6000 ft.
Lower Siwalik :
Chinji : bright red nodular shales with fewer grey
sandstones, 3000 ft.
Kamlial:
hard brown
sandstones and purple
shales, 2000 ft.
Upper Murree : Soft, pale"
sandstones,
coarse
grained, with
purple
splintery and nodular
shales, 3000 ft.
Lower Murree : Indurated
dark-coloured
sandstones, deep red and
purple-coloured splintery
• shales, 5000 ft. ; at the
base the Fatehjang zone
of ossiferous sandstones
and conglomerates (Gaj)..
Unconformity
Chharat: Nummulite shale,"
variegated shales, gypseous marls and thinbedded limestone, 500900 ft. (Laki to Kirthar).
Hill Limestone: Massive
well-bedded nummuHtic
limestone, some shale and
thin coal 200-1600 ft.
(Eanikot to Laki).
Upper Siwalik : Soft earths, Pleistocene
clays and boulder-conto Lower
glomerates, 6000-10,000
Pliocene.
ft.
Middle Siwalik : Massive Upper to
sand-rock, clays
and
Middle
shales, fossihf erous at the
Miocene.
base, 4000 (?)ft.
Lower Siwalik : {Nahan) : Middle
Grey micaceous sandMiocene.
stones and red shales,
generally unfossiliferous,
3000-4000 ft.
Easauli: Lacustrine, coarse, Lower
Miocene.
soft, grey or green-coloured sandstones.
Dagshai:
Brackish-water Lower
or lagoon, bright red and
Miocene.
purple nodular clays overlain by fine sandstones.
Subathu: Grey and red Middle to
Lower
gypseous shales with subEocene.
ordinate lenticular num.mulitic limestone with
pisohtic limonite (laterite 1) at base.
At this place m u s t be mentioned t h e rather exceptional circumstance of t h e occurrence of Lower Tertiary strata in localities north of
the central crystalline axis of the Himalayas. Two or three such have
been observed, e.g. North Kashmir (Ladakh), and t h e H u n d e s province of Kumaon. Of these the L a d a k h exposure is best known. I n
236
GEOLOGY OF .INDIA
the upper Indus valley in Ladakh, to the. north of the Zanskar range,
there is a narrow elongated outlier copiposed of marine sedimentary
strata, with nummulites and other fossils associated with peridotite
intrusions and contemporaneously erupted lava-flows, ash-beds-and
agglomerates. The sedimentary part of this outlier resembles in some
measure the Subathus of the outer Himalayas. This outcrop will be
described somewhat more fully in Chapter XXVII. No marine strata
of younger age than these have been discovered in any part of the
Northern Himalayas.
Assam
In Assam the Tertiary deposits reach a very great thickness, probably exceeding that of any other part of India ; where fully developed
the sediments are more than 50,000 feet thick. Despite this, there are
several gaps in the succession, the most important one being the
absence of a large part of the Oligocene. Owing to the extreme
paucity of fossils in the greater part of Assam, it is impossible to give
very accurate correlations with other areas or with the standard time
scale, but the following table summarises the results of the-most
recent investigations ^ and indicates an approximate correlation with
the Tertiary of North-west India :
Recent and Alluvium of the Brahmaputra and Surma
Pleistocene. valleys, high-level alluvium, river-terraces,
gravels, etc.
Dihing Series, (Upper Siwalik). Thick pebble-beds with Pliocene.
clays and sands.
5000 ft.
Unconformity.
Tipam Series, {Lower and Middle SiwaliJc). Thick, coarse, Upper or
femiginous sandstones, mottled sandy Middle
12,000 ft.
clays, fossil wood and lignite.
Miocene.
Surma Series (Murree). Sandy shales and sandstones, con- Lower
glomerates.
Miocene.
13,000 ft.
Unconformity.
Barail Series, (Upper KirtJiar and Nari). Sandstones, Lower
Oligocene
shales, and carbonaceous shales.
15,000 ft.
to Upper
Eocene.
Jaintia Series, (Lower and Middle Kirihar). Alternating
sandstones and shales with coaly beds, in3000 ft.
cluding the Sylhet hmestone—the Num- Middle
mulitic limestone of Assam ; equivalent to Eocene.
part of the Disang Series.
Unconformity.
Cretaceous and Older rocks.
' P. Evans, Tertiary Succession in Assanij. JVaJw. Qeol. Min. Inst. Ind. vol. xxvii., 1932.
THE TERTIARY SYSTEMS
237
The above classification refers to the north-western part of Assam.
In the eastern portion of the province, the succession below the Oligocene-Miocene unconforrriity is :
Barail Series, {Upper Kifthar and Nari), Sandstones, Lower
15,000 ft.
shales, clays, with thick coal seams in OHgocene
Upper Assam.
to Upper
c
'
Eocene.
Disang Series, {Ranikot to Kirthar). Thick series of grey Middle to
(very thick), splintery shales with iine sandstones, partly Lower
equivalent to the Jaintia series.
Eocene.
Base not seen.
Burma
The Tertiary system of Burma is composed of rocks which differ
considerably in lithological characters from the standard sections of
North-west India, but as fossils are abundant, an approximate correlation is not difficult, although much remains to be done in the investigation of the detail^. As might be expected, the Burma succession
shows more resemblance to the succession in the neighbouring province of Assam. The Eocene beds reach a great thickness and although fbraminifera are found in some beds there are no thick developments of nummulitid limestone such as those seen in Siqd, Baluchistan,
and the Punjab. The middle part of the succession, composed of
Oligocene and Lower Miocene strata, is distinguished as the Pegu
system and is approximately correlated with the Nari and Gaj series.
I t has recently been established that a break occurs in the middle of
the system, approximately at the boundary between the Oligocene
and Miocene, so that the Pegu system really consists of two separate
units. The uppermost beds (known as the Inawaddy system) form a
great thickness of fluviatile strata corresponding both in lithological
aspects as well as in its organic characters to the upper parts of the
Manchars of Sind and of the Siwaliks of the Punjab and sub-Himalayas. In central Burma they lie with marked unconformity on the
Pegus.
The Tertiary history of Burma is largely the history of the filling up
of a north and south geosynclinal basin, 600 miles long and 150 miles
wide—the basin of the old gulf of Pegu lying between the Arakan
Yoma and the Shan Plateau—which was filled up by the deltaic deposits of the- Irrawaddy gradually pushing southward into the gulf
and ultimately replacing it by the present valley of the Irrawaddy.
Hence a marine facies of deposits preponderates towards the south
and characterises all the stages till as late as Upper Pliocene, while
GEOLOGY OF INDIA
238
in tlie north the same stages show a terrestrial facies of deposits, it
being a common feature of m a n y of th^e stages t h a t when traced'latcrally from north to south they show a variation from fluviatile to
estuarine and brackish-water, passing thence into marine further
south, in which direction the gulf-conditions persisted till the beginning of the Pliocene.
• The following table is based on the work of Cotter and Vredenburg
combined with t h a t of the B u r m a h Oil Company geologists as described b y G. W. Lepper.
Irrawaddy
System,
5000 ft.
Plateau gravels and red earth.
fFresh-water sandstones with abundant
< fossil wood, mammahan fossils.
[
Pleistocene.
Phocene
to Upper
Miocene.
Unconformity.
'„
H
p
["Sandstones, clays, and shales, with many
10,000 ft. I
^°^^^^^-
Lower
Miocene.
Unconformity.
O
M
P-i
w
H
to
><
ca
m
o
o
Lower Pegu, fMainly sandstones above, shales in the
5000< middle, and shallow-water sandstones
10,000 ft. L with coal-seams at the base; fossihferous,
Yaw Stage, fShaly clays, marine, with Nummulites.
2000 ft. •
'Marine sandstones and clays passing up
Pondaung
into fluviatile sandstones and deeply
Stage,
coloured clays containing the earliest
6500 ft.
mammalian fauna : Anthracotheroids,
Ehinoceratoids and Titanotheres.
Tabyin Clay, fGreen shales with thin coal-seams.
5000 ft.
Tilin Sand-'
r Marine sands and sandstones with Numstone,
4000 ft. < mulites.
Laungshe
r Shales containing Orbitoides and GastroSiiales,
\
poda.
10,000 ft. L
Paunggyi
fBasal unconformity; conglomerates conconglo- J taining Orthophragmina.
merate,
3000 ft.
1
Oligocene.
Upper
Eocene.
Middle
Eocene.
Lower
Eocene.
The Tertiary basin of B u r m a is separated from the Palaeozoic a n d
Mesozoic highlands of t h e Shan Plateau t o the east by a great n o r t h
THE TERTIARY SYSTEMS
239
and south boundary fault. On the west, the Pegu and Eocene rocks
outcrop in the form of a large monoclinal fold running north and
south through the foothills of the Arakan Yomas. This range is still
largely a terra incognita to geologists, and thus it is impossible to say
what was the na-tiire of the western limit of the Burma Tertiaries.
From the above resume of the stages of Tertiary history of North
India, it must have been gathered that the Tertiary records of India
are far better than the Primary and Secondary ones. It was entirely
within these ages that the geomorphic evolution of India, as a separate
entity, was initiated and completed, for, as we have seen in the preceding pages, in the Mesozoic age even the skeletal outhnes of this
area could not be discerned. AH the earth-features north of the
Vindhyas came to be stamped upon it during the latter half of the'
Tertiary. Its physical isolation from the Asiatic continent was brought
about by the emergence of the great mountain-barriers of the West,
North, and East. Concomitantly with these was produced the extraordinary trough or sunken-valley region of India—a depression 1900
miles long and 200 miles broad in its narrower parts, separating
Northern from Peninsular India—^two distinct crust-segments. The
geological history of this vast sunien tract, now filled up by the riverdeposits of the Indo-Ganges systems, does not commence till the very
end of the Tertiary. Thus out of the three great geomorphic divisions
' of the Indian region two owe their evolution to processes operating
during or subsequent to the Tertiary era of the earth's history.
REFERENCES
H. B. Medlicott, Geological Structure and Relations of the Himalayas, Mem.
G.8.I. vol.'iii. pt. 2, 1864.
G. E. Pilgrim, Tertiary Fresh Water Deposits of India, Bee. O.S.I, vol. xl. p t 3,
1910.
I E. W. Vredenburg, A Review of the Tertiary Sequence of Sind, Pal. Indicu, New
Series, vol. iii. pt. 1, 1909.
G. de P. Cotter, Geology of the Attock District, Mem. 0.8.1. vol. Iv. pt. 2, 1933.
L. D. Stamp, Outlines of Tertiary Geology of Burma, Oeolog. Mag., vol. lix., 1922,
pp. 481-501.
D. N. Wadia, Tertiaries of Jammu Hills and N.W. Punjab, Mem, 0.8.1. vol. li.
pt. 2, 1928.
H. L. Chhibber, Tertiary Igneous Activity in Burma .Geology of Burma, chapters
xxix.-xxxii. (Macmillan), 1934,
CHAPTER XVIII
THE EOCENE SYSTEM
THE Eocene system includes three divisions : the lowest, known as
the Ranikot series, directly overlies the Gardita beaumonti beds. Its
typical development is restricted to Sind, but the horizon has also
been recognised in many other parts of North-west India and in
Burma. The middle division, the LaJci series, is composed chiefly of
richly fossiliferous nummuhtic hmestones, green shales, variegated
shales and marls, while the upper, designated the Kirthar series, includes the bulk of the nummulitic Umestone of Sind and of some of
the extra-Peninsular hill-ranges. The names of the series are derived
from hill-ranges in Sind. After summarizing each of the three series
of the Eocene we shall describe the developments in the more important areas in which the rocks have been studied
Ranikot Series
This series is typically developed at Ranikot, on the Laki range,
and occupies a considerable tract in Sind. The distribution of this
series is somewhat more limited than tha,t of the other members of the
Tertiary, but fossiliferous Ranikot beds have been recognised in Sind,
Kohat, the Salt-Range, Hazara, Pir Panjal, and Burma and it is proba.ble that unfossiliferous representatives occur elsewhere, as for
example in Assam.
The series, which in Sind lies with apparent conformity on the
Gardita beaumonti beds, includes in most of the North-west India
exposures a lower division of sandstones, clays, and shales, and an
upper division of limestone and shales. The Ranikot series includes
the coal-measures of the N.W. Punjab.
Fossils of the Ranikot series—The leading fossils of the Ranikot
series are: (Echinoids) Conoclypeus, Cidaris, Salenia, Ghyphosoma,
Dictyopleurus, Paralampas, Hemiaster, Schizaster; (Corals) Trochosmilia, Stylina, Gyclolites, Montlivaltia, Feddenia, Isastraea, Astraea,
Thamnastraea, Litharaea; (Gastropods) Rostellaria, Nerita, Tere-240
THE EOCENE SYSTEM
241
bellum, Velates, Crommium; (Foraminifers) Lockhartia, Alveolina,
Nummulites (N. planulatus and N. granulosa). The species N. planulatus is characteristic of the Ranikot horizon.
Laki series
Although t)f no great vertical extent, this series is of wide geographical prevalence in India. I t includes a considerable thickness of
nummulitic limestones and in places these are associated with oilbearing beds. The series is well developed in Sind, Baluchistan,
Kohat, the Salt-Eange, the north-western part of the Punjab, Jammu,
Bikaner, Assam and Burma. The rocks show numerous local variations ; there is an essentially calcareous facies which is seen in the
Salt-Range, a gypseous shaly facies which is found in Baluchistan,
whilst in Assam and Burma there is a very thick development of
dark shales at this horizon. The salt and gypsum of Kohat and of at
least the north-western part of the Salt-Range belong to the Laki
series.
The important fossil organisms contained in the Laki strata are:
Nummulites atacicus, Nummulites (Assilina) granulosa, Alveolina
oblonga, some species of Nautilus, Echinolampas, Metalia, Blagraveia,
Corbula:, Gisortia, etc., with numerous leaf impressions, fruits, seeds,
etc., of plants belonging to the angiospermous division of the flowering
plants.
. Kirthar Series (Chharat Series in pari;)
Like the Ranikot and Laki, this series derives its name from a range
in western Sind.
The Kirthar nummulitic limestone forms a conspicuous group of
rocks in many parts of extra-Peninsular India, particularly Sind,
Baluchistan, Kohat and Hazara, and to a more limited extent in the
outer parts of the Himalaya, the central Assam range, and Burma.
The prominent nummulitic limestone scarps of the Salt-Range are
older, being of Laki age. In its type-area, Sind, it attains a great
thickness of massive homogeneous limestone, capping all the high
ranges of the Sind-Baluchistan frontier. There is no doubt that the
nummuUtic limestone of India is an eastern continuation of the same
formation of Europe, a direct connection being traceable between
these two regions through the nummulitic Hmestone formations of
Baluchistan, Iran, Asia Minor, North Africa, Turkey and Greece to
the west of Europe up to the Pyrenees. It thus forms a conspicuous
landmark in the stratigraphical record of the whole world.
242
GEOLOGY OF INDIA
Fossils of the Kirthar series—The fossils include many species of
Nummulites, of which N. laevigatus, N. perforalus, N. gizehensis,
Assilina spira, A. exponens, Alveolind, elliptica, Dictyoconoides sp.,
are the most common. Other foraminifers are Orbitoides, Orbitolites,
etc. Gastropods are present in large numbers, of which Conus,
Cypraea, Cerithium, Strombus and TuniteUa are very frequent. Portions of the corona and spines of echinoids of large size, such as
Cidaris, Cyphosoma, EcMnolampas, Micraster, Hemiaster, Sckizaster,
Conodypeus, are common. The-lamellibranchs are represented by the
genera Cytherea, Astarte, Cardita, Lucina, and Pholadomya.
Important Areas
The following are the principal locahties where Eocene rocks (Eanikot, Kirthar, and Laki series) are found : Sind, Baluchistan, the SaltBange, Kohat, the Potwar, Hazara, Kashmir, the outer Himalayas,
Assam, and Bnrma.
Sind and Baluchistan
Ranikot series. Laki series—The Sind exposures of the Eocene
provide the chief type for India. The Ranikot beds consist of soft
sandstones, clays and carbonaceous and lignitic shales, containing
pyrites in the lower part, succeeded by highly fossiliferous limestones
and calcareous shales. The lower beds, both in their mineral
composition as well as in the few dicotyledonous plants and fragmentary fossil bones that they contain, bear the impress of undoubted
fluviatile origin. The overlying limestone with intercalated shales is
about 700-800 feet in thickness, and abounds in fossil echinoidea, by
means of which the series has been classified into zones. The Laki
of Sind has been subdivided by W. F. Nuttall into-a basal laterite, ihe
Meting limestone, the Meting shales and the LaJci lim§stone. The two
limestones are lithologically similar but the lower bed is thinner and
more fossiliferous, and contains a slightly different fauna. In Baluchistan the Laki is represented by the Dunghan limestone, which
varies in thickness up to several hundred feet, and the overlying
Ghazij shales, about 1500 feet thick.
Kirthar series—The Laki series is overlain by the Kirthar beds, a
slight unconformity occurring in some sections, where the lowest bed
is often a dark conglomeratic hmestone. For the most part the lower
Kirthar rocks are thick, massive, white, rather sparsely fossiliferous
limestones with occasional shales. Higher in the sequence shales
THE EOCENE SYSTEM
243
form a much greater proportion of the beds, but in the highest beds
white limestones are again abundant.
The Salt-Range
Ranikot—The lowest Eocene bed in the Salt-Range is a ferruginous
pisolite, which passes laterally into a haematite clay and haematitic
sandstone. This is in many places overlain by a thin gypseous and
carbonaceous shale. These beds have received-the name Dhak Pass
beds. They are in turn followed by the Khairabad limestone, a brown
and grey nummulitic Hmestone which shows very great variations in
thickness. In the eastern part of the range the Ranikot series exhibits
a predominantly shaly facies—the Patala beds—which overlie the
attenuated Khairabad Hmestone and include thin coal seams. All
these beds belong to the Ranikot and not to the Laki as was previously
supposed. The coal is worked in a number of small mines in the face
of the Salt-Range, and the shales have provided a source of alum.
Laki—The lowest Laki beds of the Salt-Range tend to be somewhat
shaly and are known as the Nammal limestone-shales; above them
Siwalik Sandstone outtisr
Nummulitic limestone oliff
FiQ. 28.—SKtch and section to show the nummulitic (Laki) limestone
scarp in the Salt-Range. (Wynne, Mem. G.8.I. xiv.)
comes a more uniformly calcareous development, the Sakesarlimestone,
a hght-coloured, somewhat cherty limestone which covers a large area
of the Salt-Range. It has a well-defined series of joints and consequently a tendency to weather in cliffs having the aspects of
" mural escarpments ", presenting from a distance the gSneral appearance of ruined walls or fortifications.. Some of the finest cliffs of the
range are produced in this manner by the action of the weathering
agents. The mass of the rock is nearly pure calcium carbonate, made
up almost wholly of foraminiferal shells, mostly of Nummulites, which
on weathered surfaces of the rock stand out as little ornamented
discs, flat or edgewise-. In microscopic sections of this rock the
internal structure of the Nummulites, as well as other fossils, is clearly
revealed, where crystallisation has not destroyed the organic struc-
244
GEOLOGY OP INDIA
tures. There are a large number of other fossils |)resent as well, b u t
they are difficult to extract from the unweathered rock.' Large chert
or flint nodules are irregularly dispersed in'the limestone. The uppermost beds (Bhadrar Beds) are more argillaceous. They are found on
the plateau a t the top of the range b u t se:ldom enter into the southward-facing scarp.
No Kirthar beds are known in the main p a r t of the Salt-Range but
they m a y occur in the north-eastern spurs towards Jhelum.
I n the north-western portion of the Salt-Range a few miles southeast of Kalabagh, E . R. Gee has described a remarkable passage of the
Sakesar limestone into massive gypsum. I n the same neighbourhood,
the Bhadrar beds are also associated with gypsum and show considerable resemblances to the lower p a r t of the Chharat series of the
northern portion of the Potwar. This change from limestone into
gjnpsum is evidently a n alteration phenomenon. Slightly further
north-west of the point where this change takes place the gypsura is
intimately associated with red marl and salt and a little further northwest a t Mari-Indus and Kalabagh the salt is worked on a large scale.
Recent work b y Gee has demonstrated t h a t the Saline series of this
p a r t of the Salt-Range is clearly of Laki age, and not (as was previously thought) of Cambrian or pre-Cambrian age. This brings the
salt and gypsum into line with a similar group of beds found in the
K o h a t district and believed to be of Laki age.
[A brief reference has already been made to the Saline series of the central
part of the Salt-Range (Khewra, Waroha, etc.). The gypsum, s5lt, and red
marl underlie the Cambrian sequence but the junction is demonstrably an
irregular one and there has been much discussion aboutiBie relations between the Cambrian Purple sandstone and the underlying beds (p. 106). I t
is thought by some geologists that the disturbance is of small extent and is
merely an expression of the difference in competence of the beds above and
below. This explanation necessitates the assumption that there are two
separate Saline series in the same neighbourhood, one of Cambrian and one
of Eocene age. This seems an improbability especially in view of the very
close similarity of the supposed two sets of beds, and other geologists have
interpreted the disturbed junction between the Saline series and the overlying Cambrian rocks as a thrust-fault of major importance which has
brought the Cambrian strata on to the Eocene Saline series. So far no definite evidence has been forthcoming to show that the Saline series of, the
central portion of the Salt-Range is really of Eocene age but the Salt-Range
is known to include a series of important over-thrust faults and it does not
seem improbable that there is a thrust-plane running along the base of the
range. Further evidence of movement between the Saline series and the
overljring beds is provided by the sections near Musa Khel; here the red
marl and gypsum are overlain not by Cambrian beds but by the Talchir
THE EOCENE SYSTEM
245
boulder-bed and at many places along the junction the boulders have been
greatly sheared.
Near Khewra, the accumulation of gypsum and rock-salt is on a large
scale. At the Mayo Salt Mines, at Khewra, there is a mass of nearly pure
crystalline salt of a light pink colour, interbedded with some seams of impure red earthy salt (Kalar), of the total thickness of 300 feet. Above this
is another bed of the thickness of 250 feet. The upper deposit is not so pure
as the lower, for it contains more intercalations of Kalar and is associated
with other salts, viz. calcium sulphate, and magnesium, potassium, and
calcium chlorides in greater proportions. The lateral extension of the saltbeds appears to be very great, amounting to several square miles in area
and there is thus a very large supply of salt from the Khewra deposits. To
this must be added the salt contained in the red marl at other parts of the
range, and worked in several smaller mines. The associated gypsum occurs
in large masses and also in smaller beds ; it exhibits an irregular bedding
and varies greatly in purity and in degree of hydration, passing at times into
anhydrite.
The origin of the salt-marl is not known with certainty. Oldham suggested that it is an alteration product of pre-existing sediments by the
action of acid vapours and solutions. Christie has brought forward evidence to show that the salt and gypsum were formed by the evaporation of
sea-water in inland or enclosed basins which were intermittently cut off
from the main ocean by barriers. The red saline earth or Kalar-seams are
held to indicate the last stage of the desiccation of the sea-bed ; the occurrence of potassium-salts mentioned below, just underneath the Kalar, is
pointed to as further evidence in support of the evaporation theory ; for,
in a sea-basin undergoing desiccation, the salts of potassium are the last to
bfe precipitated, after nearly 98 per cent, of the water has evaporated. It is
argued that the stratification-planes which were originally present, both in
the enclosing marl and in the salt, have been obliterated subsequently by
superficial agencies as well as by the effects of compression and earthmovements on a soft plastic substance like the marl.
In 1920 Pascoe adduced evidence to prove that the apparent infraCambrian position of the salt-marl is not its normal stratigraphic position,
but that the salt and gypsum, both of which he believes to be of sedimentary
origin, are of Eocene age, their present position being brought about'by an
overthrust.
There is no doubt that although much of the Saline series outcrop is devoid of clear stratification, other parts show the clearest disposition of the
different components of the Saline series into distinct beds which are of
sedimentary origin. This is particularly shown by the dolomites and shales
associated with the red marl, and also by the bands of gypsum and salt.
This prominent stratification shows that hypotheses based on an " igneous "
or " intrusive " Origin are inapplicable, and that the Saline series is in the
main of sedimentary origin. Nevertheless, the discovery in Kohat and in
the north-west end of the Salt-Range shows that the gypsum is—at least in
part—an alteration product of limestones. The intimate association of
limestones and shales with the gypsum in the Salt-Range is closely paralleled in Kohat.
24G
GEOLOGY OF INDIA
Economics—Tte economic importance of the salt deposits is great, as
they produce about 150,000 tons of salt pet year. Besides the chloride of
sodium, there are found other salts* of use in agriculture and industries. Of
the latter the salts of Potassium (Sylvite, Kainite, Blodite and Langbeinite), which occur in seams underlying beds of red earthy salts (Kalar), are
the most important. Magnesium salts are Epsomite, Kieserite and
Glauberite.]
Kohat,
The Rock-salt deposits of Kohat—A short distance to the north-west
of the Salt-Range at Bahadur Khel and elsewhere in the hills of the
Kohat district, there are outcrops of Kirthar rocks which are remarkable for being underlain by a great thickness of gypsum and rock-salt..
At Bahadur Khel about a thousand feet of the:^ beds are laid bare in
a perfect anticlinal section; the beds of rock-salt, which are seen at
the centre of the anticline, are overlain by gypsum, the upper part of
which is interbedded with green clay and shale. These beds are in
turn succeeded by red clays and by Kirthar limestones containing
Nummulites, Alveolina and other fossils. In lateral extent the outcrop
of rock-salt is traceable for several miles. The salt is chemically pure
crystalline sodium chloride with some admixture of calcium sulphate,
but with no associated salts of potassium or magnesium as in the
Salt-Range deposits of the same mineral, from which also the Kohat
salt differs in its prevailing dark-gre^ colour^ and in being slightly
bituminous. I t appears quite probable that the two deposits, in spite
of these slight differences, have had a common origin, and are of the
same age, and that the apparent infra-Oambrian position of the
Salt-Range salt-deposits, as seen near Khewra, is due to overthrust
faulting.
In the extreme north-west of Kohat the Ranikot beds are strongly
developed in the Samana range and have been studied in considerable
detail by Col. L. M. Da vies. The basal Hangu beds are sandstones and
shales with an abundant moUuscan fauna ; these constitute the lowest
Eocene horizon found in India ; the higher beds are mainly limestones
{Lockhart limestones). A more normal facies of the Laki beds (as compared with the Bahadur Khel development) is exposed near Kohat
itself. The lowest beds are green clays and shales ; these are overlain
by the Shekhan limestone and this by a gypseous red clay. Above this
comes the Kirthar series with the Kohat shales, limestones and shales,
at the base followed by the Nummyjite shale and Alveolina limestone.
The Laki and Kirthar limestones and accompanying shales have been
THE EOCENE SYSTEM
247
traced eastwards and north-eastwards, through the Margala and Kala
Chitta hills and the Hazara mountains to Muzaffarabad qn the
Jhelum and thence into Kashmir.
Potwar
East of Kohat, in the Kala Chitta hills, in the northern part of the
Potwar the Eocene beds present a somewhat different facies. There
is a strong development of limestone^ which include both Ranikot
and Laki beds, and a thin coaly horizon presumably corresponding to
the coal of the Salt-Range. These limestones, which are not strikingly
fossiliferous, have been termed Hill Limestone. They are overlain by
gypseous limestones which are followed by variegated shales with a
few fresh-water fossils. This horizon, known as the Planorbis beds,
appears to be the top of the Laki Series, and is associated with
seepages of oil. The Kirthar series is represented only by the Kohat
shales and the Nummulite shales, the higher beds having been removed during the Oligocene denudation. The range of beds from the
Planorbis beds upwards is known as the Chharat series.
Hazara
Eocene rocks, principally composed of nummulitic limestone, play
a prominent part in the geology of Hazara and, indeed, of the whole
country around the N.W. frontier. At the base, the coal-bearing
Ranikot series is identified, though it does not possess any economic
resources, the quantity as well as the quality of coal being very inferior. The nummulitic limestone is a grey or dark-coloured massive
rock of great thickness interbedded with nummulitic shale beds and
is thus somewhat different fromrthe equivalent beds in the Salt-Range.
The limestone passes upwards into the Chharat series of shales and
limestones which are unconformably overlain by the Murree series of
fluviatile deposits.
The Eocene of Hazara extends eastwards beyond the Jhelum into
Kashmir, following the great bend of the mountains and, as mentioned in the next section, it joins up with the nummulitic border
fringing the south-western foot of the Pir Panjal.
Kashmir
The strong band of nummuHtic limestones and associated Kohat,
belonging to the, Ranikot and Laki series, which stretches from strata
through the Hazara mountains to Kashmir, persists as a. narrower
248
•
GEOLOGY OF INDIA
band across the Jhelum, where it turns abruptly round the great
syntapal re-entrant of the mountains and runs along the foot of the
Pir Panjal for more than 150 miles. The width varies greatly, the
band widening and narrowing between the two Panjal thrusts
(page 310) which bound it on either side. The Eocene is also associated with the large inliers of Permo-Carboniferous limestones (page
161) in the younger Tertiaries of the Jammu hills, and includes deposits of coal, and aluminium and iron ores. The largest of these inliers
are near Riasi and Poonch. Among these the Laki horizon is recognised by the presence of species of Assilina, Alveolina and Nummulites
in the nummulitic limestone. A ferruginous pisolite occurs at the
base of the Eocene and is workable as an ore of iron. Also associated
with the basal beds at both these localities there occurs an extensive
deposit of coal and bauxite and bauxite clays. The occurrence of
bauxite near the base of the Eocene, indicating a great regional unconformity with the underlying Palaeozoic limestone, is suggestive of
a lateritic origin.
Outer Himalayas
The extent and boundary of the Eocene gulf of North India, referred to on page 226, can be roughly judged by the extent and distribution of the outcrops of Nummulitic limestone preserved to-day—•
a more or less continuous belt extending from Sind and the Sulaiman
hills, where it attains maximum development, through Hazara,
Muzaffarabad and the Pir Panjal chain, to beyond Dalhousie and
Subathu; thence with decreasing width and some intermissions to
NainiTal. '
The Eocene of the Outer Himalayas of Simla is distinguished as the
the Subathu series, which is collateral with part of the Kirthar series,
together with its underlying Laki series. The Subathu series is typically
developed near Simla, from a military station near which the group
takes its name. The rocks are red and grey, gypsiferous and calcareous shales, with some interbedded sandstones and subordinate
limestones in which Nummulites, and other fossils, are found. This
development differs from the more usual Laki and Kirthar beds in the
small proportion of limestone. There is also a difference in colour and
texture, the Subathu limestone being grey to black in colour, very
compact and thinly bedded. The lower beds are very variable and
inconstant; there is a workable coal-seam in one locality, but this is
missing from the type area, the lower beds being instead ferruginous
sandstone and grits containing pisolitic haematite and limonite.
THE EOCENE SYSTEM
249
Assam
The Eocene rocks occupy a large area in Assam, and offer several
points of interest. The lowest beds exhibit two sharply contrasted
facies, one in the east of the province and the other in the west. In
the Naga hills (in the eastern area) the lowest Eocene beds are the
Disang shales—a great thickness of very well bedded dark-grey shales
with thin well-cemented sandstones. Towards the interior of the •
hills separating Assam from Burma, the shales become hardened and
slaty and are associated with quartz veins and serpentine. It is just
possible that in this area some of the beds referred to the Disang
series are of pre-Tertiary age^
In the north-west of Assam, there is developed a calcareous facies
of the Eocene ; this occupies a large area in the Shillong plateau (Garo
hills, Khasi and Jaintia hills). The lowest beds here have recently
been termed by C. S. Fox the Tura stage ; they include sandstones and
shales and thin seams of coal. This stage is now believed to include
the Cherra sandstone, a band of hard coarse sandstone, and the various
outcrops of thin coal occurring in and near the Garo hills; these were
previously thought to be of Cretaceous age. These beds rest with no
marked discordance on the Cretaceous but overlap on to the gneiss
and other metamorphic rocks. At the base is commonly found kaolin
and occasionally laterite. The Tura beds are followed by nummulitic
limestones {Sylhet limestone stage) which show considerable lateral
variation ; shales and even sandstones are locally developed. The
fauna is fairly rich and shows affinities with the Middle Kirthar of
North-western India. Above these hmestones are the Kopili alternations including shale, thin coal, thin limestone, and thin sandstone;
these beds also are fossiUferous. The range of beds including the Tura,
Sylhet limestone, and Kopili alternation stages is known as the
Jaintia series, corresponding in age to the upper part of the Disang
series.
Both the Jaintia series and Disang series are'overlain by the very
thick Barail series which is of considerable economic importance as it
contains thick seams of coal. This series includes thick hard sandstones which give rise to the Barail range which is the " backbone " of
Assam ; in addition there is a fairly large proportion of argillaceous
beds which increases shghtly in a north-eastern direction. The Barail
series has been sub-divided into stages on lithological grounds but as
fossils are extremely rare it has not been possible to correlate these
stages precisely with those in other areas. The Barail beds show an
250
GEOLOGY OF INDIA
important lateral variation ; when traced from south-west to northeast, the carbonaceous material very steadily increases in amount and
the carbonaceous shales pass into coaly sixales, shaly coals, and thence
into thin coals and so in Upper Assam into thick coals of good ^.uality.
In this area, the upper portion of the ^arail series forms the coalmeasure sub-series but although the coal seams are fairly numerous,
the thick workable seams are restricted to a small portion of the
sequence. A few fossils have 'been found near the coal horizon and
these suggest an uppermost Eocene age. It is therefore probable that
the Barail series is partly Upper Eocene and partly Lower OUgocene.
Oilshows are found in association with the Barail series in the Surma
valley and in Upper Assam. There is no separation of'' oil-measures ''
and "coal-measures" for, although most of the oilshows are
well, below the thickest of the coal seams, oilsands often occur in
between the thinner coal seams and petroliferous coal seams have
been recorded.
Burma
The Eocene rocks in Burma are developed-on a large scale, reaching
a thickness of well over 20,000 feet. They show a facies of deposits
very different from that of their equivalents in North-west India (Sind,
Baluchistan, North-West Frontier Province, the Salt-Range, Kashmir, etc.) but have considerable resemblances to the Eocene of Assam.
Cotter has divided them into six stages (vide Table on page 238). The
Tertiary sequence commences with a basal conglomerate, Paunggyi
conglomerate, of Ranikot age, resting over a somewhat obscure group
of rocks which form a large part of the Arakan Yoma from Cape
Negrais northwards. These are known as the Axial, Mai-i and Negrais
groups which probably include beds from Triasic to Cretaceous age.
The greater part of the Lower Eocene is made up of the thick Laungshe
shales which probably correspond to the Disang shales of Assam and
are mainly of Laki age.- A few thin seams of coal are met with in the
overlying Tabyin clays. The Upper Eocene beds are of great interest.
The Pondaung sandstones, about 5,000 feet thick, mark a temporary
retreat of the nummulitic sea which was thrown back by thick deltaic
accumulations, in which are preserved the earliest fossil mammals of
the Indian region. These belong to the Amynodonts, Metamynodonts
and Titanotheres, the ancestral forms, of rhinoceroses, and the highly
generalised extinct group of ungulates (the Anthracotheres)—Anthracotherium, Anthracohyus, and Anthracokeryx. Marine conditions were
THE EOCENE SYSTEM
251
soon resumed, however, before the Eocene period came to a close, and
in the Yaw stage there is a considerable development of marine beds
containing foraminifera.
REFERENCES
W. T. Blapford, Geology of W. Sind, Mem. O.S.I, vol. xvii. pt. 1, 1879.
P. M. Duncan and W. P. Sladen, Tertiary Pauna of Sind, Pal. Indica, sers. vii. and
xiv. vol. i. pts. 2, 3 and 4, 1882-1884.
E. W. Vredenburg, Tertiary System in Sind, Mem. G.8.I. vol. xxxiv. pt. 3, 1906.
E. S. Pinfold, Structure and Stratigraphy of N.W. Punjab, Rec. 0.8.1. vol. xUx.
pt. 3, 1918.
E. H. Pascoe, Petroleum Deposits of Punjab and N.W. Frontier Provinces, Mem.
0.8.1. vol. xl. pt. 3, 1921.
W. L. F. Nuttall, Stratigraphy of the Laki Series, Q.J.6.S. London, vol. Ixxxi.
pt. 3, 1925.
L. M. Davies, Ranikot Beds at Thai, Q.J.O.S. London, vol. Ixxxiii. pt. 2, 1927;
Fossil Fauna of the Samana Range, Pal. Indica, N.S. vol. xv., 1930.
L. M. Davies and E. S. Pinfold, Eocene Beds of the Punjab Salt-Range, Pal. Indica,
N.S. vol. xxiv. mem. 1, 1937.
P. Evans, Tertiary Succession in Assam, Tran^. Min. Oeol. Inst. Ind. vol. xxvii.,
1932.
E. R. Gee, Geology of the Salt-Range, Mem^ G.S.I. {under preparation).
CHAPTER XIX
THE OLIGOCENE AND LOWER MIOCENE SYSTEMS
OLIGOCENE
Restricted Occurrence—The Oligocene system is very poorly represented in India ,and it seems that dmring a part of this period a considerable amount of what is now the Tertiary outcrop was undergoing
denudation which resulted in the removal of such Ohgocene deposits
as had been formed, as well as some of the Eocene. The fullest developments of Oligocene rocks are in Sind and Burma. Rocks which
are probably of Oligocene age occur also in Assam. In the few areas
in which it is developed, the Oligocene appears to lie conformably
upon the Eocene, although,it is not impossible that there is a palaeontological break at this horizon. The Oligocene system is usually
separated from the overlying Miocene beds by an unconformity!or at
least a palaeontological break.
The Oligocene system appears to be absent from Kohat, the Punjab, Kashmir and the North-West Himalaya.
Baluchistan
Flysch—In Baluchistan there is a great thickness of shallow-water
sandstones and green'arenaceous shales, with only a subordinate limestone ; this closely resembles the Flysch of Switzerland and covers a
wide tract on the Mekran coast. This formation is designated the
Kojak shales. Fossils are rare but a few gastropods-have been found
indicating the Oligocene age of these beds.
Sind
Nari Series—The Oligocene beds in Sind are more interesting than
the almost unfossiliferous Baluchistan Oligocene. They are known as
the Nari series and overlie the Kirthar limestone-with apparent conformity.
'
252_
'
THE OLIGOCENE AND LOWER MIOCENE
253
The name is derived from the Nari river, along the banks of which
a section of the series is seen. The lower part of the Nari is composed
of limestone and calcareous rocks, but they give place to finely-bedded
sandstones and shales in the upper part. At the top the group consists of coarse deposits, massive sandstones and conglomerates. The
shaly partings among the sandstones contain plant impressions, and
are thought to'be of fluviatile deposition. Among the calcareous
bands of the upper part of the Nari, the foraminifers attain their"
highest development, manifested as much by the organisation of the
specific types as by the size attained by the individuals of the species.
Large shells or tests oi Nummulites of 2 to 3 inches in diameter are not
uncommon. The most frequent species are : N. intermedius, N. sublaevigatus, N. vascus, accompanied by Lepidocyclina, and some other
foraminifers. Other fossils are: Montlivaltia, Schizaster, Breynia,
Eupatagus, Clypeaster, Lucina, Venus, Area, Corbula, Ostrea (sp.
angulata) and Natica, Valuta, etc.
The Nari strata are overlain with apparent conformity by the Gaj
series which appears to be of Lower Miocene age.
Assam
Barail Series—It is probable that the uppermost part of the B.arail
series of Assam is of Oligocene age but the extreme rarity of fossils
makes it impossible to establish the age with certainty. The Barail
series is overlain with marked unconformity by Lower Miocene rocks.
Burma
Pegu Series—A very fossiliferous development of the Oligocene
occurs in Burma and reaches a thickness of as much as 10,000 feet.
These beds form the lower half of the Pegu system, the upper half of
the system being of Miocene, age and separated from the underlying
beds by an unconformity. The Lower Pegus have been subdivided
into three stages. The lowest, the Shwezetaw sandstones, locally contains a few thin seams of impure coal; when traced from south to
north the group shows a passage from marine beds into a continental
facies. The Shwezetaw sandstones are overlain by the Padaung clays
with a characteristic Middle Oligocene fauna.- Above the Padaung
clays, there is the Singu stage of Vredenburg including both sandstones and shales, but the Buimah Oil Company geologists have put
forward a different classification for all the beds above Padaung clays
and they have termed the highest OUgocene rocks the Okhmintaung
254
GEOLOGY OF INDIA
sandstones—a formation which shows great variation in thickness. •
The Okhmintaung sandstone is separated b y a marked" palaeontological break from the overlying Upper Pegu rocks.
Petroleum—The Oligocene beds of Burpaa are of importance as a
source of petroleum ; this valuable minerM is also found in the Miocene and there are oilshows i^ the u p p e r , p a r t of the Eocene. Tlie
Pegu system of B u r m a has yielded large quantities of petroleum and
its associated products. The oil of Yenangyaung has been known from
ancient times. I t was formerly obtained from wells dug by h a n d t o
considerable depths and was used as a preservative of wood-work, as a
medicine, for lubricating, a n d as an illuminant. The most important
oilfields are Yenangyaung, Singu, Lanywa, Yenangyat, a n d Minbu,
all of which are in a small area in central Burma. The oil is found a t
the summit of anticlines a n d is obtained b y drilling t o v e r y considerable depths. The production of petroleum in Burma is about 250
million gallons per year a n d the total amount produced to date
amounts to approximately 8,500 million gallons.
Petroleum—Petroleum is a liquid hydrocarbon of complex chemical composition, of varying colour and specific gravity (0-8-0-98). Crude petroleum
consists of a mixture of hydrocarbons—solid,^ liquid and gaseous. These
include compounds belonging to the paraffin series (C„H2n+2) ^'^'^ ^1^°
some unsaturated hydrocarbons and a small proportion belonging to the
benzene group. Petroleum accumulations are usually associated with some
gas (methane, ethane, etc.) called natural gas.
Origin of Petroleum—The origin of petroleum has been much debated;
at one time it was thought that it had an igneous origin and the action of
steam on metallic carbides was cited as an example of a possibly analogous
process. I t is now generally held that oil has an organic origin. This has
been established not only by careful consideration of the circumstances in
which oil is found throughout the world but also by the presence of optically active constituents in petroleum.
Mode of Occurence—Petroleum occurs in the pores and minute interstices of sands and in crevices inJimestones and is always closely associated
with sediments which are of shallow water, usually marine, origin. The oil
is derived from decomposition of the organic matter contained in the sediments but the method by which the transformation into petroleum takes
place is not yet completely known. I t is evident that there must be special
conditions in which there is incomplete oxidation of the;,carbon and hydrogen and it has been suggested that the action of bacteria is a factor in these
processes, especially in the elimination of the nitrogen of the animal tissues.
I t is possible that the change takes place in different stages.
1 The impure bituminous substance sold in the bazaars as a drug of many virtues
(Salajit) is a solid hydrocarbon found in the more exposed parts of the higher Himalayas
as a superficial deposit. This substance, however, has nothing in common with
petroleum, being of entirely different, and recent, organic o'rigin.
THE OLIGOCENE AND LOWER MIOCENE
255
At first the petroleum is disseminated throughout the geological formation in which it originated but the pressure of overlying beds forces it to
migrate into the most porous rocks and consequently it is generally found in
sand beds and sandstones intercalated amongst clays and shales, although
in some areas it occurs in the fissures and crevices of limestones. It is rarely
found without gas, and saline water is likewise often present, associated
with the oil. Oil in commercial quantities is not usually found where the
component strata are .horizonta], but in inclined and folded strata t i e oil
and gas are found collected in a sort of natural chamber or reservoir, in the
highest possible situations, e.g. the crests of anticlines. In.such positions
the gas collects at the summit of the anticlines, with the oil immediately
below it. This follows of course from the lower density of the oil as compared with the water saturating the petroliferous beds. " In all cases there
must apparently be an impervious bed above to prevent an escape of the
oil and gas, and in this there is a certain similarity to the conditions requisite for artesian wells, but with the difference that the artesian wells receive their supplies from above and must be closed below, while the oil and
gas wells receive their supplies from below and must be closed above. Both
require a porous bed as a reservoir, which in the one case, ideally, but not
always actually, forms a basin concave above, in the other concave below." ^
Where the rocks are not saturated with the water, oil may occur in different
circumstances, for example in the bottoms of synclines, but this type of
accumulation is unknown in India. The porous sand beds, sandstones,
conglomerates or fissured limestones which contain the oU must be capped
by impervious beds in order that oil be.not dissipated by percolation in the
surrounding rocks.
" Gas—The oil usually contains a large proportion of hydrocarbons which
oinder norn\al pressure would be gaseous, but the pressures at great depths
below the surface are sufficient to liquefy these hydrocarbons. In addition,
other hydrocarbons (such as marsh gas) which are not Hquefied by pressure
are readily soluble in petroleum under pressure ; in consequence, when the
puncturing of an oilsand by drilhng into it brings about a great local reduction in pressure there follows a brisk evolution of gas. This gas, escaping
towards the well through the minute crevices in the sand or limestone,
i» carries the oil with it. In this way the oil reaches the well and, if the pres*!sure is sufficient, it will come up to the surface—sometimes with great force.
Occasionally a well on reaching the oilsand may get out of control, and the
oil flows high above the grounds but both in Burma and India every care is
taken to avoid waste both of the oil and of the gas which plays so important
a part in bringing about' the production of oil.
Migration—The oil and gas are usually not indigenous to the rocks con- taining them but have been concentrated from a fairly large area by the
combined effects of gravitation, capillary action and percolation, and underground water. In some cases the oil occurs many hundreds of feet above
the original source.
Petroleum Areas in India—Sir E. H. Pascoe has drawn attention to
1 Chamberlin and Salisbury, Geology, vol. ii, 1909.
256
GEOLOGY OF INDIA
the analogy between the three petroleum areas of India—Burma,
Assam, and the north-west Punjab, which appear to have been gulfs
or arms of the nummulitic sea which we're filled up by sedimentation.
G. W. Lepper has pointed out that the most prolific fields in Burma
are situated on the eastern margin of a broad syncline corresponding
approximately to the Chindwin-Irrawaddy valley. He suggests that
the bulk of the oil-forming sediments were deposited in a shallow
marine environment and that most of the oil of the Burma oilfields
has migrated into them from the sediments of this long and broad
syncUne.
LOWER MIOCENE
Distribution—Unlike the Ohgocene,'the Miocene system is very
fully developed in India, being found in all the Tertiary areas of the
extra-Peninsula. It is convenient to deal separately with the Lower
Miocene since in several areas this presents a notably different development from the upper portions of the system. In Sind the Lower
Miocene rocks are known as the Gaj series, in the Potwar and Kashmir
as the Murree series. In the Outer Himalayas the term Sirmur was
applied to a group ranging from Eocene to Miocene but this term is
inconvenient as it does not represent a natural unit, the Oligocene
being absent. Consequently the term Sirmur system is now seldom
used. The upper part of this group of rocks includes two series—
Dagshai and Kasauli which belong to the Lower Miocene. In Assam
the Barail series is unoonformably overlain by the Surma series which
is of Lower Miocene age. In Burma the Upper Pegus are important
since they contain a petroliferous horizon, and are very fossiliferous.
Sind
Gaj Series—The Nari strata are overlain with apparent conformity
by the Gaj series ; this consists of richly fossiliferous dark-brown coral
limestone, with shales, distinguished from the underlying Miri by the
absence of Nummulites. The higher beds are red and ohve shales
which are sometimes gypseous ; these in turn pass up into a series of
clays and sandstones whose characters suggest deposition in an estuary
or the broad mouth of a river. This shows a regression of the seaborder and its replacement by the wide basin of an estuary. Fossils
are very numerous in the marine strata, representing every kind of
life inhabiting the sea. The commonly occurring forms are : Ostrea
(sp. 0. multicostata and 0. latimarginata), Tellina, Brissus, Breynia,
i
THE OLIGOCENE AND LOWER MIOCENE
257
Echinodiscus, Clypeaster, Echinolampas, Temnechinus, Eupatagus,
Lepidocydina and Orbitoides. The species Ostrea' latiinarginata is
highly characteristic of the Gaj horizon, it being met with also in the
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parallel group of deposits forming the upper part of the Pegu system
of Burma. It is evident from the estuarine passage-beds that the
Upper Gaj was the time for the expiry of the marine period in Sind
W.Q.l.
E
258
GEOLOGY OF INDIA
and the beginning of a continental period. On the land which
emerged from thie sea, a system of continental deposits began to be
formed, which culminated in an alluvii,! formation of great thickness
and extent enclosing relics of the terrestrial life of the time. Rhinoceros is the only land-mammal whose remains have been hitherto obtained from the Upper Gaj beds.
Bugti beds—In the Bugti hills of the Bugti country, in East Baluchistan, the fluviatile conditions had established themselves at an earlier
date, the marine deposits in that country ceasing with the Nari epoch..
The overlying strata, i.e. the lower part of the Gaj, are fluviatile sandstones containing a remarkable fauna of vertebrates, of Upper Oligocene or Lower Miocene affinities. The leading fossils are : (Mammals)
AntJiracotherimn, CadurcotJierium, Diceratherium, Baluchitherium (a
rhinoceratid, one of the largest land-mammals), Brachyodus, Teleoceras and Telmatodon, together with a few fresh-water molluscs, among
which are a number of species of JJnio. These beds are known as the
Bugti beds.
Salt-Range, Potwar, Janunu hiUs
The Potwar trough—One of the most perfect developments and exposures of the whole Tertiary sequence in India is observed in the
geosynclinal trough of the Potwar, a plateau lying between the SaltEange and the foot-hills of the N.W. Punjab. In this area, with the
exception of the Oligocene break, continuous sedimentation took
place from the Ranikot stage onwards to late Pleistocene, resulting in
deposits, 25,000 feet thick, in which fossils belonging to most of the
Tertiary time-divisions are recognised. On a floor constituted mainly
of Mesozoic rocks there occur about 1000 feet of the Nummulitics,
overlain by 6000 feet of the ferruginous, brackish-water sediments of
Aquitanian and Burdigalian age, the Murree series, succeeded by over
16,000 feet of the fluviatile and sub-aerial SiwaUk strata. At the top,
the Upper Siwaliks pass transitionally into the Older and Newer
Pleistocene alluvia, loess, gravels, etc.
The Potwar trough forms almost the north-western extremity of
the much wider and larger Indo-Gangetic synclinorium, also filled up
by Tertiary and post-Tertiary deposits, of which the former may be
regarded as a small scale replica. ^
Murree Series—In the eastern end of the Salt-Range, in the Potwar,
and in the hills fringing the Jamniu and Kashmir Himalaya, the
1 Mtmoirs, O.S.I. vol. li. pt. 2,1928; Quart. Jour. Geol. Min. Met. Soc. Ind. vol. iv.
No. 3, 103].
THE OLIGOCBNB AND LOWER MIOCENE
259
various members of the Eocene are overlain by alternating sandstones and shales, the Murree series, very variable in thickness, but
exceeding 8000 feet where fully developed. At the base of the series
there is often a well-marked conglomeratic bed with bone fragments
and derived numniulites. Por some time the age of these beds was
uncertain. The nummulites are of Eocene age (mainly Kirthar) and
the other organic remains of Miocene (Gaj) age. I t was therefore
thought that the horizon represented a passage from the Eocene
through the Oligocene to the Miocene. When it was recognised that
the nummulites were all derived by erosion of the underlying Eocene
rocks, the difSculty disappeared and the basal Murrees took their
correct place in the succession. This basal zone has been termed the
Fatehjang beds. Above the Fatehjang beds comes a great thickness of
red and purple shales veined by calcite, with grey and purple, falsebedded, sandstones, and concretionary clay pseudo-conglomerates.
The whole thickness is unfossiliferous in the main, but for a few impressions of the leaves of a palm Sabal major and some other obscure
leaves and tissues of -plants, with rarely some Vnionid shells. These
beds are known as the Lower Murrees. The Upper Murrees are
softer, coarser, and paler Sandstones bearing occasional impressions
of dicotyledon leaves. They are associated with shales very similar to
those of the Lower Murrees but forming a smaller proportion of the
succession.
The Lower Murrees especially are usually found in narrow isoclinal
folJs and this, together with their unfossiliferous nature, makes it
difficult to work out details of the succession.
The range of age presented by the Murree series is difficult to determine, but it is clear that they are in the main Lower Miocene ; it is
not impossible that the lowest beds range down into the Oligocene.
There is no sharp upward limit to the series, the passage into the overlying Kamlial stage being quite gradual.
The Murree series has a very restricted development in the SaltRange, being_absent from the greater part of the area. The gap between the Eocene and the overlying beds is thus greater than further
north. In the western part of the Salt-Range the Eocene is followed
by Kamlial beds, but in the trans-Indus area fuxther west successively
higher Siwalik horizons rest upon the Eocene.
Petroleum—In the Potwar, the Murree series is occasionally
associated with petroleum and has yielded a production of about
120 million gallons of oil at Khaur. It is believed that the oil has
migrated into the Murree series from the underlying Eocene.
260
GEOLOGY OF INDIA
Outer Himalayas
Dagshai and Kasauli Series—The broiad outcrop of the Murree
series in the Jammu hills narrows towards the east and merges into
the typical Dagshai-Kasauli band of the Simla area, a connection between the two being discernible in some plant-bearing beds in the
valley of the Ravi. The Dagshai beds overlie the Subathus without
any marked discordance but there is nevertheless a large break, the
whole of the Oligocene being absent. The lower part of the Dagshai
series is made up of bright red nodular clay ; the upper is a thickly
stratified, fine-grained, hard sandstone which passes up, with a perfect transition, into the overlying KasauK group^ of sandstones, which
rocks are the chief components of the Kasauli series. No fossils are
observed in the Dagshai group except/wcoit^ marks and worm-tracks,
fossils which are of no use for determining either the age of the deposit
or its mode of origin. The Kasauli group also has yielded no fossils
except a few isolated plant remains and a Unionid. The only traces
of life 'visible in this thick monotonous pile of grey or dull-green
coloured coarse, soft sandstones are some impressions of the leaves of
the palm Sabal major. These are of importance because they enable
the Kasauli horizon to be recognised further north-west in the Jammu
hills.
Assam
Surma Series—The coal-measures of the Assam hills, belonging to
the Barail series described in the last chapter, are unconformably
overlain by the Surma series, representative of the Gaj horizon of
Sind. The Surma series occupies a wide extent in the Naga hills.
North Cachar hills, and Surma valley of Assam, and extends southwards through Chittagong to the Arakan coast of Burma. It is composed of sandstones and sandy shales, mudstones and thin conglomerates, generally free from carbonaceous content. In, the Garo hills
a small range of beds in the Surma series has yielded a large number of
marine fossils and another fossiliferous bed has been-described from
a slightly lower horizon in the Surma valley. Both faunas belong to
the Lower Miocene; otherwise the series is remarkably unfossiliferous. Indications of petroleum are common in the Surma series in
several localities.
Burma
Upper Pegu Series—The Upper Pegu rocks of Lower Miocene age
form an important part of the Burma Tertiary sequence. As mentioned on pages 1253-4 there is a break at the top of the Oligocene and
THE OLIGOCENE ANT) LOWER MIOCENE
261
there is also a strong unconformity between the Pegus and the overlying Irrawaddy series. Consequently the thickness of the Upper
Pegus is very variable. Petroleum is found in the Miocene beds but
these are hardly as important a source of this mineral as the Oligocene. The abundant fossils of the Upper Pegus enable the age of the
greater part of the group to be definitely identified as Lower Miocene;
it is however possible that the uppermost Pegu beds are of Middle
Miocene age. The Upper Pegus, like the Lower Pegus, show evidence"
of passing northwards into rocks deposited in more shallow water
conditions. The extent of the unconformity between the Pegus and
Irrawaddy varies considerably in different localities and it has been
suggested that in some parts of Burma there is very little break between the two sets of beds.
Igneous action during the Oligocene and Lower Miocene
The Middle Tertiary was the period for another series of igneous outbursts in many parts of extra-Peninsular India. The igneous action
was this time mainly of the intrusive or plutonic phase. Unfortunately
it is difiicult to fix the precise age of these intrusions. The early Eocene
rocks were pierced by large intrusive masses of granite, syenite,
. diorite, gabbro, etc. In the Himalayas, in Baluchistan and in Burma
the records of this hypogene action are numerous and of a varied
nature. Intrusions of granite took place along the central core of the
Himalayas. In Baluchistan the plutonic action took the form of
bathyliths of granite, augite-syenite, diorite, porphyrites, etc., while
in Upper Burma and in the Arakan Yoma it exhibited itself in
peridotitic intrusions piercing through the Eocene and possibly Oligocene strata. " In the Myitkyna district of Upper Burma, a basaltic
tuff appears to be interbedded with the Tertiary rocks which are
mainly of Eocene or Oligocene age.
In all the above Tertiary provinces of India that we have reviewed
so far, from Sind to Burma, the transition from an earlier marine type
of deposits to estuarine and fluviatile deposits of later ages must have
been perceived. The passage from the one type of formation to the
other was not simultaneous in all parts of the country, and marine
conditions might have persisted in one part long after a fluviatile
phase had established itself in another ; but towards the middle of
the Miocene period the change appears to have been complete and
universal, and there was a final retreat of the sea from the whole of
262
GEOLOGY OF INDIA
north India. This change from the massive marine nummuUtic limestone of the Eocene age, containing abunjlance of foraminifera, corals
and echinoids, to the river-deposits of the next succeeding age crowded
with fossil-wood and the bones of elephants and horses, deer and
hippopotami, is one of the most striking physical revolutions in India.
We must now turn to the great system of Upper Tertiary riverdeposits which everywhere overlies the Middle Tertiary, enclosing in
• its rock-beds untold relics of the higher vertebrate and mammalian
life of the time, comprising all the types oi the most specialised
mammals except Man.
BEEERENCES
W. T. Blanford, Geology of W. Sind, Mem. G.S.I, vol. xvii. pt. 1, 1879.
G. E. Pilgrim, Tertiary Eresh-water Deposits of India, Bee. G.S.I, vol. xl. pt. 3,
1910.
E. H. Pasooe, Oa-fields of India, Mem. G.S.I, vol. xl. 1912-1920; Bee. G.S.I, vol.
xxxviii. pt. 4, 1910.
P. M. Duncan and W. P, Sladen, Tertiary Eauna of W. India, Pal. Indica, sers. vii.
and xiv., vol. 1, pt. 3.
G. E. Pilgrim, Vetrebrate Eauna of the Bugti Beds, Pal. Indica, N.S., vol. iv.
mem. 2, 1912.
A. B. Wymie, Tertiaries of the Punjab, Bee. O.S.I, vol. x. pt. 3, 1877.
E. S. Pinfold, Stratigraphy of N.W. Punjab, Bee. G.S.I, vol. xlix., 1918.
G. de P. Cotter, Geology of the Attock District, Mem. O.S.I, vol. Iv. pt. 2, 1933.
P. Evans, Tertiary Succession in Assam, Trans. Min. and Geol. Inst. Ind. voL
xxvii., 1932.
CHAPTEE XX
THE SIWALIK SYSTEM
MIDDLE MIOCENE TO LOWER PLEISTOCENE
General—Upper Tertiary rocks occur on an enormous scale in the
extra-Peninsula, forming the low, outermost hills of the Himalaya
along its whole length from the Indus to the Brahmaputra. They are
known as the Siwalik system, because of their constituting the Siwalik
hills near Hardwar, where they were first known to science, and from
, which were obtained the first palaeontological treasures that have
made the system so famous in'all parts of the world. The same system
of rocks, with much the same lithological and palaeontological characters is developed in Baluchistan, Sind, Assam, and Burma, forming
a large proportion of the foot-hill ranges of these provinces. Local
names have been given to the system in the extra-Himalayan areas,
e.g. the Mekran system in Baluchistan, Manchar system in Sind, the
Tipam and Dihing series in Assam, and the Irrawaddy system in
Burma, but there is no doubt about the parallelism of all these groups.
The Siwalik deposits—The comppsition of the Siwalik deposits
shows that they are nothing else than the alluvial detritus derived
from the subaerial waste of the mountains, swept down by their
numerous rivers and streams and deposited at their foot. This process was very much like what the existing river-systems of the Himalayas are doing at the present day on their emerging to the plains of
the Punjab and Bengal. An important difference is that the former
alluvial deposits now making up the Siwalik system have been involved in the latest Himalayan systems of upheavals by which they
have been folded and elevated into their outermost foot-hills, although
the oldest alluvium of many parts of northern India serves to some
extent to bridge the gap between the newest Siwaliks and the present
alluvium. The folding of the Siwalik sediments has imparted to them
high dips and some degree of induration, both of which are of course
absent from the recent alluvial deposits of the plains of India..
In the severe compression and stresses to which they have been
263
G E O L O G Y OF I N D I A
264
subjected in the mountain-building processes, some of the folds have
been inverted or reversed, with the overturning of the fold-planes to
highly inclined positions. As is often the case with reversed folds, the
middle limb of the fold (which has to suffer the severest tension), having reached the limit of its strength, passed into a highly inclined frac-_^
ture or thrust-flane, along which the disrupted part of the fold has
U.S. '•^•
Ovetfold
Reversed fault
Fio. 30.—Diagrams to illustrate the formation of reversed faults in the
Siwalik zone of the Outer Hitaalayas.
slipped bodily over for long distances, thus thrusting the older preSiwalik rocks of the inner ranges of the mountains over the younger
rocks of the outer ranges.
The geotectonic relations of the Siwaliks—These rex^ersed overthrust faults are a characteristic and highly significant feature of the
outer Himalayas; many of the; reversed faults of the Siwalik zone
can be traced for enormous distances. Wherever the Siwalik rocks
are found in contact with the older formations, the plane of junction is
always a reversed fault, with an apparent throw of many thousand
feet, and along which the normal order of superposition of the rockgroups is reversed, the younger Siwalik beds resting under the older
Sirmur and dipping under them. This plane of contact is known as
the Main Boundary Fault. Thi^fault is a most constant feature of the
structure of the Outer Himalayas along their whole length from the
Punjab to Assam.
The Main Boundary Fault—The Main Boundary is again not
the only fault, but is one of a series of more or less parallel faults
among the Tertiary zone of the outer Himalayas, all of which exhibit
the same tectonic as well as stratigraphic peculiarities, i.e. the fault
THE SIWALIK SYSTEM
265
has taken place along the middle-hmb of the folds and the lower and
older rocks are thrust above the upper and younger, viz. the Siwalik.
under the Middle and Lower Tertiary, and the latter underneath the
still older strata of the middle Himalayas.
The researches of Middlemiss and Medlicott in Himalayan geology
have led to the suggestion that the Main Boundary is not of the nature
of a mere ordinary dislocation which limits the boundary of the
present distribution of the' Siwaliks, but marks the original limit of
deposition of these strata against the cliff or foot of the then existing
mountains, beyond which they did not extend, could never, in fact,
extend. Subsequent to their deposition this boundary has been doubtless further emphasised by.some amount of faulting. The other faults
are also of the same nature, and indicate the successive limits of the
deposition of newer formations to the south of, and against, the advancing foot of the Himalayas during the various stages of their elevation. This view of the nature of the Main Boundary will be made
clearer by imagining that if the rocks of the Indo-Gangetic alluvium,
at present lyinig against the Siwalik foot-hills, were to be involved and
elevated in a further, future phase of Himalayan upheaval, they would
exhibit much the samefrelations to the Siwalik strata as the latter do
to the older Tertiary or these in turn do to the still older systems of the
middle Himalayas. According to this view these reversed faults were
" not contemporaneous but successional", each having been produced at the end of the period during which beds immediately to the
south of it were being deposited. The hypothesis is based on the supposition that nowhere do the Siwaliks overstep the Main Boundary
Fault, or extend as outliers beyond it, except very locally. I t is held
that if the faults had been in the main later than the deposition of the
beds there would have been many outliers to the north. Such outliers
have, however, been found in a few cases and the faults, which are
found to be of the nature of overthrusts, have been proved to be of
later date than the deposition of the Siwaliks and even subsequent
to their plication.
Again, this interpretation, though acceptable in a general way for
large tracts of the i^estern Himalayan foot-hills, is not applicable to
the eastern Himalaya of Assam. Here the faults are not of the jiature
of " boundary faults " in the sense of Medlicott and Middlemiss, but
are thrust-planes which have covered up some width of the Siwalik
terrain in their southward advance. It is possible, therefore, that the
evidence favouring the interpretation put forward by these distinguished geologists is capable of another interpretation. I t is now
266
GEOLOGY OF INDIA
known that the overthrust faults may have a throw of many thousands of feet and consequently in overthrust areas the progress of
denudation will have removed great thi'cknesses of beds from the upthrow side of the fault and it has been ^suggested that this, together
with our still imperfect knowledge of the Tertiaries of the Himalayas,
should also be taken into account in explaining the apparent restriction of the Siwaliks to a limited zone.
The palaeontological interest of the Siwalik system—The most
notable character of the Siwalik system of deposits, and that which
has invested it with the highest biological interest, is the rich collection
of petrified remains of animals of the vertebrate sub-kingdom which
it encloses, animals not far distant in age from our own times which,
therefore, according to the now universally accepted doctrine of descent, are the immediate ancestors of most of our modern species of
land mammalia. These ancient animals lived in the jungles and
swamps which clothed the outer slopes of the mountains. The more
FIG. 31.—Section to illustrate the relations of the outer Himalaya to
the older rocks of the mid-Himalaya (Kumaon Himalaya)..
L.S. Lower Siwalik sandstones.
U.S. Upper Siwalik conglomerate.
M.S. Middle Siwalik sand-rock.
N. Older rocks.
(After C. S. Middlemiss.)
durable of their remains, the hard parts of their skeletons, teeth, jaws,
skulls, etc., were preserved from decay by being swept down in the
streams descending from the mountains, and entombed in rapidly
accumulating sediments. The fauna thus preserved discloses the great
wealth of the Himalayan zoological provinces of those days, compared
to which the present world looks quite impoverished. Many of the
genera disclose a wealth of species, now represented by scarcely a third
of that number, the rest having become extinct. No other mammalian
race has suffered such wholesale obliteration as the Proboscideans.
Of the nearly thirty species of elephants and elephant-like creatures
that peopled the Siwalik province of India, and were indigenous to it,
only one is found living to-day. The first discovered remains were
obtained from the Siwalik hills near Hardwar in 1839, and the
THE SIWALIK SYSTEM
great interest which they aroused is evident from the following popular description
by Dr. Mantell: " Wherever gullies
or fissures expose the section of the
beds, abundance of fossil bones appear,
lignite and trunks of dicotyledonous trees
occur, a few land and fresh-water shells
of existing species are the only vestiges of
moUusca that have been observed. Eemains
of several species of river-fish have been
obtained. The remains of elephants and
of mastodontoid animals comprise perfect
specimens of skulls and jaws of gigantic
size. The tusks of one example are 9 feet
6 inches in length and 27 inches in circumference at the base.^ This collection is
invested with the highest interest not only
on account of the number and variety of the
specimens, but also from the extraordinary
assemblage of the animals which it presents.
In the sub-Himalayas we have entombed
in the same rocky sepulchre bones of the
. most ancient extinct species of mammalia
with species and genera which still inhabit
India : Eleurogale, Hyaenodon, Dinotheria,
mastodons, elephants, giraffes, hippopotami,
rhinoceroses, horses, "camels, antelopes,
monkeys, struthious birds and crocodilian
and chelonian reptiles. Among these mammalian reHcs of the past are the skulls and
bones of an animal named Sivatherium
that requires a passing notice. This creature
forms, as it were, a link between the ruminants and the large pachyderms.
It
was larger than a rhinoceros, had four horns,
^ This haa been much exceeded in some later finds,
e.g. a specimen discovered by the writer in the upper
Siwalils; beds near Jammu, in which the left upper
incisor of Stegodon ganesa was found intact with the
maxillary ap_paratus and the upper molars. The tusk
measured from tip to socket 10 ft. 7 in., the circumference at the proximal end being a little over 25 inches.
267
M ' l ^^•
.SS
oo
;p3
wiig
268
GEOLOGY OF INDIA
and was furnished with, a proboscis, thus combining the horns of a
ruminant with the characters- of a pa,chyderm. Among the reptilian
remains aje skulls and bones of a gigantic crocodile and of a land
turtle which cannot be distinguished from those of species now
living in India. B.ut the most extraordinary discovery is that of
bones and portions of the carapace of, a tortoise of gigantic dimensions, having a length nearly 20 feet! It has aptly been named the
Colossochelys Atlas."
Rapid evolution of Siwalik fauna—^After the first few glimpses of the
mammalian fauna of the Tertiary era in the Bugti beds and that in the
Perim Island, this sudden bursting on the stage of such a varied population of herbivores, carnivores, rodents and of primates, the highest
order of the mammals, must be regarded as a most remarkable instance of rapid evolution of species. Many factors must have helped
in the development and differentiation of this fauna ; among those
favourable conditions, the abundance of food-supply by a rich angiospermous vegetation, which flourished in uncommon profusion, and
the presence of suitable physical environments, under a genial climate,
in a land watered by many/ivers and lakes, must have been the most
prominent.
'
- '
This magnificent assemblage of mammals, however, was not truly
of indigenous Indian origin ; it is certain that it received large accessions by migration of herds of the larger quadrupeds from such
centres as Egypt, Arabia, Central Asia and even from distant North
America by way of the land-bridge across Alaska, Siberia and Mongolia. According to Pilgrim ^ our hippopotamus, pigs and proboscideans had their early origin in Central Africa, from where they
radiated out and entered India during late Tertiary, through Arabia
and Iran; while the rhinoceros, horse, camel and the group of Primates, probably all originating in North America, had as their evolutionary centres various intermediate countries in Central and Western
Asia and were migrants to India through some^passes on the northwest or north-east of the rising Himalayan barrier."
The elephant, like the horse, has been a world traveller and instead
of the two solitary species inhabiting India and South Africa at the
present day, it had in late Tertiary times spread to and peopled almost
every country of the world except Australia.
Among the lower Siwalik mammals there are forms, like the
Sivatherium, which offer illustrations of what are called synthetic types
' Proceedings, 12th Indian Bcitnce Congress, Benares, 1925.
THE SIWALIK SYSTEM
,
269
(generalised or less differential types), i.e. the early primitive animals
that combined in them the characters of several distinct genera which
sprang out of them in the process of further evolution. They were
thus the common ancestral forms of a number of these later species
which in the progress of time diverged more and more from the parent
type.
Lithology—The Siwalik system is a great thickness of detrital rocks,
such as coarsely-bedded sandstones,, sand-rock, clays "and conglomerates measuring between 15,000 and 17,000 feet in thickness. The
bulk of the formation, as already stated, is very nearly alike to the
materials constituting the modern alluvia of rivers, except that the
foriner are somewhat compacted, have undergone folding and faulting
movements, and are now resting at higher levels, with high angles of
dip. Although local breaks exist here and there, the whole thickness
is one connected and complete sequence of deposits, from the beginning of the Middle Miocene to the close of the Siwalik epoch—Lower
Pleistocene. The lower part, as a rule, consists of fine-grained
micaceous sandstones,' more or less consolidated, with interbedded
shales of red and purple coloiirs : silicified mono- and dicotyledonous '
wood and often whole tree-trunks are most abundant throughout the
Siwalik sandstones, and leaf-impressions in the shales. The upper
part is more argillaceous, formed of soft, thick-bedded clays, capped
at places, especially those at the debouchures of the chief rivers, by an
extremely coarse boulder-conglomerate, consisting of large rounded
boulders of siliceous rocks.
The lithology of the Siwaliks suggests their origin; they are chiefly
the water-worn debris of the granitic core of the central Himalaya,
deposited in the long and broad valley of the " Siwalik " river (p. 40).
The upper coarse conglomerates are the alluvial fans or talus-cones
at the emergence of the mountain streams ; the great thickness of
clays and sands represents the silts and finer sediments of the rivers
laid down in flood-plains ; while it is probable that the lower, e.g.
Kamlial beds, were formed in the lagoons or estuaries of the isolated
sea-basins that were left by the retreating sea as it was driven back by
the post-Murree upheavals. .These lagoons and estuaries gradually
freshened and gave rise to fluviatile and then to subaerial conditions
of deposition.
The composition as well as the characters of the Siwalik strata
everywhere bears evidence of their very rapid deposition by the
rejuvenated Himalayan rivers, which entered on a renewed phase
of activity consequent on the uplift of the mountains. There is
270
GEOLOGY OF INDIA
very little of lamination to be seen in the finer deposits ; the
stratification of the coarser sediments is also very r u d e ; the great
thickness of clays and sands represents the silts and finer sediments
of the rivers laid down in flood-plains ; while current-bedding
is universally present.
There is again little or no sorting of
grains in the sandstones, which are composed of unassorted sandy
detritus derived from the Himalayan gneiss, in which m a n y of its
constituent minerals can be recognised, e.g. quartz, felspar, micas,
hornblende, tourmaline, rragnetite, epidote, garnet, rutile, zircon,
ilmenite, etc.
[Under the direction of P . Evans a great deal of detailed examination
of heavy mineral constituents of the Upper Tertiary sediments of India
has been carried out. The results of several thousand analyses have
afforded useful data regarding the distribution of hornblende, epidote,
kyanite, staurolite, etc., which are likely to be of value for correlation
purposes where other means such as fossils or stratigraphic proofs are not
available.]
The idea of the older geologists t h a t the whole Siwalik system of
rocks were deposits of the n a t u r e of alluvial fans, talus slopes, etc., a t
the debouchers of the Himalayan rivers very much along the sites of
their present-day channels, does not appear to be tenable on the.ground
of the remarkable homogeneity t h a t the deposits possess. N o t only
do they show on t h e whole uniformity of lithological composition a t
such distant centres as Hardwar, Simla hills, Kangra, J a m m u and
Potwar, b u t also there is a striking structural u n i t y of disposition
along a definite and continuous line of strike. This negatives a n y
theory of the deposition of these rocks in a multitude of isolated
basins.
The periodic uplift of t h e Himalayas, accompanied b y the encroachment of the mountain-foot gradually towards t h e rapidly filling
depression to the south resulted in t h e main drainage channels being
pushed southwards. As t h e uplift proceeded, each periodic uprise of
the mountains rejuvenated the vigorous young streams from the
north, while the drainage from the south became enfeebled and disorganised so t h a t in the building up of'the Siwalik pile t h e sediments
from the Gondwana mainland had but, little share. H o w far southwards the Siwaliks extended is not certain, b u t it is highly probable
t h a t a considerable breadth of the Siwaliks lies buried under the
alluvium of the Ganges.
C^ssification—On palaeontological'grounds t h e system is divisible
THE SIWALIK SYSTEM
271
into three sections, the passage of the one into the other division
being, however, quite gradual and transitional:
Boulder-conglomerate
Coarse boulder-conzone :
glomerates, thick
Blephas namadicus,
earthy clays, sands,
Equus,
Camelus,
and pebbly grit.
Upper
Buffelus palaeinpassing up into
• Siwaiifc,
dicus.
older alluvium.
6000Pinjor zone:
Eichly fossiliQOOO
ft,
i/\J\J\J XV*
E. jAanifrons, Hemiferous in the Sibos, Stegodon.
walik hills.
Tatrot zone :
; Hippohyus, Leptohos.
Dhok Pathan zone :
Grey and white sandStegodon, Mastodon,
stones and sandHippopotamus,
rock with shales
large Giraffoids,
and clays of pale
Middle
Sus, Merycopotaand drab colours.
Siwalik,
mus.
Pebbly at top.
6000The richest Si8000 ft. \
wahk fauna occurs
in the Salt-Range.
Nagri zone :
Massive, thick, grey
Mastodon, Hipparsandstones
with
ion, Prostegodon.
fewer shales and
clays, mostly red
coloured.
Chinji stage :
Bright red nodular
Listriodon,
Amphishales and clays
cyon, Giraffokeryx,
with fewer grey
Tetrabelodon.
sandstones
and
pseudo-conglomerXiower
ates.
UnfossiliSiwalik,
ferous in the Si(Nahan), •
walik hills (Na4000hans).
5000 ft.
Kamlial stage:
Dark, hard sandAceratherium,
Telstones and red and
matodon, Tetrabelopurple shales and
don, Anthropoids,
pseudo-conglomerHyoboops.
ates.
Fossiliferous in
the Punjab.
Upper
Murree,
Conformable passage d awnwards into Upper
Murree sandstones an d shales.
Lower
Pleistocene to
Lower
PUocene
Upper to
Middle
Miocene
(Pontian).
Middle
Miocene.
Helvetian.
(Burdigalian.)
The Pot war terrain immediately north of the Salt-Kange and the
272
GEOLOGY OF INDIA
Kangra-Hardwar tract may be regarded as type-areas of the Siwaliks
both as regards stratigraphy and faunas.
Siwalik Fauna
The Siwalik deposits enclose a remarkably .varied and abundant
vertebrate fauna in which the class Mammalia preponderate. The
first collections were obtained from the neighbourhood of the Siwalik
hills in the early* thirties of the last century, and subsequent additions were made by discoveries in the other Himalayan foot-hills. It
has been recently considerably enriched by discoveries in the Potwar
and Kangra areas, by Dr. Pilgrim. He has brought to light, in a series
of brilliant palaeontological researches, a number of rich mammaliferous horizons among these deposits, which are of high zoological and
palaeontological interest. These have established the perfect uniformity and homogeneity of the fauna over the whole Siwalik province, and have enabled a revised correlation of the system. The
following is a list of the more important genera and species of Mammalia classified according to Dr. Pilgrim.
Upper Siwalik:
Primates : Simia, Semnopithecus, Papio.
Carnivores : Hyaenarctus sivalensis, Melivora, Mustela, Lutra,
Canis, Vuljpes, Hyaena, Crocuta, Panthera, Ursus, Hystrix,
Viverra, Machaerodus, Felis cristata.
Elephants : Mastodon sivalensis, Stegodon ganesa, S. clifti, S.
insignis, Elephas planifrons, E. hysudricus, E. namadicus.
Ungulates : Rhinoceros palaeindicus, Equus sivalensis, Sus Jalconeri, Hippopotamus,, Camelus antiquus,Jjriraffa, Indratherium, Sivalherium giganteum, Gervus, Moschus, Bujfelus palaeindicus, Bucapra, Anoa, Bison, Bos, Hemibos, Leptobos.
Middle Siwalik:
Primates: Palaeopithecus, Semnopithecus, Dryopithecus, Ramapithecus sp., Sug'rivapithecus, Cercopithecus, Macacus.
Carnivores: Hyaenarctos, Indarctos, Palhyaena, Mellivorodon,
Lutra, Amphicyon, Machaerodus, Felis.
Eodents : Hystrix.
THE SIWALIK SYSTEM '
273
Elephants : Dinotherium, Tetrabelodon, Prostegodon catUleyi and
latidens, Stegodon clifti, Mastodon hasnoti.
Ungulates : Teleoceras, Aceratherium, Hipparion (very common),
Merycopotamus, Tetraconodon, Hippohyus, Potamochoeras^
Listriodon, Sus punjabiensis. Hippopotamus irravatiais,
Borcaiherium, Tragulus, Hydaspitherium, Aceratherium,
Vishnuthriim,
Cervus simplicidens, Oazella, Iragoceras,
Anoa.
Lower Siwalik:
Primates : Sivapithecus indicus, Dryopithecus, Indraloris, Bramapithecus, Palaeosimia.
Carnivores : Dissopsalis, Amphicyon, Palhyaena, Vishnufelis.
Proboscidians : Dinotherium, Trilophodon.
Ungulates : Aceratherium, Hyotherium, Anthracotherium, DorcaSwwe, Dorcatherium, Hemimeryx, Brachyodus, Hyoboops,
Girajfokeryx, Conohyus, Sanitherium, Listridon, Telmatodon,
Besides these the lower vertebrate fossils are :
Birds : Phalacrocorax, Pelecanus, Struthio, Mergus.
Reptiles : (Crocodiles) Crocodilus, Gharialis, Rhamphosuchus;
(Lizard) Varanus;
(Turtles) Colossochelys atlas, Bellia,
Trionyx, Chitra ; Snakes, Pythons.
Fish : Ophiocephalus, Chrysichthys, Rita, Arius, etc.
Special interest atta,ches to the occurrence of about eleven genera of
fossil primates in the Siwahk group. These fossils furnish important
material for the study of the evolution of the highest order of Mammals, the phylogeny of the living anthropoid apes, and the probable
lines of human ancestry.
A most interesting and representative collection of the Siwalik
fossils of India is arranged in a special gallery, the Siwalik gallery, in
the Indian Museum, Calcutta.
Age of the Siwalik system—From the evidence of the stage of
evolution of the various types composing this fauna, and from their
affinity to certain well-established mammaliferous horizons of Europe,
which have furnished indubitable evidence of their age because of
their interstratification with marine fossiliferous beds, the age of the
Siwalik system is determined to extend from the Middle Miocene to
274
•
GEOLOGY OF INDIA
the Lower and even Middle Pleistgcene. The Middle Siwaliks are
believed to be homotaxial with the well-known Pikermi series of
Greece, of Pontian, i.e uppermost Miocene, age.
A parallel series of deposits is developed in other parts of the
extra-Peninsula, as already alluded ',to. These have received local
names but they are in most cases, also fluviatile or sub-aerially
deposited sandstones, sand-rock, clays and conglomerates, containing abundance of fossil-wood and (in some areas) mammalian remains
agreeing closely with the Siwaliks.
Mekran system—The Mekran system in Baluchistan differs from
the equivalents in other areas in having marine fossils. I t includes
a great thickness of sandstones and shales and towards the top of the
succession are pebble beds which correspond approximately to the
Upper Siwaliks. The occurrence of a marine fauna in the Mekran
system is a feature of some importance but sufficient work has not yet
been done to enable a detailed succession to be naade out.
Manchar system—In Sind the Manchar system has been divided •
into a lower group which is fossiliferous and is equivalent to the
fossiliferous beds of the Potwar from the base of the Siwaliks to the
Dhok Pathan zone, and an upper group which probably corresponds
to the uppermost portion of the Upper Siwaliks. ^
Tipam and Dihing series—In Assam the Siwalik system is approximately equivalent to the Tipam and Diking"series. The Tipam series
consists typically of coarse ferruginous sandstones and mottled clay,
becoming conglomeratic towards the top. I t overlies with apparent
conformity the Lower Miocene Surma series and presumably corresponds with either the Lower or Middle Siwaliks, but owing to the
paucity of fossils no precise correlation is possible. The Dihing series
consists mainly of pebble beds resting unconformably on the Tipam
series. These deposits presumably correspond to the Upper Siwaliks.
Irrawaddy system—In Central Burma, the lower portion of the
Siwalik system appears to be missing and^there is a pronounced break
between the Upper Pegus of Lower Miocene age and the overlying
Irrawaddy system of Upper Miocene to Pliocene age. The Irrawaddy
system is made up largely of coarse, current-bedded sands and
occasional beds of clay and conglomerate with locally at the base a
conspicuous " red-bed " of lateritic origin. The total thickness may
reach 10,000 ft. Two fossiliferous horizons occur in this series,
separated by about 4000 ft. of sands. The lower, containing Hipparion and Aceratherium, denotes the Dhok Pathan horizon of the SaltRange, while the upper, characterised hy species of Mastodon,
THE SIWALIK SYSTEM
275
Stegodon, Hippopotamus and Bos, is akin to the Tatrot zone of Upper
Siwaliks. The sediments are remarkable for the large quantities of
fossil-wood associated with them and they were originally known as
the " fossil-wood group ". Hundreds and thousands of entire trunks
of silicified trees and huge logs lying in the sandstones suggest the
denudation of thickly forested eastern slopes of the Arakan Yoma.
Further north in Burma it is probable that the Irrawaddy system extends to somewhat lower horizons than in Central Burma and the
boundary between the Pegu and Irrawaddy rocks is often difficult to
fix.
REFERENCES
H. Falconer and P. T. Cautley, Fauna Antiqua Sivalensis, 1846, London.
G. E. Pilgrim, Correlation of the Siwalik Mammals, Bee. G.8.I. vol. xliii. pt. 4,
1913 ; Tertiary Fresh-water Deposits of India, Bee. O.S.I, vol. xl. pt. 3,1910.
R. D. Lydekker, Siwalik Fossils, Pal. Indica, series x. vols. i. ii. iii. iv.
Gi E. Pilgjim, Pal. Indica, N.S. : Fossil Giraffidae, vol. iv. mem. 1, 1911 ;
Fossil Suidae, vol. viii. mem. 4, 1926 ; Fossil Camivora, vol. xviii, 1932 ;
Fossil Bovidae, under preparation.
C. S. Middlemiss, Geology of the Sub-Himalayas, Mem. O.S.I, vol. xxiv. pt. 2,
1890.
A. B. Wynne, Bee. 0.8.1. vol. x. pt. 3, 1877.
D. N. Wadia; Siwaliks of Potwar and Jammu Hills, Mem. O.S.I, vol. li. pt. 2,
1928.
E. H. Colbert, Siwalik Mammals, Trans. Amer. Phil. Soc., N.S., vol. xxvi., 1935.
CHAPTEE XXI
THE PLEISTOCENE SYSTEM
THE GLACIAL AGE IN INDIA
The Pleistocene or Glacial Age of Europe and America—The close of
the Tertiary era and the commencement of the Quaternary is marked
in Europe, North America and the northern world generally, by a
great refrigeration of climate, culminating in what is known as the
Ice Age or Glacial Age. The glacial conditions prevailed so far south
as 39° latitude north, and countries which now experience a temperate .
climate then experienced the arctic cold of the polar regions, and were
covered under ice-sheets radiating from the higher grounds. The
evidence for this great change in the climatic conditions of the globe
is of the most convincing nature, and is preserved both in the physical
records of the age, e.g. in the characteristic glaciated topography;
the " glacial drift " or moraine-deposits left by the glaciers ; and the
effects upon the drainage system of the countries, as well as in the
organic records, e.g. the influence of such a great lowering of the
temperature on the plants and animals then living ; on the migration or extinction of species and on their present distribution.
A modified Glacial Age in India—Whether India, that is, parts lying
to the south of the Himalayas, passed through a Glacial A ^ , is an ^
interesting though an unsettled problem. In India, it must be understood, we cannot look for the actual existence of iqe-sheets during the
Pleistocene glacial epoch, because a refrigeration which can produce
glacial conditions in Northern Europe and America would not, the
present zonal distribution of the cUmate being assumed, be enough to ^
depress the temperature of India beyond that of the present temperate
zones. Hence we should not look for its evidence in moraine-debris
and rock-striations (except in the Himalayas), but in the indirect
organic evidence of the influence of such a lowering of the temperature
and the consequent increase of humidity, on the plants and animals
then living in India. Humidity or dampness of climate has been
found to possess as much influence on the distribution of species in
-276"'
THE PLEISTOCENE SYSTEM
277
India as temperature. From this point of view sufficient evidence
exists of tHe glacial cold of the northern regions being felt in the plains
of India, though to a much less extent, in times succeeding the Siwalik
epoch after the Himalayan range had attained its full elevation.
The great Ice Age of the northern world was experienced in the
southerly latitudes of India as a succession of cold pluvial epochs.
The nature of the evidence for an Ice Age in the Peninsula—This
evidence, derived from some peculiarities in the fauna and flora of the
hills and mountains of India and Ceylon, is summarised by W. T.
Blanford—one of the greatest workers in the field of Indian geology
and natural history.
" On several isolated hill ranges, such as the Nilgiri, Animale,
Shivarai and other isolated plateaus in Southern India, and on the
mountains of Ceylon, there is found a temperate fauna and flora
which does not exist in the low plains of Southern India, but which
is closely allied to the temperate fauna and flora of the Himalayas,
the Assam Eange, the mountains of the Malay Peninsula and Java.
Even on isolated peaks such as Parasnath, 4500 feet high, in Behar,
and on Mount Abu in the Aravalli Eange, Eajputana, several Himalayan plants exist. I t would take up too much space to enter into
details. The occurrence of a Himalayan plant like Rhododendron
arboreum and of a Himalayan mammal Hke Martes flavigula on both
the Nilgiris and Ceylon mountains will serve as an example of a
considerable number of less easily recognised species. In some cases
there is a closer resemblance between the temperate forms found
on the Peninsular hills and those on the Assam Eange than between
the former and Himalayan species, but there are also connections between the Himalayan and the Peninsular regions which do not extend
to the eastern hills. The most remarkable of these is the occurrence
on the Nilgiri and Animale ranges, and on some hills further south, of
a species of wild goat, Capra hylocrius, belonging to a sub-genus [Hemitragus) of which the only known species, Capra Jeemlaica, inhabits the
temperate regions of the Himalayas from Kashmir to Bhutan. This
case is remarkable because the only other wild goat found completely
outside the palaearctic region is another isolated form in the mountains of Abyssinia.
" The range in elevation of the temperate flora and fauna of the
Oriental regions in general appears to depend more on humidity than
temperature, many of the forms which in the Indian hills are peculiar
to the higher ranges being found represented by the allied species at
lower elevations in the damp Malay Peninsula and Archipelago, and
278
GEOLOGY OF INDIA
some of the hill forms being even found in the damp forests of the
Malabar coast. The animals inhabiting the Peninsula and Ceylonese
hills belong for the most part to species distinct from those found in
the Himalayan and Assam ranges, etc., in some cases even genera are
peculiar to the hills of Ceylon and Southern India, and one family of
snakes is unrepresented elsewhere. There are, however, numerous
plants and a few animals inhabiting the hills of Southern India and
Ceylon which are identical with Himalayan and Assamese hill forms,
but which are unknown throughout the plains of India.
" That a great portion of the temperate fauna and flora of the
Southern Indian hills has inhabited the country from a much more distant epoch than the glacial period may be considered as almost certain, there being so many peculiar forms. I t is possible that the species
common to Ceylon, the Nilgiris and the Animale may have migrated
at a time when the country was damper without the temperature
being lower, but it is difficult to understand how the plains of India
can have enjoyed a damper climate without either depression, which
must have caused a large portion of the country to be covered by sea,
a diminished temperature, which would check evaporation, or a
change in the prevaihng winds. The depression may have taken place,
but the migration of the animals and plants from the Himalayas to
Ceylon would have been prevented, not aided, by the southern area
being isolated by the sea, so that it might be safely inferred that the
period of migration and the period of depression were not contemporaneous. A change in the prevailing winds is improbable so long as the
present distribution of land and water exists, and the only remaining
theory to account for the existence of the same species of animals and
plants on the Himalayas and the hills of southern India is depression
of temperature."
Ice Age in the Himalayas—When, however, we come to the Himalayas, we stand on surer ground, for the records of the glacial age
there are unmistakeable in their legibility. At many parts of the
Himalayas there are indications of an extensive glaciation in the immediate past, and that the present glaciers, though some of them are«
among the largest in the world, are ijierely the shrunken remnants of
those which flourished in the' Pleistocene age. Enormous heaps
of terminal moraines, now grass-covered, and in some cases treecovered, ice-transported blocks, and the smoothed and striated
hummocky surfaces and other indications of the action of ice on land
surface are observed at all parts of the Himalayas that have been
explored from Sikkim to Kashmir at elevations several thousand feet
THE PLEISTOCENE SYSTEM
279
below the present level of descent of the glaciers. On the Haramukh
mountain in Kashmir a mass of moraine is described at an elevation
of 5500 feet. Grooved and polished rock-surfaces have been found
at Pangi in the Upper Chenab valley, and at numerous localities in
the Sind and Lidar valleys, on cliif-faces at 7500 feet level. In the Pir
Panjal, above 6500 feet, the mountains have a characteristic glaciated
aspect, while the valleys are filled with moraines and fluvio-glacial
drift. On the southern slopes of the Dhauladhar range an old moraine
(or what is believed to be such) is found at such an extraordinarily low
altitude as 4700 feet, while in some parts of Kangra, glaciers were at
one time believed, though not on good evidence, to have descended
below 3000 feet level. In Southern Tibet similar evidences are
numerous at the lowest situations of that elevated plateau. Equally
convincing proofs of ice-action exist in the interruptions to drainage
courses that were caused by glaciers in various parts of the mountains.
Numerous small lakes and rock-basins in Kashmir, Ladakh and
Kumaon directly or indirectly owe.their origin to the action of glaciers
now no longer existing. A more detailed survey and exploration of
the Himalayas than has been possible hitherto will bring to light
further proofs.
The ranges'of the Middle Himalayas, which support no glaciers today, have, in some cases, their summits and upper slopes covered with
moraines. The ice-transported blocks of the Potwar plains in Attock
and Eawalpindi (referred to on page 303) also furnish corroborative
evidence to the same effect. (Note also the testimony of some hanging valleys (p. 21), and of the well-known desiccation of the Tibetan
lakes (p. 22).)
'
'
The extinction of the Siwalik mammals—one further evidence—
Further evidence, from which ah inference can be drawn of an Ice
Age in the Pleistocene epoch in India, is supplied by the very striking
circumstance to which the attention of the world was first drawn by
the great naturalist, Alfred Russel Wallace. The sudden and widespread reduction, by extinction, of the Siwalik Jtnammals is a most
startling event for the geologist as well as the biologist The great
Carnivores, the varied ^races of elephants belonging to no less than
twenty-five to 'thirty species, the Sivatherium and numerous other
tribes of large and highly specialised Ungulates which found such
suitable habitats in the Siwalik jungles of the Pliocene epoch, are to be
seen no more- in an immediately succeeding age. This sudden disappearance of the highly organised mammals from the'fauna of the
world is attributed by the great naturalist to the effect of tEe intense
280
GEOLOGY OF INDIA
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cold of a Glacial Age. It is a well-known fact that the more highly
specialised an organism is, the less fitted it is to withstand any sudden
change in its physical environments ; while the less differentiated
and comparatively simpleorganisms are more hardy and survive such
changes either by-slowly adapting themselves to the altered surroundings or by migration to less severe environments. The extinction of
the large number of Siwalik genera and species, and the general impoverishment of the mammalian fauna of the Indiau region, therefore,
furnish us with an additional argument in favour of an " Ice Age "
(though, of course, greatly modified and tempered in severity) in
India, following the Siwaliks.
Interesting glaciologica! investigations have been made in the
Kashmir Himalaya and in the Karakoram by DainelU, Grinlinton
and De Terra. Dainelli records four distinct phases of glaciation in the
N.W. Himalaya recognised by their moraines. Some indications of
the oscillation of glacial and interglacial periods have been recognised
in the heavy Pleis'tocene drift filling the Sind and Lidar valleys of
Kashmir. De Terra has attempted a correlation of the moraines of
successive glaciations with the Upper Siwalik stages of the Punjab.
He believes that the terminal and ground moraines of the Kashmir
glaciers merge into- the boulder-conglomerate of the foot-hills and
with the system of river terraces of the main valleys of Kashmir.
The system of lacustrine and river deposits known as Karewas in
Kashmir contain many terminal moraines embedded in them. The
moraines at some places contain finely laminated " varved " glacial
clays.
REFERENCES
W. T. Blanford, Geology of India, vol. i. Introduction, 1879.
W. Theobald, Extension of Glaciers within Kangra District, Rec. O.S.I, vol. vii.
p. 86.
R. D. Oldham, Glaciation of the Sind Valley, Kashmir, Bee. Q.S.L vol. xxxL
pt. 3. 1904.
Grinlinton, Glaciation of the Lidar Valley, Kashmir, Mem. G.S.I, vol. xlix. pt. 2,
1928
Dainelli, Italian Expedition io the Himaktya (1913-14), vols, i-xiii. Bologna,
1923-1935.
De TerTa,'s investigations in Kashmir and Western Tibet are in course of publication.
CHAPTER XXII
THE PLEISTOCENE SYSTEM (Continued)
THE INDO-GANGETIC ALLUVIUM
The plains of India—The present chapter will be devoted to the geology of the great plains of North India, the third physical division of
India' which separates the Peninsula from the extra-Peninsular
regions. I t is a noteworthy fact that these plains have not figured at
all in the geological history of India till now, the beginning of its very
last chapter. What the physical history of this region was during the
long cycle of ages, we have no means of knowing. That is because the
whole expanse of these plains, from one end to the other, is formed,
with unvarying monotony,'of Pleistocene and Sub-Recent alluvial deposits of the rivers of the Indo-Gangetic system, which have completely shrouded the old land-surface to a depth of some thousand
feet. The solid geology of the country is thus totally obscured underneath this mantle, which has completely buried all the past geological
records of this vast tract. The deposition of this alluvium commenced
after the final upheaval of the mountains and has continued all
through the Pleistocene up to the present. The plains of India thus
afford a signal instance of the imperfection of the geological record as
preserved in the world, and of one of the many causes of that imperfection.
Nature of the Indo-Gangetic depression—In the Pleistocene period,
the most dominant features of the geography of India had come into
existence, and the country had then acquired almost its present form,
and its leading features of topography, except that the lands in front
of the newly-upheaved mountains formed a depression, which was
rapidly being filled up by the waste of the highlands. The origin of
this depression, or trough, lying at the foot of the mountains, is doubtless intimately connected with the origin of the "latter, though the
exact nature of the connection is not known and is a matter of discussion. The great geologist, Eduard Suess, has suggested, as we have
already seen, that it is a " fore-deepJ.' in "front of the high crust-waves
" 282
THE PLEISTOCENE SYSTEM
283
of the Himalayas as they were checked in their southward advance by
the inflexible solid land-mass of the Peninsula. On this view the depression is of a synclinal nature—a synclinorium. From physical and
geodetic considerations, Sir S. Burrard has arrived at a totally novel
vi6w of the origin of the depression. He considers that the IndoGangetic plains occupy a deep " rift-valley ", a portion of the earth's
surface sunk in a huge crack or fissure in the sub-crust, between
parallel dislocations or faults'on its two sides. The formation of this
great,crack, 1500 miles long, and several thousand feet deep, in the
crust of the earth was, according to this view, intimately connected
with the elevation of the Himalayan chain ; was, in fact, according to
Burrard, the prime event in the whole series of physico-geographical
changes that took place at this period in the earth's history. This
view, which is based on geodetic observations and deduction alone,
has got few geological facts in its support, and is not adopted by geologists, who conceive that the' Indo-Gangetic dgpression is only of
moderate depth, and that its conversion into the flat plains is due to
the simple process of alluviation. On this view, a long-continued
vigorous sedimentation, loading a restricted, slowly-sinking belt of the
country, the deposition keeping pace with subsidence, has given rise
to this great tectonic trough of India. According to the latter view,
these plains have been formed by the deposition of the detritus of the
mountains by the numerous rivers emerging from them during a
period of great gradational activity. The continuous upheaving of the
mountains must have rejuvenated the streams often and often, thus
multiplying their carrying capacity to several times their normal powers.
It must also be remembered that this increased stream-energy was
expended on a zone of recent folding and fracturing whose disintegration must have proceeded with extreme rapidity. All these were
most favourable conditions for the quick accumulation of sediments
in the zone of lodgment at the foot of the mountains. Cf. Kgs. 29
and 33.
Extent and thickness—The area of these alluvial plains is 300,000
square miles, covering the largest portion of Sind, Northern Rajputana, the whole of the Punjab, the United Provinces, Bihar, Bengal
and half of Assam. In width they vary from a maximum of 300
miles in the western part to less than 90 piiles'in the eastern. The
total thickness of the alluvial deposits is not ascertained, but from
the few borings that have been made it appears that the thickness is
more than 1300 feet below the level of the ground-surface and nearly
1000 feet below the level of the sea. All the borings that have
284
GEOLOGY OF INDIA
hitherto been made, for the purpose of obtaining a supply of
artesian water, have failed to reach the rocky bottom, nor have
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THE PLEISTOCENE SYSTEM
285
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Oldham calculated the depth of the alluvium from geological considerations to be about 15,000 feet near its northern limit, from which
the floor slopes upwards to its southern-edge where it merges with the
Vindhyan uplands of the Deccan. Recent calculations fromgeodetic
surveys, however, give a much lesser thickness for these lighter
deposits resting on the dense Archaean bed-rock.^ How far southwards the Murree and Siwalik deposits of the foot-hills zone extend
underneath the alluvium we have no means of determining, except by
gravity and magnetic surveys. The depth of the alluvium is at a
maximum between Delhi and the Rajmahal hills and it is shallow in
Rajputana and between Rajmahal and Assam. Its floor is probably
not an even plane, but is corrugated by inequalities and buried
ridges. Two such ridges have been marked out by geodetic surveys :
an upwarp of'the Archaeian rocks in structural prolongation with the
Aravalli axis, between Delhi and Hardwar ; and a ridge, submerged
under the Punjab alluvitim, striking north-west from Delhi to the SaltRange. There is a considerable amount of flexure and dislocation at the
north margin of the trough where it passes into the zone of the various
boundary faults at the foot of the Himalayas. This tectonic strain
explains the well-known seismic instability of this part of India, it
being the belt encompassing the epicentres of the majority of the
known Indian earthquakes.
Changes in rivers—The highest elevation attained by the plains is
900 feet above the sea level; this is the case with the tract of country
between Saharanpur, Umballa, and Ludhiana, in the Punjab. The
above tract is thus the present watershed which divides the drainage
of the east, i.e. of the Ganges system, from that of the west, i.e. the
Indus and rivers of the Punjab. There exists much evidence to prove
that this was not the old. water-parting. The courses of many of the
rivers of the plains have undergone great alterations. Many of the
rivers are yearly bringing enormous loads of silt from the mountains,
and depositing it on their beds, raise them to the level of the surrounding flat country, through which the stream flows in ever-shifting
channels. A comparatively trifling circumstance is able to divert a
river into a newly scoured bed. The river Jumna, the sacred Saraswati of the Hindu Shastras, in Vedic times flowed to the sea, through
Eastern Punjab and Rajputana, by a channel that is now occupied by
an insignificant stream which loses itself in the sands of the Bikaner
desert. In course of time, the Saraswati took a more and more
^ E. A. Glennie, Gravity Anomalies and the Structure of the Earth's Crust, Survey
of India, Dehra Dun, 1932.
286
GEOLOGY OF INDIA
•i
easterly course and ultimately merged into the Ganges at Prayag.
It then received the name of Jumna.^
Most of the great Pimjab fivers'have frequently shifted their
channels. In the time of Akbar, the iChenab and Jhelum joined the
Indus at Uch, instead of at Mithankot, 60 miles downstream, as at
present. Multan was then situated, on the Ravi; now it is 36 miles
from the confluence of that river with the Chenab. 150 years ago the
Beas deserted its old bed, which can still be recognised between
Montgomery and Multan, and joined up with the Sutlej near Ferozpur, several hundred miles upstream.^
The records of the third centuiy B.C. show that the Indus flowed
more than 80 miles to the east of its present course, through the now
practically dry bed of a deserted channel, to t h e R a n n of Cutch,^
which was then a gulf of the Arabian Sea. The westering of the Indus
is thus a'very pronounced phenomenon, for which different causes
have been suggested. An old river bed, the Hakra, Sotra, or Wahind,
more than 600 miles in length, the channel o£ a lost river, is traceable
from near Hoshiaipur at the foot of the Himalayas, through Bhatinda,
Bikaner and Bhawalpur to Sind.* It is probably the old bed of the
Saraswati (the Jumna when it was an affluent of the Indus) at a time
when the Sutlej and Beas flowed independently into the Indus
beyond Mrdtan,
. Great changes have likewise taken place in Bengal and in the Gangetic delta since 1750 ; and hundreds of square miles of the delta have
become habitable since then. In 1785 Kennel, the great geographer
of Bengal, found the Brahmaputra flowing through Sylhet; now it
flows 70 miles westwards. At that time the Tista flowed southward
through Dinajpur and joined the Ganges; now it has a south-easterly
course and discharges into the Brahmaputra.^
Old maps of Bengal show that hardly one hundred years ago the
river Brahmaputra, which n o ^ flows to the west of Dacca, and the
elevated piece of ground to its north, known as the Madhupur jungle,
then flowed a great many miles to the east of these locahties. This
^ Quart. Jour. Geol. Society, xix. p. 348, 1863. The above example illustrates what,
in a genera] manner, was the behaviour of the majority of the. rivers of this tract, including the Indus itself, which is supposed to have been originally confluent with the
Ganges. See also. Pascoe, ibid. vol. Ixxv. pp. 138-155 (1919); and Piigrim, Journ.
Asiat. Soc. Bengal, vol.-xv. (1919), pp. 81-99.
^ General Cunningham, The Ancient Geography of India, London, 1871.
' The Rann of Cutch, Journ. Boy. Geog. Soc., vol. xl., 1870.
*Maj. C. IT. Oldham, On the Lost River of the Indian Desert, Calcutta Review, 1874.
' Physical Oeorjraphy- of Bengal, from the Maps and Writings of Maj. J. Eeiinel,
1764-1776. Calcutta, Bengal Secretariat, 1926.
THE PLEISTOCENE SYSTEM
287
change appears to have been accomplished suddenly, in the. course
of a few years.
Lithology—The rocks are everywhere of fluviatile and subaerial
formation—massive beds of clay, either sandy or calcareous, corresponding to the silts, mud, and sand of the modern rivers. Gravel
and sand become scarcer as the distance from the hills increases. At
some depths from the surface there occur a few beds of compact sands
and even gravelly conglomerates. A characteristic of the clayey part
of the.alluvial plains, particularly in the older parts of the deposits, is
the abundant dissemination of "impure calcareous matter in the form
of irregular concretions—Kanlcar.- The formation of Kankar concretions is due to the segregation of the calcareous material of the
alluvial deposits into lumps or nodules somewhat like the formation of
flint in limestone. The alluvium of some districts contains as much as
30 per cent, calcareous matter. Some concretionary limonite occurs
likewise in the clays of Bengal and Bihar.
Classification—With regard to the geological classification of the
alluvial deposits, no very distinctly marked stages of deposition occur,
the whole being one continuous and conformable series of deposits
whose accumulation is still in progress. But the following divisions
are adopted for the sake of convenience, determined by the presence
in them of fossils of extinct or living species of mammals :
3. Deltaic deposits of the Indus, the Ganges, etc. Eecent.
2. Newer alluvium : Khadar of the Punjab.
Fossils, chiefly living species, including relics of Man.
1. Older alluvium : BJiangar of the Ganges valley.
Fossils of Elejihas antiquus, Equus namidicus, Manis
gigantea, extinct species of Rhinoceros, Hippopotami, etc.
Rocks of unknown age : possibly the extension of Archaean, Purana
and Gondwanas of the Peninsula and of Nummulitic, Murree and
Siwalik of the sub-Himalayas.
The Bhangar—The Bhangar, or older alluvium of Bengal and the
United Provinces, corresponds in age with the Middle Pleistocene,
while the Khadar gradually passes into the Eecent. The former generally occupies the higher ground, forming small plateaus which are too
elevated to be flooded by the rivers during their rise.
As compared to the Bhangar, the Khadar, though newer in age,
occupies a lower level: than the former. This, of course, happens in
288
GEOLOGY OP INDIA
conformity with the principle that as a river becomes older in time, its
deposits become progressively younger ; and as the bed of the river
is continually sinking lower, the later' deposits occupy a lower position
along its basin than the earlier ones. Such is the case with all old
river deposits {e.g. river-terraces and iiood-plains). Remnants of
the Bhangar land are being eroded by every change in the direction of
the river channels, and are being planed down by their meandering
tendencies.
The Khadar. The Ganges delta—The Khadar deposits
rule, confined to the vicinity of the present channels. The clays have
less Kankar, and the organic remains entombed in them all belong to
still living species of elephants, horses, oxen, deer, buffaloes, crocodiles, fishes, etc. The' Xhadar imperceptibly merges into the deltaic
and other accumulations of the prehistoric times. The delta of the
Ganges and the Brahmaputra is merely the seaward prolongation of
the Khadar deposits of the respective river-valleys. I t covers an area
of 50,000 square miles, composed of repeated alternations of clays,
sands and maris with, recurring layers of peat, lignite and some foresfcbeds.
Southern Bengal has'been reclaimed from the sea at a late date in
the history of India by the rapid southward advance of the Ganges
and Brahmaputra delta through the deposition of enormous loads of
silt. J. Fergusson has stated that only 5000 years ago the sea washed
the Rajmahal hills and that the country round Sylhet was a lagoon of
that sea, as was also a large part of the province of Bengal at a later
date. The cities of Bengal all became estabUshed as the ground
became desiccated enough to be habitable, only about 1000 years ago.
The diversion of the Brahmaputra to the east of Madhupur some centuries ago and its later deflection again to the west in the mi(iile of
the nineteenth century is a well-recorded event. This diverted portion
which broke away from its course to join the Ganges v/^as named the
Jumna. The eastern sea-face of the delta is changing at a rapid rate
by the formation of new ground and new islands, while the .western
portion of the deltaic coast-hne has remained practically unchanged
since Rennell's surveys of the .1770's.
The Indus delta^Similarly the Indus delta is a continuation of the
Khadar of the Indus river. This delta is a well-defined triangle with
its apex at Tatta ; it is of much smaller area than the Ganges delta,
since it is probable that the present delta is not of a very old age, but
is of comparatively late formation. From old maps of Sind it is found
that the delta has grown in size considerably during late historic
THE PLEISTOCENE SYSTEM
289
times and tliat the river lias swung from the Gulf of Cambay in the
south-east to Cape Mqnze in the north-west, frequently changing the
character of the coast-Une. It is inferred from various evidences that
the Indus, within historic times, had a very much more easterly
course, and discharged its waters at first into the Gulf of Cambay and
then into the Rann of Cutch. Both in Sind and Cutch there exist
popular traditions, as well as physical evidence, to support the inference. (See p. 286.)
Observation of the Khadai' deposits of the Lower Indus basin of
Sind shows that this strip of country is being aggraded by the deposition of silt by the river, till at places the Indus bed is nearly 70 feet
higher than the level of the surrounding country. The river thus is in
danger of leaving its bed in flood-time. The sub-Recent history of the
river proves t"hat such desertion of the channel has not been uncommon and that the Indus has wandered over the plains of eastern Sind
and N.W. Cutch over a wide amplitude of territory, raising the level
of the invaded-country by the annual deposit of silt.
A few other vernacular terms are employed to denote various
superficial features of geological importance in this area :
Bhaber denotes a gravel talus with a somewhat steep slope fringing
the outer margins of the hills everywhere. It resembles the alluvial
fans or dry-deltas. The rivers in crossing them lose themselves by the
abundant percolation in the loose absorbent gravels. The student
will here see the analogy of this Bhaber gravel with the Upper Siwalik
conglomerates. The latter was, in fact, an old Bhaber slope sealed up
into a conglomerate by the infiltration of a cementing matrix.
Terai is the densely forested and marshy zone below Bhaber. • In
these tracts the water of the Bhaber slopes reappears and maintains
them in a permanent marshy or swampy condition.
The term Bhur denotes an elevated piece of land situated along the
banks of the Ganges and formed of accumulated wind-blown sands,
during the dry hot months of the year.
In the drier parts of the alluvial plains, a peculiar saline efflorescent
product—Reh ^ or Kallar—is found covering the surface and destroying in a great measure its agricultural fertihty. The Reh salts are a
mixture of the carbonate, sulphate and chloride of sodium together
with calcium and magnesium salts derived originally from the
chemical disintegration of the detritus of the mountains, dissolved by
percolating waters and then carried to the surface by capillary action
in the warm dry weather. (See p 366.)
• > Rec. G.S.I. vol. xiu. pt. 2, 1880.
W.O.I.
I
290
GEOLOGY OF INDIA
The Dhands of Sind are small, shallpw, alkaline or saline lakes
formed in hollows of the sand-dunes. The salts, darbonate, chloride
ank sulphate of soda are brought to th'ese by water percolating through
the blown sands and accumulated in the basins, which form important
concentrations of natron at some places.^
In the alluvial tract lying between south-east Sind and Cutch, there
are likewise found fair-sized beds and lenses of pure rock-salt buried
in the sand deposits. The total quantity of salt so buried is of the
order of several million tons.
Economics—Though not possessed of any mineral resources, these
alluvial-plains are the highest economic asset of India because of their
agricultural wealth. The clays are an unlimited store for nide
earthenware and brick-making material, which is the only buildingmaterial throughout the plains ; while the Kankar is of most extensive use for lime and cement-making and also for road-construction.
These plains are an immense reservoir of fresh sweet water, stored in
the more porous, coarser strata, beneath the level of saturation, which
is easily accessible by means of ordinary borings in the form of wells.
The few deep borings that have been made have given proof of the
prevalence of artesian conditions in some parts of the plains, and in a
few cases artesian borings have been made with successful results.
A considerable amount of success has attended tube-well boring
experiments in the plains at many places ; wells of large calibre, and
of a depth of 200-400 feet are supplying water for agricultural use in
lands unprotected by irrigation.
Rajputana desert—Of the same age as, or slightly newer than, the
alluvial formation just described are the aeolian accumulations of the
great desert tract of India, known as the Thar. The Thar, or Rajputana desert, is one wide expanse of wind-blown sand stretching from
the west of the Aravallis to the basin of the Indus, and from the
southern confines of the Punjab plains, the basin of the Sutlej, to as
far south as lat. 25°, occupying an area 400 miles long by 100 miles
broad, concealing beneath it much of the solid geology of the region.
The desert is not one flat level waste of sands, but there are numerous
rocky projections of low elevation in various parts of it, and its surface is further diversified by the action of the prevailing winds, which
have heaped up the sands in a well-marked series of ridges, dunes and
hillocks. The rocky prominences which stand up above the sands belong to the older rocks of the country, presenting in their bare, bold
and rounded outcrops, and in their curiously worn and sand-blasted
1 Mem. G.S.i. vol. xlvii. pt. 2, 1923.
THE PLEISTOCENE SYSTEM
291
topography, striking illustrations of the phenomena of desert-erosion.
The aspect presented by the sand-hills resembles that of a series of magnified wind-ripples. Their strike is generally transverse to the
prevailing winds, though in a few cases, e.g. those occurring on the
southern part of the desert, the strike is parallel to the wind-direction.
In both cases the formation of the sand-ridges is due to wind-action,
the longitudinal type being characteristic of parts where the force of
the wind is great, the transverse type being characteristic of the more
distant .parts of the desert where that force has abated. The windward slope is long, gentle and undulatory, while the opposite slope
is more abrupt and steep. In the southern part of the desert these
ridges are of much larger size, often assuming the magnitude of hills
400 to 500 feet high. All the dunes are slowly progressing inland.
Composition of the desert sand—The most predominant component
of the sand is quartz in well-rounded grains, but felspar- and hornblende-grains also occur, with a fair proportion of calcareous grains.
The latter are only casts of marine foraminiferal shells, and help to
suggest the site of origin of the sands wjth which they aie intimately
mixed.
As is characteristic of all aeolian sands, the sand-grains are well and
uniformly rounded, by the ceaseless attrition and sorting they have
received during their inland drift. In other respects the Rajputana
sand is indistinguishable from the sand of the sea-shore.
Origin of the Rajputana desert^:;;The origin of the Indian desert is
attributed, in the first instance, to a long-continued and extreme degree of aridity of the region; combined with the sand-drifting action
of the south-west monsoon winds, which sweep through Rajputana for
several njonths of the year wittfout precipitating any part of their
contained moisture. These winds transport inland clouds of dust and
sand-particles, derived in a great measure from the Rann of Cutch and
from the sea-coast, and in part also from the basin of the Lower Indus.
There is but little rainfall in Rajputana—the mean annual fall being
not much above 5 inches—and consequently no water-action to carry
off the detritus to the sea, which has hence gone on accumulating year
after year. A certain proportion of the desert sand is derived from the
weathered debris of the rocky prominences of this tract, which are
subject to the great diurnal as well as seasonal alternations of temperature characteristic of all arid regions. The daily variation of heat
and cold in some parts of Rajputana often amounts to 100° Fahr. in
the course of a few hours. The seasonal alternation is greater. This
leads to a mechanical disintegration and desquamation of the rocks.
292
GEOLOGY OF INDIA
prodiicing an abundance of loose debris, wbicli there is no chemical or
organic (or humus) action to convert into a soil-cap.
The desert is not altogether, as thd name implies, a desolate treeless waste, but does support a thin scrubby vegetation here and there,
which serves to relieve the usually dreary and monotonous aspects of
its limitless expanses ; while, in the neighbourhood of the big Rajputana cities, the soil is of such fertility that it supports a fairly large
amount of cultivation. Wells of good water abound in some places,
admitting of some measure of well-irrigation.
Besides the above-described features of the great Indian desert, the
Thar offers instructive illustrations of the action of aeolian agencies.
As one passes from Gujarat or even Central India to the country west
and south of the Aiavallis one cannot fail to notice the striking change
in the topography that suddenly becomes apparent, in the bare and
bold hill-masses and the peculiar sand-blasted, treeless landscapes one
sees for miles around under a clear, cloudless sky. Equally apparent
is the abundance of mechanical debris, produced by the powerful
insolation, the disintegration of the bare rock-surface by desquamation, the saHne and alkaline efflorescences of many parts, the general
absence of soil and humus. A more subtle and less easily understood
phenomenon of the Eajputana desert is the growing salinity of its'
lake-basins by wind-borne salt dust from the sea-coasts.^
The Eann of Dutch—This vast desiccated plain terminates to the
south-west in the broad depression of the Rann of Cutch, another
tract of the Indo-Gangetic depression which owes its present condition to the geological processes of the Pleistocene age. This tract is a
saline marshy plain scarcely above the sea level, dry at one part of the
year and covered by water at the other part. I t was once an inlet of
the Arabian Sea, which has now been silted up by the enormous
volume of detritus poured into it by the small rivers discharging into
it from the east and north-east. From November to March, that is,
during the period of the north-east or retreating monsoons, the Rann
is a barren tract of dry salt-encrusted mud, presenting aspects of
almost inconceivable desolation. " Its flat unbroken surface of dark
silt, baked by the sun and bUstered by saline incrustations, is varied
only by the mirage and great tracts of dazzhngly white salt or extensive but shallow flashes of concentrated brine; its intense silent
desolation is oppressive, and save by chance a slowly passing caravan
of camels or some herd of wild asses, there is nothing beyond a few
bleached skeletons of cattle, salt dried fish, or remains of insects
» Rec. G.S.I. vol. X. pt. 1, 1877, and Mem. ols.1. vol. xxxv. pt. 1, 1902.
T H E PLEISTOCENE SYSTEM
293
brought down by floods, to maintain a distant and dismal connection
between it and life, whicli it is utterly unfit to support." ^ During the
other half of the year it is flooded by the waters of the rivers that are
held back owing to the rise of the sea by the south-west monsoon gales.
A very little depression of this tract would be enough to convert
Kathiawar and Cutch into islands. On the other hand, if depression
does not take place, the greater part of the surface of the Eann will be
gradually raised by the silts brought by the rivers with each flood, and
in course of time converted into an arable tract, above the reach of the
' sea, a continuation of the alluvial soil of Qujarat.
REFERENCES
J. Fergusson, Delta of the Ganges, Quarterly Journal of the Geological Society, six.
1863.
T. G. Carless, Delta of the Indus, Journal of the Royal Oeographical Society, viii.
1838.
A. B. Wynne, Geology of Cutch, Mem. O.S.L vol. ix. pt. 1, 1872.
H. B. Medlicott, The Plains of the United Provinces, Bee. O.S.I, vol. vi. pt. 1,
1873.
T. H. D. La Touche, Mem. G.S.I, vol. xxxv. pt. 1, 1902. (See the Plates at the
end of the Memoir illustrating features arising from desert-erosion.)
R. D. Oldham, Structure of the Gangetic Plains, Mem. G.S.I, vol. xUi. pt. 2, 1917.
D. N. Wadia, The Tertiary Geo-synoline of Northern India, Quart. Journ. Oeol.
Soc. of India, vol. iv., 1932.
^ Wynne, Mem. 6.S.I. yol. ix. 1872.
CHAPTER XXIII
THE PLEISTOCENE SYSTEM {Continued)
LATERITE
Laterite, a regolith peculiar to India—In this chapter we shall consider
laterite, a most wide-spread Pleistocene formation of the Peninsula
and Burma, a product of subaerial alteration highly peculiar to India.
Laterite is a form of regolith peculiar to India and a few other tropical
countries. Its universal distribution within the area of the Peninsula,
and the economic considerations that have of late gathered round it,
no less than its obscure mode of origin, combine to make laterite an
important subject of study in the geology of India.
Composition—Laterite is'a kind .of vesicular clayey rock, composed
essentially of a mixture of the hydrated oxides of alumina and iron
with often a small percentage of other oxides, chief among which are
manganese and titanium oxides. The two iirst-named oxides are
present in variable ratios, often mutually excluding each other;
hence we have numerous varieties of laterite which have bauxite at
o»e end and an indefinite mixture of ferric hydroxides at the other.
The iron oxide generally preponderates and gives to the rock its prevailing red colours ; at places the iron has concentrated in oolitic concretions, at other places it is completely removed, leaving the rock
bleached, white or mottled. At some places again the iron is replaced
by manganese oxides ; in the lateritic cap over the Dfharwar rocks this
is particularly the case. Although the rock originally described as
^ laterite by Buchanan from Malabar does contain clay and considerable amounts of combined silica, in the wide terrains of what is
obviously' the same rock in other parts of India, there is no clay
(kaolin), the silica present is colloidal and mechanically associated.
According to present usage it is the latter, clay-free rock which has
come to be regarded as typical laterite. According to the preponderance of any of the oxides, iron, alumina, or manganese, at the different
centres, the rock constitutes a workable ore, of that, metal. Usually
between the lateritic cap and the underlying basalt or other rocks over
'294-
THE PLEISTOCENE SYSTEM
295
wtioh it rests, there is a lithomarge-like rock, or -bole, a sort of transitional product, showing gradual passage of the underlying rock
(basalt or gneiss) into laterite.
Laterite has the peculiar property of being soft when newly
quarried, but becoming hard and compact on exposure to the air. On
account of this property it is usually cut in the form of bricks for
building purposes. Also loose fragments and pebbles of the rock tend
to re-cement themselves into solid masses as compact as the original
rock.
Distribution of laterite—Laterite occurs principally as a cap on the
summit of the basaltic hills and plateaus of the highlands of the
Deccan, Central India, and Central Provinces. In its best and most
typical development it occurs on the hills of the Bombay Deccan. In
all these situations it is found capping the highest flows of the Deccan
Traps. The height at which laterite is found varies from about 2000
feet to 5000 feet and considerably higher, if the ferruginous clays and
lithomarges of the Nilgiri mountains are to be considered as one of the
many modifications of this rock. In thickness the lateritic caps vary
from 50 to nearly 200 feet; some of these are of small lateral extent,
but others are very extensive and individual beds are often seen covering an immense surface of the country continuously. Laterite is by
no means confined to the Deccan Trap area, but is found to extend in
isolated outcrops from .as far north as the Rajmahal hills in Bihar ^
to the southern extremity of the Peninsula. In these localities
the laterite rests over formations of various ages and of varying
lithological composition^e.^. Archaean gneiss, Dharwar schist,
Gondwana clays, etc. Laterite is of fairly wide occurrence in parts
of Burma also.
High-level laterite and low-level laterite—The laterite of the abovenoted areas is all of high level, i.e. it never occurs on situations below
2000 feet above the sea level. The rock characteristic of these occurrences is of massive homogeneous grain and of uniform composition.
This laterite is distinguished as high-level laterite, to differentiate it
from the low-level laterite that occurs on the coastal lowlands on both
sides of the Peninsula, east and west. On the Malabar side its occurrences are few and isolated, but on the eastern coast the laterite occurs
almost everywhere rising from beneath the alluvial tracts which fringe
the coast. Laterite of the low-level kind occurs also in Burma, in Pegu,
and JVIartaban. Low-level laterite difters from the high-level rock in
^ These hills are for the most part composed of Jurassic traps, in addition to a substratum of Gondwana rocks ; the summit of the traps is covered with laterite.
296
GEOLOGY OF INDIA
being mucli less massive and in being of detrital origin, from its being
formed of the products of mecTianicali disintegration of the high-level
laterite. As a rock-type, laterite cannot be said to constitute a distinct petrological species ; it shows a great deal of variation from place
to place, as regards both its structure and its composition, and no
broad classification of the varieties is possible; but the above distinction of the two types of high and low level is well established, and
is based on the geological difference of age as well as the origin of the
two tjrpes.
Theories of the origin of laterite—The origin of laterite is intimately
connected with the physical, climatic, and denudational processes at
work in India. The subject is full of difficulties, and although many
hypotheses have been advanced by different geologists, the origin of
the (high-level) laterite is as yet a much-debated question. One
source of difficulty lies in the chemical and segregative changes which
are constantly going on in this rock, which obliterate the previously
acquired structures and bring about a fresh rearrangement of the constituents of the rock. It is probable that laterites of all the different
places have not had one common origin, and that widely divergent
views are possible for the origin of the different varieties.
From its vesicular structure and its frequent association with
basalts, it was at first thought to be a volcanic rock. Its subaerial
nature was, however, soon recognised beyond doubt, and later on it
was thought to be an ordinary sedimentary formation deposited either
in running water, or in lakes and depressions on the surface of the
traps. Still later views regard the rock as the result of the subaerial
decomposition in situ of basalt and other aluminous rocks under a
warm, humid and monsoonic climate. Under such conditions of
climate the decomposition of the silicates, especially the aluminous
silicates of crystalline rocks, goes a step further, and instead of kaolin
being the final product of decomposition, it is further broken up into
silica and the hydrated oxide of alumina (bauxite). The vital action
of low forms of vegetable life was at one time suggested as supplying
the energy necessary for the breaking-up of the silicates to this last
stage. The silica is removed in solution, and the salts of alkalies and
alkaline earths, derived from the decomposition of the ferromagnesian
and aluminous siKcates, are dissolved away by, percolating water.
The remaining alumina and iron oxides become more and more concentrated and become mechanically mixed with the .other products
liberated in the process of decomposition. The vesicular or porous
structure, so characteristic of Igjfcefite, is due to molecular segregation
THE PLEISTOCENE SYSTEM
297
taking place among the products left behind. For the latest views on
laterite and bauxite of India see Dr. C. S. Fox's memoir. ^
Mr. J. M. Maclaren ^ declared that laterite deposits are due to the
metasomatio replacement (in some cases by mechanical replacement)
of the soil or sub-soil by the agency of mineralised solutions brought
up by the underground percolating waters ascending by capillary
action to the superficial zone.
From the highly variable nature of this peculiar rock, it is possible
that every one of the above causes may have operated in the production of the laterites of different parts according to particular local conditions. Sir Lewis Fermor is of this opinion,'and has declared that no
one hypothesis will be able to account for all the laterite deposits of
the Indian Peninsula.
Laterite rock-bodies are subject to secondary changes, a fact which
introduces further complexity. " Under conditions of free drainage
and high rainfall (2,500 mm. per year, or more) the laterite may
accumulate^without much further change, the soluble products of
hydrolysis being rapidly lost by leaching. On the other hand, under
impeded drainage conditions and alternations of wet and dry seasons,
the fluctuating ground water, carrying dissolved silica and bases, may
effect a complete change in the laterite, whose gibbsite component,
according to Harrison, is converted into secondary kaolins, stained
red by hydrous iron oxide residues." In this manner some authorities
have explained the formation of the vast masses of red earth capping
igneous rock-terrains of humid tropics, such as the gneissic areas of
Madras. This implies a resilicification of the bauxitic or gibbsitic base
of laterite.into secondary clays.*
The age of laterite—The age of the existing high-level laterite cap
is not detoyminable with certainty; in part j t may be Pliocene, or
even older, in part its age is Post-Tertiary (Pleistocene) or somewhat
later, and it is probable that some of it may still be forming at the
present day ; that of the low-level, coastal laterite must obviously be
stiil younger. The earliest remains of prehistoric man in the shape of
stone implements of the Palaeolithic type are found embedded in large
numbers in the low-lying laterite.
There is evidence, however, that important masses of laterite
' Bauxite and Aluminous Laterite Occurrences of India, Mem. O.S.I, vol. xlix. pt. 1,
chap. i. 1923.
^ Geological Magazine, Dec. V. vol. iii. 1906.
^ F . Hardy, Some Aspects of Tropical Soils, Trims. Third Int. Cong. Soil 8c. vol. u,
1935.
298 ^
GEOLOGY OK INDIA
were formed in the Eocene, and even in earlier ages. A thin but constant sub-stratum of pisolitic haeniatilje, red earth or of bauxite occurs
at the base of the Nummulitio series in North-West India. Its subaerial mode of origin under the above 'conditions being granted, there
is no reason why ^t should be restricted to any particular age only.
According to several authorities latemte is seen at several other horizons in the stratigraphical record of India, especially those marking
breaks or unconformities when the old land-surfaces were exposed for
long durations to the action of the subaerial agents of change: A ferruginous lateritic gravel bed among the rock-records of past ages is,
therefore, held to be of the same significance as an unconformity conglomerate.
Economics—As stated above, laterite is at times, according to conditions favouring the concentration of any particular metallic oxide,
a valuable ore of iron or an ore of aluminium and manganese. The use
of laterite as an ore of iron is of very old standing, but its recognition
as a source of alumina is due to Sir T. H. Holland, and of manganese
to Sir L. L. Fermor. In several parts of southern India and Burma
laterite is quarried for use as a building stone from the facility with
which it can be cut into bricks; In fact the term-Iaterite originally,
has come from the Latin word later, a brick.
Laterite does not yield good soil, being deficient in salts as well as in
humus.
REFERENCES
L. L. Permor, Laterite, Geol. Magazine, Deo. V. vol. viii. 1911.
C. S. Pox, 3Iem. O.S.I, vol. xlix. pt. 1, 1923 ; Mining Magazine, vol. xxvi. pp. 8296, and Records O.S.I, vol. Ixix. pt. 4,1936 ; Aluminous Laterite and Bauxite,
London (1932).
P. Lake, Geology of 8. Malabar, Mem. O.S.I, vol. xxiv. pt. 3, 1890.
Sir T. H. Holland, Geol. Magazine, Deo. IV. vol. x. 1903.
References to Laterite in 0.8.1. publioations are too numerous to quote. The <*»
earlier Mems. vols. i. ii. ix. and x. may be oonsulted for descriptive purposea.
•AFTER XXIV
PLEISTOCENE AND BECENT
Examples of Pleistocene and Recent Deposits—Among the Pleistocene
and Eecent deposits of India are the following, each of which in its
respective locality is a formation of some importance. The highlevel river-terraces of the Upper Sutlej and other Himalayan rivers
and of the Narbada, Tapti and Godavari among the Peninsular rivers ;
the lacustrine deposits (Upper Karewa) of the Upper Jhelum valley
in Kashmir and the similar accumulations (Tanr) in the Nepal valley;
the foramin^ral sandstone (Porbander stone) of the Kathiawar coast
and the Teris of the Tinnevelli and Travancore coasts ; the aeolian
deposits of the Godavari, Kistna and Cauvery banks (resembling the
BJiur of the Ganges valley) and the loess deposits of the Salt-Range,
Potwar, and of Baluchistan ; the fluvio-glacial deposits of the Potwarplateau ; the stalagmitic cave-deposits of the Karnul district; the
black cotton-soil or Reg^r of Gujarat and the Deccan; the greatgravel-slopes (daman) of the Baluchistan hills, etc., are examples,
amqpg many other's, of the Pleistocene and later deposits of India,
each of which require a brief notice in the present chapter.
Alluvium of the Upper Sutlej—Ossiferous clays, sands and gravels,
the remains of the Pleistocene alluvium of the Upper Sutlej, ^ are found
in the Hundes province of the Central Himalayas covering several
himdreds of square miles and resting at a great height above the
present level of the river-bed. These deposits were laid down in the
broad basin of the Upper Sutlej while it was at a considerably higher
level, enclosing numerous relics of the living beings that peopled this
part of the Himalayas.' The old alluvium of the river is now being
deeply trenched by the very Sutlej which has already cut out of it a
picturesque and deep, narrow gorge some 3000 feet in depth. Th#
chief interest of the Hundes deposits attaches to the mammalian
fossils preserved in the horizontally bedded gravels. These deposits
have so far not been investigated systematically and only Rhinoceros,
1 Bee. G.S.I. vol. xiv. pt. 2, 1881.
299
300
GEOLOGY OF INDIA
Pantholops, Equus, Bos and Capra have so far been known from
isolated specimens.
_
,
Tapti and Narbada—In ihe broad basins of many of the Peninsular
rivers large patches of ancient alluvium occur, characterised by the
presence of fossils belonging to extinct species of animals. Of these the
old alluvial remains of the Narbada and Tapti are remarkable as lying
in deep rock-basins, at considerable elevations above their present
bed. Among other vertebrate and mammalian fossils, ^ these ancient
river sediments have preserved the earliest undoubted traces of man's
existence. Scattered in their alluvia are the stone-knives, hatchets,
arrows and other implements of man which he manufactured out of any
hard stone that he came across, whether it was Cuddapah quartzite or
Vindhyan sandstone, or the amygdaloidal agates.
There is some proof that the Narbada in those days was confluent
with the Tapti, and that its separation into a distinct channel was
effected at a comparatively late date by earth-movements. That the
course of the Narbada has undergone a serious disturbance during late
geological time is corroborated by another piece of evidence, namely
the precipitous falls of this river at Jabalpur.
The Karewas of Kashmir—The valley of Kashmir is an alluviumfilled basin, a large part of which is of recent formation by the river
Jhelum. More than half of its area, however, is occupied by outliers
of a distinctly older alluvium, which forms flat mounds or platforms,
sloping away from the high mountains that border that valley on all
sides. These deposits, known in Kashmir language as Karewas,^ are
composed of fine silty clays with sand and bouldery gravel, the coarse
detritus being, as a rule, restricted to the peripheral parts of the
valley, while the finer variety prevails towards the central parts.
The bedding of the Karewas is for the greater part almost horizontal,
but where they abut upon the Pir Panjal, or the mountains of the
south-west border of the valley, they show evidence of a good deal of
upheaval, dipping sometimes as much as 40° at some places, the direction of the dip being towards the valley.*
Middlemiss' work in the Pir Panjal and elsewhere has greatly
modified the views regarding the age and thickness of these deposits.
a
^ Crocodilus, Trionyx, Pangshura, TJrsus, Bubalus, Bos, Equus, Sus, Oervus, Elephas,
Hippopotamus and Rhinoceros. Besides these, shells of land-molluscs such as Melania,
Pianorhis, Paludina, Lymnia, BulUnus, Unio are found in the alluvium of the Narbada.
^ F. Drew, Jammu and Kashmir Territories, p. 210, 1875.
' Recent investigations have revealed some Karewa deposits even on the summit of
the Pir Panjal (11,000 ft.), thus proving that the latter mountains have been elevated
nearly 5000 ft. since the Karewas were_deposited. Sec. G.S.I. vol. xliv. pt. 1, 1914.
PLEISTOCENE AND RECENT
301
He has sliown that their thickness amounts to 4500 feet at least, and
that the lower part of the Karewa deposits is considerably older than
any of the glacial moraines on the Pir Panjal and may be of Middle
Siwalik age. In the Upper Karewas several successive terminal
glacial moraines, composed of boulders, pebbles and sands, separated
by fine clays (some of them of the type of varved clays), denoting the
deposits of the warm interglacial periods of melting ice, have been
observed. In some sections of the Karewas, according to some
observers, deposits of three or four distinct glacial periods can be
made out.
The Karewas, in their upper part at least, are supposed to be the
relics of old extensive lake-basins which intermittently came into
existence during the warm interglacial periods of melting ice and
which periodically filled the whole valley of Kashmir from end to end
to a depth of more than 1000 feet. This old alluvium has been subsequently elevated, dissected, and in a great measure removed by
subaerial denudation as well as by the modern Jhelum into the Karewa
outliers of to-day. For further information regarding Karewa see
Chapter XXVII.
_ .
Old alluvial deposits, to which a similar origin is ascribed, are found
in the Nepal valley, and are known there under the local name of
Tanr. They contain a few peat and phosphatic beds enclosing mammalian relics.
Porbander stone (Miliolite)—In a previous chapter it was mentioned
that all along the eastern coast of India, from the Ganges delta to the
extremity of the Peninsula, there is a broad strip of Tertiary and PostTertiary alluvium containing marine shells and other fossils. The
Tertiary part of these deposits has been described already under the
title of the Cuddalore series, in Chapter XVII; the remaining younger
part occupies small tracts both on the east and west coast. That on
the east coast, however, assumes a considerable width and forms large
tracts of fertile country from the Mahanadi to the Cape. On the
Malabar coast this alluvial belt is very meagre and is confined to the
immediate vicinity of the coasts except at its north end, where it
widens out into the alluvial flats of Gujarat. On the Kathiawar coast
at some places a kind of coastal deposit occurs known as the Porbander
stone (sometimes also as Miliolite), which is noteworthy. It is composed of calcarequs wind-blown sand, the sand grains being largely
made up of the casts of foraminifers, the whole compacted into a white
or cream-coloured, rudely-bedded freestone. The rock known as
Junagarh limestone is a typical aeolian hmestone, situated 30 miles
302
GEOLOGY OF INDIA
inland from the sea coast and 200 feet thick. It is mainly composed
of fragments of calcareous shells (rdost of them of living species)
cemented by lime. About 6'to 12 per cent, of foreign particles of the
Girnar igneous rocks enter into the composition. It is believed that
the Kathia^yar peninsula stood 150 feet lower than at present and
was probably in Pleistocene time an island or group of islands. From
their softness and the ease with which they receive dressing and ornamental treatment, these limestones are a favourite material for
architectural purposes in many parts of the Bombay Presidency. ^
'Sand-diines—Sand-dunes are a common feature along the Indian
coasts, particularly on the Malabar "coast, where they have helped to
form a 'large number of lagoons and backwaters, which form such a
prominent feature of the western coast of India. In Orissa there are
several parallel ridges of sand-dunes on the plains fronting the coast
which are held to indicate the successive positions of .the coast-line.
Sand-loving grasses and other vegetation help to check the further
progress of the dunes inland.
Sand-dunes are also met with in the interior of the Peninsula, in the
broad valleys of the Kistna, Godavari, etc., occupying a wide stretch
of the coastal terrain of Orissa. They are also common in the lower
Indus valley, in Cutch and for a considerable distance inland on the
Mekran coast. The sand is blown there by the strong winds blowing
through these valleys during the hot-weather months. A large
volume of sand is thus transported and accumulated along the river
courses, which are unable to sweep, them away (cf. Bhur land of the
Ganges valley).
The peculiar form of sand-hills known as Teri on the Tinnevelli
coast is also of the same origin.
Loess—In the country to the west of the Indus, in N.W. Punjab,
and on the Salt-Range, there are subaerial Pleistocene accumulations ^'
of the nature of loess, a loose unstratified earthy or sandy deposit but
little differing in composition from the alluviuni of the plains. Loess,
however, differs from the latter in its situation at all levels above the
general surface of the plains and in its being usually traversed by fine
holes or tubes left by the roots of the grasses growing upon it. The
lower parts of Baluchistan are largely covered with wind-blown, more
or less calcareous and sandy earth, unstratified and loosely consolidated. On the ilat plateau top of the Salt-Range loe^s is a very widespread superficial deposit, and on many plateaus, which form the
summit of this range, the accumulation' of loess from the dust and
1 Fedden, MemZO.S.I. vol. xxi, 1885.
PLEISTOCENE AND RECENT
303
sand blown from the Punjab plains is yet in progress. The inequalities of the surface, produced by its irregular distribution, are the cause
of the numerous shallow lakes ^ on the summit of the Salt-Range.
Loess is also a prevalent superficial formation in the country to the
north (Potwar), where its dissection by an intricate system of branching ravines has produced had land tracts.
The conditions that have favoured the^growth of loess in these parts
are their general aridity and long seasons of drought. These give rise
to dust-storms of great violence in the hot-weather months preceding
the monsoons, which transport vast clouds of dust and silt from the
sun-baked plains and dried-up river-basins, and heap them on any
elevated ground or accidental situation. The isolated dust-mounds
one notices in some parts of the Punjab are attributable to this cause.
Potwax fluvio-glaeial deposits—Potwar ^ is an elevated plain lying
between the northern slopes of the Salt-Range and the Rawalpindi
district. A few feet below the ordinary surface alluvium of some parts
of these plains is found a curious intermixture of large blocks of rooks
up to 50 feet in girth, with small pebbles and boulders, the whole
embedded in a fine-grained clayey matrix. The material of the blocks
suggests their derivation from the high central ranges of the Himalayas, while their size suggests the action of floating ice, the only
agency which could transport to such distances such immense rockmasses. Scattered moraine and erratic blocks, assigned to the action
of floating ice during the last Glacial period, are found between Attock
and Campbellpur on the surface of the Potwar plateau. The Indus
river is noted for floods of extraordinary severity (owing to accidental
damsdn the upper narrow gorge-like parts of its channel or that of any
of its tributaries).^ Many such floods have been known since historic
times, and some have been recorded in the chronicles. The water so
held up by the dam spreads out into a wide lake-like expanse in the
broader part of the valley above the gorge. In the Pleistocene times,
when, as has been shown in a previous chapter, the Himalayas were
experiencing arctic conditions of climate, the surface of the lake would
be frozen. Thesudden draining of the lake, consequent on the removal
of the obstacle by the constantly increasing pressure of the waters
resulting from the melting of the ice in springtime, would result in the
> Rec. G.8.I. vol. xl. pt. 1, 1910.
*Sec. G.S.I. vol. jc. pt. 3, 1877, Bee. G.S.I, vol. xiii. pt. 4, 1880, and vol. Ixi. pt. i~
1929.
' For an interesting account of some of the recent disastrous floods of the Indus and
their cause, obtained from eye-witnesses and from personal observations, see Drew,
Jammu and Kashmir Territories. London, 1875.
304
GEOLOGY OF INDIA
tearing off of blocks and masses of rocks frozen in and surrounded by
the ice. The rushing debacle would float down the ice-blocks with
the enclosed blocks of rock, to be dropped where the ice melted and the
water had not velocity enough to carry or push them further. This
would, of course, happen at the site wHere the river emerged from its
mountain-track and entered the plains.. The above is regarded as the
probable explanation of the origin of the Potwar deposits. It thus
furnishes us with another cogent evidence of the existence of glacial
conditions, at any rate in the Himalayas.
Cave deposits—Caves.^ But few caves of palaeontological interest
exist in India, and of these only one has received the attention of
geologists. The caves in other countries have yielded valuable ossiferous stalagmitic deposits, throwing much light on the animal population, particularly the cave-inhabiting larger mammals, of late geological times, their habits, mode of life, etc. During Pleistocene times
caves were used as dwellings by prehistoric man and important relics
of his handiwork, art and culture are sometimes preserved on the
walls and floors of the caves.' The only instances of the Pleistocene
caves are a few caverns in the Karnul ^ district in the neighbourhood
of Banaganapalli, in a limestone belonging to the Kurnool series. In
the stalagmite at the floor, there occurs a large assemblage of bones
belonging to a mixture of recent and sub-recent species of genera, like
Viverra, Hystrix, Sus, Rhinoceros (extinct), and Cynocephalus, Equus,
Hyaena, Manis, etc. (living species).
A small cave in a limestone belonging to the Triassic age, occurring
in the neighbourhood of Srinagar, .near Harwan, was recently found
to contain mammalian bones on its floor. They included the remains
of sub-recent species as Gervus, Aristotelis (Sambur), Sus scropha
(European pig), and an unknown antelope. A number of small caves
are found in the great Trias limestone cliffs of Kashmir, but they have
not been investigated.
Regur—Among the residual soils of India there is one variety which
is of special agronomic and geological interest. This is the black soil,
or Regur,^ (Chernozem)- of many parts of Gujarat, the Central Provinces and other " cotton districts " of the Deccan. Regur is a highly
argillaceous, somewhat calcareous, very fine-grained black soil. It is
extremely sticky when wetted and has a capacity for retaining a
large proportion of its moisture for & long time. Among its accessory
1 Sec. G.S.I. vol. xix. pt. 2, 1S86 ; Pal. Indica, sers. x. vol. iv. pt. 2, 1886.
2 Mem. G.S.I, vol. iv. pp. 183 and 357, and vol. vi. p . 235 ; Rec. vol. iv. p. 80, 1871.
' From Telugu word Regada.
PLEISTOCENE AND.RECENT
305
constituents are a high percentage of iron oxide, calcium and magnesium carbonates, the former disseminated as hankar, and a veryvarying admixture of organic matter, humus, ranging from one to as
much as 10 per cent. It is probably owing to its iron and humus
content that the prevailing dark, often black, colour is due. The
black cotton soil is credited with an extraordinary degree of fertility
by the people ; it is in some cases known to have supported agriculture for centuries without manuring or being leifc fallow, and witli no
apparent sign of exhaustion or impoverishment.
The origin of Eegur—The origin of this soil is yet not quite certain.
It is generally ascribed to long-continued surface action on rocks like'
the Deccan Trap and Peninsular gneisses of a basic composition. The
decomposition of the basalts in situ and of aluminous rocks generally, would result in an argillaceous or clayey residue, which, by a long
cycle of secondary changes and impregnation of iron and decomposed
organic matter, humus, resulting from ages of jungle growth over it,
•would assume the chaiactei of Regui.
The thickness of the regur soil-cap is highly variable, from one foot
to 50 feet, while the composition of the soil shows considerable variation with different depth horizons, especially in its clay content and
lime segregation. The clay-fraction of black cotton soil is very rich
in silica, 60 per cent, and iron 15 per cent, with only 25 per cent of
alumina.
" Daman " slopes—^Alluvial fans or taluses fringing the mountains
of Baluchistan, and known as " Daman ", are another example of
Pleistocene deposits. These are a very prominent feature of the hilly
parts of Waziristan and Baluchistan where the great aridity and
drought favour the accumulation, of fresh angular debris in enormous
heaps at the foot of the hills. Wells that are commonly excavated in
these gravel slopes (and which are known as Karez) illustrate a peculiar
kind of artesian action. The Karez is merely a long underground,
almost horizontal, tunGel-Uke bore driven into the sloping talus tUl
it reaches the level of permanent saturation of water, which is held
in the loose porous gravel. The water is found at a sufficient pressure
to make it flow at the mouth of the well. The underground tunnel
may be several miles in length and connected with the surface by a
number of bore-holes.-^
The Human epoch—In the foregoing account of the later geological
deposits of India there is everywhere a gradual passage from the
' Vredenburg, Mem. vol. xxxii. pt. 1, 1901; Oldham, Sec. Q.S.I. vol. ixv. pt. 1,
1892.
306
GEOLOGY OF INDIA
Pleistocene to the Eecent, and from tliat to Prehistoric. These periods
overlap each other much as do the periods of human history. As in
the other parts of the world, the Pleistocene in India also is distinguished by the presence of Man and is,known as the Human epoch.
Man's existence is revealed by a number of his relics preserved
among the gravels of such rivers as the Narbada and Godavari, and
the Soan, or in other superficial alluvia, both in South and North
India. On the surface of the Potwar plateau there are found scores of
sites containing flint artefacts of ? Chellean industry in hundreds of
flakes and cores. Stratigraphically these implements are dated by
being preserved in a few cases in the topmost beds of the Upper
Siwalik boulder-conglomerate and in the older alluvium of the Soan. ,
These archaic human relics consist of various stone implements that
prehistoric man used in his daily life, ranging from rude stone-chippings, cores and flakes to skilfully fashioned and even polished instruments like knives, celts, scrapers, arrow-heads, spears, needles, etc.,
manufactured out of stone or metal or bone. These instruments
(" artefacts ") become more and more numerous, more widely scattered, and evince an increasing degree of skill in their making and in
their manipulation as we ascend to newer and younger formations.
This testimony of his handwork furnishes us with the best basis for
the classification of this period into three epochs :
3. Iron Age.
2. Bronze Age.
1. Stone Age.
Recent, circa 6000 B.C.
Neolithic—^polished tools. Sub-Recent, circa
20,000-8000 B.C.
Palaeolithic—rude tools. Md. and Up. Pleistocene, ;2OO,0O0-2O,O0O B.C.
These three stages of the Human epoch, decipherable in the Pleisto- .
cene records of the other parts of the world, are.recognisable in the '^•
numerous relics of man discovered in India. Besides bronze implements, the primitive Indian used implements made of copper, a
material which he obtained from some deposits of native copper in
Southern India.'The existence of man in an age earlier than the older alluvia of the
Narbada and Godavari is a matter of conjecture only. No signs of the
existence of human beings are observed in the Upper Siwalik, except
perhaps in the top-most strata. Whether he was a witness of nature's
^ Prehistoric and Protohistoric Relics of Southern India, by R. B. Foote, Madras, 1915;
Old Ohipped Stones of India, by A. C. Logan, Calcutta, 1906.
PLEISTOCENE AND RECENT
307
last great phenomenon, the erection of the Himalayan chain to its
present height, or whether he was a contemporary of the Sivatherium
or the Stegodon, is a profoundly interesting speculation, but for which
no clue has been hitherto discovered. The question has hardly received any attention in India in the past due mainly to the paucity or
absence of cave-deposits. It is, however, possible that valuable geological and anthropological data may be obtained by search in the
Upper Siwalik, in the older alluvia and river terraces, the travertine
deposits of springs, loess caps and mounds, etc.
Here, however, we reach the limits of geological inquiry. Further
inquiry lies in the domains of anthropology and archaeology.-^
Few changes of geography have occurred in India since the Pleistocene. After the great revolutions at the end of the Pliocene, the
present seems to be an era of geological repose. A few minor warpings or oscillations in the Peninsula ; the extinction of a few species ;
the migration and redistribution of others; some changes in the
courses of rivers, the degradation of their channels a few feet lower,
and the extension of their deltas; the silting up of the Kann of
Cutch ; a few great earthquakes ; the eruptions of Barren Island
and other minor geological and geographical changes are all that the
geologist has to notice since the advent of man in India.
REPBRENGES
References to the various subjects treated in this chapter have been given
against each.
'• Ancient Hunters, W. J. Sollas (Macmillan), 1924; Prehistoric India, P. Mitra (Cal"
cutta University), 1927.
CHAPTER XXV
PHYSIOGRAPHY
IN the light of what we have seen of the geological history of India, a
brief re-examination of the main physiographic features of the country
will be of interest. Every geological age has its own physiography,
and, therefore, the present surface features of India are the o.utcome, in
a great measure, of the latest chapters of its geological history.
Principles of physiography illustrated by India—Physiography is
that branch of geology which deals with the development of the existing contours of the land part of the globe. In the main, dry land owes
its existence en masse to earth-movements, while the present details of
topography, its scenery and its landscapes, are due to the action of the
various weathering agents. In the case of elevated or mountainous
regions of recent upheaval, the main features are, of course, due to
underground forces, hypogene agencies ; but in old continental areas,
which have not been subject to crustal deformation for long ages, the
epigene or meteoric forces have been the chief agents of earth-sculpture. Land areas of great antiquity, therefore, possess earth-features
of a subdued relief; ultimately it is the fate of the centres of ancient
continents to be overspread by deserts. In the latter class of earthfeatures there is no correspondence observable between the external
configuration of the regions and their internal geological structure.
Here the high ground does not correspond to anticlinal, or the hollows
and depressions of the surface to synclinal folds. ^The accumulation
of the eroded products derived from the degradation of the elevated
tracts by the subaerial, meteoric agencies in a low, broad zone of
lodgment, gives rise to a third order of land-forms—the plains of
alluvial accumulation.
The three physiographic divisions of India afford most pertinent
illustrations of the main principles of physiography stated above.
The prominent features of the extra-Peninsula, the great mountain
border of India, are those due to upheaval of the crust in late Tertiary times, modified to some extent by the denuding agents which
have since been operating on them ; those of the Peninsula are the
. -308
PHYSIOGRAPHY
309
results of subaerial denudation of a long cycle of geological ages, modified in some cases by volcanic, and in others by sedimentary accumulations ; while the great plains of India, dividing these two regions,
owe their formation to sedimentary deposition alone, their persistent
flatness being entirely due to the aggrading work of the rivers of the
Indus-Ganges system during comparatively recent times.
Whatever may be the cause of the upward and downward movements of the earth's surface, which have originated the broad features
of its rehef—the great ocean basins, continents and mountains—
whether it be the contraction of the earth due to its loss of heat, or the
disturbance of its isostatic conditions, movements of depression must
always be in excess of elevation. In fact, uplift can only take place on
a minor scale and only locally, where any two adjacent master-segments of the earth's sphere in their subsidence squeeze between them,
and ridge up an intervening area by the enormous tangential thrusts
involved in the sinking of the former. On this view, briefly expressed,
the Himalayas have come into existence by the compression of the
geosynclinal belt of sediments, a comparatively weak zone in the
earth's circumference, between the great plateau of Central Asia and
the horst of Gondwanaland.
The main elements of the physiography of a country are five :
(1) Mountains.
(2) Plateaus and Plains.
(3) Valleys.
(4) Basins.
(5) Coast-hnes,
1. MOUNTAINS
Mountains may be (1) original or tectonic, or (2) subsequent or
relict. The student already knows that these two types characterise
the two major divisions of India. Tectonic mountains include (a) accumulation-mountains and (6) deformation-mountains. Volcanoes,
dunes or sand-hills and moraines are examples of the former, while
mountains produced by the deformation or wrinkling of the earth's
crust are examples of the tectonic type. In the latter the rehef of the
land is closely connected with its geological structure, i.e. the strike,
or trend, of these mountains is quite conformable with their axis of
uplift. They are divisible into two classes : (i) folded mountains, and
(ii) dislocation-mountains. Of these, the first are by far the most important, comprising all the great mountain-chains of the earth. The
Himalayas, as also all the other mountain-systems of the extraPeninsular area, are of this type.
310
GEOLOGY OF INDIA
The Structure of the Himalayas—The structure of the outer or subHimalayan ranges is generally of great, simplicity ; they are made up
of a series of broad anticlines and synclines of the normal type, a
modification of the Jura type of mountain structure. These outer
ranges, dissected into a series of escarpments and dip-slopes, are
separated by narrow, longitudinal tectonic valleys or depressions,
called Duns. The reversed strike-faults mentioned on page 264 are a
characteristic feature in the tectonics of these sub-Himalayan ranges.
The most prominent of these is the Main Boundary Fault, which extends along the length of the mountains from the Punjab to Assam.
We have seen on page 265 the true nature of these faults and the significance attached to them.
Many of the ranges of the outer Himalayas and several of the middle Himalayas as well, are of the orthoclinal type of structure, i.e., they
have a steep scarp on the side facing the plains and a gentle inclination facing Tibet. It is a characteristic of the folds of this part of the
Himalayas that the anticlines are often faulted steeply in their outer
or southern limbs, the fault-scarp lying in juxta-po'sition with much
younger rock-zones.
This zone is succeeded by a belt of more compressed isoclinal folds,
which are strictly autochthonous in their position. It is followed, in
the Pir Panjal range and in the Simla-Chakrata area, by a system of
over-folds of the recumbent type, severed by reversed faults that have
passed into thrust-planes, along which large slices of the mountains
have moved bodily southwards—the Nappe zone of the Himalayas. ^
Two more or less parallel and persistent planes of thrust have been
traced at the foot of the Pir Panjal range along its whole length from
the Jhelum to the Ravi. The outer of these has thrust the autochthonous Carboniferous-Eocene belt of rocks over the Mid-Tertiary
Murree series, while the inner thrust has driven the older Purana
schists and slates of the central mountains over the autochthonous
Carbon-Eocene rocks along an almost horizontal plane of thrust
(Kashmir nappe).
In the Krol belt of the Simla Himalayas a tectonic sequence has
been worked out, revealing at least two nappes of Palaeozoic and
older rocks over-riding the autochthonous fold-belt of the Tertiary
rocks of the outer Himalayas. These are the Krol nappe and the
Garhwal nappe, separated by two distinct thrust-planes. In the
^ Pilgrim and West, Structure of the Simla Bofsks, Mem. O.S.I, vol. liii, 1928;
Wadia, Bee. O.S.I. vol. Ixv, pt. 2, 1931 and vol. Ixviii. pt 2, 1934; Auden, Mec. G.8.1.
vol. Ixvii. pt. 4, 1934.
PHYSIOGRAPHY
311
neighbourhood of Solon and Subathu, Nummulitic and Dagshai strata
crop out as windows bora beneath Palaeozoic rocks of the Krol nappe. ^
The structure of the inner Himalayas has not yet been the subject
of such intensive study and investigation as that which has so far
unravelled the inner architecture of the Alps. A great deal of investigation in the central ranges, especially the zone of most complex
folding and intrusion, remains to be done before which it is possible
to say anything regarding the structure of these mountains except in
very general terms. Bast of Kumaon no systematic geological work
has yet begun. The evidence so far obtained, however, tends to show
that large areas of the Western Himalayas possess a comparatively
simple' type of mountain tectonics, and the piles of nappes, their
complex re-folding, digitations and inversions such as those to which
modern theory ascribes the formation of the Swiss Alps, have not been
observed on the same scale of intensity or order of magnitude. The
thrusts in the Himalayas that have driven sheets of older rocks over
the newer recall rather tKe thmst-planes of the Scottish Highlands.
The great sedimentary basins of Hazara and Kashmir, lying between
the crystalline axis and the zone of the great thrusts (the nappe zone)
reveal a system of normal open anticlines and synclines without shearing, or reduplication, indicating that the nappes have undergone no
subsequent body deformation.
As we approach the central crystalline axis of the Himalayas, however, there is manifested a puzzling monotonous uniformity of rockfacies—a uniformity that is only apparent—^induced by the regional
and thermal metamorphism to which the rocks have been subjected.
The folds become more densely packed and over-folds, inversions and
thrust-planes assume increasing intensity. Situated within these
areas of tectonic deformation are circumscribed belts of comparatively less altered rocks. Plutonic injections assume a greater role
and serve to make the structure more complex by obliterating distinction between the crystalline and sedimentary series.
From a tectonic point of view, according to present data, we may
divide the Western Himalayas into the following structure-zones :
The Foreland. North fringe of Gondwanaland, covered under Tertiary
sediments.
1. Siwalih belt—Jura type of folds of Upper Tertiary river-deposits.
2. Sirmur belt—more compressed isoclinal folds of lagoon sediments.
> Pilgrim and West, Structure of the Simla Rocks, Mem. O.SJ. vol. liii, 1928;
Wadia, Bee. G.S.I, vol. Ixv, pt. 2,1931 and vol. Ixviji. pt. 2,1934 ; Auden, Eec. G.S.I.
vol. Ixvii. pt. 4, 1934.
312
GEOLOGY OF INDIA
Autochthonous Fold Zone.
3. Carboniferous-Eocene 6eit—recumbent folds of the Eocene with
cores of Carbon-Trias rocks—Panjal voloanics, or Krol series.
Nappe Zone.
,
4. Purana Slate 6eZ«—unfossiliferous slates containing Palaeo- and
Meso-zoio outcrops which have expanded out in the Hazara
and Kashmir sedimentary basins.
5. Crystalline belt—of the central axial chain of metamorphic rocks
with granite intrusions—a geanticline within a geosyncline.
6. Tibetan 6ett—marine sediments of Cambrian to Eocene age in the
Himalayan geosyncline.
The Nappe Zone of Kashmir
In these mountains the nappe zone of inner Himalayan rocks has travelled
far along a horizontal thrust (Panjal thrust) so as to lie fitfully sometimes
against a wide belt of the autochthone, at other times almost against the
foreland. The Kashmir nappe is composed mostly of pre-Cambrian sediments (Salkhala series) with a superjacent series (Dogra Slate), forming
the floor of the Himalayan geosyncUnal that has been ridged up and
thrust forward in a nearly horizontal sheet-fold. On this ancient
basement lie syncHnal basins containing a more or less full sequence
of fossiliferous Palaeozoic and Triassic marine deposits in various parts
of Kashmir. The latter are detached outUers of the Tibetan marine
zone, which in the eastern Himalaya is confined to the north of the
central Himalayan axis.
In the nappe zone to the north are more thrusts, not easily recognisable
in the crystalline complex which builds the Great Himalayan range of the
centre. These thrusts, bowever, are not of wide regional or tectonic
significance. As a tectonic unit, the Great Himalayan range is made up of
the roots of the Kashmir nappe, the principal geantioHne within the main
Himalayan geosyncline, consisting of the Archrean and pre-Cambrian sedimentary rocks together with large bodies of intrusive granites and basic
masses. Several periods of granitic intrusions have been observed, the
latest being post-Cretaceous, or still later, connectgd with the earlier
phases of the Himalayan uplift. A subordinate element of the Great
Himalayan .range is formed b y the southward extensions of the representatives of the Tibetan belt of marine formatio'ns belonging to the Palaeozoic
and Mesozoic.
The Nappes of the Simla Himalaya
Detailed mapping and study of the metamorphic gradations in ancient
rock-complexes have led G. E. Pilgrim and W. D. West to conclude that
the rocks of the Simla-Chakrata area, lying to the north of the Tertiary
belt (Outer Himalaya), are not in the normal position as previous observers _
liad believed, but have undergone complex inversions and thrusting. Four
PHYSIOGRAPHY
313
overthrusts are noted wliioh have trespassed over the 64 miles broad
Upper Tertiary area of Kangra and constricted it to barely 16 miles at
Solon. The thrusts represent flat recumbent folds of great ampKtude,
showing bodily displacement from the north towards the autochthonous
belt of the south-west. The pre-Cambrian (Jutogh and Chail series) is
piled up on the Carboniferous and Permian systems (Blaini and Krol
series), the entire sequence being totally unfossiliferous. Evidence of the
superposition of the highly metamorphosed pre-Cambrian (Jutogh and
Chail series), building some of the conspicuous mountain tops of the area
(KHppen) over the less altered Lower Palaeozoics and Blaini beds (Upper
Carboniferous), is obtained by a study of relative metamorphism and the
structural relations of thrusts and discordaiices. The older rocks, now
isolated, were once part of a continuous sheet over this area, but are now
separated from the roots in the north by the deep valley of the Sutlej. To
the south of the thrust zone, in the foothills, the older Tertiaries (Nummulitics) are separated from newer Tertiaries of the foothills by the series
of parallel reversed faults which have been designated as boundary faults :
(1) separating the Upper Tertiary from the Lower Tertiary, and (2) separating the Lower Tertiary from pre-Tertiary rocks. This last " boundary "
fault is really an overthrust corresponding with the Murree thrust of the
Kashmir mountains. Medlicott, Oldham and Middlemiss regarded these
faults and thrusts not as dislocations, but also as limits of deposition, no
Upper Tertiary occurring north of the outer fault and no Upper or Lower
Tertiary occurring north of the inner fault. Though this conception still
holds true to a large extent there are exceptions here, as in the other parts
of the Himalaya, viz. the occurrence of Nummuhtic and later Tertiaries to
the north of the inner Hne of faulting.
*
The nappe zone of the Simla region makes a more striking feature than
in Kashmir. I t commences some miles north of Solon and follows a
meandering E.S.E. course, separating the Krol (Permo-Carboniferous) belt
by the two great thrusts, Jutogh and Giri, which correspond with the
Panjal thrusts of the western Himalaya. The outer Umit of the Krol belt
is the Krol thrust, corresponding to the Murree thrust of Kashmir. As
shown by West and Auden, the Kiol thrust itself is steeply folded by later
disturbances which have plicated the KJrol belt. This Krol belt, which
tectonically corresponds with the Panjal range of Kashmir Himalayas,
extends along the Outer Himalayas for 180 miles south-east of Solon in a
tightly compressed sequence of Permo-Carboniferous strata. Near Solon,
Tertiary rocks crop out as windows from under the Krols.
East of Nahan the Krol thrust transgresses southwards and overlaps the
main boundary fault. Broadly speaking, the Kjol zone of Simla corresponds with the autochthonous fold-belt of Kashmir, but as with the latter
area, the autochthone is often greatly narrowed and at places obliterated
by the approach of the nappe-front of the gently incHned over-thrust shoes
from the north. Here and there as at Solon, the Krol zone itself is deformed and thrust forward over the Nummuhtics.
Massive porphyritic granite is intruded on a large scale into the preCambrians. This granite is part of the central crystalline axis of the
Himalaya, as in Kashmir and Hazara.,
314
GEOLOGY OF INDIA
The Superposed Nappes of the Garhwal Himalaya
The tectonics of this part of the Himalaya are discussed in a recent paper
by J. B. Auden.i Two nappes, the Krol and the Garhwal nappe, are
superposed one on the other and thrust forward to the obliteration of the
autochthone at places. Middlemiss' and > Griesbach's previous study of
this section of the Himalaya had given, in conformity with the tectonic
ideas prevalent then, a simple interpretation to the profile across the
Garhwal Himalaya, involving no horizontal displacements.
Proceeding north-east from the Sub-Himalayan Upper Tertiary zone
(Siwalik and Dagshai), there are encountered, according to Auden, the
following well-defined units:
(1) The autochthonous fold-belt comprising a substratum of Simla Slates
folded in with the Eocene, Dagshai and Siwahk series.
(2) The Krol nappe, comprising a thick succession of rocks in the Krol
series (probable Permo-Carboniferous) overthrust upon the Nummulitics
and Dagshai of (1).
(3) The Garhwal nappe superposed on the Krol nappe, the relations
being such that the Nummulitic, Jurassic and Krol rocks belonging to the
underlying Krol nappe completely surround the older Pateozoic metamorphosed and schistose series of roclTs of the superincumbent nappe and
dip below them in a centripetal manner.
(4) The Great Himalayan range of crystalKne phyllites and schists,
together with the phyllites, para-gneisses and schists, and intrusive granite
bodies.
(5) The Tibetan zone of fossiliferous sediments ranging in age from
Cambrian upwards to the Cretaceous (see Fig. 45, p. 441).
The northern flank of t h e Himalayas, beyond t h e crystalline axis,
revealed in the gigantic Tibetan escarpments which front t h e P u n j a b
Himalayas, such as those of Spiti, Garhwal and Kumaon, shows again
a somewhat simpler t y p e of structure, b u t beyond this not much is
known regarding their architecture.
The deep inflexions in the trend-line of the Himalayas noted in Chapter I,
p. 6, are an interesting study in the mechanisrti of mountain-building and
the reactions of the old stable blocks of the earth against the weaker zones,
the geosyncHnes. Eield work in the N.W. Himalayan syntaxis has proved
that the stratigraphy, structure and rock-components on the Kashmir
flank of the syntaxis pass over into Hazara right round the re-entrant angle
without any discordance, individual folds being traceable from one side of
the loop to the other. This feature is ascribed to the circumstance that the
Hiihalayan system of earth-waves as they emerged from the Tethys has
been pressed against and has moulded itself on the shape of a tongue-Uke
projection from the Indian Peninsular shield, one of the most rigid segments of the earth's crust. On meeting, with this obstruction the northerly
earth-pressures were resolved into two components, one acting from N.E.
the other from N.W., against the shoulders of this triangular promontory
of the Peninsular horst.
^Rec. G.S.I. vol. Ixxiii. pt. 4, 1937.
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GEOLOGY OF INDIA
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The tentatively postulated
syntaxis of tiie Assam Himalayas beyond the Tsangpo
(Brahmaputra) gorge is believed to have originated through
the obstruction offered by
the granite massif of the
Assam Plateau functioning as
the pivot. The resistance of
the Assam plateau to folding •
movements is manifested in
the perfect horizontality of its
strata. In the pre-Himalayan
period this plateau, with the
broken chain of Eajmahal
and Hazaribagh hills, formed
the structural backbone of
Northern India.
The sections reproduced in
Figs. 31 and 32 from Middlemiss ^ give an idea of the
structural relations of the
sub-Himalayan belts. Figs.
34 and 35 summarise current
ideas on the structure of the
Himalayas. Fig. 34 gives a
diagrammatic section of the
Kashmir nappe superposed on
the S.W. flank of the Pir
Panjal range. K g . 35 is a
representation of the Simla
nappe over-riding the outer
Himalaya of Simla.
Mountain ranges which are
the result of one upheaval
are known as Monogenetic;
those of several successive
upheavals Polygenetic. The
two outer parallel belts of
deposits of the Sirmur and
Siwalik systems very clearly
mark two successive phases
of uplift subsequent to their
deposition.
1 Mem. G.'S.I. vol. xxiv. pt. 2,1890.
PHYSIOGRAPHY
317
The mountain-ranges of Sind-Baluchistan and Burma, to the west
and the east of the Himalayas, are of a more simple geological structure, and, in the succession of normal anticlines and synclines of which
they are built up, recall the type of mountain-structure known as the
Appalachian. In the former area, especially, the mountains reveal a
very simple immature type of topography. Here the hill-ranges are
anticlines with intervening synclines as valleys. The sides of the
mountains, again, are a succession of dip-slopes.
In regions of more advanced topography, with greater rainfall and
a consequently greater activity of subaerial denudation, e.g. the outer
and middle Himalayas, this state of things is quite reversed, and the
valleys and depressions are carved out of anticlinal tops while the
more rigid, compressed synclinal systems of strata stand out as
elevated ground.
While the broad features of these regions are solely due to movements of uplift, the characteristic scenery of the mountains, the serried
lines of range behind range, separated by deep defiles and valleys, the
bewildering number of watersheds, peaks and passes and the other
"rugged features which give to the mountains their characteristic relief
and outline, are the work of the eroding agents, playing on rocks of
different structures and varying hardnesses. ^
, Among the mountains of the extra-Peninsula, the Salt-Kange must
/be held as an illustration of a dislocation-mountain. Its orthochnal
outline, i.e. its steep southern scarp and the long gentle northern slope,
suggests that these mountains are the result of a monoclinal uplift
combined with a lateral thrast flom the noith, •which has depressed the
southern part of the monocline under the Punjab plain, while the
[ upper part has travelled some distance over it along a gentle plane of
:J thrust.^ The Assam ranges, on the other hand, have a diiferent origin
and history, having as their back-bone a granite massif. The plateau
part of Assam has not undergone any considerable tectonic disturbance, save an uplift of epeirogenic kind subsequent to the Eocene.
These two ranges, at either extremity of the plains of India, share
some common physical features and are unique in their physiography
among the mountain-systems of India.
' The extremely rugged and serrated aspect of the lofty central ranges of the Himalayas, which are constantly'subject to the action of snow and ice, contrasts strongly
with the comparatively smooth and even outlines of the lesser Himalayas. . The
scenery of the outer Siwalik ranges; is of a different description, the most conspicuous
feature in it being a succession of escarpments and dip-slopes with broad longitudinal
valleys in between.
" E . R. Gee.
318
GEOLOGY OF INDIA
• '
The mountains of the Peninsula—With the exception of the now
deeply eroded Aravalli chain, all the Other mountains of the Peninsula
are mere hills of ciroumdenudation, the'relics of the •old high plateaus of
South India. The Aravalli range, marking the site of one of the oldest •
geosynclines of the world, is still the most dominant mountain-range
of the Indian peninsula, with summits reaching up to 4000 and 5000
feet. It was peneplaned in pre-Cretaceous times but has been since
slightly upwarped and dissected in the central part, though large tracts
of western Rajputana are a peneplain of low relief. Structurally the
Aravallis are a closely plicated synclinorium of rocks of the AravalH
and Delhi systems, the latter forming the core of the fold for some 500
miles from Delhi to Idar in a N.E.-S. W. direction. Its curving southeast boundary is a fault—the great boundary fault of Raj putana, which
brings up the Vindhyans against the Aravalli system. The hills south
of the Vindhyas (with the possible exception of the Satpuras) are mere
prominences or outliers left standing while the surrounding parts have
disappeared in the prolonged denudation which these regions have
undergone. Many of these " mountains " are to be regarded as ridges
between two opposing drainages. It is this circumstance which, first
of all, determined their trend and has subsequently tended to preserve
them as mountains.
2. THE PLATEAUS AND PLAINS
•
Plateaus are elevated plains having an altiifcude of more than 1000
feet. They may be of two kinds : (1) Plateaus or plains of accumulation, whether sedimentary or volcanic, and (2) plateaus and plains of
erosion.
Volcanic plateau—The best example of a plateau of accumulation
in India is the volcanic plateau of the Deccan, built up of horizontal
lava-sheets, now dissected into uplands, hills, valleys and plains. Its
external configuration corresponds exactly with the internal structm-e,
in the flat table-topped hills and the well-cut stair-like hill-sides. The
Western Ghat country abounds in such plateaus.
Erosion plateau—Plateaus of erosion result from the denudation of
a tectonic mountain-chain to its base-level and its subsequent upheaval. In them there is no correspondence at all between the external relief and geological structure. Some parts of Rajputana and
Central India afford an example of plain of erosion (peneplain) ; parts
of the Potwar plateau are another. The Archaean terrain of Chhota
Nagpiur contains peneplaned tracts studded with a few isolated worn
PHYSIOGRAPHY
319
hill-tops (inselbergs), detached by circumdenudation. The Parasnath
hill and the numerous solitary eminences of southern Chhota Nagpur
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are good examples of such inselbergs rising over the general level or
undulating contours of a 'peneplaned plateau country. The Assam
320
GEOLOGY OF INDIA
plateau must be regarded as a plateau of erosion, a detached, outlying
fragment of tlie Peninsula, connected with it through the intermittent
Rajmahal hills. I t has received some epeirogenic uplift since early
Tertiary.
Plains of accumulation—The great plains of the Indus and Ganges
are plains of sedimentary accumulation. The horizontally stratified
alluvium has the simplest geological structure possible, which is in
perfect agreement with their flat level surface.
3. VALLEYS
A valley is any hollow between two elevated tracts through which
a stream or river flows. Valleys are grouped into two classes according to their origin :
(1) Tectonic, or Original Valleys.
(2) Erosion-Valleys.
VaUey of Kashmir a tectonic vaUey—Tectonic valleys are exceptional features in the physiography of a country. They owe their
origin (1) to differential movements within the crust, such as troughfaulting, the formation of synclines, which may be regarded as the
complementary depression between two mountain-chain's, or (2) to the
irregular heaping-up of volcanic or morainic matter. The valley of
Kashmir, the Nepal valley and the many Duns of the sub-Himalayas
are instances of tectonic valleys, these being synclinal troughs enclosed between two contiguous anticlinal flexures. This aspect is,
however, somewhat modified by the deep alluvium which has filled up
t^e bottom as well as that which rests on the slopes of the bordering
mountains. Some valleys also result from the irregular accumulation
of volcanic or morainic material or of dunes of sand. Valleys
which run along fault-planes or fissures in the crust are also
tectonic valleys, being determined by movements of earth;
examples of such " fissure-valleys", according to some geologists, are afforded by the Upper Narbada and Tapti (page
17), which flow not in shallow base-levelled channels of their
own eroding, but in deep, linear fault-troughs filled with
older alluvia. These faults were of post-Deccan Trap formation, caused by the tectonic movements in North India. Such
valleys are of very rare occurrence, however, though it is
probable that the deep " rifts" of Baluchistan have originated
in this manner.
PHYSIOGRAPHY
-
32l
Erosjon-Valleys
Valleys of the Himalayas. The transverse gorges—With the exceptions noted above, the great majority of the valleys of the Peninsula
as well as of the extra-Peninsula are true erosion-valleys. The most
prominent character of the major Himalayan valleys is their transverse course, i.e. they run across the strike of the mountain, in deep
gorges or canons that the rivers have cut for themselves by the slow,
laborious process of vertical corrasion of their beds. The only exceptions are the head portions of the Indus, Brahmaputra, the Ganges,
and a few of their principal tributaries, which, for a part of their
course, are longitudinal streams and flow parallel to the mountainstrike. The cause of this peculiarity of the Himalayan system of
valleys has already been explained in Chapter I, as arising from the
situation of the watershed to the north of the main axis of uplift of the
Himalayas. Hence the zone of the highest, snow-capped ranges is
deeply trenched by all the rivers as they descend from their watershed
to the plains of India. The " curve of erosion " of these valleys, which
are yet in an immature stage of river-development, is, of course, most
irregular and abounds in many inequalities. The most conspicuous
of these is an abrupt fall of nearly 5000 feet, which most rivers have, as
they cross from the central Himalaya zone into the middle Himalaya
zone, proving that the former zone is one of late special upHft. The
same valleys, as they enter the end-portion of their mountain track—
the Siwalik zone—cut through the very deposits which they themselves laid down at an earlier period of their history. Thus here also
the apparently paradoxical circumstance is witnessed, that " the
rivers are older than the hills which they transverse ", which, on
equally trustworthy evidence, is true for the greater part of the
Himalayas. (See Chapter I.)
The configuration of the Himalayan valleys—'The transverse gorges
of the Himalayas, which are such characteristic features of the mounr
tains, illustrate several interesting phases of river-action. In the first
place their physical configuration in the eastern and western parts of
the mountains is quite different. In the Kashmir Himalaya the upper
courses of these streams show a series of abrupt alternations of deep
precipitous U- or I-shaped gorges with broad, open V-shaped valleys,
the latter always being found above the gorge-hke portions. In the
Eastern Himalayas of Sikkim and Nepal, on the other hand, the valley
courses are uniformly broad, with gently sloping sides, and they do not
exhibit the abrupt changes. This difference is due to the fact that the
322
- GEOLOGY OF INDIA
eastern part is a region of heavy rainfall, and hence the valley-sides
are subject as much to erosion as the bed of the channel; here lateral
corrasion is scarcely less marked than the vertical or downward
corrasion of the bed. In the Western Himalaya, on the other hand,
the rainfall is much smaller. River-erosion is the chief agent of denudation, hence deep defiles are cut out, of the hard crystalline rocks,
and broad V-hke valleys from the softer clay rocks. The latter yield
more readily to river-action because of the absence of any protective
covering of vegetation.
The Himalayan valleys are all in an early or immature stage of their
development; they have been rejuvenated again and again with every
upheaval of the inner higher ranges, hence the varying lithological
characters and structures of the surface over which they flow have
given rise to a number of waterfalls, cascades, and rapids in their
courses. These will gradually disappear by the process of headerosion, and in the later stages of valley-growth will be replaced by
ravines and gorges. The narrow defiles of the Himalayan valleys are
liable to be choked up by various accidental circumstances, such as
landslips, glaciers, etc., and produce inundations of a terrific nature,
when the dam is removed. ^Several of these floods are recorded within
recent times. ^ Many of the Himalayan valleys have been important
high-roads of commerce with Tibet, Chinese and Russian Turkestan,
etc., since very ancient times.
The deep gorges and canons, so characteristic of the Salt-Range and
Baluchistan, are due chiefly to climatic causes. The river at the
bottom is actively corrading and lowering its bed, while there is no
denuding agency to lower the banks in. these arid, rainless countries,
at au equal rate. The limestone rocks of the above districts have also
been a factor in evolving these features.
Valleys of the Peninsula—The valleys, of the Peninsula offer a striking contrast to those of the extra-Peninsula, for the former have all
reached the adult stage of their development. The principal valleys
of the Peninsula are broad and shallow, their gradients low, and by
reason of the levelling process being in operation for a long series of
ages, they are near the attainment of their base-level. Their cwrw of
erosion is, in the majority of cases, a regular curve from the source to
the mouth.
An exception to the above general case is afforded by the falls of
the Narbada near Jabalpur. Their existence in a river channel of such
great antiquity is inexplicable, and must be ascribed to recent tectonic
1 Chap. I. p. 39.
PHYSIOGRAPHY
323
disturbances (page 300). Tte physiograpMc features of t t e Narbada
valley are of interest. To the north, the fault-trough is bounded by
the great table-topped sandstone escarpments of the Vindhyan range,
500-800 feet high, and to the south are the gentle slopes of the Satpura
or the Mahadev hills, falling away in a series of abrupt scarps to the
Tapti river at their south foot. The eastward extension of the Vindhyan scarps, the Kaimur hills, continue the range along the north
flank of the Son Valley. The sources of the Son, Narbada and the
• MahanadiJie around the trap plateau of Amarkantak.
The above remarks only apply to the valleys of the eastern drainage.
The small but numerous streams that discharge into the Arabian Sea
are all in a youthful state of development, being all actively eroding,
torrential streams. Many of them abound in rapids and falls, of
which the most famous are the Gersoppa Falls on the Eiver Sharavati
in the North Kanara district, but there are a number of other lessknown instances. This greater activity of the westerly flowing
' streams, as compared to the opposite system of drainage is, of course,
due to the former streams having to accomplish the same amount of
descent to the coast as the latter, but within a far shorter distance of
their watershed. Under such circumstances, a river performs much
head-erosion, with the result that the watershed goes on continually
• receding. This process will continue till the watershed has receded to
J about the middle of the Peninsula and brought the grade of the
' channels on either side to an approximate equality.
4. BASINS OR LAKES
'' Basins or lakes. Functions of lakes—We have already considered
the great troughs of India—the Indo-Gangetic and Potwar troughs,
the West Rajputana alluvial basin, all of which are parts of the great
synclinorium of North India, ^ and the Irrawaddy trough of Burma ;
these are a part of the structural framework of India. We have here
to consider the minor topographic depressions. Lakes are larger or
smaller depressions on the surface, the majority of which are filled
with water, which, according to local conditions, may be fresh,
brackish or salt. Lakes are of importance as regulators of the watersupply of rivers, ensuring for them a more or less even volume of water
at all times and seasons, and preventing sudden inundations and
droughts. Their effect on the hydrography of a country like India,
would be very beneficial, but as stated before, in the chapter oru
* E. D. Oldham, Structure.of the Gangetio Plain, Mem. O.S.I, vol. xlii. pt. 2, 1917-
324
GEOLOGY OF INDIA
Physical Features, there are very few lakes in India of any considerable magnitude. Hence basins as a feature in the physiography of
India play but little part. The origins of lakes are diverse. The
following are a few Indian examples :
Types of lakes—(1) Tectonic lakes are due to differential earthmovements, some of which are of the :nature of symmetrical troughs,
while others are due to fracture or subsidence of the underlying strata.
The old Pleistocene lakes of Kashmir, whose existence is inferred from
the Karewa deposits of the present day, were of this type..
(2) Volcanic tasins. These are crater-lakes or explosion-crater
lakes. The famous Lonar lake of salt water in the Buldana district,
Berar, occupies a hollow which is supposed to have originated in a
violent volcanic explosion—{explosion-crater).
(3) Dissolution basins. These are due to a depression of the surface by underground solution of salt-deposits, or of soluble rocks like
gypsum and limestone. Some of the small lakes on the top of the
Salt-Range may be due to this circumstance, aided by the irregular
heaping of the loess deposits on its surface. Some of the Kumaon
lakes also are of this nature.
(4) Alluvial basins. These are formed by the uneven deposition of
sediments in deltas of rivers (Jhils); some lakes are formed of the
deserted loops of rivers (bayeau lakes), etc. The present lakes of the
Kashmir valley are alluvial basins of this nature, while the Pangkong,
Tsomoriri and the Salt-Lake of Ladakh in Kashmir territory are explained by Drew to have had a somewhat different origin. ^ They have
been formed by the alluvial fans from the side valleys (the tributaries) crossing the main valley and forming a dam which the waters
of the main valley were unable to sweep away. A number of the
lakes of Tibet have also originated in this manner, while some are supposed to have originated by differential earth-movements—tectonic
basins.
" "•
(5) Aeolian basins are hollows lying among wind-blown sand-heaps
and dunes. These are small and of temporary duration. Some of the
Salt-Range lakes are aeolian basins; the numerous Dhands, small
saline or alkaline lakes of Sind and W. Rajputana, are other examples,
- (6) Eock-fall basins are lakes produced by landslips or land-slides,
causing the precipitation of large masses of rock across the streamcourses. They are sometimes permanent. The small lakes of Bundelkhand are examples. The Gohana lake of Garhwal, formed by a huge
landslip across a tributary of the Ganges in 1893, is a recent instance.
^ Jummu and Kashmir 'Jlerrito'ries, London, 1875.
PHYSIOGRAPHY
325
(7) Glacial lakes. They are often prevalent in districts which bear
the marks of glaciation. In some cases the hollows are of glacial
erosion (true rock-basins),^ in other cases they are due to heaps of
morainic debris constituting a barrier across glacial streams. Numerous tarns and lakes on the north-east slopes of the Pir Panjal are
examples. Some of the Kumaon lakes are ascribed the latter origin.
Old glacial basins, now converted into grassy meadows, and bounded
by terminal moraines, are met with in front of some of the Himalayan
glaciers (which are now retreating). Some of the margs of Kashmir
are illustrations of such moraine-bound basins.
The Chilka lake of Orissa and the Pulicat lake of Nellore are lagoonlike sheets of brackish water which owe their origin to the deposition
of bars or spits of sand, drifted up along the coast by the action of
oblique sea-currents, across the mouths of small bays or inlets. The
lagoons of the Travancore coast (kayals) are of this nature.
5. COAST-LINES
The coast-lines of a country are the joint product of epigene and
hypogene agents. A highly indented coast-line is generally due to
subsidence, while a recently elevated coast is fronted by level plains
or platforms, cliffs and raised beaches.
In old lands, which have not undergone recent alteration of level,
many of the features are the result of the combined marine and subaerial erosion.
Coast-lines—The coast-line of India is comparatively uniform and
regular, and is broken by few indentations of any magnitude. For
the greater part of its length a sandy and gently-shelving coast-strip
is washed by a shallow sea. The proportion of the seaboard to the
mean length of the sides of the Peninsula is very small. The western
sea-board has, however, a large number of shallow lagoons and backwaters all along its length, which constitute an important topographic feature of these coasts. This coast is exposed to the action of
the persistent south-west monsoon gales which blow from May to
October, and is, therefore, subject to a more active erosion by the seawaves than the east coast.- The rapidity of the coastal erosion is,
however, in some measure retarded by the gently shelving nature of
the sandy shores, and also by the lagoons and back-waters, both of
which factors help to break the fury of the waves. The coasts are
fronted by a low submarine plain or platform, where the sea is
* The small lakes and tarns on the Pir Panjal are supposed to be of this description.
326
-
GEOLOGY OF INDIA
scarcely 100 fathoms deep. This " plain of marine denudation " is.
much broader on the western coast ths^n on the eastern. On both the
coasts* there are " raised-beaches " or more or less level strips of
coastal detritus, situated at a level higher than the level of highest
tides. This is a proof of a slight recent elevation of the coasts.
The Arakan coast, with its numerous estuaries and inlets extending
inland from a broad submarine shelf, is an excellent instance of an
area that has undergone sub-recent depression. P. Evans has suggested
that the whole of the Malay region, which was once a continuous
stretch of land from Assam to the Dutch East Indies, has been converted into a chain of islands and peninsulas by prolonged submergence of the land or a rise of the sea level.
For recent changes of level on the west coast and on the floor of the
north Arabian sea, see p. 32.
REFERENCES
W. H. Hobbs, Earth-Features and their Meaning (Maomillan), 1912.
R. D. Salisbury, Physiography (John Murray), 1909.
Sir S. G. Burrard and H. H. Hayden, The Geography and Qeology of the Himalaya
Mountains, 1907; Second Edition, revised by Sir S. G. Burrard and A. M.
Heron, 1932.
References to the physiographic features of India are scattered in numerous
publications of the G.8.I., especially in the writings of Blanford, MedUcott, Oldham, Hayden and many other geologists.
CHAPTER XXVI
ECONOMIC GEOLOGY
IN tlie preceding chapters we have dealt with the stratigraphical and
structural geology of India. I t is necessary for the student of Indian
geology to acquaint himself with the various mineral products of the
rock-systems of India and the economic resources they possess. In
the following few pages we shall deal with the occurrence, the geological relations and some facts regarding the production of the most
important of these products. For fuller details as well as for statistics,
leferencfe may be made to the excellent Quinquennial Reports of the
Mineral Production.of India, published by the Geological Survey of
India. 1
Por our purpose the various useful products which the rocks and
minerals of India yield, can be classified under the following heads :
(1)
(2)
(3)
(4)
(5)
(6)
Water.
Clays, Sands.
Lime, Cements, etc.
Buildiiig-Stones.
Coal, Petroleum, etc.
Metals and Ores.
(7) Precious and Semi-precious
Stones.
(8) Other Economic Minerals
and Mineral Products.
(9) Soils.
1. WATER
Wells. Springs. Artesian weUs—Besides its use for domestic and
agricultural purposes, water has many important uses in manufacturing and engineering operations, and the geologist is often called upon
to face problems regarding its sources and supply. Porous waterbearing strata exist everywhere among the old sedimentary formations as well as among recent alluvial deposits, but a knowledge of
the geological structure is necessary in order to tap these sources with
the maximum of efficiency. A large part of the rain that falls in
India is speedily returned to the sea, only a very small percentage
' Also the instructive series of Bulletins of Indian Industries and Labour (Mineral
series). J . Coggin.Brown, India's Mineral Wealth (Oxford University Press), 1936.
327
328
GEOLOGY OF INDIA
being allowed to soak underneath the ground. This arises from the
peculiar monsoonic conditions of its climate which crowds into a few
months all the rainfall of the year, which rapidly courses down in
flooded.streams and rivers. The small percentage' which is retained
soaks down and, flowing in the direction of the dip of the more pervious strata, saturates them up to a certain level (level of saturation)
and, after a variable amount of circulation imderground, issues out
again, on a suitable outlet being found, whether in the form of springs,
wells or seepages. In India the great alluvial plains of the Indus and
Ganges ate a great reservoir of such stored-up water, and yield large
quantities of sweet water by boring to suitable depths below the surface. Wells, the most common source of water in India, are m«rely
holes in the surface below the line of saturation, reaching the more
porous of the rock-beds, in which water accumulates by simple
drainage or by percolation. Springs are common in the rocky districts
where pervious and impervious strata are interbedded and inclined or
folded; or where a set of rocks is traversed by joints, fissures or
faults. If a porous water-bearing stratum with a wide outcrop is enclosed between impervious strata above and below it, and bent into a
trough, conditions arise for artesian wells "when a boring is made
reaching the water-bearing stratum. Such ideal conditions, however,
are rarely realised actually, but there are some other ways by which
less perfect artesian action is possible. The formation of an underground water-tight reservoir, either by the embedding of tongues of
gravel and sand under -impervious alluvial clays, the abutting of inclined porous strata against impervious unfissured rocks by means of
faults, or the intersecting of large fissures in crystalline rocks, gives
rise to conditions by which water is held underground ynder a sufficient hydrostatic pressure to enable it to flow out when an artificial
boring is made reaching the water. Artesian wells^ are not of common
occurrence in India, nor are conditions r_equisite for the formation of
artesian areas of any magnitude often met with. The best known
examples are those of Quetta along with the Karez already referred to
(p. 305) in the great gravel slopes (Daman) of Baluchistan. Artesian
wells are possible in the alluvial districts of North India and in
Gujarat,^ by the embedding of pockets of loose gravel or coarse sands
in the ordinary alluvium. The introduction of artesian wells into the
arid parts of this country, suffering from irregular or scanty rainfall,
' Instances of successful artesian borings in Gujarat are numerous. Artesian wells
also exist in the alluvial tract in Rawalpindi, Pondicherry, South Arcot, Sylhet, and
several other rock-bound depressions. Por additional information on artesian wells
in India see Vredenburg's Mem. G.S.I..v«l.'xxKii. pt. I, 1901,
ECONOMIC GEOLOGY
329
would be of great utility for the purposes of irrigation, but a knowledge of the geological structure of the district is essential before any
costly experiment can be undertaken in borings.
Tube-wells of 200 to 400 feet depth are simpler means by which
supplies of underground water of good quality can be tapped in the
alluvial districts, for domestic, industrial and, to a subordinate
extent, even for agricultural use. Tube-wells of one to two inch
diameter yield from 200 to 400 gallons of water per hour in many
parts of the plains of North India, while those of 6 to 8 inch diameter
yield as much as 60,000 gallons per hour. Wells of this calibre are,
however, few and their discharge depends more on the water-bearing
capacity of the substratum tapped than on the diameter of the tube.
Tube-well water, being derived from depth', is bacteriologically purer
and freer from organic impurities than ordinary well or surface waters,
though there may be a greater proportion of the chemically dissolved
salts in them.
In the drier parts of the country it is of the utmost importance that the
sub-soil water-level should be conserved by such devices as inverted wells,
tanks or reservoirs, constructing of small dams across glens and ravines, so
as to impovmd the run off from the rainfall for the benefit of wells situated
downstream. Such dams, made of earth, masonry or loose rock-fill, in the
foot-hills of mountainous country are of greater service in underground
water conservation than large projects for damming rivers. In such districts it is often found that construction of new, or renovation of old, tanks
or reservoirs improves the yield of surrounding wells. These devices replenish the underground water storage by diverting into the soil a part of
the surface! rainfall which would otherwise run away uselessly into the
rivers.
Mineral springs—Thermal '^ and mineral springs occur in many
parts of India, * especially in the mountainous districts like Sind,
Assam, Salt-Range, in the foot-hills of the Himalayas, in Kashmir, etc.
Among them are sulphurous (which are the most common), saline,
chalybeate, magnesian and other springs according to the principal
mineral content of the waters. There are over 300 such thermal and
mineral springs known in India.^ Thermal sulphurous springs are very
numerous on the outcrops of Eocene Nummulitic rocks in Rawalpindi
' There are several thermal springs in the Karakpur hills. One of these, the Sitahind, near Monghyr, is well known. At Gangotri, the source of the Ganges, there is
another well-known spring of hot water. At the boihng springs of Manikarn (Kulu)
people cook their food in the jets of issuing water. Tatta pani in Poonch is a thermal
sulphurous spring of large volume of discharge; temp, about 190° F. Bajgir (Patna),
Thanna (Bombay), Jwalamukhi (Kangra), Jamnotri (Tehri Garhwal) are other wellknown examples.
* Thermal Springs of India, Memoirs O.S.I, vol. xix. pt. 2, 1882.
330
GEOLOGY OF INDIA
district and in Sind. Some springs in the latter area have a
temperature over 120° F. Chalybeate springs are common in the
foot-hills of the Himalayas. Several Springs of radio-active water are
known, e.g. at Tuwa in the Panch Mahals, Bombay, where unusually
high radio-activity was detected by Fathers Steichen and Sierp.
Fairly large radium-emanations were observed in the waters of the
springs at Vajrabai and Unai near Bbmbay.^ Many medicinal virtues are ascribed to such springs in Europe. In India no such powers
are recognised in them, and where, in a few cases, they are recognised,
no economic benefit is derived from them. They are invested with
religious sanctity rather than exploited for commercial gain.
2. CLAYS
China clay—Clay, that kind of earth which, when moistened, possesses a high degree of tenacity and plasticity, is of great industrial
use in the making of various kinds of earthenware, tiles, pipes, bricks,
etc., and when of sufficient purity and fine grain, it is of use in the manufacture of glazed pottery and high-grade porcelain, for all of which an
immense demand exists in the modern world. ^ Pure china-clay, or
kaolin, occurs in deposits of workable size among the Upper Gondwan^ rocks of the Rajmahal hills of Bengal, in Singhbhum, Mysore,
Delhi, and in Jabalpur. China clay, which has resulted from the decomposition of the felspar of the gneisses, occurs in some aggregates
in some districts of Madras.
Terra-cotta—China clay which is somewhat impure and coloured
buff or brown, is known as terra-cotta, which finds employment in the
making of unglazed large-size pottery, statuettes, etc., and to some
extent for architectural purposes. Terra-cotta clay deposits are of
more common occurrence in India and Burma than pure kaolin.
The kaolin (pure china clay) deposits of the Rajm.ahal hills at Colgong.(Pattarghatta) are of much interest, both as regards the quantity
available and the purity of the material, for the manufacture of very
superior grades of porcelain.^ Similar deposits, though on a more
restricted scale, are found in Bhagalpur and in Gtaya.
Fire-clay^Fire-clay is clay from which most of the iron and salts of
potassium and sodium are removed, and which, therefore, can stand
the heat of furnaces without fusing. Fire-clay from which fire-bricks
^ Indian Medical Gazette, vols, xlvi and xlviii, 19H and 1913.
* Clays, their Occurrence, Properties and Uses, H. Reis, 1906.
« M, Stuart, Bee. Cf.S.I. vol. xxxviii. pt. 2, 1909.
ECONOMIC GEOLOGY
331
of high refractory quality can be manufactured occurs in beds at the
western side of the R^jmahal hills, near Dandot in the Salt-Range and
in the vicinity of Kolar, Mysore State. It also occurs as underclays
in the Gondwana coal-measures and associated with other coalbearing series, and is now raised for various manufactures in considerable amounts near Barakar.^ Besides these localities, fire-clay of
texture and refractoriness suitable for the manufacture of furnacebricks is obtained from, a number of localities in the Central Provinces,
Bengal, etc., where its deposits are of fairly wide distribution. A
seven-foot bed of fuller's earth occurs in the Salkhala series of Budil,
Rajaori (Jammu Province) containing a large stock of the mineral.
The variety known as bentonite, of use in several industries, occurs in
association with a Siwalik conglomerate near Bhimber, Jammu Province. The bed is two feet thick and extends for many miles. Bentonitic clays have recently been found in Jodhpur State.
Fuller's earth—Fuller's earth is a kind of white, grey or yellow
coloured clay. It has a high absorbent power for many substances,
for which reason it is used for washing and cleaning purposes. I t is
found, among many other places, in the Lower Vindhyan rocks of
Jabalpur district (Katni). It is also obtained from some districts of
Mysore, from the Khairpur State in Sind and from the Eocene rocks
of Jaisalmer and Bikaner in Rajputana, where it is quarried and sold
under the name of Multani mattee.
Ordinary alluvial clay, mixed with sand and containing a certain
proportion of iron, is used for brick-making and crude earthern
pottery. Fine-grained clay, mixed with fine sand, is used in tilemaking. Mangalore, together with some surrounding places, is the
home of a flourishing tile industry, where tiles, suitable for paving,
roofing and ceiling are manufactured.
The total production of clays in India for industrial purposes is
worth about £27,000 per annum on an average ; this may be contrasted
with the value of clays raised in the United States of America for
various manufactures, which amounts to £72,000,000 per year.
SANDS
Glass-sand—Pure quartz-sand, free from all iron impurities and
possessing a uniform grain and texture, is of economic value in the
manufacture of glass. Such sands are not common in India, but in
«
^ W. Off. Bates, Indian Earths and Clays, Trans. Min. and Oeol. Inst. Ind., vol.
xxxviii. 1933.
332
GEOLOGY OF INDIA
recant years good sands have been obtained from crushing of pure
quartzose Vindhyan sandstones at Several localities in the United
Provinces, from Gondwana (Damuda) sandstone of Rajmahal hills
and from Cretaceous sandstones found at Sankheda in the Baroda
State. Sand-deposits of requisite purity suitable for glass manufacture are found in Hoshiarpur district, Punjab, and at Sawai Madhupur
in Jaipur State. Good-quality sands suitable for glass-making also
occur in the Sabarmati river and at Jabalpur. A pure quartz-grit at
Barodhia in the Bundi State, thick deposits of a pure, white, soft,
granular quartzite in Poonch State, and masses of crumbling powdery
silica resulting from metasomatic replacement of limestone, near
Garhi HabibuUah, Hazara, are other available supplies. Ordinary
white sand is used in India for the manufacture of inferior varieties of
glass, while articles of better quaUty are manufactured out of crushed
quartz at Talegaon (Poona), Jabalpur, and at Ambala, Allahabad
and Madras.
Common river-sands are used in mortar-making. Recent calcareous
sands, consisting mostly of shells of foraminifera, have consolidated
into a kind of coarsely-bedded freestone.at some places on the west
coast of the Arabian Sea—Miliolite. (See Magnetite sand, Monazite
sand. Gem sand, etc.) ^
3. LIME, CEMENTS, Etc.
Mortax. Cement—^Lime for mortar-making is obtained by burning
limestone, for which most kinds of limestones occurring in the various
geological systems of India are suitable, but some are especially good
for the purpose. Lime, when mixed with water and sand, is called
mortar, which, when it loses its water and absorbs carbonic acid gas
from'air, " sets " or hardens, hence its use as a bjnding or cementing
material. In the plains of India, the only available source of hme is
" Kankar ", which occurs plentifully as irregular concretions disseminated in the clays. The clay admixture in Kankar is often in
sujfEcient proportion to produce on burning a hydraulic lime. Travertine or calc-tufa, sea-shells, recent coral limestones, etc., are also
drawn upon for the kiln, where a suitable source of these exists.
When limestone containing argillaceous matter in a certain proportion is burnt, the resulting product is cement, in which an altogether
different chemical action takes place when mixed with water, ^he
burning of hmestone (CaCOj) and clay (AlgOg, SiOg nHjO) together
' Sands and Crushed Socks, A* B. Searle, Oxford Technical Publications, 1923
ECONOMIC GEOLOGY
333
results in the formation of a new cliemical compound—silicate and
aluminate of lime—which, is again acted upon chemically when water
is added, hardening it into a dense compact mass. For cementmaking, either some suitable clayey limestone is used or the two ingredients, limestone and clay, are artificially mixed together in proper
proportion. The former is known as Eoman Cement, the latter as
Portland Cement. The occurrence of enormous masses of Nummulitic,
Vindhyan and older limestones in the Punjab, Central Provinces,
Eajputana, Central India, Assam and other parts, in association with
clays and shales, offers favourable conditions for cement manufacture.
Natural cement-stones of suitable composition exist in some parts of
India. Kankar also may be regarded as one of them.
Eecent experiments by Dr. C. S. Fox have shown that a high-grade,
rapid hardening cement, rich in aluminous content (Cement fondu)
of utiKty in special structures, can be manufactured from aluminous
laterites, mixed with appropriate quantity of limestone. Pig-iron is
a bye-product.
4. BUILDING-STONES
Rocks are quarried largely for use as building-stones.^ Not all
•rocks, however, are suitable for this purpose, since several indispensable qualities are required in a building-stone which are satisfied by
but a few of the rocks from among the geological formations of a
country. Rocks that can stand the ravages of time and weather,
those that possess the requisite strength, an attractive colour and
appearance, and those that can receive dressing—whether ordinary
or ornamental—without inuch cost or labour, are the most valuable.
Susceptibility to weather is an important factor, and very costly experiments have been made to judgfe of the merits of a particular stone
in this respect.
With this in view the architects of new Delhi, who require a most
extensive range of materials for a variety of purposes, building as well
as architectural, invited the opinion of the Geological Survey of India
in regard to the suitability of the various building and ornamental
stones quarried in the neighbouring areas of Rajputana and Central
India. A special officer of the Survey was deputed to advise on the
matter after an examination of the various quarries that are being
worked in these provinces.
In northern India, the ready accessibility of brick-making materials
* Stones for Building and Decoration^ G. P. Merrill, 1910.
334
XJEOLOGY OF I N D I A
in unlimited quantities lias rendered the use of stone in private as well
as public buildings subordinate. Excellent material, however, exists,
and in quantities sufficient for any demand, in a number of the rocksystems of the country, whose resources in rocks like granites, marbles
limestones and sandstones are scarcely utilised to their full extent.
An enumeration of even the chief and the more prized varieties of
these would form a catalogue too long for our purpose.
Granites—Granite, or what passes by that name, coarsely foliated
gneiss, forms very desirable building-stones, very durable and of an
ornamental nature. These rocks, by reason of their massive nature
and homogeneous grain, are eminently adapted for monumental and
architectural work as well as for massive masonries. Its wide range in
colour and appearance—white, pink, red, grey, black, etc.—renders
the stone highly bfnamental and effective for a variety of decorative
useS; The charnockites of Madras, the Arcot gneiss. Bangalore gneiss,
the porphyries of Seringapatam, and many other varieties of granite
obtained from the various districts of the Peninsula are very attractive examples. Its durability is such that the numerous ancient
temples and monuments of South India, built of granite, stand to-day
almost intact after centuries of wear, and to all appearance are yet
good for centuries to 'come. From their wide prevalence, forming
nearly three-fourths of the surface of the Peninsula, the Archaean
gneisses form an inexhaustible source of good building and archi-'
tectural material.^
Limestones—Limestones occur in many formations, some of which
'are entirely composed of them. All of them, however, are not fit for
building purposes, though many of them are burnt for lime. In the
Cuddapah, Bijawar and Aravalli groups Umestones attain consider" able development, some of them of great beauty and strength. They
have been largely drawn upon in the construction of many of the noted
monuments of the past in all parts of India. Vindh^an limestones are
extensively quarried, as already referred to, in Central India and elsewhere, and form- a valued source for lime and cement, as well as
building-stone. The Gondwanas are barren of calcareous rocks, but
the small exposures of the Bagh and Trichinopoly Cretaceous include
excellent limestones, sometimes even of an ornamental description.
1 In connection with the building of the Alexandra docks at Bombay, a series of
tests on Indian granites was undertaken. These have proved that the granites from
South Indian quarries are equal to or better than Aberdeen, Cornish or Norwegian
granites in respect of compressive strength, resistance to abrasion, absorption of water,
and freedom from voids. The verdict of the various experts consulted was altogether
favourable to the use of Indian granites for purposes for which imported granites alone
wpre considered suitable. (Indian Granites, ^pmbay Port Trust Papers, 1905.)
ECONOMIC GEOLOGY
'
335
The NummuKtic "limestones of the extra-Peninsular districts are an
enbrnious repository of pure limestone, and when accessible ,are in
great requisition for burning, building, as well as road-making purposes. "
Marbles—The marble-deposits of India are fairly wide""-spread and
of large extent. The principal source of the marbles of India is the
crystalline formation of Rajputana—the Aravalh series. Marble
quarries are worked at Mekrana (Jodhpur), Kharwa (Ajmer), Maundla
and Bhainslana (Jaipur), Dadikar (Alwar), and some other places,
from which marbles of many varieties of colour and grain, including
the beautiful chaste white variety of which the Taj Mahal is built, are
obtained. It was the accessibility of this store of material of unsurpassed beauty wliich, no doubt, gave such a stimulus to the Mogul
taste for architecture in the seventeenth century.
A saccharoidal dolomitic marble occurs in a large outcrop near
Jabalpnr, where it is traversed by the Narbada gorge. The famous
quarries of Mekrana supply white,^grey and pink marbles ; a handsome pink marble comes from Narbada in the Kishengarh State.
Jaisalmer in Rajputana supplies a yellow shelly marble, while a lovely
green and mottled marble of unsurpassable beauty is obtained from'
Motipura, from an exposure of the Aravalli rocks in the Baroda State.
A mottled rose or pink marble is found in the same locality and also in
one or two places in the Aravalli series of Rajputana and of the Narsingpur district of the Central Provinces. The Kharwa quarries of
Ajmere produce green and yellow-coloured marbles. Black or darkcoloured marbles come from Mekrana and from the Kishengarh State,
though their occurrence is on a more limited scale than the lighter
varieties. A dense black marble, capable of taking an exquisite
polish, largely employed in the ancient buildings of Delhi, Agra and
Kashmir, with highly ornamental effect, is furnished by some quarries
in the Jaipur State. Coarse-grained marbles are more suitable for^
architectural and monumental uses ; it is the coarseness of the grain
which is the cause of the great durability of marble against meteoric
weathering. The fine-grained, purest white marbles are reserved for
statuary use, for which no other varieties can be of service.
I t is a most regrettable fact, however, that the above-noted deposits of Indian marbles do not find any market to encourage their
systematic quarrying. There is no considerable demand for indigenous
marbles in India, nor do facilities exist for their export to foreign
countries. The deposits, therefore, have to wait the demand of a
more thriving and more aesthetic population in the future.
336
GEOLOGY OF INDIA
A fine collection of Indian marbles, representing the principal
varieties, is to be seen in the Indian Mi^seum, Calcutta.
Serpentine—Serpentine forms large outcrops in the Arakan range of
Burma and also in Baluchistan. It occprs as an alteration-product of
the basic and ultra-basic intrusions of Cretaceous and Miocene ages.
From its softness and liability to weather on exposure it is of no use
for outdoor architectural purposes, but serpentines of attractive
colour are employed in internal decorations of buildings, and the
manufacture of vases, statuary, etc. Serpentinous marble (Verde
antique) is rare in India.
Sandstones. Vindhyan sandstones—The Vindhyan and, to a lesser
extent, the Gondwana formations afford sandstones admirably suited
for building works. The most pre-eminent amoifg them are the
Upper Vindhyan sandstones, which have been put to an almost inconceivable number of uses. From the rude stone-knives and scrapers
of the palaeolithic man to the railway telegraph boards, and the
exquisitely-carved monoliths of his present-day successor, these sandstones have supplied for man's service an infinity of uses. It' is the
most widely quarried stone in India, and being both a freestone as
well as a flagstone, it can yield, according to the portion selected, both
gigantic blocks forj5ilIars from one part, and thin, slate-like slabs for
paving and roofing from another part.
Dr. V. Ball,i iQ writing about Vindhyan sandstones, says, " The^
diificulty in writing of the uses to which thes.e rocks have been put is
not in finding examples, but in selecting from the numerous ancient
and modern buildings which crowd the cities of the United Provinces,
and the Ganges valley generally, and in which the stone-cutter's art is
seen in the highest prefection." Some of the Vindhyan sandstones
are so homogeneous and soft that they are capable of receiving a most
elaborate carving and filigree work.
Gondwana sandstones—Another formation possessing resources in
building-stones of good quality is the Upper Gondwana, which has
contributed a great store of building-stone to Orissa and Chanda.
The famous temples of Puri and the othef richly ornamented buildings of these districts are constructed of Upper Gondwana sandstones.
The Jurassic (Umia) sandstone of Dhrangadhra and the Cretacebiis
sandstone underlying the Bagh beds of Gujarat (Songir sandstones)
furnish Gujarat with a very handsome and durable stone for its important public and private buildings.
vol. EconomQeology_ofJndia, cl iii.881.'i
ECONOMIC GEOLOGY
.,
337
Among tlie Tertiary sandstones, a few possess the qualities requisite in a building-stone, e.g. tlie Murree and Kamlial (Tarki) sandstones ; but the younger Siwalik sandstones are too unconsolidated
and incoherent to be fit for employment in building work.
Quartzites—Quartzites are too hard to work and have a fracture
and grain unsuitable for dressing into blocks.
Laterite—Laterites of South India are put to use in building-works,
from the facility with which they are cut into bricks or blocks when
freshly quarried and their property of hardening with exposure to air.
Its wide distribution from Assam to Comorin makes laterite a widely
used material for road-metal.
Slates—Slates for paving and roofing are not of common occurrence
in India, except in some mountainous areas, e.g. at Kangra and Pir
Panjal in the Himalayas and Rewari in the Aravallis. When the
cleavage is finely developed and regular, thus enabling them to be
split into thin even plates, the slates are used for roofing ; when the
cleavage is not so fine, the slates are used for paving. True cleavage^
slates are rare in India ; what generally are called slates are either
phyllites or compacted shales in which the planes of splitting are not
cleavage-planes.
The chief slate-quarries of India are those of Kangra, in the Kangra
• . district; Rewari, in the Gurgaon district; and Kharakpur hills, in
„ 'the Monghyr district.
" Traps—Besides the foregoing examples of the building-stones of
India, a few other varieties are also employed as such when readily
available and where a sufficient quantity exists. Of these the most
important are the basalts of the Deccan, which, from their prevalence
over a wide region of Western India, are used by the Railways and
i Public Works Department for their buildings, bridges, the permanent
m way, etc. The traps furnish an easily workable and durable stone of
great strength, but its dull, subdued colour does not recommend it to
popular favour. Of late years some trachytic and other acidic lavas
of Ught buff and cream colours have found great favour in the building
of public edifices.
5. COAL 1
Production of coal in India—Coal is the most important of the
mineral products raised in India. Within the last forty years India
1 The Coalfields of India, Mem. G.S.I, vol. xli. pt. 1, 1913 ; C. S. Fox, The Jharia
Coalfield, 3fem. G.S.I. vol. Ivi, 1930 ; The Lower Gondwana Coalflelds, vol. lix, 1934 ;
The Tertiary Coalfields of India, under publication ; E. R. Gee, The Raniganj Coalfield,
Mem. G.S.I. vol. Ixi, 1932.
•W.O.I.
Y
338
GEOLOGY OF INDIA
has become an important coal-producing country, the annual production -now nearly supplying her owp internal consumption. The
yearly output from the Indian mines has risen to over 23,000,000 tons
but, for various industrial causes, the market value at the pit-head of
Indian coal has declined to barely half of its value in 1924. Of this
output, by far the largest portion—89-5%—is derived from the coalfields of Bihar and Orissa ; 5-5% from'the Singareni field of the
Haiderabad State; about 3-5% from the Central Provinces mines,
and 1% from the Umaria field of Central India. This gives a total of
98% for the production of coal from the Peninsula. In its geological
relations the coal of the Peninsula is entirely restricted to the Damuda
series of the Lower Gondwana system. The remainder of the coal
raised in India comes from the Lower Tertiary, Eocene, or Oligocene
rocks of the extra-Peninsula, viz. Assam (Makum), Salt-Range
(Dandot), Baluchistan (Khost) and Bikaner (Palana). Of these, the
Assam production is the most important and promising for the future ;
it averages nearly 2% of the total Indian produce, while it also
approaches Gondwana coal in its quality as a fuel.
The following table shows the relative importance of the various
coal-fields of India, with their yearly output in round numbers :
Gondwana Coal
Bihar and Orissa.
1.
2.
3.
4.
5.
Eaniganj
Jharia
Giridih
-'
Bokaro
Karanpura
Tons
-
-
-
-
-
-
6,000,000
10,000,000
700,000
1,500,000
450,000
-
Central India,
1. Umaria and Sohagpur -
-
.
.
-
250,000
-
. -
-
-
250,000
800,000
200,000
Central Provinces.
1. Bellarpur 2. Pench Valley
3. Korea 1
-
-
Haiderabad.
1. Smgareni and Tandur
1 Fermor, Mem. G.S.I^YOI
700,000
XK. pt. 2, 1914.
ECONOMIC GEOLOGY
339
Tertiary Coal.
1.
2.
3.
4.
Assam (Makum) - '
BiflucMstan (Khost)
Salt-Eange
Bikaner (Palana)
300,000
15,000
85,000
35,000
In the Riasi district of Jammu Province coal of anthracite quality
occurs in some widely distributed seams of 1-20 feet thickness in
association with Nummulitic strata. The latter occur as inliers in the
Murree series (p. 431). The coal-seams are distributed over 36 miles
of country in three or four coalfields. Middlemiss has estimated the
quantity available at 100,000,000 tons, with mining at ordinary
depths. Some of the Riasi anthracites contain 60-82 per cent, of
fixed carbon.^
In general, the Gondwana coal is a laminated bituminous coal in
which dull and bright layers alternate. Anthracite, i.e. coal in which
the percentage of carbon is more than 90, and from which the volatile
compounds are totally eliminated, is not found in India. The volatile
compounds and ash are, as a rule, present in too large a proportion to
allow the carbon percentage to rise above 55 to 60, generally much less
than that. Moisture is absent from the coal of the Gondwana fields,
but sulphur and phosphorus are present in variable quantities in the
coals of the difi:erent parts of the Peninsula.
It is probable that a large extent of coal-bearing Gondwana rocks
lies hidden underneath the great pile of lavas of the Deccan trap. At
several places, chiefiy in the Satpuras, the denudation of the latter
has exposed coal-bearing Gondwana strata, from which it is reasonable to infer that considerable quantities of the valuable fuel are buried
under the formation in this and more westerly parts. Of the coal of
younger age, worked from the extra-Peninsula, Assam coal is of a high
grade as fuel, while that of the Punjab has a lower percentage of fixed
carbon. In the former it rises to as much as 53%, in the latter it
never goes beyond 40%. The latter coal, properly a lignite, is more
bituminous, friable and pjo-itous, and contains much moisture. The
two last qualities make it liable to disintegration on exposure, and
even to spontaneous combustion. With regard to its geological rela• tions, the extra-Peninsular coal is mostly of Eocene age. The SaltRange coal comes from the Ranikot series, and in Assam there are
three horizons—one at the bottom and one at the top of the Jaintia
• Middlemiss, Mineral Survey Reports, Jammu and Kashmir State, Coalfields of
Biasi, Jammu, 1930.
340
GEOLOGY OF INDIA
series (corresponding to a part of the Kirthar) and a much more important one in the Barail series at apprqximately the Eocene-Oligocene boundary. In Burma impure coal occurs at various horizons in
the Eocene and in the Shwezetaw sandstojnes of Lower Oligocene age.
The Tertiary coal of Palana (Bikaner) is'properly speaking a lignite
(brown coal) though belonging to the Eocene. The lowest thin coal of
Assain has been regarded as of Cretaceous age but this now seems improbable and it has been here classed with the Eocene ; a few thin
seams of brown coal occur in the Jurassic strata of Cutch and possibly
some of the coal of the Mianwali district is of this age, although it is
more probably of Kanikot age.
Several warning notes have been sounded of late years regarding
the small available reserves of coal in India and the approaching exhaustion of coal for metallurgical use. Fermor estimates the reserves
of good quaUty easily accessible coal in the known Indian coalfields
at about 4521 million tons made up of 1700 million tons of coking coal
and the rest non-cokiug coal. Fox's estimates for these respectively
ai;e ^:
Reserves of good quality Coal
Giridih and Jainti fields 40 milUon tons
Raniganj, Jharia, Bokaro and Karanpura 4600
,,
Son valley fields - ' 80
„
Talchir fields - 200
„
Satpura
fields
-30
„
Ballalpur-Singareni fields 50
„
Total
- 5000
Reserves of good coking Coal
Giridih field
Raniganj field Jharia field
Bokaro field
Karanpura field
Total
30 haillion tons
250
„
900
„
320
„
not estimated
-
-
- 1500 million tons
The hitherto coal-less area of Kashmir has lately been found to
possess fuel deposits of considerable size, belonging to Pliocene or
even newer age. Thin seams of brown coal or lignite occur interstratified with the top beds of the older Karewa series within a few
> Mem. G.SJ.solriix, 1934.
ECONOMIC GEOLOGY
341
feet from the surface. Over a hundred miUion tons of moderategrade lignite is easily recoverable from one area. The percentage of
combustible matter is generally about 55. i
PEAT
The occurrence of peat in India is confined to a few places of high
eleva^on above the sea. True peat is found on the Nilgiri mountains
in a few peat-bogs lying in depressions composed of the remains of
Bryophyta (mosses). In the delta of the Ganges, there are a few layers
of peat composed of forest vegetation and rice plants. In the numerous Jhils of this delta peat is in process of formation at the present
day and is used as a manure by the people. Peat also occurs in the
Kashmir valley in a few patches in the alluvium of the Jhelum and in
swampy ground in the higher valleys ; it is there composed of the
debris of several kinds of aquatic vegetation, grasses, sedges and
rushes. Similar deposits of peat are in course of formation in the
valley of Nepal. The chief use of peat is as a fuel, after cutting and
drying. It is also employed as a manure.
- PETROLEUM
t Distribiiiion of Oil—The occurrence of petroleun? in India is re' stricted to the extra-Peninsula, where it is found in Tertiary rocks of
ages ranging from Lower Eocene to Middle Miocene.^ There are three
regions in which oil production has been obtained. The most important is the Chindwin-Irrawaddy valley of Burma ; to the west Ues
the Assam-Arakan oil belt stretching from Upper Assam southwestwards through the Surma valley and Chittagong to the Arakan
coast. In North West India, oil indications have been observed in
Baluchistan, the Punjab,* and the N.W. Frontier Province.
Burma—In Burma, there are oil and gas seepages in the upper half
of the Eocene and in the Pegu rocks (Ohgocene to Miocene). The oilfields are situated on anticlines in which the porous sands interbedded
with impervious clays present favourable conditions for the accumulation and storage of oil. The fields are situated in a belt which closely
follows the line of the Chindwin and Irrawaddy. In the Yenangyaung
> C. S. Middlemis3, Bee. G.S.I, vol. Iv; pt. 3, 1924.
2 E. H. Pascoe, Oil-fields of India, Mem. O.S.I, vol. xl, 1911-1920.
' E. S. Pinfold, Occurrence of Oil in the Punjab, Journ. Asiat. Soc. Beng., N.S. vol.
xiv, 1918.
342
GEOLOGY OF INDIA
field (Magwe district), production is obtained mainly from the Lower
Miocene and Upper Oligocene ; in the more northern fields of Singu
(Magwe district), Lanywa, and Yenangyat (Pakokku district) the
production is from the Oligocene.^ Yenangyaung yields about 130
million gallons a year and Singu about 80 million gallons. Lanywa
and Yenangyat in the Pakokku district together produce about
20 milhon gallons per year. Further south in the Minbu district small
fields yield about 3 to 4 million gallons annually.
Assam—In Assam, oil seepages occur in rocks ranging from Eocene
to probably Middle Miocene. The only productive field is Digboi, in
the Lakhimpur district, where the annual yield has in recent years
come up to about 60 miUion gallons. The Badarpur field which at one
time yielded about 4 million gallons annually, became exhausted in
1933, but exploratory drilling has been continued in neighbouring
anticUnes. Further south, on the Arakan coast, although there are
numerous oil and gas shows, the production of oil is negligible.
North West India—Oilshows occur in various districts along the
North-Western Frontier, particularly in the Potwar region. Most of
the oil-shpws are in the lower part of the Chharat series (Laki) or in the
basal beds of the overlying Murrees or Siwaliks. In spite of energetic
prospecting of large areas the only commercially productive field is
at Khaur in the Attock district. The output reached a maximum of
19 million gallons in 1929 but subsequently declined to about 4
million gallons. Lately successful boring to a depth of 7100 ft. in
the adjacent Dhulian dome has increased the production again.
Although the Khaur production has come from the Murree series, it
is believed that the origin is in the underlying J^ocene rocks from
which the oil has migrated upwards. The deeper drilUng has recently
proved the occurrence of oil and gas in the Eocene Umestones here and
in the neighbouring Dhuhan area.
Natural Gas—Natural gas (chiefly marsh gas- with somie other
gaseous hydrocarbons) usually accompanies the petroleum accumulations.^ The gas may occur in separate sands containing little or no
oil, but most of the natural gas of India is found closely associated with
the^oil, and supplies the propulsive force which carries the oil from
the oilsands into the wells and, if the pressure is sufficient, brings the
oil up to the surface. Since gas is essential for the production of the
oil and is also valuable as a source of fuel on the oilfields, care is taken
1 G. W. Lepper, Proc. World Petrol. Gong., 1933; P. Evans, Trans. Min. Geol. Inst.
Ind. vol. xxix. pt. 1, 1934.
^ C. T. Barber, Natural Gas Resources of Burma, Mem. O.S.I, vol. Ixvi. pt. 1, 1935.
,
"^
ECONOMIC GEOLOGY
.
343
to prevent the waste of gas, which was formerly so common in the
oilfields.
The total contribution to world supply of petroleum by India and
Burma is rather over, 300 million gallons per year and this represents
only 0-6 per cent of the total world output. In addition to the oil
produced in India and Burma, about 200 million gallons are imported
from foreign countries.
6. METALS AND ORES
General. Neglect of ore-bodies in India—India contains ores of
manganese, iron, gold, aluminium, lead, copper, tungsten, tin, chromium, and a few other metals in minor quantities, associated with the
crystalline and older rocks of .the country. In the majority of the
cases, however, the ore bodies are'worked, not for the extraction of the
metals contained in them, but for the purpose of exporting the ores as
such in the raw condition, since few smelting or metallurgical operations are carried on in the country at the present time. For this
reason the econoihic value of the ores realised by the Indian miners is
barely half the real market-value, because of the heavy cost of transport they have to bear in supplying ores to the European manufacturer at raies current in the latter's country. The absence of metallurgical enterprise in this country at the present day has led to a total
neglect of its ore-deposits, except only those whose export in the raw
condition is paying. This is a serious drawback in the development
of the mineral resources of India, the cause for which lies in the present
imperfect and.undeveloped state of the country's industries. Sir
T. H. Holland, in his review of the mineral production of India,
poiSted out in 1908 that the " principal reason for the neglect of the
metalliferous minerals is the fact that in modern metallurgical and
chemical developments the bye-product has come to be a serious and
indispensable item in the sources of profit, and the failure to use the
bye-product necessarily involves neglect of minerals that will not pay
to work for the metal alone. Copper-sulphide ores are conspicuous
examples of the kind ; many of the most profitable copper mines of
the world would not be worked but for the demand for sulphuric acid
manufacture, and for sulphuric acid there would be no demand but for
a string of other chemical industries in which it is used. A country like
India must be content, therefore, to pay the tax of imports until industries arise demanding a sufficient number of chemical products to
complete an economic cycle, for chemical and metallurgical industries
344
GEOLOGY OF INDIA
are essentially gregarious in their habits." Many of the ore-deposits
of India, although of no economic value under the conditions prevailing at the present day, are likely to become so at a future day when
improved methods of treatment, and better industrial conditions of the
country may render the extraction of the metals more profitable.
From this consideration the large yearly exports of such ores as
manganese out of India are doubly harmful to the interests of the
country.
Gold
Occurrence—Gold occurs in India, both as native gold, associated
with quartz-veins or reefs, and as alluvial or detrital gold in the sands
and gravels of a large number of rivers. The principal sources of the
precious metal in India, however, are the quartz-reefs traversing the
Dharwar rocks of Kolar district (Mysore State), which are auriferous
at a few places.^ The auriferous lodes of the Kolar goldfields are contained in the above-mentioned quartz-veins, which run parallel to one
another in a north-south direction in a belt of hornblende-schists.
The most productive of these is a single quartz-vein, about four feet
thick, which bears^gold in minute particles. Mining operations in this
reef have been carried to a depth of 7400 feet, one of the deepest mining
shafts in the world, and have disclosed continuance of the same richness and method of distribution of the ore in the gangue. The gold is
obtained by crushing and milling the quartz, allowing the crushed orei
mixed with water to run over mercury-plated copper boards. The
greatest part of the gold is thus dissolved by amalgamation. The
small residue that has escaped with the sUme is extracted by the
cyanide process of dissolving gold.
Production of vein-gold—The annual yield of gold from the Kolar
fields is nearly 340,000 ozs., valued, at the present price of gold, at more
than £2,000,000. Next to Kolar, but far below it in productiveness^ is
the Hutti gold-field of the Nizam's, dominions, which was also worked
from a similar outcrop of Dharwar schists. It produced 21,000 ozs. of
gold in 1914, but the output fell off and the mine has been closed. A
few quartz-veins traversing a band of chloritic and argillaceous schists,
also of Dharwar age, support the Anantpur field of Madras, whose
yield in 1915 approached 24,000 ozs. This mine ceased operations
after several vicissitudes in 192f. At some other places in the Peninsula, besides those named above, the former existence of gold is revealed by many signs of ancient gold-working in diggings, heaps of
/
I Kolar Gold-Field, Mem. G.S.I, vol. xxxiii. pts. 1 and 2, 1901.
ECONOMIC GEOLOGY
345
crushed quartz, and stone-mortars, which, have (as has often happened in India with regard to other metalhferous deposits) guided the
attention of the present workers to the existence of gold.
Alluvial gold—The distribution of alluvial gold in India is much
wider. Many of the rivers draining the crystalline and metamorphic
tracts in India and Burma are reputed to have auriferous sands, but
only a few of them contain gold in a sufficient quantity to pay any
commercial attempt for its extraction. The only instance of successful exploitation of this kind is the dredging of the upper Irrawaddy
valley for the gold-bearing gravel at its bed, for some years ; but the
returns fell off and operations were closed down in 1918. In this way
some 5000 to 6000 ozs. of gold was won a year. Alluvial gold-washing
is carried on in the sands and gravels of many of the rivers of the
Central Provinces, and in sections of the Indus valley at Ladakh,
Baltistan, Gilgit, Attock, etc., but none of them are of any richness
comparable to the above instance. The quantity won by the indigent
workers is just enough to give them their day's wages with only
occasional windfalls.
Copper
Occurrence—Copper occurs in some districts of India—Singhbhum,
Chota Nagpur, etc. ; in Rajputana—Ajmere, Khetri, Alwar, Udaipur,
and at several places in the outer Himalayas, in Sikkim, Kulu, Garhwal, etc. But the only deposits worked with some degree of success
are those of the Singhbhum district, Mosaboni mines, which yield about
180,000 tons of ore per year, valued at Rs. 25 lacs. In 1934, 6300 tons
of refined copper was produced from the ore mined at Mosaboni, the
most important copper mines in India. In Singhbhum the copperbearing belt of rocks is persistent for about 80 miles along a zone of
overthrust in the Dharwar schists and intrusive granite. The deposits worked at the Mosaboni mines consist of low-grade sulphide
ore assaying 2-4% of copper. Somewhat richer ore-shoots have been
located lately in the vicinity. ^ There was a flourishing indigenous
copper-industry in India in former years, producing large quantities
of copper and bronze from the Rajputana, Sikkim, and Singhbhum
mines, the sites of which are indicated by extensive slag-heaps and
refuse " copper-workings ". Important copper-mines existed in
Ajmere and in Khetri (in the Jaipur State) within historic times.
Copper ore is found at Bawdwin in the Northern Shan States of
• J. A. Dunn, Mineral Deposits of Eastern Singhbhum, Mem. G,S.I. vol. Ixix. pt, 1,
1937.
346
GEOLOGY OF INDIA
Burma in association with the deposits of lead, zinc and silver ores ;
reduction of the Bawdwin copper-ores produced about 12,000 tons
of copper-matte, valued at Rs. 30 lacs, in 1933.
The copper ores of Singhbhum and Rajputana occur as veins or as
disseminations in the Dharwar schists .and phyllites. In a great
number of cases, however, the ore occurs in too scattered a condition
to be worth working ; it is only rarely that local concentration has
produced workable lodes or veins. The most common ore is the sulphide, chalcopyrite, which by surface-alteration passes into malachite,
azurite, cuprite, etc.
Native copper occurs at some places in South India. In Kashmir
large isolated masses of pure native copper have been found in the bed
of the Zanskar river, but their source is unknown. They occur there
as water-worn nodules, weighing up to 22 lbs.
Copper ores of Sikkim—The copper deposits of Sikkim attracted
much attention once.^ In this State valuable lodes of the metal are
proved to exist in association with compounds of bismuth and antimony, together with ores Uke pyrrhotite, blende and galena. With
regard to the geological relation and mode of origin, the Sikkim deposits are similar to those of Singhbhum. The former are also associated with schists and gneiss of the Dahng series, which are the Himalayan representatives of Dharwars. In both cases again the mode of
origin of the ore bodies is the same, viz. they have resulted from the
metasomatic replacement of the country-rock by copper-bearing
solutions derived from granite and other intrusions associated with
the Dharwar rocks of South India or the Dalings of Sikkim. Lack of
adequate communications for transport are the chief obstacles to
successful exploitation of these o'res.
Iron
Occurrence—Iron occurs on a large scale in India, chiefly in the form
of the oxides : haematite and magnetite. It prevails especially in the
Peninsula, where the crystalline and schistose rocks of the Dharwar
and Cuddapah systems enclose at some places ferruginous deposits of
an extraordinary magnitude. Among these, massive outcrops of
haematite and magnetite of the dimensions of whole hills are not unknown. But the most common mode of occurreiice of iron is as
laminated haematite, micaceous haematite and haematite-breccia;
> H. H. Hayden, Eec. G.8.I. vol. xxi. pi 1, 1904.
ECONOMIC G E O L O G Y
347
lateritic haematite also forms large deposits, together with haematiteand magnetite-quartz-schists, the metamorphosed products of original
ferruginous sands and clays. The high-grade haematitic ore-bodies
of Singhbhum, together with those of Keonjhar, Bonai and Mayurbhanj,^ discovered of late, are believed to be of Upper Dliarwar or still
newer age, the remaryable concentration of the metal iron in them
being ascribed to post-Cuddapah metasomatic action, to original
marine chemical precipitation of the oxides, carbonates and other
compounds of iron, to volcanic action and other agencies. These orebodies, many of them containing 60 per cent, of iron-oxides, are
thought to be the largest and richest deposits of iron perhaps in the
world, surpassing in magnitude the Lake Superior ores. They are
estimated to contain about three thousand million tons of metallic
iron. 2
The Damuda series of Bengal holds valuable deposits of bedded or
precipitated iron ore in the ironstone shales. Some iron ore is enclosed
in th» Upper Gondwana haematitic shales. The Deccan Traps, on
weathering, liberate large concentrates of magnetite sands on long
stretches of the sea-coast. Iron is a prominent constituent of laterite,
and in some varieties the concentration of limonite or haematite has
reached so high that the rock is smelted for iron. In the Himalayas,
likewise, there occur large local deposits of this metal in the Purana
formations as well as in association with the Eocene coal deposits.
* Economic value—The only deposits that are profitably worked at
the present day are the ironstone shales of Burdwan, the high-grade
ores of Mayurbhanj, Singhbhum and Manbhum, Bababudan hills,
Mysore State, find to a less extent those of the Central Provinces.
The aggregate produce of iron in 1936 reached 1,540,000 tons of pigj iron and 660,000 tons of finished steel.
•"^ Iron seems to have been worked on an extensive scale in the past,
as is evident from the widely scattered slag-heaps which are to be seen
in almost every part of South India. The iron extracted was of high
quality and was in much demand in distant parts of the world. The
fame of the ancient Indian steel, Wootz—a very superior kind of steel
exported to Europe, in days before the Christian era, for the manufacture of swords and other weapons—testifies to the metallurgica
skill of the early workers.
' The discovery of important deposits of iron-ore in the Mayurbhanj State is due
to P. N. Bose, Rec. O.S.I. vol. xxxi. pt. 3, 1904.
* H. C. Jones, Iron-ore Deposits of Bihar'and Orissa, Mem. G.S.I, vol. bciii. pt. 2,
1934; J. A. Dunn, Mem. O.S.I, vol. Ixix. pt. 1, 1937.
348
GEOLOGY OF INDIA
Every year India imports iron and steel materials (hardware,
macliinery, railway plant, bars and sheets, etc.) to the value of nearly
32 crores of rupees.
'
Distribution—A list of localities which contain the most noted deposits of iron ore will be interesting. ,
In the Madras Presidency the most important deposits are those of
Salem, Madura, Mysore (Bababudan hills), Cuddapah and Karnul,
while Singhbhum, Manbhuin, Burdwan, Sambalpur and Mayurbhanj
are the iron-producing districts of Bihar and Orissa. In Bengal proper, the Damuda ironstone shales contain a great store of metallic
wealth, which has been profitably worked for a long time, both on
account of its intrinsic richness as well as for its nearness to the chief
source of fuel. In Assam also iron occurs with coal. In the Central
Provinces the most remarkable iron deposit is that of the Chanda
district, where there is a hill 250 feet high, Khandeshwar by name, the
entire body of which is iron ore. Jabalpur, Drug, Eaipur, and Bhilaspur have likewise large aggregates of valuable haematitic ores which
have been so far prospected only in part. In Bombay the chief source
of iron is laterite and the magnetite-sands of rivers draining the trap
districts, both of which arp largely drawn upon by the itinerant lohars.
Important reserves of high-grade ores of Dharwar age are met with'
in Goa and Ratnagiri, with low percentage of silica and 'of phosphorus
below the Bessemer limit. In the Himalayas the Kumaon region has
been known to possesg some deposits. Workable iron-ore is met with
in the Riasi district, Jammu hills, in association with the Nummulitic
series, which supported a number of local furnaces for the manufacture of munitions of war during the last two centuries.
Manganese
Production of manganese in India—With the exception of Russia
(the Caucasus), India is the largest producer of manganese in the
world. Within the last thirty years, the export of manganese ore has
risen from a few thousand tons to 900,000 tons annually. The output
has fallen in recent years to 550,000 tons. The major part of this output is exported in the ore condition, only a small part of it being
ctated in the coruntry for the production of the metal, or for its man,uafterure into fero-manganese, the principal alloy of manganese and
iron.
Distribution. Geographical—The chief centres of manganese mining,
or rather quarrying (for the method of extraction up till now resorted
ECONOMIC GEOLOGY
349
to is one of open quarrying from the hillsides), aire the Balaghat,
Bhandara, Chhindwara,-Jabalpur and Nagpur districts of the Central
Provinces, which yield nearly 60 per cent, of the total Indian output.
Sandur and V^a^apatan in Madras take the next place, then come
the Panch Mahal and Belgaum districts of Bombay, and Singhbhum,
Keonjhar §nd Gangpur in Bihar and Orissa, Chitaldrug and Shimoga
districts of Mysore, and Jhalna in Central India.
Geological—Dr. Fermor has shown that manganese is distributed,
in greater or less proportion, in almost all the geological systems of
India, from the Archaean to the Pleistocene, but the formation which
may be regarded as the principal carrier of these deposits is the Dharwar. The richly manganiferous facies of this system—the Gondite and
Kodurite series—contain enormous aggregates of manganese ores such
as psilomelane and braunite, pyrolusite, hoUajndite, etc. Of these' the
first two form nearly 90 per cent, of the ore masses. The geological
relation of the ore bodies contained in these series and their original
congtitution have been referred to in the chapter on the Dharwar
system (p. 80). Besides the Dharwar system, workable manganese
deposits are contained in the laterite-Iike rock of various parts of the
Peninsula, where the ordinary Dharwar rocks have been metasomatically replaced by underground water containing manganese solutions. According to the mode of origin, the two first-named occurrences belong to the syngenetic type of ore bodies, i.e. those which were
formed contemporaneously with the enclosing rock, while the last
belong to the epigenetic class of ores, i.e. those formed by a process of
concentration at a later date.
A voluminous memoir on the manganese-ore deposits of India by
Dr. (now Sir) L. L. Fermor, published by the Geological Survey of
India, 1 contains valuable information on the mineralogy, economics
and the geological relations of the manganese of India.
Ores which contain from 40 to 60 per cent, of manganese are common and are classed as manganese ores. There also exist ores with an
admixture of iron of from 10 to 30 per cent. : these are designated
ferruginous manganese ores; while those which have a still greater
proportion of iron in them are known as manganiferous iron ores.
The ayerage cost of Indian manganese ore delivered in London is
less than Es. 30 per ton of first grade ore, i.e. with a manganese
percentage greater than 50.
Uses—The chief use of manganese is in metallurgy for the manufacture of ferro-manganese and spiegeleisen, both of which are alloys
» Mem. G.S.I. vol. xxxvii. 1909.
350
GEOLOGY OF INDIA
of manganese and iron. Manganese is employed in several chemical
industries as an oxidiser, as in the manufacture of bleaching powder,
disinfectants, preparation of gases, etc. Manganese"is employed in
the preparation of colouring materials, for glass, pottery-paints, etc.
The pink mineral, rhodonite (silicate of manganese), is sometimes cut
for gems on account of its attractive colour and appearance.
Alxuninium
Bauxite in laterite—Since the discovery that much of the clayey
portion of laterite is not clay (hydrated silicate of alumina), but the
simple hydrate of alumina (bauxite), much attention has been
directed to the possibility of working the latter as an ore of aluminium.^ Bauxite is a widely spread mineral in the laterite cap of the
Peninsula, Assam and Burma, but the laterites richest in bauxite are
those of the Central Provinces, especially of Katni, and of some hilltops in the Balaghat district in which the percentage of alumina is
more than 50. Other important deposits are those of Mandla, Seoni,
Kalahandi, Sarguja, Mahaba,leshwar, Bhopal and the Palni hills and
some parts of Madras. The total quantity of ore available from these
deposits is very large, obtainable by simple methods of surface quarrymg.
.
.
.
.
Extensive deposits of bauxite and aluminium ore, analysing 60 to
80 per cent. AlgOg, have been discovered in association with the Nummulitics of Jammu and Poonch, where some million tons of ore is exposed in surface strata. Their mode of occurrence also suggests a
lateritic origin, e.g. by a desilication of large, subaerially exposed,
spreads of infra-Nummulitic clay-beds on a series of low, gently inchned dip-slopes: With deposits of the ore so wide-spread and of such
magnitude the aluminium resources of India should be considered
large, but so far no reduction of the bauxite to metalUc aluminium has
been carried out in India. The average annual imports of aluminium
metal goods into India come to about 100,000 cwts.
Uses—Aluminium has a variety of apphcations in the modern industries. It is esteemed on account of its low density, its rigidity and
malleability. Besides its use for utensils, it has many applications in
electricity, metallurgy, aeronautics, etc. It is largely employed in the
manufacture of alloys with nickel, copper, zinc and magnesium, in the
preparation of chemicals, refractories, abrasives, and aluminous
,* C. S. Fox, Aluminous Laterites, Mem. G.S.I, vol. xKx, 1923; Bauxite Resources of
India, Mining Magazine, vol. xxvi. Feb. 1922; Bauxite and Aluminous Laterite,
Ixindon, 1932 ; Coggin Brown, Bulletin of I. I. and L. No. 2, 1921; No. 12, 1921.
ECONOMIC GEOLOGY
,
351
«
cement. The present output of Indian bauxite is insignificant
and is ciiiefly consumed in the cement-malcing industry, refinement of oil, etc.
Lead, Silver, Zinc
I
-I \
Very little lead is produced in India at the present time^ though
ores of lead, chiefly galena, occur at a number of places in the Himalayas, Madras, Rajputana and Bihar, enclosed either among the
crystalline schists or, as veins and pockets, in the Vindhyan limestones. Lead was formerly produced in India on a large scale. The
lead ores of Hazaribagh, Manbhum and some districts of the Central
Provinces are on a fairly large scale, and they are often argentiferous,
yielding a few ounces of silver per ton of lead. But all of these are
lying unworked ; their remunerative mining is impossible because of
the cheap price of imported lead.
, Lead ores of Bawdwin—The only locality where a successful lead
industry ^ exists is Bawdwin in the Northern Shan States of Upper
Burma, where deposits of argentiferous galena occur on an extensive
scale in a zone of highly fractured volcanic and metamorphosed rocks
of Cambrian age.^ Large reserves of lead, zinc and silver ores have
been proved in these mines and are under energetic exploitation. The
country-rocks are felspathic grits and rhyolitic tuffs, the felspars of
which are replaced by galena. Blende and copper-pyrites are associated with the lead-ores, together with their alteration-products in
the zone of weathering—cerussite, anglesite, smithsonite, and
malachite.
For many years the Bawdwin lead was worked more from the heaps
of slags left by the old Chinese workers of these mines than from the
ores mined from deposits in situ. The annual production now reaches
74,000 tons of metallic lead, extracted from 445,000 tons of the ore
mined.
•
The Bawdwin ores belong, geologically, to the class of metasomatic
replacements, the original minerals of the country-rock having been
substituted chemically by the sulphides and carbonates of lead and
zinc, by the process of molecular replacement.
Silver—India is the largest consumer of silver in the world, the
extent of its average annual imports being £10,000,000. But with the
exception of the quantity of silver won from the Kolar gold-ores,
aggregating on an average about 25,000 ozs., no silver is produced in
• Coggin Brown, Bull. I. J. and L. No. 19, 1922.
2 Rec. G.S.I. vol. xxxvii. pt. 3, 1909.
;
GEOLOGY OF INDIA
; country. The production of silver from the rich argentiferous lead0 ores of the Bawdwin Mines of Burma, ]iowever, has shown a
trked increase. The silver content of the Bawdwin lead-ores varies
im 10-30 ozs. per ton of lead, and with the: steady increase in the
tput of lead of late years there has been^a corresponding rise in the
aount of silver raised. In 1929 the figures touched 7,280,000 ozs.,
iliied at over a crore of rupees.
Zinc—A considerable amount of zinc is obtained in the mining of
ilena from the Bawdwin mines. The ore is blende intimately mixed
ith galena. The average yearly output of zinc was about 90 tons,
ut in the year 1923 the quantity raised suddenly increased to 18,000
jns. In 1935 the quantity of zinc-concentrate produced at the
famtu plant was 78,000 tons, valued at over 40 lacs of rupees. I t is
bought that the Bawdwin zinc deposits will prove as important as,
f not more important than, the lead deposits in the near future.
A workable deposit of zinc-blende of considerable purity occurring
n lenticular veins and lodes has been discovered in the Eiasi district
of Kashmir in association with a Palaeozoic limestone.
Tin
Tin ore of Mergvii and Tavoy—With the exception of a few isolated
occurrences of cassiterite crystals in Palanpur and its occurrence in
situ in the gneissio rooks of Hazaribagh, the only deposits of tin ore, of
workable proportions, are those of Burma—the Mergui and Tavoy
districts of Lower Burma, ^ which have supplied a large quantity of
tin from a remote antiquity. The most important tin ore is cassiterite,
occurring in quartz-veins and pegmatites, associated with wolfram,
molybdenite and some sulphides in granitic intrusions traversing an
ancient schistose series of rocks (provisionally named the Mergui
series), and also in pegmatitic veins intersecting both the rocks. But
the greater proportion of the ore is obtained, not fromjbhe deposits in
situ, but from the washing of river-gravels {stream-tin or tin-stone) and
from dredging the river-beds of the tin-bearing areas, where the ore is
collected by a process of natural concentration by running water.
The value of the total amount of tin concentrates (roughly 6000 tons
yearly) produced in Burma has of late risen to nearly Rs. one crore
per year, of which the larger share belongs to Tavoy.
^Eec. 0.8,1. vols, xxxvii and xxxviii. pts. 1, 1908 and 1909, Annual Reports;
Coggin Brown and A. M. Heron, Ore Deposits of Tavoy, Mem. O.S.I, vol. xliv. pt. 2,
1923.
^BCONOMIC GEOLOGY
353
Wolfram
ft
Wolfram of Tavoy—Previous to 1914, Burma contributed nearly a
third of the total production of wolfram of the world, but subsequently
it increased its output to a much larger extent, heading the list of the
world's producers of tungsten, with 3600 tons of ore per annum.
Since 1921 wolfram-mining has gone through many vicissitudes, the
present yearly output of'4000 tons being regarded as a recovery.
The most important and valuable occurrences of wolfram are in the
Tavoy district of Lower Burma,^ where the tungsten-ore is found in
the form of the mineral wolframite in a belt of granitic intrusions
among a metamorphic series of rocks {Mergui series). The tin-ore,cassiterite, mentioned on the preceding page, occurs in the same group
of rocks, at places associated with wolframite. Wolfram chiefly occurs
in quartz-veins or lodes, associated with minerals like tourmaline,
columbite, and molybdenite. From its mode of occurrence as well a's
from its association with the above-named minerals, it is clear that
wolfram is of pneumatolytic origin, i.e. formed by the action of
. " mineralising " gases and vapours issuing from the granitic magma.
The cassiterite has also originated in a similar manner.
Wolfram is also found in India in Nagpur, Trichinopoly and
Rajputana, but not in quantities sufficient to support a mining
industry.
Uses of tmigsten—Tungsten possesses several valuable properties
which give to it its great industrial and mihtary utility. Among these
the most important is the property of " self-hardening ", which it
imparts to steel when added to the latter. Over 95 per cent, of the
\^olfram mined is absorbed by the steel industry. All high-speed steel
cat1;ing-tools have a certain proportion of tungsten in them. Tungsten-steel is largely used in the manufacture of munitions, of armour
plates, of the heavy guns, etc., which enables them to stand the heavy
charge of modern explosives. Tungsten, by repeated heating, is given
the property of great ductiUty, and hence wires of extreme fineness
and great strength, suitable for electric lamps, are manufactured.
The value of tungsten-ore (wolframite) was more than £80 per ton
before the great rise in the industry during the war.
1 Mem. O.S.I. vol. xUv. pt. 2, 1923 ; Bee. G.S.I, vol. xliii, pt. 1, 1913 ; op cit. vol. 1.
pt. 2, 1919.
364
GEOLOGY OF INDIA
Chromium
Occurrence—Cliromite, the principal ore of chromium, occurs as a
product of magmatic differentiation in the form of segregation masses
and veins in ultra-basic, intrusive rocks, like dunites, peridotites, serpentines, etc. In such form it occurs in Baluchistan, Mysore and in
Singhbhum. The Baluchistan deposits are the most important and
are capable of much larger output than the present yearly one of some
12,000 tons. Chromite occurs in the Quetta and Zhob districts in the
serpentines associated with ultra-basic intrusions of late Cretaceous
age. The Mysore and Singhbhum deposits produce respectively
14,000 and 5000 tons yearly. Some chromite occurs in t h e ' " Chalk
"hills " (magnesite-veins) near Salem, but it is not worked. Large
deposits of chromite occurring in dunite intrusions forming mountainmasses have been discovered by the Mineral Survey of Kashmir in the
Dras valley of Ladakh, Kashmir.
Uses—Chromite is used in the manufacture of refractory bricks for
furnace-hnings. Its further use lies in its being the raw material of
chromium, An alloy of chromium and iron (ferro-chrome) is used in
the making of rustless and stainless steels and armour-plates. A large
amount of chromium is used in the manufacture of mordants and
pigments, because of the red, yellow and green colours of its salts.
In all the above occurrences chromite is a primary ore of magmatic
origin.
Other Metals
Ores of the following metals also occur in India, but their deposits
ar'3 of very Umited proportions and are not at the present day of any
considerable economic value :
Antimony—Sulphide of antimony, stibnite, is found in deposits f
considerable size at the end of the Shigri glacier in the province of
Lahoul, but the lodes are inaccessible. It occurs mixed with galena
and blende in the granitoid gneiss of that area. Stibnite is also found
in Vizagapatam and in Hazaribagh. But the production of stibnite
from these bodies is variable, and there does not appear to be any
commercial possibility ^oi them unless metallic antimony is extracted
on the spot.
Arsenic—SulpWdes of arsenic, orpiment and realgar, form large deposits in Chitral on the North-West Frontier and in Kumaon. The
orpiment-niines "f t^^^ first locahty are well known for the beautifully
foliated masses of pure orpiment occurring in them, and form the chief
ECONOMIC GEOLOGY
355
indigenous source, but the output has fallen off considerably of late
years. The orpiment occurs in calcareous shales and marble in close
proximity to a dyke of basic intrusive rock. The chief use of orpiment
is as a pigment in lacquer-work ; it is also employed in pyrotechnics
because of its burning with a dazzhng bluish-white light. ^ Arsenopyrite occurs near Darjeeling and in the Bhutna valley, Kashmir.
Cobalt and nickel—Cobalt and Nickel-ores are not among the economic products of India. A few crystals of the sulphide of both
these metals are*found in the famous copper-mines of Khetri, Jaipur,
Rajputana. The Behta of the Indian j ewellers is the sulphide of cobalt,
which is used for the maldng of blue enamel. Nickehferous pyrrhotite
and ohalcopyrite occur at some places in South India, e.g. in the
auriferous quartz-reefs of Kolar, in Travancore, etc., but the occurrences are not of sufficient magnitude to support mining operations.
Small deposits of nickeliferous pyrites, containing 1 -7 per cent, of Ni
have been found in the Purana rocks of Ramsu and Buniyar and in
the Carboniferous limestone (Great limestone) of Riasi, Kashmir.
Zinc—Besides the ore associated with the lead-ores of Bawdwin
(p. 352), some zinc occurs with the antimony deposits of Shigri, and
the copper-deposits of Sikkim. Smithsonite is found at Udaipur in
Rajputana and a few other places.
Lodes of zinc-ore, blende, occur in the Riasi district, Kashmir in
Carboniferous limestones. The veins are lenticular, swelling to nests
of over 500 cubic feet. Some thousand tons of blende masses occur
as float ore on the surface.
7. PRECIOUS AND SEMI-PRECIOUS STONES«
Diamonds
Panna and Golconda diamonds—In ancient times India had acquired great fame as a source of diamonds, all the celebrated stones of
antiqidty being the produce of its mines, but the reputation has died
out since the discovery of the diamond-mines of Brazil and the Transvaal, and at the present time the production has fallen to a few stones
annually of but indifferent value. Even so late as the times of the
Emperor Akbar, diamond-mining was a flourishing industry, for the
field of Panna alone is stated to have fetched to his Government an
annual royalty of 12 lacs of rupees. The localities noted in history as
' Ccggin Brown, Bulletin of 1.1, and L. No. 6, 1921.
* Goodchild, Precious Stones (Constable).
356
GEOLOGY OF INDIA
•
the great diamond centres were Bundelkhand (for " Panna diamonds " ) ; the districts of Kurnool, Cuddapah, Bellary, etc., in the
Madras Presidency (for the " Golcond'a diamonds " ) ; and some places
in Central India such as Sambalpur^ Chanda, etc. The diamondiferous strata in all cases belong to the Vindhyan system of deposits.
A certain proportion of diamonds were also obtained from the surfacediggings and alluvial-gravels of the rivers of these districts. Two
diamond-bearing horizons occur among the Upper Vindhyan rocks of
Central India : one of these (Panna State) is a thin conglomerate-band
separating the Kaimur sandstone from the Kewah series, and the other,
also a conglomerate, lies between the latter and the Bhander series.
The diamonds are not indigenous to the Vindhyan rocks but have been
assembled as rolled pebbles, like the other pebbles of these conglomerates, all derived from the older rocks. The original matrix of the
gem from which it separated out by crystallisation, is not known with
certainty. Probably it lies in the dykes of basic volcanic rocks associated with the Bijawar series.^ The most famous diamonds of India
from the above-noted localities are : the " Koh-i-noor ", 186 carats ;
the "Great Mogul", 280 carats; the "Orloff", 193 carats; the
" P i t t " , 410 carats; the value of the last-named stone, re-cut to
136f carats, is estimated at £480,000,
Rubies and Sapphires (Corundum)^
Burma rubies—Crystallised and transparent varieties of corundum,
when of a beautiful red colour, form the highly valued j ewel ruby, and,
when of a light blue tint, the gem sapphire. Rubies of deep carminered colour, " the colour of pigeons' blood ", and perfect lustre are
often of greater value than diamonds. Rubies are mined at the
Mogok district (Ruby Mines district) of Upper Burma, north of
Mandalay, which has been a celebrated locality of this gem for a long
time. The best rubies of the world come from this district from an
area covering some 25 to 30 sq. miles, of which Mogok is the centre.
The matrix of the ruby is a crystalline limestone—ruby limestone
(see p. 60)—associated with and forming an integral part of the surrounding gneisses and schists. .The rubies are found in situ in the
limestone along with a number of other secondary minerals occurring
in it. Some stones are also obtained from the hill-wash and alluvial
• Vredenburg, Ecc. Q.S.I, vol. xxxiii. pt. 4, 1906 ; K. P. Sinor, The Panna Diamondfield, Bombay, 1932.
» T. H. Holland, Corundum, Q.S.l., 1898.
ECONOMIC GEOLOGY
f
357
detritus. The output of the Burma ruby-mines amounted, some years
ago, to over £95,000 annually, but it has declined of late years.^ The
average annual royalty of Es. 1,70,000 indicates the state of the industry at the present day.
Sapphires of Kashmir—The Burma ruby area also jaelds sapphires
occasionally, a sapphire weighing 1000 carats was found in 1929 and
another of 630 carats in 1930 from Mogok, but a larger source of
sapphires in India was up till lately Kashmir. The gem was first discovered in Kashmir in 1882; it there occurs as an original constituent
of a fine-grained highly felspathic gneiss at Padar in the Kishtwar
district of the Zanskar range, at a high elevation. Transparent
crystallised corundum occurs in pegmatite veins cutting actinoliteschist lenticles in Salkhala marble, at an altitude of 15,000 feet.
Associated minerals in the pegmatite are prehnite, tourmaline, beryl,
spodumene and lazulite. Sapphires were also obtained from the talusdebris at the foot of the hill-slopes. Stones of perfect lustre and of
high degree of purity have been obtained from this locality in the
earlier years, but the larger and more perfect crystals, of value as
gems, appeared to have become exhausted since 1908 ; late discovery,
however, by the Mineral Survey of Kashmir has revealed a large
quantity of crystallised transparent corundum. The bulk of the output from the mines is confined to what are called " rock-sapphires ",
valueless for gems and of use as abrasives, watch jewels, etc.
Spinel
Spinel when of sufficient transparency and good colour is used in
jewellery ; it constitutes the gem ballas-ruby when of rose-red colour
and spinel-ruby when of a deeper red. Rubicelli is the name given to
an orange-red variety. Spinel-rubies occur in the Burmese area associated with true rubies ; also to some extent in Ceylon, in the wellknown gem-sands of Ceylon, along with many other semi-precious
and ornamental stones.
Jadeite
Jade is a highly-valued ornamental stone on account of its great
toughness, colour and the high lustrous polish it takes; it is especially
valued in China, to which country almost the whole Indian output is
exported. A large number of mineral compounds pass under the name
1 One ruby from the Mogok mines, 38J carats in weight, was sold for £20,000 in
London in 1875.
358
GEOLOGY OF INDIA
oi jade, but the true mineral, also named nephrite, so much sought
after, is a comparatively rar© substance. Its occurrence is not known
in India, but a mineral very much similar to it in many of its qualities
and known asjadeite, is largely quarried in Burma. True jade comes
into India from the Karakash valley of South Turkestan.
Occurrence. Formation^The stones are of various shades of green,
violet, orange, red, blue, o.r milk-white colour, and even black. Jade
belongs to the group of amphiboles, being allied mineralogically to
the species tremolite, while jadeite, resembling the latter in many
of its physicaLcharacters, is more allied to the p3rroxene group, being
a species of spodumene. The occuLrrence of the latter mineral in India
is principally confined to the Miocene rocks of Upper Burma (Mjdtkyina district), where its extraction and export is a long-established
and remunerative industry. I t occurs either as boulders in the
alluvial gravels or as an alteration-product in the large serpentinous
intrusions in the district of Tawmaw.^ The formation of jade in
serpentine is regarded by some as due to magmatic segregation " taking place in the basic igneous intrusions of Miocene age. By others its
presence is attributed to the effects of contact metamorphism on a
dyke of nepheline-albite rock traversing masses of serpentine.
In the period of its greatest prosperity, the jade industry was a
flourishing trade in Burma, but at present it has considerably lessened,
which is to some extent due to the inferior quality of the jadestone
obtained. In 1932 Burma exported 3000 cwts. of jadestone of the
aggregate value of Rs. 3,26,000.
Sang-e-Yeshm, regarded as jade in the Punjab, is only a variety of
serpentine. I t differs from the original mineral in all its characters,
being not so tough, much softer and incapable of receiving the exquisite polish of jade.
Beryl
Emeralds and aquamarines—Beryl when transparent and of perfect colour and lustre is a highly valued gem. Its colour varies much
from colourless to shades of green, blue or even yellow. The muchprized green variety is the emerald, while the blue is distinguished as
aquamari'he. Emeralds are rare in India. Aquamarines suitable for
use as gems are obtained from pegmatite-veins crossing the Archaean
gneiss at some places in Bihar and Nellore. Good aquamarines also
occur in the Coimbatore district and in Kishengarh (Rajputana),
iBleeok Bee. O.S.I, vol. xxxvi. pt. 4, 1908.
»H. L. Chhibberr '
•^
ECONOMIC GEOLOGY
359
from both of wHch localities stones of considerable value were once
obtained. Eecently a new and highly productive locality for aquamarines has been discovered in the Kashmir State in the Shigar valley
in Skardu, whence crystals of considerable size and purity are
recovered. The gem occurs in coarse pegmatite veins traversing
bio'tite-gneiss.
Common beryl occurs in very large crystals, sometimes a foot in
length, in the granite-pegmatite of many parts of India, but only rarely
do they include some transparent fragments of the required purity.
Chrysoberyl
Chrysoberyl is a stone of different composition from beryl. It is of
greenish-white to ohve-green colour. A few good stones in the form
of platy crystals of tabular habit are obtained from pegmatite-veins
in Kishengarh in Eajputana, which also yield mica and aquamarines.
They are found in some felspar-veins in the nepheline-syenites of
Coimbatore. Usually they are too much flawed and cracked to be
suitable for cutting as gems. Chrysoberyl crystals when possessing
a chatoyant lustre are known as " Cat's eyes ". Alexandrite is the deep
emerald-green variety found in Ceylon.
Garnets
.
Garnet as a gem-stone—Garnet possesses some of the requisites of a
gem-stone—a high refractive index and lustre, a great hardness, a
pleasing colour, transparency, etc.—and would be appreciated as such,
were it but put on the market in restricted quantitites. Garnets are
most abundant in the raetamorphosed rocks of Rajputana and Ceylon,
especially in the mica-schists, and large transparent crystals are frequently found. Quantities of garnets are exported to foreign countries for use in cheap jewellery. The variety used for this purpose is
almandine, of crimson to red and violet colours. Crystals of large size,
derived from Purana mica-schist, are worked at Jaipur, Delhi and at
Kishengarh, where they are cut into various shapes for gems. Those
of Kishengarh are considered to be the finest in India, and support a
regular industry of about a lac of rupees yearly.
Zircon
Zircons occur in various parts of India, but nowhere quite flawless
or with the degree of transparency required in a gem. Hyacinth (the
transparent red variety) is found at Kedar Nath on the Ganges.
360
GEOLOGY OF INDIA
Tourmalines
Red and green tourmalines—Pellucid and beautifully coloured
varieties of tourmaline, red, green or bl^ue, are worked as gems. The
fine red transparent variety Rubellite is obtained from the ruby-mines
district of Burma, where it occurs in decomposed granite veins. The
green variety known as Indicolite pccurs in Hazaribagh (Bengal) and
in the Padar district of Kashmir, where also some transparent crystals
of rubellite are found. The latter tourmaHnes possess greater transparency, but are much fissured. Gem-tourmaUnes are also obtained
from Ceylon from the noted gem-sands or gravels of that island.
Other gem-stones of India
Besides the above-named varieties, other crystallised minerals,
when of fine colour and attractive appearance and possessing some of
the other quaUties of gems, e.g. hardness, transparency, etc., are cut
for ornamental purposes in different parts of the country. Among
such minerals are the pleochroic mineral iolite or- cordierite of Ceylon ;
kyanites or cyanites found-at Narnaul in the Patiala State ; rhodonite
(pink manganese siUcate) of some parts of the Central Provinces;
apatite (a sea-green variety) met with in the kodurites of Vizagapatam. Moonstone and amazon-stone are ornamental varieties
of felspar, the former a pearly opalescent orthoclase, met with
in Ceylon, and the latter a green microcline occurring in Kashmir
and elsQwhere.
Gem-cutting is a regular industry in places like Delhi, Jaipur and
Ceylon.
Agates
Various forms of chalcedonic silica, agates, carnelian, blood-stone,
onyx, jasper, etc., are known under the general name of ahik (agate)
in India. The principal material of these semi-precious stones is obtained from the amygdaloidal basalts of the Deccan, where various
kinds of chalcedonic silica have filled up, by infiltration, the steamholes or cavities of the lavas. The chief place which supplies raw
akik is Eatanpur in the Eajpipla State, where rolled pebbles of these
amygdules are contained in a Tertiary conglomerate. On mining, the
stone's are first baked in earthen pots, which process intensifies the
colouring of the bands in the agates. The cutting and polishing is
done by the lapidaries of Cambay, who fasliion out of them (after a
ECONOMIC GEOLOGY
.
361
most wasteful process-of cljipping), a number of beautiful but small
articles and ornaments. The annual output at Eatanpur is about 100
tons. Cambay used to be a large market of Indian agates in past years
for different parts of tLe world.
Rock Crystal
Rock-crystal, or crystallised, transparent, quartz, is also cut for
ornamental objects, such as cheap jewels (vallum diamonds), cups,
handles, etc. The chief places are Tanjor, Kashmir, Kalabagh, etc.,
from whence crystalline quartz of requisite purity and transparency
is obtained.
Amethyst and Rose-Quartz, the purple and pink-coloured varieties
of rock-crystal are cut as ornamental stones and gem-stones. Amethyst
occurs in some geodes in Deccan Trap, filling up lava-cayities, near
Jabalpur; it also occurs in Bashar State, Punjab. Eose quartz is
found in Chhindwara and Warangal, C.P.
Amber
Amber is mineral resin, i.e. the fossilised gum of extinct coniferous
trees. I t is extracted by means of pits from some Miocene clay-beds in
the Hukawng valley of North Burma. A few cwts. are produced
annually, from 50 to 200, with an average value of 90 to 100 rupees
per cwt. I t occurs in round fragments and lumps, transparent or
translucent, often crowded with inclusions and with veins of calcite.
Amber is employed in medicine, in the arts, for jewellery, etc., and is
highly prized when of a transparent or translucent nature.
8. ECONOMIC MINERALS AND MINERAL PRODUCTS
Here we shall consider the remaining economic mineral products,
mostly non-metallic minerals of direct utility or of application in the
various modern industries and arts. They include salts and saline
substances, raw materials for a number of manufactures, and substances of economic value such as abrasives, soil-fertilisers, the rare
minerals, etc. With regard to their geological occurrence, some are
found as constituents, original or secondary, of the igneous rocks;
some as beds or lenticles among the stratified rocks, formed by
chemical agencies; while others occur as vein-stones or ganguematerials occurring in association with mineral-veins or lodes or
362 •
•
GEOLOGY OP INDIA
filling up pockets or cavities in t t e rocks. The more important of
these products are :
I
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
Salt.
Saltpetre. •
Alum.
Borax.
Reh.
Mica.
Corundum.
Kyanite and Sillimanite.
Beryl.
Monazite.
Graphite.
Steatite.
Gypsum.
Salt
.
14. Magnesite.
,-,,
15. Asbestos.
16. Barytes,
17. Fluor-spar.
18. Phosphatic Rocks.
19. Mineral Paints.
20. Uranium.
21. Titanium.
22. Vanadium.
23. Rare Minerals.
24.'Pyrite.
25. Sulphur.
Sources of salt. Sea-water. Brine-wells—There are three sources of
production of this useful material in India : (1) sea-wiiter, along the
coasts of the Peninsula; (2) brine-springs, wells and salt-lakes of some
arid tracts, as of Rajputana and the United Provinces ; (3) rock-salt
deposits contained in Cutch, Mandi State, the Salt-Range and in the
Kohat region. The average annual production of salt from these
sources is a little over If million tons, the whole of which is consumed
in the country. The first is the most productive and an everlasting
source, contributing more than 80 per cent, of the salt consumed in
India. The manufacture is carried on at some places along the coasts
of Bombay and Madras, the process being mere solar evaporation of
the sea-water enclosed in artificial pools or natural lagoons. A solid
pan of salt results, which is afterwards refined by recrystallisation.
Concentration from brine springs and wells is carried on in various
parts of the United Provinces, Bihar, Delhi, Agra, the delta of the
Indus, Cutch and in Rajputana. The principal sources of salt in the
last-named province are the salt-lakes of Sambhar in Jaipur, Dindwana and Phalodi in Jodhpur, and Lonkara-Sur in Bikaner. The
salinity of the lakes in this area of internal drainage was for long a
matter of conjecture, but the investigations of Holland and Christie ^
have conclusively shown that the salt is brought as fine dust by
the south-west monsoon from the Rann of Cutch and from the sea^Eec. G.S.I. voh sxxviu-pt. 2, 1909.
ECONOMIC GEOLOGY
•
363
coasts, and is dropped in the interior of Rajputana when the velocity
of the winds passing ov^r it has decreased.
Rock-salt mines—The rock-salt deposits of Northern India also
constitute an immense source of pure crystallised sodium chloride.
At Khewra, in the Jhelum district, two beds of rock-salt 550 feet thick
are worked ; they contain ^se seams of pure salt totalling 275 feet
intercalated with only a few earthy or impure layers unfit for direct
consumption. The horizontal extension of these beds or lenticles is
not known definitely, but it is thought to be great. Smaller salt-mines
are situated at some other parts along these mountains. A salt-deposit of even greater vertical extent than that worked at Khewra is
laid bare by the denudation of an anticline in the Kohat district, lying
north of the Salt-Range. Here the salt is taken out by open quarrying
in the salt-beds at the centre of the anticline near Bahadur Khel. The
thickness of the beds is 1000 feet and their lateral extent 8 miles. The
salt is nearly pure crystaUised sodium chloride, with a distinct greyish
tint owing to slight bituminous admixture. Salt-beds of considerable
size occur in the Mandi State, while some million tons of pure rocksalt, produced by evaporation of sea-water in enclosed basins_, occurs
embedded in the sands of the Rann of Cutch and in the alluvial tract
south-east of Sind.
The average annual amount of rock-salt extracted from the
mines in the Salt-Range, Kohat and Mandi State, is about
170,000 tons.
Other Salts—The Salt-Range deposits contain, beside sodium
chloride, some salts of magnesium and potassium. The latter salts
are of importance for their use in agriculture and some industries.
Numerous seams of potash-bearing minerals (containing a potassium
percentage from 6 to 14 per cent.), such as sylvite, kainite, langbeinite,
etc., have been found, generally underlying the layers of red earthy
salt (kalar).^
Carbonate-^Carbonate and sulphate of soda were formerly derived
from the Reh efflorescences of the alluvial plains of Northern India.
The extent of these accumulations may be judged from an estimate of
the quantity of sodium carbonate available, viz. several million tons
per annum, from the Reh efflorescences in the soils of United'Provinces.^ Carbonate of soda forms a large ingredient of the salt-water
of the Lonar lake, in Buldana district, from which it was formerly
extracted for commerce. The Lonar lake is estimated to contain
» Eec. GlS.I. vol. xliv. pt. 4, 1914.
2 E. R. Watson and K. C. Mukerji, Joum. I. I. and L. vol. ii, 1922.
364
GEOLOGY OF INDIA
about 7000 tons of alkaKne salts. But the cheap supply of chemically
manufactured soda prohibits any industrial working of these salts
now.^
The Dhands, or alkaline lakes (p. 2Q0), of eastern Sind are another
source of sodium salts, carbonate, chloride, and sulphate. The production of crude sodium carbonate and bi-carbonate in 1934 was
about 2000 tons.^
Saltpetre or Nitre (Potassium Nitrate)'
India, principally the province of Bihar, used to export this compound in very large amounts before the introduction of artificially
manufactured nitrate, and constituted the most important source of
supply to Europe and the United States of America.
Mode of occurrence of nitre—Saltpetre is a natural product formed
in the soil of the alluvial districts by natural processes under the
pecuUar conditions of climate prevailing in those districts. The
thickly populated agricultural province of Bihar, with its alternately
warm and humid climate, offers the most favourable conditions for
the accumulation of this salt in the sub-soil. The large quantities of
animal and vegetable refuse gathered round the agricultural villages
of Bihar are decomposed into ammonia and other nitrogenous substances ; these are acted upon by certain kinds of bacteria, {nitrifying
bacteria) in the damp hot weather, with the result that at first nitrous
and then nitric acid is produced in the soil. This nitric acid readily
acts upon the salts of potassium with which the soil of the villages is
impregnated on account of the large quantities of wood and dung
ashes constantly being heaped by villagers around their habitations.
The nitrate of potassium thus produced is dissolved by rain-water and
accumulated in the sub-soil, from which the salt re-ascends to the surface by capillary action in the period of desiccation'following the rainy
weather. Large quantities of nitre are thus left as a saline efflorescence
on the surface of the soil along with some other salts, such as chloride
of sodium and carbonate of sodium.
Its production—The efflorescence is collected from the soil, lixiviated
and evaporated, and the nitre separated by fractional crystallisation.
I t is then sent to the refineries for further purification. In past years
> Bee. G.S.I. vol. xli. pt. 4, 1912.
2 Mem. G.8.I. vol. xlvii. pt. 2, 1923.
* Hutchinson, Saltpetre, its Origin and Extraction in India, Bulletin 68 (1917),
Agricultural Department of India.
^
ECONOMIC GEOLOGY
335
Bihar alone used to produce more than 20,000 tons of nitre per year.
The present aggregate export of refined nitre from Bihar, Punjab,
Sind and other parts of India hardly amounts to 10,000 tons.
Uses—The chief use for nitre or saltpetre was in the manufacture
of gunpowder and explosives before the discoveries of modern chemistry brought into use other compounds for these purposes. Nitre is
employed in the manufacture of sulphuric acid and as an oxidiser in
numerous chemical processes. A subordinate use of nitre is as manure
for the soil.
Aliun
Alums are not natural but secondary products manufactured out of
pyritous shales or " alum shales ".
[Production—Pyritous shales when exposed to the air, under heat and
moisture, give rise to the oxidation of the pyrites, producing iron sulphate
and free sulphuric acid. The latter attacks the alumina of the shales and
converts it into aluminium sulphate. On the addition of potash-salts, such
as nitre or common wood-ashes, potash-alum is produced, and when
common salt or other soda-salts are introduced, soda-alum is produced. In
this way several alums are made, depending upon the base added.
The natural weathering of the shales being a very slow process, it is
expedited in the artificial production of alum by roasting it. The roasted
shale is then lixiviated and concentrated. A mixture of various'soda and
potash-salts is then added and the alum allowed to crystaUise out.]
The most common alums produced in India are soda, and p'otash
alums. There was a flourishing alum industry in the past in Cutch,
Rajputana and parts of the Punjab. But it is no longer remunerative
in face of the cheap chemical manufactured alums, and is carried on
only at two localities, Kalabagh ^ and Cutch. The principal use of the
alum -manufactured in India is in the dyeing and tanning industries.
Soluble sulphates of iron and copper—copperas and blue-vitriol—
are obtained as bye-products in the manufacture of alums from
pyritous shales.
Borax
•
Borax from Tibet^Borax occurs as a precipitate from the hot
springs of the Puga valley, Ladakh, which occur in association with
some sulphur deposits. Borax is an ingredi,ent of many of the saltlakes of Tibet, along with the other salts of sodium. The borax of the
Tibetan lakes is obtained either by means of diggings, on the shores of
i-i?ec. G.S.I. vol. xl. pt. 4, 1910.
366
GEOLOGY OF INDIA
the lakes, or by the evaporation of their waters. The original source
of the borax in these lakes is thought to be the hot springs, like those
of Puga mentioned on the preceding'page.
Like nitre, alum and similar products, the borax trade, which was
formerly a large and remunerative one, has seriously declined owing
to the discovery of deposits of calcium borate in America, from which
the compound is now synthetically prepared. The industry consisted
of the importation of partly refined borax into the Punjab and United
•Provinces, from Ladakh and Tibet, and its exportation to foreign
countries. About 16,000 cwts. were thus exported yearly, valued at
Rs. 360,000', whereas now it is only about 1000 cwts. Borax is of use
in the manufacture of superior grades of glass, artificial gems, soaps,
varnishes and in soldering and enamelling.
Reh or Kallar
•
The •origin of reh salts—Reh or Kallar is a vernacular name of a
saline efflorescence composed of a mixture of sodium carbonate, sulphate and chloride, together with varying proportions of calcium and
magnesium salts found on the surface of alluvial soils in'the drier
districts of the Gangetic plains. Reh is not an economic product, but
it is described here because of its negative virtues as such. Some soils
are so much impregnated with these salts that they are rendered quite
unfit .for cultivation. Large tracts of the country, particularly the
northern parts of United Provinces, Punjab and Rajputana, once
fertile and populous, are through its agency thrown out of cultivation
and made quite desolate. The cause of this impregnation of the salts
in the soil and sub-soil is this,: The rivers draining the mountains
carry with them a certain proportion of chemically dissolved matter,
besides that held in mechanical suspension, in their waters. The salts
so carried are chiefly the carbonates of calcium ajid magnesium and
their sulphates, together with some quantity of sodium chloride, etc.
In the plains-track of the rivers, these salts Und their way, by percolation, into the sub-soil, saturating it up to a certain level. In many
parts of the hot alluvial plains, which have got no underground
drainage of. water, the salts go on accumula'ting and in course of time
become concentrated, forming new combinations by interaction between previously existing salts. Rain water, percolating downwards^
• dissolves the more soluble of these salts and brings them back to tha
surface during the summer months by capillary action, where they
form a white efflorescent crust. The reclaiming of these barren kallar
ECONOMIC GEOLOGY
367
lands into cultivable soils hy tlie removal of these salts would add
millions of acres to the agricultural area of India and bring back under
cultivation what are now altogether sterile uninhabited districts.
The carbonate and sulphate of soda, the chief constituents of Reh,
were formerly of some use as a source of salts of alkalies, and w.ere produced in some quantity for local industry, but their production is no '
longer remunerative. (See p. 363)
Mica
Uses of Mica—Mica (muscovite) finds increased uses in many industries, and is a valuable article of trade. The chief use is as an insulating material in electric goods ; another is as a substitute for glass
in glazing and many other purposes. For the latter purpose, however,
only large transparent sheets are suitable. Formerly an enormous
amount of what is called scrap-mica (small pieces of flakes of mica),
the "waste of inica-naines and quaiiies, was considered valueless and
was thrown away. A use has now been found for this' suljstance in
the making of micanite—mica-boards—by cementing small bit^ of
scrap mica under pressure. Micanite is now employed for many purposes in which sheet mica was formerly used. Scrap mica is also
ground for making paints, lubricants, etc.
The mica-deposits of the Indian peninsula are considered to be the
finest in the world, because of the large size and perfection of the
crystal plates obtainable at several places. This quality of the mica is
due to the immunity from all disturbances such as crumpling, shearing, etc., of the parent rocks. Crystals more than three yards in diameter are obtained occasionally from the Nellore mines, from coarse
pegmatite veins traversing Archaean schists and gneisses, from which
valuable flawless sheets of great thinness and transparency are cloven
off.
Mica-deposits of Nellore and Hazaribagh—India is the largest producer of mica in the world, contributing, of late years, more than
170,000 cwts. per year, bringing in a return of Es. 90,00,000. The
whole output of the mines is exported, there being no indigenous industry to absorb any part of the product, or for the manufacture of
micanite. Although muscovite is a most widely distributed mineral
in the crystalline rocks of India, marketable mica is restricted to a few
pegmatite-veins only, carrying large perfect crystals, free from
wrinkling or foreign inclusions. These pegmatite veins cross the
^ c h a e a n and .Dharwar crystalHne rocks, granites, gneisses and
368
GEOLOGY OF INDIA
schists, but tiey become the carriers of good mica only when they cut
through mica-schists. The principal mica-mining centres in India are
the Hazaribagh, Gaya and Monghyr districts of Bihar, the Nellore
district of Madras, and Ajmere and Merwara in Eajputana. Of these
Bihar is the largest producer, while Eajputana contributes only 4 per
cent, of the total.^ The dark-coloured micas, biotite, phlogopite, etc.,
have no commercial use.
Lepidolite, lithia mica, the source of Uthium oxide, occurs in
pegmatite veins and lenses of 30 ft. width and 300 to 400 yards length
in the Bastar State of the Central Provinces, containing over 3 per
cent, of Hthium oxide. The mineral is of use in the glass and porcelain
industries.
Corundum^
Occurrence. Distribution—Corundum is an original constituent of
a number of igneous rocks of acid or basic composition whether
plutonic or volcanic. I t generally occurs in masses, crystals, or
irregular grains in pegmatites, granites, diorites, basalts, peridotites,
etc.. The presence of corundum under such conditions is regarded as
due to an excess of the,base AlgOg in the original magma, over and
above its proper proportion to form the usual varieties of aluminous
silicates.^ India possesses large resources in this useful mineral, which
are, for the most part, concentrated in Mysore and Madras. Other
localities are Singhbhum ; Eewah (Pipra,), where a bed of corundum
800 yards long, 70 yards wide and 30 feet thick is found ; the Mogok
district (Euby Mines district), in Upper Burma ; Assam (Khasi hills);
some parts of Bihar ; the Zanskar range in Kashmir, etc. In Burma
the famous ruby-hmestone contains a notable quantity of corundum
as an essential constituent of the rock, some of which has crystalhsed
into the transparent varieties of the mineral, ruby and sapphire. In
Madras there is a large area of corundiferous rocks^covering some parts
of Trichinopoly, Nellore, Salem and Coimbatore. Jvfoslly the corundum occurs in situ in the coarse-grained gneisSes,-in.small round grains
or in large crystals measuring some inches in.size. It also forms a
constituent of the eleaolite-syenites of Sivamalai and of the coarse
felspar-rock of Coimbatore.
1 Mica Deposits of India, Hem. O.S.I, vol. xxxiv. pt. 2, 1902; Bull, of 1.1, and L.
No. 15.
2 T. H. Holland, Corundum, G.S.I., 1898.
' In the above instances corundum occurs as an original constituent of the magma,
but the mineral also occurs in many cases as a secondary product in the zones of
contacfc-metamorphism around plutonic intrusions, ^
,
ECONOMIC GEOLOGY
369
s
Uses—The chief use of corundum is as an abrasive material because
of its great hardness. Emery is an impure variety of corundum, mixed
with iron-ores and adulterated with spinel, garnet, etc. The abrading
power of emery is much less than that of corundum, while that of
corundum again is far below that of the crystallised variety sapphire.
As an abrasive corundum has now many rivals, in such artificial products as carborundum, alundum, etc. Corundum is used in the form
of hones, wheels, powder, etc., by the lapidaries for cutting and.
polishing gems, glass, etc.
The total annual production in India averages about 6000 to 7000
cwts., valued at about Es. 30,000.
Other abrasives. Millstones—While dealing with abrasives, we
might also consider here materials suitable for millstones and grindstones that are raised in India. A number of varieties of stones are
quarried for cutting into millstones, lihough rocks that are the most
suitable for this purpose are hard, coarse grits or quartzites. There is
a scarcity of such rocks in most parts of the country and hence the
stones commonly resorted to are granites, hard gritty Vindhyan sandstones and Gondwana grits and sandstones, chiefly of the Barakar stage.
Grindstones—Grindstones, or honestones, are cut from any homogeneous close-grained rocks belonging to one or the other of the
following varieties : fine sandstones, lydite, novaculite, hornstone,
fine-grained lava, slate, etc.
Kyanite and SiUimanite
These aluminous silicates, owing to their possessing certain valuable properties as refractories at high temperatures, especially in the
manufacture of ceramics, have come into prominence of late years.
India possesses considerable resources in both these minerals and can
meet the demands of European and American markets for a long time.
Kyanite occurs mainly in Singhbhum as kyanite-quartz rock and as
massive kyanite-rock in beds of enormous size in the Archaean schists ;
sillimanite occurs also in the same rock-system in the Rewah State
(Pipra village) and in the Khasi plateau of Assam. Corundum occurs
with these in close relationship, forming a group of highly aluminous
schists and gneisses. A high degree of purity, with percentage of
aluminum silicate reaching 95 to 97, characterises both these minerals
from Rewah, Assam and Singhbhum. The present day exports of
kyanite are about 24,000 tons, value Rs. 350,000. ^
> J. A. Dunn, Mem. G.S.I, vol. lii. pt. 2, 1929 ; and Mem. G.S.I. vol. Ixix, 1937.
W.O.I.
2A
370
GEOLOGY OF INDIA
Beryl
Beryl occurs in the mica-pegmatite of Bihar, Nellore, and Rajputana. Jaipur and Ajmer-Merwarai contain some workable deposits
of this mineral from which large crystals up to two feet in diameter are
sometimes obtained. The industrial use of Beryl lies in the 12 per
cent, or so of BeO employed in the manufacture of copper-beryllium
alloy. The Rajputana mines exported about' 300 tons in 1933;
value Rs. 7,200.
Monazite
Monazite is a phosphate of the rare earths—cerium, lanthanum
and didymium—but its economic value depends upon a small percentage of thorium oxide, which it contains as an impurity. Monazite
was discovered some years ago in the Travancore State in riverdetritus and along a long stretch of the coa^t from Cape Comorin to
Quilon. At some pJaees the monazite-sands have been concentrated
by the action of the sea-waves into rich pockets. Besides monazite,
the other constituents of-the sand are magnetite, ilmenite, garnets,
etc.; those with a high proportion of monazite have a density of 5-5
with a light yellow colour.
Monazite of Travancore. i Its occurrence—The monazite of Travancore is derived from the pegmatite-veins crossing the charnockites of
the district. Its original formation is ascribed to pneumatolytio
agencies during the later period of consolidation of the cbarnockite
magma. It is also a small accessory constituent of the main rock.
The percentage of thoria, yielded by the Travancore monazite, on
which the commercial value of the mineral depends, is variable from
8 to 10 per cent. In 1918 India exported concentrated monazite
sands of the value of £58,000 (2100 tons). The present output is of
much reduced dimensions.
Uses—The industrial use of monazite lies in the incandescent properties of thoria. and the other oxides of the~rare earths which it contains. These substances are used in the manufacture of mantles and
filaments for incandescent lamps.
Graphite
Occurrence—Graphite occurs in small quantities in the crystalline
and metamorphic rocks of various parts of the Peninsula, in pegmatite
and other veins, and as lenticular masses in some schists and gneisses.
1 Tipper, Rec. O.S.I, yol. xUv. pt. 3, 1914.
ECONOMIC GEOLOGY
371
It forms an essential constituent of the rock known as khondalite of
Orissa, a quartz-sillimanite-garnet-grapliite schist. But the majority
of these deposits are not of workable dimensions. Graphite occurring
under such conditions is undoubtedly of igneous origin, i.e. a primitive
constituent of the magma. Graphite resulting from the metamorphism of carbonaceous strata, and representing the last stage of the
mineralisation of vegetable matter, is practically unknown in India,
except locally in the highly crushed Gondwana beds of the outer
Himalayas. The largest deposits of graphite are in Ceylon, which has
in the past supphed large quantities of this mineral to the world, its
yearly contribution being nearly a third of the world's total annual
produce. The graphite here occurs as filling veins in the granulites
and allied gneisses belonging to the Charnockite series. The structure of the veins is often columnar, the columns lying transversely to
the veins. Travancore until lately was another important centre for
graphite-mining, deriving the mineral from the Charnockite series of
gneisses, supplying annually about 13,000 tons of the mineral (valued
at Rs. 780,000). The graphite industry has practically ceased in Travancore of late years owing to the increasing depths to which mining
operations have become necessary.
A few other locaHties have been discovered among the ancient
crystalline rocks, where graphite occurs, viz. Merwara in Rajputana, Sikkim, Coorg,- Vizagapatam and in the Ruby Mines
district of Upper Burma, but the quantity available is not large.
Rajputana produced nearly a thousand tons in 1916 of a rather
low grade.
Uses—The uses of graphite lie in its refractoriness and in its high
heat conductivity. For this purpose it is largely employed in the
^manufacture of crucibles. Its other uses are for pencil manufacture,
as a lubricant, in electrotyping, etc.
Steatite
Mode of origin of steatite—Massive, more or less impure, talc is put
to a number of minor uses. From its smooth, uniform texture and
soapy feel, it is called soapstone. It is also known as pot-stone from
its being carved into plates, bowls, pots, etc. Steatite is of wide occurrence in India, forming large masses in the Archaean and Dharwar
rocks of the Peninsula and Burma; workable deposits occur in
Behar, Jabalpur, Salem, Idar and Jaipur (Rajputana) and Minbu (in
Burma). The Rajputana deposits carry the mineral in thick lenticular
372
GEOLOGY OF INDIA
beds of wide extent in the schists. Some of these beds persist for
miles. At most of these places steatite is quarried in small quantities
for commercial purposes. In its geological relations, steatite is often
associated with dolomite (as in Jabalpur) and other magnesian rocks,
and it is probable that it is derived from these rocks by metamorphic
processes resulting in the conversion of the magnesium carbonate into
the hydrated silicate. In other cases it is the final product of the
alteration of ultra-basic and basic eruptive rocks. At Jabalpur and
other places it is carved into bowls, plates and vases ; it is also used in
soap-making, in pencils, in the paper industry, and as a refractory substance in making jets for gas-burners. The' substance has also of late
come into use aa a special type of refractory, resistant to corrosive
slags and as a paint of high quality for protecting steel. ^ The annual
production at present is about 8500 tons of the value of about Rs. 2
lacs.
Gypsum
Gypsum forms large bedded masses or aggregates occurring in association with rocks of a number of different geological formations. It
has not found many uses in India, as is shown by the extremely low
price of the product, Ee. 1 for about 15 cwt. in some of the localities
where it is quarried. Large deposits of gypsum occur in the SaltRange and Kohat in association with rock-salt deposits, and in the
Tertiary clays and shales of Sind and Cutch. In Jodhpur and Bikaner
beds of gypsum are found among the silts of old lacustrine deposits
and are of considerable economic interest locally. Millions of tons of
gypsum, the alteration-product of pyritous limestone of Salkhala age,
are laid bare in the mountains of the Uri district of Kashmir in a stretch
of about 25 miles along the strike of the country-rocks. In Spiti the
gypsum occurs in immense masses replacing Carb6niferous limestones.
In some cases gypsum occurs as transparent crystals (selenite) associated with clays. The handsome massive and granular variety, known
as alabaster, is used in Europe for statuary, while the silky fibrous
variety, known as satin-spar, is employed in making small ornamental
articles.
The industrial use of gypsum is in burning it for making plaster-ofParis. In America it is increasingly used for fire-proofing wall-boards.
I t is also used as a surface-dressing for lands in agriculture, and as a
fertiliser, with considerable benefit to cerjtain crops.
ECONOMIC GEOLOGY
373
Magnesite'
Mode of occurrence of magnesite—^Large deposits of magnesite occur
in tlie district of Salem as veins associated with other magnesian rocks
such as dolomite, serpentines, etc. The magnesite is beheved to be an
alteration-product of the dunites (peridotite) and other basic mag- '
nesian rocks of Salem. When freshly broken it is of a dazzling white
colour and hence the magnesite-veins traversing the country haveTjeen
named the Chalk hills of Salem. The magnesite of Salem is of a high
degree of purity, is easily obtained and, when calcined at a high temperature, yields a material of great refractoriness. Other places in
South India also contain magnesite-veins traversing basic rocks, viz
Coorg, Coimbatore, Mysore and Trichinopoly. The industrial uses of
magnesite arein the manufacture of refractory materials for use in the
steel industries and as a source of carbonic acid gas. It is also manufactured into cement (Sorel cement) for artificial stone, tiles, etc.
The combined output of Salem and Mysore magnesite workings reach
a total of about 15,000 tons, valued at Rs. one lao.
Asbestos*
Two quite different minerals are included under this name : one a
variety of amphibole resembling tremoHte and the other a fibrous
variety of serpentine (chrysotile). Both possess much the same
physical properties that make them valuable as commercial products.
Asbestos (both the real mineral and chrysotile) has been discovered at
majiy places in India, but at only a few localities to be of any commercial use, viz. Pulivendla (Cuddapah), where excellent chrysotile
asbestos occurs at the contact of a bed of Cuddapah limestone with a
dolerite sill; in the Hassan district of the Mysore State and the
Saraikala State of Singhbhum. Much of the latter, which is of the
actinolite variety, however, does not possess that softness or flexibility
of fibre on which its industrial appHcation depends. Asbestos has
found a most wonderful variety of uses in the industrial world of today, viz. in the manufacture of fire-proof cloth, rope, paper, millboards, sheeting, belt, paint, etc., and in the making of fire-proof
safes, insulators, lubricants, felts, etc.
Asbestos (amphibole) occurs in pockets or small masses or veins in
» Middlemias, Bee. G.S.I, vol. xxix. pt. 2, 1896.
' Coggin Brown, Bulletin of 1.1, and L. No. 20, 1922; A. L. Coulson, Asbestos in
Madras, Mem. G.8.I. vol. Ixiv. pt. 2, 1934.
374
GEOLOGY OF INDIA
the gneissic and schistose rocks. The chrysotile variety forms veins
in serpentine. The available supplies in India are suificient to meet
any expansion of indigenous asbestos industry. In 1929 about 300
tons were produced from Madras and Sarai Kela, but the extraction
has fallen off now due to lack of deinand.
Barytes
Barytes occurs at many places in India in the form of veins and as
beds in shales, in sufficient quantities, but with few exceptions the
deposits were not worked till late because of the absence of any demand
for the mineral. The chief localities for barytes are Guddapah and
Kurnool ^ districts ; Alwar State; Salem; and Sleemanabad (in the
J abalpur district). Barytes is used as a pigment for mixing with white
lead, as a flux in the smelting of iron and manganese, in paper-manufacture, in pottery-glazes, etc. The annual production approximates
5500 tons, valued at Rs. 41,500.
Fluor-spax
This mineral is of rather rare occurrence in India. Veins of fluorite
occur in the rocks of some parts of the Peninsula and the Himalayas,
in gneiss in Kishengarh, in the Vindhyan limestone in Rewah, in
granite in the Sutlej valley, Simla Himalaya, but the quantity available is not considerable in any place. The chief use of fluor-spar is as a
flux in the manufacture of iron, of opalescent glass, enamel, etc.
Phosphatic Deposits ^
Native phosphates, as apatite, or rock-phosphates, as concretions,
are highly valued now as artificial fertilisers or manures, either in the^^
raw condition or after treatment with sulphuric "acid, to convert them
into acid or superphosphates. Their farity in a country like India,
whose primary industry is agriculture, is mostl-egrettable. The only •
occurrence of phosphatic deposits on a sufficient scale is in connection with the Cretaceous beds of Trichinopoly, where phosphate of
lime occurs in the form of septarian nodules disseminated in the claybeds. The quantity available is about 8,000,000 tons. A like deposit
near Mussoorie, overlying the Deoban limestone, is very rich in tri1 A. L. Coukon, Mem. 0.8.1. vol. Ixiv. pt. 1, 1933.
' Sir Edwin Pascoe, India's Resources in Mineral Fertilisers, Bvll. 1.1, and L. No. 42,
1929.
ECONOMIC GEOLOGY
'
375
calcium'phosphate. Massive apatite occurs as an abundant constituent of the mica-pegmatites of Hazaribagh and of the mica-peridotite dykes in the Bihar coalfields and in some schistose rocks of Bombay and Madras. It is also found on a large scale in lenticular aggregates in the Dharwar rocks of Dalbhum, in Singhbhum, where the
phosphate is estimated to be present in 250,000 tons quantity.
A source of phosphatic material for use as mineral fertihser exists in
the basic slag formed in the manufacture of steel. Over 30,000 tons of
this slag is being dumped annually at the steel works for want of any
present demand.
India imports phosphatic manures of the value of Es^ 12 lacs
annually.
Mineral Paints
Substances used for mineral paints—^A number of rock and mineral
substances are employed in the manufacture of paints and colouring
materials in Europe and America. Substances which are suitable for
this purpose include earthy forms of haematite and limonite (ochres,
geru); refuse of slate and shale quarries, possessing the proper colour
and degree of fineness ; graphite ; laterite ; orpiment; barytes ;
asbestos ; steatite, etc. Many of the above substances are easily
available in various parts of India and some are actually utilised for
paints and pigments, viz. a black slate for making black paints ;
laterite and geru (red or yellow levigated ochre) for red, yellow or
brown colouring matters; barytes as a substitute for white lead;
orpiment for yellow and red colours in lacq'uer work.^ Large quantities of red and yellow ochre in association with graphite-bearing
slate (carbon-content 25-30 per cent.) occur in the Salkhala system of
deposits in the Uri Tehsil of Kashmir State. These minerals have been
found suitable for manufacture of mineral paints.^
Uranium
Pitchblende of Gaya—Pitchblende (Uraninite) occurs in nodular
aggregates, in patches of basic segregations in a pegmatite vein crossing the gneisses and schists in the Singar mica-mines at Gaya.^ It is
associated with other uranium minerals—uranium-ochre, torbernite,
and also columbite, zircon, triplite, etc. These minerals have great
> Coggin Brown, Bulletin of I. I. and L. No. 20, 1922.
^ G. S. Middlemiss, Mineral Surv. Rep. J. and K. State (Graphite and Ochre), Jammu,
1926.
3 Rec. G.S.I. vol. I. pt. 4, 1919.
376
GEOLOGY OF INDIA
commercial value because of the small proportion of radium that they
contain. Eecent investigations in the Gaya pitchblende deposits have
proved that -the latter are very promising in their radium-content.
Further prospecting in the area, howeyer, has not disclosed the presence of any considerable deposits of pitchblende. Besides pitchblende,
other radium-bearing minerals and radio-active earths have been
found.' Samarskite, a complex niobate and tantalate, is found in the
mica-bearing pegmatite of Nellore in masses weighing 200 lbs.
Titanium
Titanium occurs in its two compounds, ilmenite and rutile, the
former of which is of fairly wide distribution in the charnockites and
other gneisses of the Peninsula and Eajputana. It occurs plentifully
on the Travancore coast as black sand along with monazite sand.
Here the concentration of the mineral, derived from the disintegration
of its parent rock, has reached large volumes, covering a coast-line of
100 miles length from Nindikarai to Liparum, found Cape Comorin.
In 1933 nearly 53,000 tons were exported ; value £62,000.
The chief use of ilmenite is in the manufacture of white paints, the
opacity and covering power of titanium-oxide being high. I t is also
used in alloys with iron.
Rutile is also abundantly distributed in small crystals throughout
the crystalline schists of the Peninsula.
Vanadium
Vanadium-bearing iron-ore, containing VjOg in quantity varying
from 1-6 per cent., has recently been discovered in deposits of considerable size, but with a fitful distribution of the Vanadium-content,
in Mayurbhanj State. Its exact paragenesis and relation with the
country-rocks are not yet known, but the ore occurs in association
with basic intrusions in Dharwar schists.
The Rare Minerals
The rare minerals of India—The pegmatite veins of the crystalline
rocks of India contain a few of what are called the rare minerals as
their accessory constituents. The rare elements contained in them
have found an extended use in modern industries such as mantlemanufacture, the manufacture of special kinds of steels, and other
products of highly speciaUsed uses in the present-day industries.*
' Cahen and Wootton, Mineralogy of the Rarer Metals, 1912 (C. GrifGin).
ECONOMIC GEOLOGY
377
The most common of these are : wolfram and monazite, which have
been already dealt with ; columbite and tantalite (niobates and tantalates of the rare-earths), which occur in the mica-pegmatites of
Gaya, Hazaribagh, Nellore, etc.; gadolinite (a silicate of the yttrium
earths), which is found in a tourmaline-pegmatite associated with
cassiterite in Palanpur; and molybdenite, which is found in the
crystalline rocks of Chhota Nagpur, Godavari Agency, Madura and
in the elaeolite-syenite-pegmatite of Rajputana and of Travancore.
Another rare mineral, thorianite, has been found in Travancore and
Ceylon, containing from 60-80 per cent, of thoria and a considerable
amount of helium. Allanite occurs in the pegmatites of Nellore, with
sipylite, a niobate of erbium with other rare earths.
Zircon is found with uranium minerals and with triplite in the micamines of Gaya and in the nepheline-syenites of Coimbatore. Cyrtolite
is a radio-active variety found in some of these localities.
Platinum and iridium occur as rare constituents of the auriferous
gravels of some parts of Burma.
Pyrite and Sulphur
Pyrite is a mineral of very wide distribution in many formations,
from the oldest crystalline rocks to the youngest sediments, but
nowhere is it sufdciently abundant to be of commercial utility in the
preparation of sulphur and sulphuric acid. The economic value of
pyrite^ lies in its being a source of sulphur and not as an ore of iron,
because the high proportion of sulphur in it is injiurious to the iron.
The only occurrences of any considerable scale, are those of the
pyritous shales of Kalabagh and the Dandot collieries on the SaltRange, but the chances of sulphur manufactured out of these deposits
to compete against imported sulphur are very few, and no attempt is
m^de for its development. Large stores of sulphur exist in connection
with metallic sulphides, notably of copper and lead, which, when they
are worked in India for the recovery of the metals will liberate the
sulphur, as well, in large amounts.
Sulphur in small quantities is obtainable as a sublimation product
from the crater of Barren Island volcano, and from some of the extinct volcanoes of Western Baluchistan, and was formerly worked at
Sanni ^ in the Kalat State. Many of the sulphur springs precipitate
some quantities of fine powdery sulphur near their outlets. Sulphur
1 Fox, Bulletin of 1.1, and L. No. 28, 1922.
«Bee. O.S.I. vol, xlvi, pt. 2, 1919.
378
GEOLOGY OF INDIA
occurs in the Puga valley of Ladakli. It is found there both as a
deposit from its hot springs and also as filling up fissures in quartzschists.
These sources are, however, too insignificant to meet the demand
for sulphur in the country which is satisfied largely by imports from
foreign countries. Large reserves of sulphur are available in the leadzinc-silver ores of Bawd win (page 351).
Sulphuric acid—Sulphur has many important uses, much the most
important being the manufacture of sulphuric acid. With regard to
the last-named compound we may quote the following valuable statement : " Sulphuric acid is a key to most chemical and many metallurgical industries ; it is essential for the manufacture of superphosphates, the purification of mineral oils, and the production of ammonium sulphate, various acids, and 9, host of minor products ; it is a
necessary link in the chain of operations involved in the manufacture
of alkalies, with which are bound up the industries of making soap,
glass, paper, oils, dyes, and colouring matter ; and, as a bye-product,
it permits the remunerative smelting of ores which it would be impossible otherwise to develop. During the last hundred years the cost of
a ton of sulphuric acid in England has been reduced from over £30
to under £2, and it is in consequence of the attendant revolution in
Europe of chemical industries, aided by increased facilities for transport, that in India the manufactures of alum, copperas, blue vitriol and
alkalies have been all but exterminated; that the export trade in
nitre has been reduced instead of developed ; that the copper and
several other metals are no longer smelted ; that the country is robbed
every year of over 90,000 tons of phosphate fertilisers, and that it is
compelled to pay over 20 millions sterling for products obtained in
Europe from minerals identical with those lying idle in India."^
SOILS
Soil formation—The soils of all countries are, humanly speaking, the
most valuable part of the regolith or surface rocks and constitute in
many cases their greatest natural asset. They are, broadly speaking,
either the altered residue of the underlying rocks, after the other soluble constituents are removed, mingled with sorne proportion of decomposed organic matter {residual soil); or the soil-cap may be due
to the deposition of alluvial debris brought down by the rivers from
^Sec. G.8.I. vol. xlvi. 1915,'p. 295.
ECONOMIC; GEOLOGY
379
the higher grounds {drift soil). The origin and growth of soils, howevei, is a subject of great complexity involving a long series of changes
ending in the production of the clay-factor and other colloids of the
soils. The soil of the Peninsula, for the greater part, is of the first description, while the great alluvial mantle of North India, constituting
the largest part of the most fertile soil of India, is of the second class.
We can easily imagine that in the production of soils of the first kind,
besides the usual meteoric agencies, the peculiar monsoonic conditions
of India, giving rise to alternating humidity and desiccation, must
have had a large share. These residual soils of the Peninsula show a
great variety both in their texture and in their mineralogical composition, according to the nature of the subjacent rock whose waste has
given origin to it. They also exhibit a great deal of variation in depth,
consistency, colour, etc. However, the soils of India, so far as their
geological peculiarities are concerned, show far less regional variation
than those in other countries, because of the want of variety in the
geological formations of India.^
Broadly speaking the soils of the Indian Peninsula differ markedly
from the soils of European countries, which are largely of post-GIacial
growth and in which the pedogenic processes have not been in operation long enough to mature them. The latter soils have close affinities
with their rocky substratum, both as regards composition and morphology. Podsolisation is a common character of these soils. In both
these respects the soils of Peninsular India offer a- contrast and, being
far older than the Glacial period of Pleistocene age, have attained full
maturity. The effect of these factors is to introduce many changes in
the composition, structure and texture and to modify profoundly the
clay-factoir of the soils. This is best seen in the two characteristic
Indian soils—laterite and black-cotton soil. Podsols, except among
some mountain and forest soils of North India, are uncommon in the
rdst of the country. The alluvial soils of the vast Indo-Gangetic
• plains likewise differ from Peninsular soils and from the majority of
European soils in having undergone but little pedogenic evolution
since their deposition by river agency, so late as in sub-Recent times.
They are still largely immature and have not developed any characteristic soil profile, or differentiation into zones.
The soils of Soutli India—Over the large areas of metamorphic rocks
the disintegration of the gneisses and schists has yielded a shallow sandy
or stony soil, whereas that due to the decomposition of the basalts of
' The Geological Foundations of the Soils of India, Sec. O.S.I., vol. Ixviii, pt. 4,
1935.
380
GEOLOGY OF INDIA
the Deccan, in the low-lying parts of the country, is a highly argillaceous, dark, loamy soil. This soil contains, besides the ordinary ingredients of arable soils, small quantities of the carbonates of calcium
and magnesium, potash, together with traces of phosphates, ingredients which constitute the chief material of plant-food that is absorbed
by their roots. The latter soil is, therefore, much more fertile as a rule
than the former. The soil of the metamorphic rocks is thin and .
shallow in general (except where it has accumulated in the valleybasins), because of the slowness with which the gneisses and schists
weather. The soil in the valleys is good, because the rain brings the
decomposed rock-particles and gathers them in the hollows. In these
situations of the crystalline tract the soils are rich clay-Ioam,s of great
productiveness.
Soils of sedimentary rocks—The soils yielded by the weathering of
the sedimentary rocks depend upon the composition of the latter,
whether they be argillaceous, arenaceous or calcareous, and upon
their impurities. Soils capping the Gondwana outcrops are in general
poor and infertile, because Gondwana rocks are coarse sandstones and
grits with but little of cementing material. They are thin sandy soils,
capable of supporting tillage only, with copious manuring. Argillaceous and impure calcareous rocks yield good arable soils. Reference must here be made to the remarkable black soil, or regur of
large areas of the Deccan which has already been described on page
304. The greater parts of Rajputana, Baluchistan and the Frontier
Provinces are devoid of soils, because the conditions requisite for the
growth of soils are altogether absent there. The place of soil is taken
by another form of regolith, e.g. wide-spread scree and talus-slopes,
coluvial gravels, blown sand and loess. In thevHimalayan region soilformation is a comparatively rapid process, the damp evergreen
forests playing an important part in the generation and conservation^,
of the soil-cap. The unforested southern slope's of these mountains
are generally devoid of soil covers. Likewise deforestation of some
tracts of the outer Himalayas has been followed by a stripping of their
soil-cover, due to accelerated erosion of the unprotected surface.^
' I B the past few years attention is being forcibly drawn to the increasing aridity
of parts of the Hoshiarpur district of the Punjab, the northward progress of the sands
from the southern desert, the deepening of the water-table and the gullying and erosion
of Jracts that were, three or four generations ago, covered under a fertile soil-cap. These
adverse effects are ascribed to the destruction of forests which once clothed the SiwaUk
foot-hills. Similar effects have been noticed in other sub-montane districts also and
serve to impress the important role played by forests in moderating the denudation by
rain, in regulating the run off, in conserving the suH-soil water and in binding and protecting the soil-cap from wind and wateterosion,
ECONOMIC GEOLOGY
381
The loess caps of the higher parts of the Punjab possess many of the
qualities of an excellent soil, but its high porosity tends to lower the
underground water-table to inaccessible depth.
Alluvial soils—The alluvial soils of the great plains of the Indus and
Ganges, as also of those of the broad basins of the Peninsular rivers,
are of the greatest value agriculturally. They show minor variations
in density, colour, texture and porosity, moisture-content and in the
composition of their clay-factor. In spite of minor difference in composition, from district to district, in general they are Ught-coloured
loamy soils of a high degree of productiveness, except where it is destroyed by the injurious reh salts. There are, however, a number of
physical and organic factors which determine the characters and
peculiarities of soils and their fertility or otherwise ; this subject is,
however, beyond the scope of this book and cannot be discussed
further.^ (See pages 305 and 366.)
' The following books on study of soils may be consulted : G. W. Robinson, Soils—
T%eir Origin, Constitution and Classification, London, 1932 ; P. Vegeler, Tropical Soils,
London, 1933.
CHAPTER XXVII.
(APPENDIX)
GEOLOGY OP KASHMIR
THE object of the present chapter is to give in brief outline the geology
of a province which contains, within a small geographical compass, one
of the finest developments of the stratified record seen in the Indian
region and perhaps in the world. In describing the geology of Kashmir
passing references will be made to the adjoining districts of Hazara
and Simla. These three provinces are connected by some common
features and have received more attention from geologists than other
areas of the Himalayas. A very large section of the fossiliferous geological record is exhibited in the hills and mountains surrounding the
beautiful valley of Kashmir in localities easily accessible to students,
and thus offering facilities for the study of the stratigraphical branch
of the science, which are met with in no other parts of India. In this
happy combination of circumstances the Vale? of Kashmir is unique as
an excursion ground for students of geology, as much foj-its wealth of
stratigraphic results, as for its physiographic phenomena, its orographic features, its glaciers, etc.
We shall- describe in the present chapter the geology and physical
features of the country comprising the territories of the Jammu and
Kashmir State, with some sketch notes on the geologically surveyed
parts of Hazara on the west and Simla-Chakrata on the east, constituting a large area in the North-West Himalaya. Incidentally,
therefore, the subject of this chapter will also be a recapitulation of "^
the main facts of the orography and geology of the best explored parts
of the Himalayas. Even within this there are large districts which are
geologically unknown, e.g. the portion east of the Ravi and west cff the
Sutlej is yet largely unexplored ground, while districts such as Baltistan, Zanskar and Ladakh are very imperfectly known.
PHYSICAL FEATURES
• The orographic features—There is a close uniformity in physical
features and geological constitution of the sub-Himalayan tract from
Rawalpindi to Dehra Dun, cohered by the Siwahk and Sirmur rock3S2
GEOLOGY OF KASHMIR
383
systems. A description of the Jammu hills may be taken broadly as a
type. An admirable account of the geography of the Kashmir-Himalayan region is given by Frederick Drew in his well-known book, Jammu
and Kashmir Territories (E. Stanford, London, 1875). What follows in
this section is an abridgement from this author's description, modified,
to some extent, by incorporating the investigations of later observers.
The central Himalayan axis, after its bifurcation near Kulu, runs as
one branch to the north-west, known as the Zanskar Eange, terminating in the high twin-pteaks of Nun Kun (23,447) (" the Great Himalaya
Range " of Burrard); the other branch runs due west, a Uttle to the
south of it, as the Dhauladhar Range, extending further to the northwest as the high picturesque range of the Pir Panjal, so conspicuous
from all parts of the Punjab. Between these two branches of the
crystalline axis of the Himalayas lies a longitudinal valley with a
south-east to north-west trend, some 84 miles long and 25 miles broad
in its middle, the broadest part. The long diameter of the oval is
parallel to the general strike of the ranges in this part of the Himalayas. The total area of the Kashmir valley is 1900 sq. miles, its mean
level about 5200 feet above the sea. The ranges of mountains which
surround it at every part, except the narrow gorge of the Jhelum at
Baramula, attain, to the north-east and north-west, a high general
altitude, some peaks rising above 18,000 feet. On the south-western
border, the bordering ridge, the Pir Panjal, is of comparatively
lower altitude, its mean elevation being 14,000 feet. The best known
passes of the Pir Panjal range, the great high-ways of the past, are the
Panjal Pass, 11,400 feet; the Budil, 14,000 feet; Golabghar Pass,
12,500 feet; the Banihal Pass, 9300 feet; Tata Kuti and Brahma
Sakal are the highest peaks, above 15,500 feet in elevation.
The Outer Ranges (the Sub-Himalaya or the Siwalik Ranges)
The simple geological structure of the outer ranges. The " dims "
—The outermost ranges of the Kashmir Himalaya rise from the plains
of the Punjab, commencing with a gentle slope from Jammu, attain
to about 2000 feet altitude, and then end abruptly in steep, almost
perpendicular, escarpments inwards. Then follows a succession of
narrow parallel ridges with their strike persistent in a N. W.-S.E. direction, separated by more or less broad longitudinal or strike-valleys (the
basins of subsequent streams). These wide longitudinal or strikevalleys inside the hills are of more frequent occurrence in the eastern
parts of the Himalayas, and attain a greater prominence there, being
384
GEOLOGY OF I N D I A
known there as " duns " {e.g. Dehra Dun, Kothri Dun, Patii Dun, etc.).
In the Jammu hills the extensile, picljuresque duns of Udhampur and
Kotli are quite typical. The Kashmir valley itself may be taken as an
exaggerated instance of a dun in the middle Himalaya. These outer
hills, formed entirely of the younger Tertiary rocks, rarely attain to
greater altitude than 4000 feet or thereabouts. The outer ranges of
the sub-Himalayan zone, bounded by the. Ravi and the Jhelum, the
two east and west boundaries of the Kashmir State, are known as the
Jammu hills. Structurally, as well as lithologically, they partake of
the same characters as are seen in the hills to the east and west of it,
which have received a greater share of attention by the Indian geologists. Eanges situated more inwards, and formed of older Tertiary
rocks (of the Murree series), reach a higher altitude, about 6000 to 8000
feet. At the exit of the great rivers, the Chenab and the Jhelum, there
is an indentation or a deep flexure inwards into this region corresponding to an abrupt change in the direction o£ the strike of the hills.
In the case of the Jhelum at Muzafferabad this flexure is far more
conspicuous and significant, the result of the syntaxial bend of the
whole mountain-system, the strike of the whole Himalayan range
there changing from thfe usual south-east—north-west to north and
south and thence undergoing another deflection to north-east—
south-west. (See p. 314.)
The Middle Ranges (Lesser or Middle Himalayas—The Panjal and
Dhauladhar Range) ^
The Panjal Range. " Orthoclinal" structure of the Middle ranges—
This region consists of higher mountains (12,000-15,000 feet) cut into
by deep ravines and precipitous defiles. The form of these ranges
bears a great contrast to the outer hills described above, in being •
ridges of irregular direction that branch again and again, and exhibiting much less correspondence between the hneation of the hills and
the strike of the beds 'constituting them. In the Pir Panjal, a singularly well-defined range of mountains extending from the Kaghan
valley to beyond the Ravi valley, which may be taken as a type of the
mountains of the Middle Himalaya, these ridges present generally a
steep escarpment towards the plains and a long gentle slope towards
Kashmir. Such mountains are spoken of as L .'ing an " orthoclinal "
' For a connected account of the geology of Pir Panjal, see Middlemiss, Rec. vol. xH.
pt. 2, 19H, and Wadia, Geology of Poonch and Adjoining Area, Mem. 0.iS.I., vol. 11.
pt. 2, 1928.
GEOLOGY OF KASHMIR
385
structure, with a " writing-desk " shape (see Fig. 38, p. 391). To this
cause (among several others) is due the prespnce of dense forest vegetation, the glory of the Middle Himalaya, clothing the north and
north-eastern slopes, succeeded higher uprby a capping of snows, while
the opposite, southern slopes are, except in protected valley-slopes,
barren and devoid of snow, being too steep to maintain a soil-cap for
the growth of forests or allow the winter-snows to accumulate.
South-east of the Ravi, the Pir Panjal is continued by the Dhauladhar
range, passing through Dalhousie, Dharamsala and Simla. Geologically the middle Himalaya of this part are different from the foothills, being composed of a zone of highly compressed and altered rocks
of various ages, from the Purana and Carboniferous to Eocene. The
axial zone of the Panjal range is composed of the Permo-Carboniferous. For map of the Pir Panjal, see PI. XV.
. Inner Himalayas
The zone of highest elevation. Physical aspects of the inner Himalayas—To the north of the Pir Panjal range, and enclosing between
them the valley of Kashmir, are the more lofty mountain-ranges of
the innermost'zone of the Himalayas, rising above the snow-line into
peaks of perpetual snow. In the North Kashmir range an offshoot of
the Zanskar range, which forms the north-eastern border of the valley,
there are peaks of from 15,000 to 20,000 feet in height. Beyond this
range the country, with the exception of the deep gorges of the Middle
Indus, is a high-level plateau-desert, utterly devoid of all' kind of
vegetation. Here there are elevated plateaus and high mountainranges separated from one another by great depressions, with majestic
peaks towering to 24,000 feet. The altitude steadily increases farther
north, till the peak K'', on the mighty Karakoram or Mustagh range,
attains the culminating height of 28,265 feet—the second highest
mountain in the world. The Karakoram chain is the watershed between India and Turkestan. The valleys of these regions show varying characters. In the south-east is the Changchenmo whose width is
from five to six miles, with a mean height of 14,000 feet above the sealevel. From that to the north-west the height of the valley-beds descends, till in Gilgit on the very flanks of the gigantic peak of Nanga
Parbat, Diyamir, (26,620 feet), the rivers have cut so deeply through
the bare, bleak mountains that the streams flow at an elevation of only
5000 and, in one case, 3500 feet above the level of the sea. At places,
in north and north-east Kashmir, there are extensive flat, wide, plains
w.a.i.
2B*
386
GEOLOGY OF INDIA
or depressed tracts among the mountains, too wide to be called valleys, of whicli the most conspicuous are the plateaus of Deosai, 13,000
feet high, Lingzhitang, 16,000 feet, and Dipsang of about the same
height. The physical features of this extremely rugged, wind-swept and
frost-bitten region vary much in character. They present an aspect
of desolate, ice-bound altitudes and long dreary wastes of valleys and
depressed lands totally diiferent from the soft harmony of the Kashmir mountains, green with the abundance of forest and cultivation.
The rainfall steadily diminishes from the fairly abundant precipitation in the outer and middle ranges to an almost total absence of any
rainfall in the districts of Ladakh and Gilgit, which in their bleakness
and barrenness partake of the character of Tibet. Ladakh is one of the
loftiest inhabited regions of the world, 12,000-15,000 feet. Its short
but warm summers enable a few grain and fruit crops to ripen. Owing
to the great aridity of the atmosphere, the climate is one of fierce
extremes, from the burning heat of some of the desert tracts of the
Punjab plains in the day, to several degrees below freezing-point at
night. Baltistan, lying directly to the north of Kashmir, and receiving some share of the atmospheric moisture, has a climate intermediate
between the latter and that of Ladakh. In consequence of the great
insolation and the absence of any water-action, there has accumulated
an abundance of detrital products on the dry uplands and valleys
forming a peculiar kind of mantle-rock or regolith of fresh, undecomposed rock-fragments. The bare mountains which rise from them
exhibit the exquisite desert coloration of the rocks due to the peculiar
solar weathering. Between Ladakh and the Dhauladhar range are the
districts of Zanskar, Lahoul and Rupshu, consisting of intricately
ramifying glaciated ranges of crystalline rocks, intersected by lofty"
valleys having but a restricted drainage into a few saline lakes and
marshes. This rugged country is crossed by a few trade-routes from
Simla and Kulu to Tibet, through high passes, 16,000 to 18,000 feet.
With the exception of a part of Ladakh, which consists of Tertiary
rocks and a basin of Mesozoic sedimentary rocks on the northern flank
of the Zanskar mountains, by far the larger part of the inner mountains is composed of igneous and metamorphic rocks—granites,
gneisses and schists.
There is no counterpart of the Kashmir basin north of the Dhauladhar in the Simla mountains. East of the Sutlej the Dhauladhar
range approaches and closes in with the Great Himalaya Eange. The
important Spiti basin of Palaeo-Mesozoic sediments Hes to the north
of the crystalhne gneissic axis of the latter.
GEOLOGY OF KASHMIR
,
387
Valleys
The transverse valleys. The configurd^>ion of the valleys—In conformity with the peculiarities of the other Himalayan rivers, briefly
referred to in the chapter on physical features, the great rivers of this
area—the Indus, Jhelum, Chenab, Ravi and Sutlej—after running for
variable distances along the strike of the mountains, suddenly make
an acute bend to the south and flow directly across the mountains.
The Sutlej, like the Indus, takes its origin in Tibet, much to the north
of the Indo-Tibet watershed. Just at the point of the bend, a large
tributary joins the niain stream and forms, as it were, its upward continuation. The Gilgit thus joins the Indus at its great bend to the
south ; the Ward wan joins the Chenab at its first curve in Kishtwar,
and the Ans at its second curve plainwards, above Riasi. The Kishenganga and the Kunhar meet the Jhelum at Domel, where the latter
takes its acutest curve southwards before emerging into the Punjab.
Similarly the Spiti river joins the Sutlej where the latter takes its final
southward turii. These transverse, inconsequent valleys of the Himalayas, as we have seen before, are of great importance in proving the
antiquity of the Himalayan rivers, an antiquity which dates before the
elevation of the mountain-system (see page 20). The configuration of
the valleys in the inner Himalaya of the Kashmir regions is very
pcQuliar, most of the valleys showing an abrupt alternation of deep
U-lhaped or I-shaped gorges, with broad shelving valleys of an open '
V-shape. This is due to the scanty rainfall, which is powerless in
eroding the slopes of the valley where they are formed of hard crystalline rocks and where the downward corrasion of the large volume of
streams produced by the melted snows is the sole agent of valleyformation. The broad valleys which are always found above the
gorge-like portions are carved out of soft detrital rocks which, having
no cover of vegetation or forest growth to protect them, yield too
rapidly to mechanical disintegration. Many of the valleys are very
deep. This is particularly seen in Drava, Karnah and Gilgit. By far
the deepest of all is the Indus valley in Gilgit, which at places is bordered by stupendous precipices 17,000 feet in height above the level
of the water at its bed. That this enormous chasm has been excavated
by the river by the ordinary process of river-erosion would be hard to
believe were not the fact conclusively proved by the presence of small
terraces of river gravels at numerous levels above the present surface
of its waters.
At Shipki the Sutlej receives its principal tributary, the Spiti river,
388
GEOLOGY OF INDIA
which has drained the wide synclinal basin of marine Palaeozoic and
Mesozoic sediments. Up to this poi^it the Sutlej is a strike-valley,
flowing along the whole length of the alluvial plateau of Hundes in a
profound 3000 feet canon, excavated through horizontally bedded
ossiferous Pleistocene boulder gravel and clay, deposited by itself at
a former stage of its history. Below Shipki the river turns south and
traverses a variety of geological formations of the Zanskar and the
Great Himalaya range, in narrow gorges that are 10,000 feet deep at
places, with perpendicular rock-chffs of 6000 to 7000 feet sheer fall.
Its passage through the sub-Himalayan Tertiary zone below Simla
shows that the river at various stages must have been impeded and
deflected in its course again and again by its own deposits.
From the presence of numerous terraces of lacustrine silt along the
channel, the former presence of a chain of lakes all along the course of
the Sutlej through the high mountains is indicated. This feature it
shares with the Jhelum, Chenab and the Kunhar.
Lakes
There are very few lakes in Kashmir, contrary to what one would
expect in a region of its description. The few noteworthy lakes are,
the Wular in the valley, the salt-lakes of Ladakh, bearing evidence of
a progressive desiccation of the country, viz, the Tsomoriri in Rupshu,
which is 15 miles long and 2 to 5 miles wide and about 15,000 feet
high ; the Pangkong in Ladakh, which is 40 miles long, 2 to 4 miles
wide and 14,000 feet in elevation. The origin of ihe two last-named
lakes is ascribed by Drew to the damming of old river courses by the
growth of alluvial fans or dry-deltas of their tributary streams across
them. These lakes have got several high-level beaches of shingle and
gravel resting on wave-cut terraces marking their successive former
levels at considerable heights above the presedt level of the water.
The wide, level valley-plains of the" Ghajigchenmo, Dipsang and
Lingzhitang, at an elevation of from 16,000-17,000 feet, may be regarded as of lacustrine origin, produced by the desiccation and silting
up of saline, lake-basins without any outlet. There are a number of
smaller lakes or tarns, both in the valley of Kashmir proper and in the
bordering mountains, most of which are of leceht glacial origin, a few
of which may be true rock-basins.
The source of the Sutlej is now known to be the t ^ o sacred icebound lakes of Manasarowar and Rakas Tal, situated behind the
Himalayan water-shed at an ajtitude of 16,000 feet to the south of the
GEOLOGY OF KASHMIR
389
peak of Kailas. Sven Hedin has proved that the Sutlej flows from the
Rakas Tal, which derives its water by subterranean drainage from the
adjacent Manasarowar and not usually through any visible channel.
Glaciers
Transverse and longitudinal glaciers—In Drew's work, already mentioned, there is a snow-map of Kashmir which admirably shows the
present distribution of glaciers and snow-fields in the Kashmir and
the adjacent regions. With the exception of a few small glaciers in the
Ghamba mountains, there are no glaciers in the middle and outer
Himalayas at present. In the Zanskar range glaciers are numerous
though small in size ; only at one centre, on the north-west slopes of
the towering Nanga Parbat (26,620 feet), they appear in great numbers and of large dimensions. One of these (the Dayamir) descends to
a level of 9400 feet above the sea, near the village of Tarshing. North
and north-east of these no glaciers of any magnitude occur till the
Hunza valley on the south of the Mustagh, or Karakoram, range is
reached, whose enormous snow-fields are drained by a number of large
glaciers which are among the largest glaciers of the world. ^ The
southern side of this stupendous mountain-chain nourishes a number
of gigantic glaciers some'of which, the Biafo, the Baltoro, the Siachen,
the Remo, and the Braldu glaciers, are only exceeded in size by the
great Humboldt of Greenland. There are two classes of these glaciers :
those which descend transversely to the strike of the mountains and
those which descend in longitudinal valleys parallel to the trend of the
mountains. The latter are of large dimensions and are more stable in
their movements, but terminate at higher elevations (about 10,000
feet) than the former, which, in consequence of their steeper grade,
descend to as much as 8000 to 7000 feet. The Biafo glacier of the
Shigar valley reaches nearly iO miles in length and the Hispar 25
miles. The lowest level to which glaciers descend in the Kashmir
Himalayas is 8000 or even 7000 feet, reaching down to cultivated
grounds and fields fully 4000 feet lower than the lower-most limit oi
the glaciers in the eastern Himalayas of Nepal and Sikkim. Many oi
these glaciers show secular variations indicative of increase or diminution of their volumes, but no definite statement of general application
can be made about these changes (p. 15). The majority of them, like
the Tapsai, are receding backwards, leaving their terminal moraines in
1 F o r results of exploration of K a r a k o r a m a n d B a l t i s t a n glaciers, papers b y Dainelli
a n d Mason m a y be consulted.
<•
GEOLOGY OF INDIA
390
front of them, which have become covered by grass and in some cases
even by trees; but others, like the iPalma glacier, are steadily advancing over their own terminal moraines. ^
Proof of Pleistocene Ice Age—There' are abundant evidences, here as
everywhere in the Himalayas, of the former greater development of
/
4r ' r ^-..-.
-—<
t ' r •} s '
.^w.
^-.
1 y^
*»-
^ j . »_-<>*
Vii
'. t-^'-^
FIG. 37.—View of the great Baltoro Glacier. (From a drawing by
Col. Godwin Austen.)
glaciers, although there are no indubitable proofs of their ever having
descended to the plains of the Punjab, or even to the lower hills of the
outer Himalayas. Large transported blocks are frequently met with
at various localities, at situations, in one case, but little above 4000
feet. The Jhelum valley between Uri and Baramula contains a number of large boulders of granitoid gneiss brought from the summit of
the Kaj Nag range (to the N.W.), some of which are as large as cottages. These are common phenomena in all the other valleys ; rockpolishing and grooving are well seen on the cliff-fa-oes of the Lidar, Sind,
and their tributaries, while typical rochesmoutonnees are not rare on
the hard, resistant rock-surfaces in the beds or sides of these valleys.
In the Sind valley, near the village of Hari (6500 feet) on the road to
Sona Marg, Drew has seen a well-grooved roche moutonnee. A little
higher up, at Sona Marg itself (9000 feet), are seen undulating valleys
made up entirely of moraines. In the valley of Kashmir proper some
of the fine impalpable buff-coloured sands and laminated clays, interstratified among the Karewa deposits, are of glacial origin (" rock
meal "), formed during melting of the ^ce in inter-glacial periods.
' For glaciers of the Hunza valley,-eeS'-Bec. G.S.I, vol. xxxv. pts. 3 and 4, 1907.
GEOLOGY OF KASHMIR
The whole north-east side of the Panjal
range and to a less extent elevations
above 6500 feet on the south-west are
covered thickly under an extensive accumulation of old motaine materials,
which have buried all its solid geology
(see Fig. 38). In northern Baltistan,
where the existing glaciers attain their
maximum development, there are other
characteristic proofs of old glaciation at
far lower levels than the lowest limits of
modern glaciers ; polished rock-surfaces,
rock-groovings, perched blocks, etc.,
occur abundantly in the Braldu valley
of this district. Many of the valleys of
this region in their configuration are of
a U-shape, which later denuding agencies
are trying to change to the normal
V-shape.
Desiccation of lakes—The well-marked
desiccation of the lakes of Skardu,
Rupshu and the other districts of north
and north-east Kashmir, is a very
noteworthy phenomenon and has' an
important bearing on this question. The
former higher levels of their waters
point to a greater rainfall and humidity
connected with the greater cold of a
glacial period.
The Tsomoriri has a
tsrrace or beach-mark at a height of
40 feet above the present level of its
waters. The Pangkong lake has similar
beaches at various levels, the highest
being 120 feet above the surface of the
present lake.
391
CJ
.g.^
Q2
m'K.
8"
.<''
STRATIGRAPHY OF KASHMIR
Introduction—The late Mr. R. Lydekker
in tlie 'eighties of the last century, made a
geological survey of Kashmir. His results
0 0 0 ^ : 1 0
O O O O Q
392
GEOLOGY OF INDIA
were published in a Memoir of tte'Geological Survey of India (vol
xxii 1883). Lydekker in his preUminary survey grouped all the
stratified formations of Kashmir into three broad d m s i o n s - t h e
Panial, the Zanskar and the Tertiary groups-the homotaxial
relations of whose constituent series and systems were not dearly
distinguished because of the absence of satisfactory fossil evidence.
Mr O S . Middlemiss, F.E.S., worked in the same field from 19081917 • Middlemiss's researches have revealed a series of fossihlerous
strata, in different parts of the province, belonging to various
divisions of the Palaeozoic and the Mesozoic, which have enabled
him to make a more perfect classification of the Kashmir record.
Thus he has resolved what was formerly one comprehensive group,
the Panial system, which encompassed almost the whole ot tHe
Palaeozoic sequence, into no less than seven well-defined systems or
series, the representatives of the Cambrian, Ordovician, bilurian
Devonian, Carboniferous and Permian, and the homotaxial
equivalents of those of the classic ground of Spiti.
^ , ,, ,
Of the Mesozoic systems the Trias is the best and most tully develop'ed ; the Juiassic and Cretaceous outcrops are few and mostly
confined to the mountains of Ladakh which have scarcely been systematically surveyed by geologists. All the Tertiary systems are fuUy
represented in the outer mountains and have been studied by a number of workers.
,
,
As stated on page 314 the broad outlines of the stratigraphy of
Hazara and North-West Kashmir are similar ; these two regions form
one more or less continuous sedimentary terrain, though now isolated
by the deep knee-bend of the mountains across the Muzaffarabad promontory of the foreland. A great regional unconformity encompassing the period from the top of the Silurian to the Middle Carboniferous
is a distinctive feature of this north-west province. The south-east^,
part of Kashmir has a continuous Palaeozoic record, similar to tliat
" The account given in the following pages is deduced from the writings of Lydekker, Middlemiss and Wadia. For more detailed information with regard t o the whole of the Palaeozoic group and the
Triassic system, the student should consult original pubhcations,
Rec. G.S.I. vol. xl. part 3,1910, and vol. Ixviii. part 2,1934. For the
remaining systems, and the tectonics of Kashmir, the present writer s
work should be consulted.^
1D. N. Wadia, Mem. 0.8.1. vol. U. pt. 2, 192^ Bee. G.8.I., vol. Ixv, pt. 2, 1931
vol. Ixvi. pt. 2, 1932, and vol. Ixxii, pt.-2, 1937.
GEOLOGY OF KASHMIR
"- 393
[The geographical disposition cJf^the main sedimentary belt in the Kashmir Himal^as calls for an explanation. While in the rest of the Himalayas
the zone of marine sediments is wholly beyond, i.e. north of, the crystalline
axis, in the Kashmir portion the most important sedimentary basin lies between two bifurcations of that axis, and in this way effaces that distinction
between the " Himalayan " and " Tibetan " zones so clearly marked in the
other parts of the moimtains.
The distinction between the middle (Himalayan) and the outer (subHimalayan) zones is, however, as clearly observable in this as in the other
parts of the Himalayas.
In the province of Hazara this confusion between the three Himalayan
stratigraphic zones is still more marked.]
THE STRATIGRAPHY OF THE SIMLA HIMALAYA
In the geosynclinal belt of the inner Himalayas of Spiti, Garhwal
and Kumaon, at the back of the crystalline axis, a complete sequence
of marine Palaeozoic and Mesozoic, in some respects more complete
than in Kashmir, is developed. The stratigraphy of the Spiti sequence
from Cambrian to Cretaceous, has been describedby the late Sir Henry
Hayden in Memoirs, vol. xxxvi, 1904. No further work has been done
in this area since then.
Of late years the stratigraphy and structure of the Simla mountains
to the south of the crystalline axis is being worked out in detail by
Pilgrim, West and Auden. A considerable amount of work has been
accomplished in the crystalline metamorphics and the Purana complex of this region and the structural disposition of the various belts of
these rocks between Simla and Chakrata settled by the discovery of unconformities and thrust-planes. Geological work in this region has to
contend against the serious difficulty of total absence of fossils in the
vast formations of slate, limestone and sandstone, presumably of
Palaeozoic and Mesozoic ages, which intervene between the Archaean
and the scantily fossiliferous Eocene. While the cause of the absence
of fossils from this large section of the geological column is yet an unsolved problem, painstaking and accurate field work has made it possible to arrange and group the various formations of this area as near
as possible in their natural order of superposition.
With the doubtful exception of the Simla slates, which may be regarded as partly of Cambrian age, and an overlying group of indeterminate Lower Palaeozoic horizon, the Jaunsar series, allied lithologically to the equally obscure Tanawal (lower part) group of HazaraKashmir, the whole of the Lower and Middle Palaeozoic is missing
from the Simla region. The next younger formation, the Blaini series.
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396
GEOLOGY OF INDIA
is correlatable, on convincing grounds, with an important datum-plane
in Indian stratigraphy, the Lower Gondwana Ice age (Permo-Carboniferous), succeeded by a series of formations which find a more or
less approximate parallel with the unfossiliferous Permian of Hazara.
The Mesozoic group, except for the occurrence of the Jurassic Tal
series, with its imperfect fauna suggesting affinities with the Spiti
Jurassic, is probably entirely missing. The Tertiary sequence is well
exposed in the sub-Himalayan belt of the Simla region and its
stratigraphy does not differ materially from that of the North-West,
the rocks, structure and classification being broadly alike in the two
areas. ^
The table on pp. 394, 395 gives an idea of the geological record as
exposed in Kashmir, Hazara and Simla areas.
AECHAEAN AND PRE-CAMBRIAN
The Crystalline Complex. " Fundamental Gneiss " with intrusive
granites—Crystalline rocks, granites, gneisses and schists occupy large
areas of the N.W. Hima,layas of Kashmir and Simla, to the north of
the Middle Range's, forming the core of the Dhauladhar, the Zanskar
and the ranges beyond in Ladakh and Baltistan. These rocks were all
regarded as igneous and called " Central Gneiss " by Stoliczka and
were taken to be Archaean in age. Later investigations have proved ,
that much of this gneiss, as is the case with that of the Himalayas as a
whole, is not of Archaean age, but is of intrusive origin and has invaded rocks of various ages at a'number of different geological periods.
Also a considerable part of this crystalline complex has now been
found to be of pre-Cambrian metamorphio sedimentary origin, forming the basement on which all the subsequent geological formations
rest. The latter have been distinguished as the Salkhala series in th^
Kashmir-Hazara area and as Jutogh series in the Simla-Chakrata
area. Some affinity of these series with the Dharwars of Eajputana
and Singhbhum is apparent; while it is difficult or impossible to demarcate the areas of truly Archaean gneiss from the wide-spread later
intrusive granites, the distinction of the sedimentary Archaeans from
the fundamental gneisses and the intrusives is in general recognisable
in many cases. The three elenients of the great basement complex of
the Himalayas are thus mixed up and may best be described at this
place : (1) the metamorphosed sedimentary Archaeans, (2) intrusive
1 Pagrim and West, Mem. G.S.I. Jfol. liii,, 1928; J. B. Auden, Bee. O.S.I. TOI.
Ixvii. pt. i, 1934.
GEOLOGY OF KASHMIR
397
granite and gneisses of later periods, (3) remnants of Archaean
granites, granulites, ortho-gneisses and schists. The presence of the
latter can be inferred from the occurrence of granite pebbles and
boulders, beds of arkose and of the widespread quartzites in the
Palaeozoic sediments. The gneisses have often assumed a coarse
granitoid aspect, while owing to extreme dynamic metamorphism, the
very much younger intrusive granites h.ave developed a gneissic structure. Foliation thus is not a criterion of age.
Petrology—Three kinds of granite have been recognised in this
complex: biotite-granite, hornblende-granite and tourmalinegranite. Of these the most prevalent is the biotite-gneiss or granite,
the one showing a quick transition to the other. The composition is
acidic ; pink orthoclase is rare, so also is muscovite ; the bulk of the
gneiss is made up of milk-white orthoclase, acid plagioclases with
quartz and a conspicuous amount of biotite, arranged in schistose or
lentici^r manner, foliation being fine, or coarse, or absent altogether.
This rock is the most prevalent Himalayan gneiss from Kashmir to
Assam. I t is often porphyritic, with orthoclase phenocrysts as much
as 2-4 inches across, giving rise .to an apparent augen structure.
Accessory minerals are not common except garnet and tourmaline.
Hornblende-gneiss is much less common, but it has a very similar
structure and composition, the biotite being replaced by hornblende,
sometimes not completely. Sphene is a common accessory. Both the
gneisses are traversed by veins of intrusive tourmaline-granite varying
from a foot to 20 or more feet in breadth, which in some cases penetrate the surrounding sedimentary strata as well. These pegmatite
and aplite veins have a greater diversity of mineial composition than
their hosts, often carrying such accessories as microcline, oligoclase,
rock-crystal, garnet, tourmaline (schorl as well as the coloured transparent varieties rubellite and indicolite), muscovite, beryl (aquamarine), fluorspar, actinolite, corundum.
Next to the gneisses the most frequent rock is biotite-schist, passing
into fine, thinly foliated, silky schists, such as chlorite-, talc-, hornblende-, muscovite-, schists.
These rocks are abundantly tiaversed by dykes, stocks and masses
of basic intrusives such as dolerite, epidiorite, gabbro, pyroxenite, etc.
Distribution—With regard to the distribution of the gneissic rocks
in the area, the main crystalline development is in the north and northeast portions, in the Zanskar range and the region beyond it, in Gilgit,
Baltistan and Ladakh, while in the ranges to the south of the valley
they play but a subordinate part. The core of the Dhauladhar range
398
GEOLOGY OF INDIA
is formed of these rocks, but they are not a very conspicuous component of the Pir Panjal range, where ]fchey occur in a number of minor
intrusions. The trans-Jheluni continuation of this range, known as
the Kaz Nag, has a larger developmbnt of the crystalline core. A
broad area of Kishtwar is also occupied by these rocks which continue
in force eastwards to beyond the valley of the Sutlej. It is from the
circumstances of the prominent development of the crystalline core in
the Zanskar range, in continuity with the central Himalayan axis,
that the range is regarded as the principal continuation of the Great
Himalayan chain, after its bifurcation at Kangra. The other branch,
the Pir Panjal, is regarded only as a minor offshoot. North of the
Zanskar the outcrop of the crystalline series becomes very wide, encompassing almost the whole of the region up to the Karakoram, with
the exception of a few sedimentary tracts in central and south-east
Ladakh. The largest occurrence of hornblende-granite is in the mountains between Astor and Deosai. Its post-Cretaceous age is definitely
proved by its intrusive contact with Orbitolina limestone at the head of .
the Burzil valley. Tourmaline-granite is of relatively subordinate
occurrence in pegmatite veins.
THE SEDIMENTARY PRE-CAMBRIAN SYSTEMS—THE
SALKHALA SERIES
The n^me Salkhala series is given to the oldest, sedimentary rocks of
the Kashmir Himalaya consisting of slates, phyllites and schists, with
interbedded crystalline limestones and flaggy quartzites. I t forms the
basement of the unfossiliferous Purana slates and the subsequent
sedimentary systems of Kashmir. Its relations with the newer rocks
are generally a profound unconformity or thrust-fault. Graphitic slate
and crystalline limestones (dolomitic), occasionally marble-beds, black
or snow white, are prominent elements of the' Salkhalas. Dynamic"^'
metamorphism, generally of a high grade is evident in the series, but.
all types of rocks are met with from dense compact' carbonaceous
slates and finely crystalline limestones to adinole-like beds, micaceous,
garnetiferous and graphitic schists, saccharoidal marble, calc-schist
and gneisses. The Salkhala sediments have been subjected to an intense granitisation at places, in Kaghan, in the ranges north of the
Kishenganga, and in the Nanga Parbat area. The argillaceous components have been converted by the injection of magma to biotitegneisses; whil^ the calcareous and dolpmitic members are changed
into dark hornblende and gainet gneisses. A host of secondary
GEOLOGY OF KASHMIR
399
minerals have resulted from metamorpliic action—phlogopite, actinolite, epidote, zoisite, sphene, idocrase, tourmaline, beryl, etc. Elsewhere the metamorphism is of a curiously subdued type and the Salkhala slates, then, are scarcely distinguished from some Dogra slates.
Stratigraphically as well as lithologically the Salkhalas are akin to
the Jutogh series of the Simla area, and it is probable that a continuous outcrop of these rocks stretches from Simla to Kaghan through
the Dhauladhar range.
The prominent peak of Nanga Parbat, Mt. Diyamir, 26,620 feet, the
culminating point of the Punjab Himalaya, is composed almost entirely of-finely schistose biotite-gneiss, a para-gneiss, with interbedded
marble, graphite-schists, etc., of Salkhala age. Through this paragneissic complex are intruded sheets and bosses of gneissose granite of
two later periods.^
PALAEOZOIC GROUP •
Dogra slates—Underlying the fossiliferous Cambrian of jS^ashmir
conformably, and at some localities showing a transitional passage
into them, there is a thick zone of slaty rocks—argillaceous cleavage
slates, with "generally oblique cleavage, with thin sandy or quartzitie
parimgs, often ripple-marked. They are quite unfossiliferous and
their exact horizon, whether Purana or possibly Lower Cambrian, is
uncertain. A lithologically identical group occurs in Hazara and
Simla, recognised as Hazara slates and Simla slates.
The Dogra slates occupy long belts in the Pir Panjal (where they
are associated with a great thickness of contemporaneous basic trap),
the Kishenganga valley and in Hazara.
Basins of Palaeozoic rocks—Fossiliferous Palaeozoic rocks of Kashmir occupy elongated ellipse-shaped patches of the country north of
the alluvial part of the valley, stretching from north-west of Hunda-.
war to the south-east end of the Kashmir sedimentary " basin ",
where it merges into the Spiti basin. The Lidar valley development
is the more typical. The long axis of this ellipse, north-west to southeast, corresponds to the axis of .a broad anticlinal flexure, in which the
whole series of Palaeozoic rocks is folded. Denudation has exposed,
in the central part of this anticlinal, a broad oval outcrop of the most
ancient fossiliferous rocks of Kashmir—the Cambrian and Ordovician
—flanked on its two sides successively by thinner bands of the younger
formations, Silurian, Devonian and Carboniferous (see PI. VIII). A
' Wadia, Geology of Nanga Parbat and parts of Gilgit District, i?ec. (?.iS./., vol. Ixvi.
pt. 2, 1932.
GEOLOGY OE INDIA
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GEOLOGY OF KASHMIR
401
similar section is exposed in the Basmai anticline of the Sind valley
between Sonamarg and Kolahoi. Palaeozoic rocks, especially of the
younger systems, are also conspicuous in the Vihi district, in east
Karnah, and, to a less degree, on the Pir Panjal, while the great series
of volcanic rocks of Upper Carboniferous age are quite ubiquitous in
their distribution over the whole area of Kashmir, forming the main
mass of the Panjal range and of the mountains bordering the valley to
the north-west, noith and north-east. Another locality which epitomises a part of the Palaeozoic sequence, overlain by the Trias, is the
large synclinal basin extending from the Wular lake to Tithwal. The
fold is traversed by the narrow serrated ridge, the Shamsh Abari, in
the steep precipices of which are displayed fine sections of the Palaeozoic folded in a simple syncline, the crest of the syncline (13,900 feet)
building a line of peaks falling away in bare rock-faces of thousands of
feet.
The above-named outcrops of Palaeozoic rocks, besides comprising
a large section of the geological history within a small compass, are of
importance in illustrating the simple type of folding and tectonics of
this part of the Kashmir nappe.
CAMBRIAN
Eocks of this system cover an extensive tract in Hundawar, at the
north-west extremity of the Kashmir valley. The Dogra slates pass
upward into imperfectly cleaved and foliated clays, arenaceous beds,
greywackes, with a few lenticular limestones. The ripple-marked surfaces of the strata are often full of convoluted casts, tubes and burrows of tubicolous Vermes, varying from threads to cylindrical pipes
reaching 2 inches in diameter. These beds pass up imperceptibly into
massive clays of bright blue colour, sandy slates and oolitic or
pisolitic limestones. At a few sporadic sites there occur crowds of
trilobites and obolaceous brachiopods, which have yielded a fauna of
Middle and Upper Cambrian affinities :^
Trilobites :
Agnostus.
Microdiscus.
Conocoryphe, 3 species.
TonJcinella, 2 species.
- Anomocare, 6 species.
CJiaungia, 3 species.
Solenopleura, 2 species.
Blountia.
Ptychoparia.
Hundwarella, 2 species.
SauMa.
iWadia, Bee. 0.8.1. vol. Ixvui, pt. 2, 1934; Cowper Reed, Pal. Indica, N.S.
vol. xxi. Mem. 2, 1934.
W.Q.I.
2o
402
GEOLOGY OF INDIA
Brachiopods:
Obolus.
Lingulella.
Acrotkele.
Botsfordia.
Lingulepis.
I
Pteropod :
Hyolithes.
Crinoid:
Eocystites.
Spoage:
Hazelia.
The most notewortliy feature of this fauna, according to Dr. Cowper Reed, is its strictly provincial character, showing no af&nities with
the adjacent Cambrian life-provinces of the Salt-Range, Spiti, or the
Persian Gulf. Many of the sixteen genera of trilobites found in this
area and all the species are new.
No good Cambrian fauna has been found in the Lidar, Sind, or Vihi
area, where the fossiliferous Silurian exhibits a conformable passage
downwards into a thick group of knotted, crudely foliated slates and
arenaceous beds, greywackes, etc. In the Wardwan valley the same
rocks reappear by a synclinal bending underneath the younger strata
of the intervening ground between it and the Lidar. Here the Cambrian slates have a phyllitic or schistose 'aspect owing to contact
metamorphism of granitic intrusions. In the Banihal valley also the
Cambrians show a considerable amount of foliation; beyond annelid
markings and indistinct pteropod shells no determinable fossils have
been found.
ORDOVICIAN
TherOrdovician is doubtfully recognised in the Lidar valley, underlying the fossiliferous Silurian. In the north limb of the Shamsh
Abari syncline near Trehgam (Hundawar Tehsil) a series of sandy
ferruginous slates, quartzose greywackes and limestones occur conformably above the Upper Cambrian in a synclinal warping of the
latter, in which the Ordovician is recognised by the presence of some
species of Orthis among them, 0. cf. calligramma, Dalm., and other
Orthid and Strophomenid brachiopods, Leptelloidea, crinoid stemjoints, etc. Fragments of proparian trilobites C^-CJieirurus) are common. The limestones, though frequently crowded with organic fragments have yielded no recognisable fossils. The Trehgam beds pass
up into the Silurian, small patches of which occur on either limb of the
main syncline underlying the Muth Quartzites.
Detailed work in the thicjj: group intervening between the Cambrian
GEOLOGY OF KASHMIR
403
and the Muth Quartzites in the core of the Basmai anticline of the
Sind valley is likely to bring to light some further outcrops of the
Ordovician.
SILURIAN
Distribution—Round the oval expanse of the core of the Lidar
anticline there runs a thin but continuous band of unmistakable
Silurian strata, from which well-preserved Silurian organisms have
been obtained. These rocks are continuously met with on the northeast side of the anticlinal from the neighbourhood of Eishmakam
in the Lidar valley to Lutherwan in the Wardwan valley. On the
south-west flank the outcrops are not as continuous, being hidden
under the recent alluvium of the Lidar and Arpat streams and their
tributaries.
Rocks—Lithologically the strata bear close resemblance to the
underlying Cambrian and Ordovician, being composed of sandy shales
or shaly sandstones with impure yellow limestones, but they are distinguished by the presence of a well-preserved suite of fossil organisms.
Limestones and calcareous rocks are less common than in the corresponding rocks of Spiti. The aggregate thickness of the fossil-bearing
Silurian strata is only 100 feet, but the organisms preserved in them
leave no doubt of their age, thus denoting a highly valued geological
horizon in India. They offer one of the few instances, in the whole of
the Indian region, where a well-defined Silurian fauna occurs. The
presumed Silurian rocks of the Shamsh Abari area are of much greater
thickness, -but they are obscurely fossiliferous, or unfossiliferous, over
wide stretches and their age is inferred from their superposition on the
Upper Cambrian, or their conformable position underneath the Muth
quartzites. A fossiliferous Silurian horizon exists in the central
Himalayas above the Haima nta system of Spiti and in the neighbouring area of Kumaon and Garhwal; another example is the Shan
States of Upper Burma. The occurrence of Silurian rocks is suspected,
on strong lithological grounds, in Poonch and in Chitral, but no index
fossil has been obtained from these localities hitherto, and their
definite correlation is a matter of doubt.
Fossils 1—The principal fossil is Orthis, which occurs in a large
number of species. Other Brachiopods belong to the genera : Leptaenia, Strophodonta, Atrypa, Meristella, Crania, Strophomena, Conchidium.
1 Cowper Reed, Silurian Fossils from Kashmir, Bee. vol. xlii. pt. 1, 1912.
404
GEOLOGY OF INDIA
Of Trilobites the following genera .occur : Calymene, lUaenus,
Phacops, Acidaspis, Encrinurus, Beyrichia.
The Cephalopods are represented by Orthoceras and Cyrtoceras.
Some corals, among whicli are Alveolites, Petraia or Lindstraemia.
The absence from this fauna of the well-known Silurian corals,
Favosites, Heliolites, Cyathophyllum, Syringopora, etc., which are
present in the homotaxial deposits of Spiti, is noteworthy. The evidence of the other fossils, however, points to a similarity between these
two deposits, a correspondence borne out by all other subsequent
formations.
DEVONIAN
Occurrence—The Devonian of Kashmir comes conformably on the
group last described. Its outcrop follows the outcrop of the Silurian
in normal stratigraphic order and is co-extensive with the latter.
Devonian strata are well seen on both the flanks of the Lidar anticlinal
as thin bands; they are also well exposed in the Wardwan district,
where their re-appearance is due to a synclinal folding.
An even band of hard, snow-white quartzites, 1000-2000 feet thick,
follows the hair-pin loop of the pitching tip of Cambrian and Silurian
outcrops in the Shamsh Abari syncline. It makes a regular even belt
lying between the Cambro-Silurian and the outcrop of the next
succeeding series, the.Panjal Volcanic series.
Petrology—The rocks regarded as Devonian are a great thickness of
massive white quartzites. This rock, both in its composition and texture as well as in its stratigraphic relations to the rocks below and
above it, exactly resembles the Muth quartzite of Spiti and Kumaon,
which has been regarded as Devonian. As in Spiti, these massive beds
of quartzite, reaching the enormous thickness of 3000 feet at places^
are totally devoid of any fossil remains. The inference of their age,
therefore, is stolely based on their stratigraphic position : the Muth
quartzites rest normally between fossilifefous Upper Silurian beds
below and fossil-bearing Carboniferous beds above, whose fossil
organisms indicate Lower Carboniferous affinities; it is, therefore,
reasonable to infer that the Muth quartzites are Devonian in part at
least. Such evidence, however, cannot be quite decisive, and it is possible that a part or the whole of the Muth quartzite series may ultimately prove to be of either of those ages—Upper Silurian or Lower
Carboniferous or both. Outcrops of theMuth series are easily detected
, by the prominent escarpmentf and cliffs which it forms, due to the
GEOLOGY OF KASHMIR
405
harder and more compact quartzites resisting the action of the denuding agencies better than the underlying slates.'
The "Devonian is well developed in Chitral. The lower part is unfossiliferous, but the Upper Devonian contains a rich fauna ; it passes
upwards into Fusulina limestones of Upper Carboniferous or Permian
age. The Devonian occurs also in parts of the Pamirs; the Sarikol
shales, previously regarded as Carboniferous, are found to be of Upper
Devonian age, with Orthoceras, crinoids and brachiopods of this
horizon.
LOWEE CARBONIFEROUS
Syringothyris Limestone Series
Distribution—Next in the order of superposition is a series of limestone strata lying conformably over the Muth quartzites. The outcrop of this limestone forms a thin band bordering the north-west half
of the ellipse we are considering; it cannot be traced further eastwards, being to a great extent hidden under superficial deposits such
as river alluvia. It has also suffered greatly by the overlapping of the
Panjal traps, which approach it from the north by successively overlapping the younger series. The present series is well exposed at
Eishmakam and Kotsu, which are good locaHties for collecting
fossils.
Outcrops of the Syringothyris limestone of considerable thickness,
2000-3000 feet, are observed in the Banihal valley of the Pir Panjal,
unconformably overlying the Cambrian. In the Sind valley, narrower
bands of this limestone conformably overlie the Muth quartzites.
Both these outcrops have suffered through the overlap of the Panjal
volcanics.
Lower Carboniferous fossils—The rocks composing the Lower Carboniferous of Kashmir are thin-bedded flaggy limestones of a grey
colour with clay or quartzite partings which occasionally assume large
bulk. The maximum thickness is over 3000 feet. The calcareous
constitution of this series readily distinguishes it from the older series,
which are devoid of strata of limestone. The limestones are crowded
with fossils principally belonging to the brachiopod class. The most
frequently occurring brachiopod, which chacacterises the series, is
Syringothyris cuspidata. This is a valuable index fossil, being also
very tj^Dical of the Lipak series of Spiti. Chonetes is found in large
numbers, together with many species oiProductus, of which the species
P. cora is the most common, while P. scabriculus and P. reticulatus are
406
GEOLOGY OF INDIA
not so abundant. Athyris, Derhyia and Rhynchonella are among other
brachiopods.
^
The age of the Syringothyris hmestone series is determined by that
of the Lipak series, with which it show^ exact parallehsm. From the
associition of Syringothyris cuspidata with species of Trilobites
{Phillipsia), regarded as Lower Carboniferous, in the Lipak group of
Spiti, Hayden has ascribed to that group a Lower Carboniferous
horizon.
MIDDLE (?) CARBONIFEROUS
Fenestella Shales
Passage beds—Overlying the upper beds of the Syringothyris limestone there comes some thickness of unfossiliferous quartzites and
shales before the first beds of the characteristic Fenestella-bearing
strata begin. These intermediate beds in their composition are allied
to the upper group—the Fenestella shales to be presently described—
but since they contain no fossils proper to that series, they are regarded
as " passage beds " between the two series.
Distribution—In distribution this group is even more restricted than
the last-described, being confined only to the north-west part of the
ellipse of the Palaeozoic anticline of the Lidar and to some outcrops
ttear Banihal and Budil in the Pir Panjal. To the south-west the series
is totally missing, having been obliterated by the overlap of the Panjal
lavas. In the Banihal anticUne a broad band of Fenestella shales series
conformably overlies and surrounds the outcrop of the Syringothyris
limestone and reaches over 3000 feet in vertical extent. Its relations
with the overlying volcanic agglomeratic slate are perfectly conformable and even transitional, some of the black shales being crowded
with pyroclastic and glassy debris, crystals of felspar, quartz, etc.
In the Hundawar basin this series, in common with the Syringothyris
limestone, is absent; the Muth quartzites here being overlain by the
Panjal Volcanic series. It is also absent from the Sind Valley.
Lithology—Lithologically the Fenestella shales are a great thickness
(more than 2000 feet) of thickly bedded quartzites interstratified with
black shales, sandy or micaceous, and thick, coarse conglomerates.
The shales are more prevalent at the base, becoming scarce at the
middle and top. The shales are the only fossil-bearing horizons in.
the series, being rich repositories of fossil polyzoa—Fenestella, which
gives the name to the series—brachiopods, corals and lamellibranchs.
GEOLOGY OF KASHMIR
407
The following is a characteristic section seen a t Lehindajjar :
Panjal agglomerate-slates.
'Uppermost Fenestella shales, not thick.
Unfossiliferous quartzites and shales, 500600 ft.
Black sandy shales with Fenestella, 100 ft.
Quartzite, 60 ft.
Fenestella J Greyish shaly sandstone, obscure fossils,
shales.
1 200 ft.
Dark shales full of Fenestella, corals, brachiopods, lamellibranchs, 150 ft.
Quartzite, 100 ft.
Sandy shales, full of Productus and other
fossils, 500 ft.
Base not seen.
Upper
Carboniferous.
Middle
Carboniferous,
(?)
Fauna—The most a b u n d a n t fossils are oasts, often ferruginous, of
species of Fenestella, the impressions of whose fan-shaped zoaria are
preserved in countless numbers, often in great perfection. Brachiopods are also a b u n d a n t in number as well as in species. The most
commonly occurring a r e : Spirifer {S. middlemissii and S. varuna),
Productus undatus, P. cora, P. lidarensis, P. spitiensis, P. scabriculus,
Dielasma, Uncinella, Aulosteges, Camarophoria, Rhynchonella ; the
lamellibranchs are : Modiola and Aviculopecten ; some pygidia of
"l^hillipsia. Besides Fenestella another polyzoon, though very rare, is
Protoretepora. The two must be carefully distinguished, for the latter
genus characterises a younger series of beds which lies over the Panjal
t r a p series.
Age of the Fenestella series—The fauna of t h e Fenestella series pos, sesses, according to Dr. Diener, strikingly individual characters of its
?own. Many of t h e fossil forms are quite special to it, bearing no relations to any definite Carboniferous horizon. For this reason their
stratigraphic position is dubitable, and m a y be a n y between Lower
and Upper Carboniferous according to the same authority.^
The disposition of the outcrops of the Fenestella shales reveals the
existence of a dip-fault traversing it along t h e Lidar basin. The fault
is not important, b u t its effect upon the outcrop on the two banks of
the river is quite illustrative. The exposure on the left bank lies much
higher up the river t h a n the right bank outcrop. This is in consequence
of a lateral shift (heave) produced b y a fault cutting across the strike
of t h e beds.
I Dieaer, Pal. Itidica, N.S., vol. v. mem. 2, 1915.
408
GEOLOGY OF INDIA
THE MID-PALAEOZOIC UNCONFORMITY OF NORTH-WEST
KASHMIR
While the records of the Palaeozoic from the Silurian to the Permian
are continuous in the Spiti Himalayas as well as in eastern Kashmir,
the geological record of north-western Kashmir and Hazara during
the greater part of this interval is a total blank. With the exception
of small patches of Muth Quartzites, the Silurian system of Kashmir,
west of the Wular lake, is succeeded by the Panjal Volcanic series
which is not older than the Uralian at the earliest. This is the most
widespread regional unconformity in the geological records of NorthWest India, equally well seen in Hazara, the western Pir Panjal and
the Punjab Salt-Range. The Hazara unconformity is proved by the
Hazara (Dogra) slates underljdng with an angular unconformity a
glacial boulder-conglomerate which is now accepted as of Talchir age.
In the Salt-Range, Cambrian beds with a Neobolus fauna are overlain
by, a bouI(3er-bed at the base of the Productus limestone with an intervening group of Damuda plant-bearing sandstones. This widespread unconformity is proof of the prevalence of continental conditions during Devonian and the greater part of the Carboniferous.
The existence of a Punjab-Kashmir-Hazara land-mass during the
Dravidian era is a well-established fact in the palaeo-geography of
North-West India.
This mid-Palaeozoic land-mass of Kashmir performed one important function; it must have served as a land-bridge between Gondwanaland and the great northern Eurasian continent (Angaraland).
It was through this land-bridge that'the terrestrial vegetation of the
Indian portion of Gondwanaland established some links with Angaraland.
When at the end of the Dravidian era, the earth movements which
supervened ushered in a new sedimentary period'on the surface of the
great continent of Gondwanaland to the south of the Himalayan sea,
this part of Kashmir, for a brief interval, formed the northernmost
frontier of Gondwanaland and was occupied by a characteristic land
vegetation—the Glossopteris flora, some typical members of which are
found entombed at six or seven widely scattered sites extending as far
north as the south flank of the Zanskar.
In all parts of Kashmir, west of the Sind valley, this unconformity
is clearly revealed, its effect being in some places exaggerated by a
progressive overlap of the Panjal Volcanic series.
I t was with the commencement of the Uralian that the Productus
GEOLOGY OF KASHMIR
409
sea of Spiti extended westward and overspread Kashmir, Hazara and
the Salt-Kange, ushering in the long period of Tethyan marine sediments that ceased only with the Middle Eocene.
Tanawal series—In the Purana and metamorphic belt of the N.W.
Himalayas, extending from Kaghan to Jammu, a voluminous series
of metamorphosed rocks of markedly arenaceous composition^
banded argillaceous quartzites, grits, phyllites and quartz-schists,
with clastic as well as crush-conglomerates—occurs in a number of
fold-faulted, disturbed longitudinal basins, one to four miles across
the strike; These have been named from the Tanawal country in
Hazara, in which similar rocks were first recognised by Wynne.
Their field relations with the Purana rocks, among which they lie, are
so distorted that it is often dif&cult to decide whether they are older
or newer than these. Their grade of stress metamorphism is sometimes higher than that of the Puranas. However, from some evidence
that the upper quartzite masses are, in a few cases, really silicified
limestones of the Sirban type (the " Infra-Trias " series) it is possible
to infer,that the whole group is newer than the slate series; but beyond suggesting that the Tanawals bridge the gap between these and
the Permo-Carboniferous, no definite age can at present be ascribed to
this group. I t is possible that the lower part of the Tanawals may be
coeval with so old a formation as the Muth series. In the Poonch Pir
Panjal these rocks show clear lateral passage into the Agglomeratic
Slate series of Upper Carboniferous age. The whole group is entirely
devoid of fossils.
In the Simla area the formation which succeeds the Simla slates is
the Jaunsar series or the Nagthat series, both unfossiliferous and of
uncertain stratigraphic position, similar in this respect to the equally
obscure Tanawals. At many localities, however, the Simla slates are
overlain unconformably by the Blaini series, the Upper Carboniferous age of which is now regarded as proved beyond serious doubt.
From the nature of their occurrence in disconnected isolated basins,
away from the wide sedimentary terrains, and their barren nature it is
conjectured that the Tanawals are a continental system of deposits,
laid down in depressions of the Hazara-Kashmir land-mass.
UPPER CARBONIFEROUS
The Panjal Volcanic Series
Middle Carboniferous eartti movements—^During the last stage of the
deposition of Fenestella shale-beds, the physical geography of the
410
GEOLOGY OF INDIA
Kashmir area underwent a-violent change, and what was before a
region of quiet marine sedimeiitation was converted into a great
theatre of vulcanicity, whereby an enormous superficial extent of the
country was converted into a volcanic region, such as Java and
Sumatra in the Malay Archipelago of the present day. The clastic and
liquid products of these volcanoes buried large areas of Kashmir under
7000-8000 f«et of lavas and tuifs. The volcanic activity was most intense during the Permian when it reached its climax, after which it
diminished greatly, though at isolated centres, as in Gurais, it persisted up to the Upper Triassic period.
Physical history at the end of Dravidian era—The earth-movements
and physico-geographical revolutions with which this igneous outburst was associated in the Kashmir area, were connected and contemporaneous with the crust-movements in other parts of India at the
end of the Dravidian era. This was the epoch of many far-reaching
changes on the face of India, as we have seen in Chapter VIII. These
changes put an end to the continental phase in Kashmir and to the
epoch of Gondwana conditions which had invaded Kashmir, converting it in fact into n north-western province of that continent.
This Gondwana epoch in the history of Kashmir was, however, of
but short duration. For the sea soon resumed its hold over this area
in the Permian times and commenced to throw down its characteristic
deposits on the geosynclinal of the Tethys, which once more brought
Kashmir within the " Tibetan " zone of the Himalayas. The marine'
Permian of Kashmir, as we shall see, is both in its physical and biological characters on a par with the Productus limestone of the SaltEange and the Productus shales of Spiti and other Himalayan areas.
Agglomeratic Slates and Trap
Rocks cf this series are divisible into two broad sections: the lower
—a thick series of pryoclastic slates, conglomerates and agglomeratic products, some thousand feet in thickness, and called by Middlemiss the " Panjal agglomeratic slates " ; and the upper—the " Panjal
traps ", an equally thick series of bedded andesitic and basaltic traps
generally overlying the agglomerates. The series covers an enormous
superficial area of the country, being only next in areal distribution to
the gneissic rocks. I t builds the majority of theJiigh peaks surrounding the Jhelum valley from the Shamsh Abari to the Kolahoi (17,799.)
Distribution^—^It is specially weU/developed in the Panjal range, of
which it forms the principafl substratum, being visible as prominently
GEOLOGY OF KASHMIR
411
on its sides and summit, as in its centre,.for the entire length of the
range from the Kishenganga valley in Karnah to its termination at the
Ravi (see PI. XV.). This circumstance gives the name Panjal to the
series. These rocks also form the black hill-masses on the north-west
continuation of the Zanskar range, beyond Nun Kun to as far as
Hazara. The Panjal volcanics, according to Lydekker, are also
developed in Ladakh, extending further to thq, north-east in the
direction, of the Changchenmo valley to the very farthest borders of
the Kashmir territory. A few outliers of the same rock are met with
in Baltistan as far north as Skardu.
The stratigraphical position of these deposits is noteworthy. The
Panjal volcanic series commences from varying horizons, from the
Moscovian, Uralian, or even Permian, in different localities and extends in its upper limit, likewise, to the Lower Permian in some places
and the Upper Trias in others. Both the lower and upper limits are
generally precisely dated by intercalation with known fossiliferous
horizons. In the Vihi district the volcanic eruptions die out with the
Lower Permian ; in the Lidar with the end of the Permian ; while in
Gurais the vulcanicity did not end till well into the Upper Trias. The
erratic nature of the traps as a stratigraphic unit is thus evident.
Nature of the Panjal slate-agglomerate—The mode of origin of the
lower part of the Panjal volcanic series, or what has been called the
" agglomeratic " slates, is not easy to understand. Much of it is composed of a fine greywacke-like matrix with embedded angular grains of
quartz. But the rock does not appear to be an ordinary sedimentary
deposit, inasmuch as the embedded fragments are quite angular and
often bficome very large in size at random. They are pieces of quartzite, slate, porphyry, granite, etc., irregularly dispersed in a linegrained matrix. The rock is generally unfossiliferous throughout,
though at a few localities several interesting suites of fossils have been
discovered^ which are identical with forms entombed in the underlying Fenestella series. The most common forms are Productus, Spirifer, Chonetes, Dielasma, Camarophoria, Strophalosia, Leptaena, Streptorhynchus, Spiriferina, Eurydesma, Aviculopecten, Sanguinolites, Conocardium, Fenestella, Euphemus and Pleurotomaria. That such a rock
could not have been the product of any simple process of sedimentation, whether subaerial or submarine, is quite clear, and the origia of
the deposit so widespread and of such uniform character is a problem;
One view is that the rock is a joint product of explosive volcanic
1 H. S. Bion, Pal. Indica. N.S. vol. xii, 1928 ; F. C. Reed, Pal. Indica, N.S. vol. xx.
mem. 1, 1932.
412
GEOLOGY OF INDIA
action, combined with ordinary subaerial deposition; the other, a
diametrically opposite view, is that it is due to frost-action under
glacial or arctic conditions, the frost-weathered debris being subsequently transported by floating ice-masses to lakes. Middlemiss
favours the former view, as being more in keeping with the actual
circumstances of the case and as congruent with the lava-eruptions
that succeeded i t ; though he points out that the absence of glassparticles, puinice fragments and other products usually associated
with tuffs, is irreconcilable with this view. Late work in the Pir
Panjal has established the pryoclastio nature of large parts of this
formation beyond any doubt. The matrix of the slate often is full of
devitrified and altered glass with phenocrysts of felspars.^ The presence of Lower Gondwana plants in beds ^immediately overlying the
v.olcanics favours the inference that the slate-conglomerate is a glacial
deposit corresponding to the Talchir boulder-beds. No facetted or
striated pebbles are, however, found in the slates, which, on the contrary, are frequently quite angular. The following section gives a
general idea of the rocks of the Panjal series.
Aggregate
thickness
some thousand feet.
5. Bedded green and purple traps, several thousand feet
• thick.
4. Greenish ash-beds, slates and agglomeratic quartzites
with amygdaloidal traps.
3. Black and grey agglomeratic slates (tuffs) with thick
beds of conglomerate containing sub-angular pebbles
of quartzite and slate.
2. Whitish quartzite and sandstones.
1. Black agglomeratic slates (tuffs) with angular or subangular pebbles of quartz, slate and gneiss.
The Agglomeratic slates of Nagmarg and Bren contain Lower Gondwana plants, associated with a series of sandstones and shales containing a marine brachiopod fauna and Eurydesma. This horizon corresponds with the Eurydesma horizon of the Salt-Range Productus series.
Panjal lavas. Petrology—Over the agglomeratic slates there comes
a great thickness of distinctly bedded massive lava-flows. In composition the lava is a basic variety of augite-andesite or basalt of
acidity varying from 49% to 60%, of a prevailing dark or greenish
colour, the green colour being due to the alteration of augite and other
constituents into epidote. Acid and intermediate differentiationproducts also occur locally and in small masses, e.g. trachyte, ceratophyre, rhyolite, acid tuffs, etc. The rock is usually non-porphyritic
and very compact in texture, but porphyritic varieties are sometimes,
>Wadia, Mem. O.S.I., vol. U. pt. 2, 1928.
•"
GEOLOGY OP KASHMIR
413
and amygdaloidal varieties are often, met with. In microscopic structure
the lavas are a micro-crystalline aggregate of plagioclase felspar and
finely granular augite, with traces of yet undevitrified glassy matrix.
Magnetite is very common in irregular grains and crystals. No olivine
is present, nor any well-formed crystals of augite. The structure is
hemicrystalline throughout, only minute prisms of white turbid felspar
being detected in a finely granular aggregate, but in some varieties
there are large prismatic phenocrysts of felspar arranged in star-shaped
or radiating aggregates giving rise to what is called glomero-'porjjhyritic
structure. Some varieties are amygdaloidal, the amygdules being
composed of silica or epidote or rarely of some zeolites. The lavas
often show widespread alteration of the nature of epidotisation,
chloritisation, and silieification. Devitrification is most common.
Green chlorite is commonly present in the felspars, and epidote is a
universal secondary product resulting from the interaction between
augite and plagioclase.
When the lavas are interbedded with the slates, the contact metamorphism induced in both the rocks is of very marked degree, the two
becoming quite indistinct from each other. At Gagribal, near
Srinagar, such an intimate association of the two kinds of rocks is seen.
Sills and dykes of coarse-textured dolerite are frequent in the bedded
trap-flows.
'
The individual flows vary in thickness from a few inches to twenty
feet or more, and are markedly lehticular. There are no fresh-water
sedimentary intercalations of the nature of " inter-trappean " beds,
but in the body of the traps there are found considerable thicknesses of
inter-trappean marine fossiliferous limestones of Permian (Sirban), and
Lower and Middle Trias age. These limestones are obviously fossiliferous and show a gradual passage into ash-beds and traps above and
below. Such inter-trappean limestones of thickness varying from
50-1000 feet, are observed in the mountains north of the Wular, in the
Uri district and in the Kaghan valley, Hazara. The total aggregate
thickness of the lava-flows measures several thousands of feet, 70008000 feet being seen in the cliffs above the Wular. But this development is often purely local; over large areas the trap is missing, its
place being occupied by agglomerate slate.
Age and vertical extension of Panjal lavas—The upper limit of the
Panjal lava-flows in Vihi is clearly defined by the directly overlying
plant-bearing beds of Lower Gondwana facies, which in turn are immediately succeeded by marine Permian rocks. In other cases, however, the flows have been found to extend to a much higher horizon,
414
GEOLOGY OF INDIA
as far as the Upper Triassic, a few flows being found locally interbedded with Umestone of that age. In general the Panjal volcanoes
ceased their eruptive activity in the Permian. These subaerial volcanic eruptions therefore bridge over the gap which is usually perceived at the base of the Permian in all other parts of India.
In addition to lava-flows there are seen dykes and laccolithic masses
of a gabbroid and doleritic magma, cutting through both the Panjal
slates and traps or earlier rocks in several parts of Kashmir.
LOWER GONDWANA BEDS
Gangamopteris Beds
Distribution—The Panjal traps are directly and conformably overlain in several parts of Kashmir by a series of beds containing Gangamopteris and Glossopteris, so eminently characteristic of the Talchir
and Damuda series of the Peninsular Gondwanas. The Gondwana
plant-bearing beds have been met with at seven localities, viz. on the
north-east slopes of the Pir Panjal, at Banihal pass, Golabgarh pass'
and near Gulmarg ; and on the opposite side of the Jhelum valley, in
Vihi; near Srinagar ; at Marahom near Bijbiara ; and at Nagmarg
on the Wular lake. Of these, the exposures a,t Eisin and Zewan in the
Vihi district are the most noteworthy because of their directly underlying fossiliferous Permian limestones, a circumstance which clearly
establishes their exact straligraphic horizon. This is illustrated in the
section in Fig. 41, p. 417. This series of beds is known as the Gangamopteris beds from the most prevalent seed-fern, impressions of whose
leaves are well preserved in the black or grey " shales ", which in their
composition are black glassy tuffs, almost entirely composed of isotropic obsidian-like glass. A fossiliferous outcrop of these beds is
visible at the Golabgarh pass of the Pir Panjal, one of the passes on
the range leading from the province of Jammu to Kashmir.
Lithology—The Gangamopteris beds are composed of a variable
thickness of cherts, siliceous shales, carbonaceous shales and flaggy
beds of quartzite, which in their constitution are largely pyroclastic.
The thickness varies from a few feet at some of the Vihi outcrops to
some hundreds of feet in the outcrop at the P&njal range. A peculiar
rock of this series is a " novaculite ", well seen at Barus and at
Khunmu. It is a compact chert-like rock of white or cream colour,
which has replaced an original limestone by silicification, forming the
base of the series and directly overlying the traps. The black shales
of many of the outcrops of the Gangamopteris beds are likewise
GEOLOGY O F KASHMIR
415
frequently silicified. On the south-west flank of the Pir Panjal
Gondwana beds (? ^ p p e r Tanawals) consisitute a thick series of
deposits some thousand feet in thickness consisting of p a r t l y metamorphosed shales, phyllites, quar'tzose grits a n d sandstones, the latter
showing extensive ripple-marking, cross-bedding a n d colour-banding.
The series is generally barren of recognisable fossils, b u t from its position above the Dogra slates in wide synclinal basins, with a basal
boulder-conglomerate, and its conformable relations t o t h e Agglomeratic Slate series, it is tentatively referred t o t h e Lower Gondwanas.^
The Golabgarh section—The section below gives the chief components of t h e series viewed a t the Golabgarh Pass.^
Zewan series. Protoretepora Umestone.
Gangamopteris
beds.
Earthy sandstones, calcareous above, passing into 230 ft.
Zewan limestones.
Hard, compact black shales
with Glossopteris; hafd
grey sandstones and inter- 400 ft.
bedded shales with Psygmophyllum,
Gangamop-.
teris and Vertebraria.
Thin-bedded, buff-coloured
compact siliceous and car- 180 ft.
bonaceous shales.
Basal conglomerate.
6 ft.
Panjal traps and ash-beds.
Permian.
Lower Gondwana.
(PermoCarboniferous.)
Upper
Carboniferous.
f o s s i l s — T h e Gondwana fossils include plant impressions together
with p a r t s of t h e skeletons of labyrinthodonts and fishes. The
plants are chiefly obtained from t h e Golabgarh outcrop, while t h e
vertebrate remains were obtained from Risin a n d K h u n m u . The
plants include a species of Gangamopteris sufficiently distinct from
those of t h e Peninsula t o be named G. kashmirensis.
Other fossils are
Glossopterisindica, Vertebrariaindica, Callipteridium, Cordaites {Naeggerathiop'sis) a n d leaves oi Psygmophyllum, a genus related t o Ginkgo.
The vertebrate fossils consist of the scales, fins, portions of skulls,
a mandible, a n d fragments of the hind-limbs of Amblypterus (a
• » M m . G.S.I. vol. li. pt. 2, 1928.
^ Middlemiss, Bee. G.S.I, vol. xxxvii. pt. 4, 1909. For another section at Zewan
see Hayden, Bee. O.S.I. vol. xxxv. pt. 1, 1908.
416
GEOLOGY OF INDIA
cartilaginous ganoid fish), together with fragmentary remains of a
species of labyrinthodont- Archegosaurus, and a cranium of an
Actinodon species, A. risinensis.
'
Age—The exact horizon,represented, by the Gangamopteris beds, in
terms of the typical Gondwana sequence, cannot be determined with
the help of the plant-remains alone, although the occurrence of Gangamopteris suggests a relatively low horizon in the Gondwana series.
But the association of this meagrely known-flora with marine strata
below and above (viz. the Middle Carboniferous Fenestella shales and
the Permian Zewan beds) is an event of the greatest importance in the
stratigraphic records of India. I t has helped to solve one of the most
difficult problems of Indian geology—the settlement of the precise
horizon of the Lower Gondwana system of India.
The plants resemble the characteristic Lower Gondwana types of
South Africa, Australia and other countries of the Southern Hemisphere, and are thus very interesting as affording us a glimpse into the
geography of the northernmost limit of the Gondwana continent
which included within its borders all these countries.
' THE PERMIAN
The Zewan Series
The Zewan beds—The Permian deposits, the local representative of
the Productus limestone of the Salt-Range and of the Productus shales
of Spiti, make a very well-marked horizon in the geology of Kashmir.
These deposits have been known since an early date as the Zewan beds,
from their exposure at the village of Zewan in the Vihi district. At
this particular locality the Gangamopteris beds are overlain by a series
of fossiliferous shales and limestones containing crowds of fossil
brachiopods and polyzoa. In other parts of Vihi this series is more'
fully formed, the portion representative, of the typical Zewan section
being succeeded by another thick group of limestone and shales underlying the Lower Triassic beds. The term " Zewan series " has consequently been amplified to receive the entire succession of beds between the Gangamopteris and the Lower Triassic beds. The base of
the Zewan series is argillaceous in composition, the shales being
crowded with the remains .of Protoretepora, a polyzoon resembling
Fenestella. The upper part is calcareous, the limestone strata preponderating. In a few shales intercalated among the latter, is contained a fauna resembling that of the Productus shales of Spiti and
417
GEOLOGY OF KASHMIR
other parts of the central Himalayas. Over the top of the series there
lie thin bands of hard limestone and shales bearing' Pseudomonotis,
Danubites and other ammonites, marking a Lower Tfias limit.
Guryul
Ravine
W.N.W.
,e.S.Ej
FIG. 41.—Section,of the Zewan series, Guryul Ra^'ine.
(Middlemias, Rec. Geological Survey of India, vol. xxxV"- pl- 4.)
A thin but continuous band of Zewan rocks is seen along the southwest hills of Vihi, which is co-extensive with the jnuch more prominent Triassio outcrop. A few thin isolated outcrops of the series are
noticed in the Pir Panjal on either side of the centr&l axis, overlying
the trap. A more voluminous development of the Perjnian is witnessed
in the watershed area of the Upper Sind and Lidar valleys, normally
underlying the Lower Trias.
The following section, very well exposed in a ravine near Khunmu
(Guryul ravine), is reproduced from Middlemiss and Hayden :
Meekoceras zone of the Lower Trias.
Shales and limestone, thin-bedded. Fossils : Pseudomof'Otis, Bel-\ ^QQ ^
lerophon,'Danubites, Flemingites.
'
Dark arenaceous shales, micaceous and carbonaceous, wth lime-1
stone intercalations at base. Fossils : Marginiferd himalay- j-300 ft.
msis, Pseudomonotis, etc.
J
W.G.I.
2D
418
GEOLOGY OF INDIA
Shales and limestone, crowded with Protoretepora, Aihyris royssii,\ „„ ,,
Producius, Dielasma, etc.
/
Dark grey limestone with shale partings. Fossils : Atliyris, Noto-] „„ ,,
thyris, etc.
.
/
'
Novaculites and tuffaceous strata of the Gangamopteris beds.
Fossils—Fossils are present in large numbers in the Zewan beds.
They include one Nautilus and two genera of ammonites, Xenaspis
and Popanoceras. The lamellibranchs are Pseudomonotis, Ayiculopecten and Schizodus; but the most predominant groups are the
brachiopods and polyzoa. The former are represented by Productus
cora, P. spiralis, P. purdoni, P. gangeticus, P. indicus, Spirifer rajah
(the most numerous), Dielasma, Martinia, Spirigera, Spiriferina,
Marginifera vihiana, M. himalayensis, Lyttonia, Camarophoria,
Chonetes, Derbya, etc. Among polyzoa the species Protoretepora ampla
is present in overwhelming numbers at some horizons. Its fan-shaped
reticulate-structured zoaria resemble those of the Fenestella, but the
former belongs to a slightly different zoological family., Acanthocladia also is a frequent form. Amplexus and Zaphrentis are the more
common corals.
Age of the Zewan series—From the palaeontological standpoint the
Zewan series is correlated with the Middle Permian system of Europe,
a conclusion amply corroborated by the stratigraphic relations .of the
series to the Lower Trias. An interesting fact revealed by the Zewan
fauna is the exact parallelism of these deposits with the middle and
upper part of the Productus limestone of the Salt-Range, most of the
genera and many of th^fepecies being common to the two regions. A
comparison of the faunas w;ith the Productus (Kuling) shales of t h e *
central Himalayas also brings out the closest zoological affinities between these three homotaxial members of the Indian Permian a n t
Permo-Carboniferous systems.^
.
Permian of Jammu ^
In the sub-Himalayan zone of Jammu hills, representatives of the,
unfossiliferous limestone, Sirban limestone of Hazara {Infra-Trias
series), of presumably Permian or Permo-Carbonif^ous age, crop out
in a chain of large and small inliers extending from Riasi tp the Poonch
valley. This is a very unusual circumstance, which finds only one .
^ Dr. Diener, Pal. Indica, N.S., yol. v. mem. 2, 1915.
»D. N. Wadia, liec. G.S.I. vol. Ixsii. pt. 2, 1937.
GEOLOGY OF KASHMIR
419
parallel in the Tal series of tlie Nepal Himalayas. In Jammu, mountainous masses of white or blue-grey dolomitic limestone are laid bare
by the removal of the overlying Eocene and Murree series from anticlinal tops. The most notable of the inliers thus exposed forms a conspicuous land-mark near Eiasi (the Trikuta hill). To the west of this
is a series of hog-backed masses of the same limestone laid bare in
denuded anticlines, generally faulted in their steep south limbs against
the younger Tertiaries of Jammu. The limestone, over 1500 feet
thick, is entirely barren of organic remains and its stratigraphic relations being nowhere exposed, it was doubtfully referred to the Kioto
limestone of Spiti and named the " Great limestone ". During late
Survey work, however, some clue to the identity of the rock has been
• discovered in the intercalation of the base of the limestone with Agglomeratic slate—an association often noticed in the Sirban limestone of
the K.aghan valley. There is also a close lithological similarity between these outcrops.
In its petrological characters this limestone shows analogy also
with the unfossiliferous Krol limestone of the Simla-Chakrata area,
constituting a wide and long belt of post-Blaini limestone and
associated rocks.
The Riasi limestone possesses considerable economic importance
and forms .one of the few noticeably mineralised rock-formations of the
North-West Himalayas. Important lodes of zinc and copper are
found in the limestone, with veins of nickeliferous pyrites and galena.
The sulphidic ores of zinc and copper are probably metasomatic replacementSj while galena and pyrites are vein-fillings. (See Fig. 43,
p. 432.)
Krol Series of Simla
The probable equivalent of the fossiliferous Upper Carboniferous
and Permian of Kashmir is the thick pile of sediments, for the greater
part obviously marine, but showing oscillations to fresh-water and
terrestrial conditions,'coming over the Blaini boulder-bed—a glacial
till consisting of ice-scratched pebbles in a fine matrix. This is superposed by pink coloured Blaini limestone, the thick series of Infra-Krol
carbonaceous slates and quartzites, overlain by the prominent limestone formation of the Simla mountains—the Krol limestone.
Though quit,e barren of fossils the Krol series, consisting of dolomitic
limestone, sandstone and shales is of high interest because of its
tectonic complexity and the greatly involved stratigraphy. The
Krol belt of the Simla Himalayas, consisting of presumably
420
GEOLOGY OF INDIA
Permo-Carboiiiferous rocks, builds an important section of the
middle Himalayas from Subatl^u to Naini Tal, in which much
detailed work has been carried out during late years. ^
Fossiliferous Permian or Permo-Carboniferous strata, mainly limestones, are observed extensively formed in the Karakoram.^ According to the Italian Expedition to these mountains, of 1913-14, the
mountains of the Gasherbrum, Golden Throne, the Crystal and Bride
Peaks are' built of these limestones. Pernlian limestones have also
been observed in the Shaksgam valley of the range.
A great thickness of Fusulina limestone of Permian or Upper Carboniferous age occurs among the crystalline limestones of the Tirich
valley in Chitral. Outcrops of Fusulina limestone extend from
Chitral into Russian Turkestan.
TRIASSIC
The Trias of Kashmir—The Trias of Kashmir, in common with the
whole length of the North Himalayas from the Pamirs to Nepal, is on
a scale of great magnitude. A superb development of limestones and
dolomites of this system is exhibited in a series of picturesque escarpments, and cliffs forming the best part of the scenery north of the
river. The Trias attains great dimensions farther north in the upper
Sind, Lidar and Wardwan valleys, and again in Gurais, Tilel and
Central Ladakh, thence extending as far as the Karakoram and
Lingzhithang plains. Another locality for the development of the
Trias, principally belonging to its upper division, is the Pir Panjal, of
which it is the youngest constituent rock-group, capping the volcanic
beds over the whole stretch of the range from beyond the Jhelum to
Kishtwar. A great part of the Triassic on the north-east flanks, however, is obscured under later formations such as the Karewas aad
moraine debris.
Lithology—^Limestones are the principal components of this
system. The rock is of a light blue or grey tint, compact and homogeneous, and sometimes dolomitic in composition. They are thinbedded in the lower part of the system, with frequent interstratifications of black sandy and calcareous shales, but towards the top they
become one monotonously uniform group of thickly-bedded limestones. They compose a very picturesque feature of th6 landscapes,
1W. B . West, Mem. 0.8.1. vol. liii, 1928; J. B. Auden, Bee. O.S.I, vol. Ixvii. pt. 4,1934.
' Pe Terra, Forschungen im westlichen Kun Lun und Karakoram-Himalaya (Berlin),
1932.
GEOLOGY OF KASHMIR
421
noticeable from all parts of the country by the light coloration
of their outcrops and their graceful long and undulating folds
interspersed with areas of close plication and inversions, both of
which characteristics bring them out in strong relief against the
-dark-coloured, craggy lavas and slates of the underlying Panjals.
GEOLOGY OF INDIA
422
Numerous springs of fresh water issue from the cliffs and prominences
of these limestones at the south-e^st end of the valley, which form
the sources of the Jhelum; the best known of these are the river-like
fountains of Achabal and Vernag and the multitudinous springs of
Anantnag and Bhawan. The lower and middle sections of the
system are rich in fossils, the abundance of the Cephalopoda and the
peculiarities of their vertical range in the strata being the means of a
very detailed zonal classification of the system, all the zones of which
are related to the corresponding ones of Spiti. The upper division of
the Trias is largely barren of fossils. The following succession of the
Triassic strata may be taken as typical:
_.
_ .
I'TJiifossiliferous massive limestone with occasional
^M
+>)'
fl J
corals and crinoids, Galamophyllia.
fpof
tiiint
\
1
Spiriferina
stracheyi and S. Jiaueri zones.
feet thick.)
iLamellibranch beds.
, Ptychites honzon: sandy shales with calcareous
layers.
Ceratite beds:
„
,,
„
„
Muschelkalk.
J Rhynchonella trinodosi beds : „
„
„
(About 900 ft.) Gymnites and Ceratite beds:
„
„
„
Lower nodular limestone and shales.
Interbedded thin limestones, thick black shales and
'• sandy Umestones.
Hungarites shales (position uncertain).
Meekoceras limestones and shales.
Lower Trias.
Ophiceras limestones.
(Over 300 ft.)
Otoceras beds (seen at a few localities only).
Lower Trias—At all the Permian localities mentioned in the last
section the Zewan series shows a conformable passage upwards into a
series of limestone strata, which in their fossil ammonites are the exact
parallels of the Ophiceras and Meekoceras zones of Spiti. The Otoceras
zone is recognised in the Sind valley, at the base of the Lower Tria^
curiously containing some Productus, a survival from the Palaeozoic.
These in turn pass upwards, after the intervention of a shaly zone (the
Hungarites zone), into the great succession of Middle Triassic limestones and shales. The best sections of the Lower Trias are those laid
bare at Pastanah and at Lam, two places on the eastern border of
the Vihi district, though the sections are somewhat obscured by
jungle-growth. Fossils : Ammonites, Xenodiscus (seven species);
Otoceras ; Ophiceras (0. sakuntala and five other species); Flemingites;
Vishnuites ; Hungarites ; Meekoceras ; Sibirites; and a new genus
of ammonite, Kashmirites. Other ce^halopods are Orthoceras and
Gryphoceras ; the lamellibranCh, Pseudombnotis, is a type form.
(
GEOLOGY OF KASHMIR
423
Middle Trias—Sections of the Middle Trias, or Muschelkalk, are
visible at many points in Vihi, e.g. at Pastanah, Khrew and Khunmu,
above Pailgani in the Lidar, and in some of the tributary valleys of the
Upper Sind. The linlestones of this part of the Trias are more frequently interbedded wjth shales, the latter being often black and
arenaceous. The Muschelkalk has yielded a very diversified fauna
of cephalopoda indicating the very high degree of specialisation reached
by this class of animals, particularly the order of the ammonites.
The specific relations of the types are in all respects alike to those of
the other parts of the Himalayas.
The Muschelkalk fauna—The principal forms of the Muschelkalk
fauna of Kashmir are Ceratites (sixteen species), Hungarites, Sibirites,
Isculites, Pinacoceras, Ptychites, Gymnites (sp. sankara, vasantsena and
other species), Buddhaites. JJhe nautiloidea are Syringonautilus, Gryphoceras, Paranautilus, Orthoceras. The lamellibranch genera are
Myophoria, Modiola, Anomia, AnodontopJiora; the brachiopods are
Spiriferina stracheyi, Dielasma and Rhynchonella; the gasteropods
are represented by a species of Euomphalus and the aberrant genus
Conularia.
Upper Trias—The Muschelkalk is succeeded, in all the above-noted
localities, by an enormous development of the Upper Triassic strata,
which are mostly unfossiliferous, but for a zone of coral-, lamellibranch- and braohiopod-bearing beds included at its lower part. An
Upper Triassic crinoidal hmestone is widely distributed in moraine
heaps clothing the N.E. slopes of the Pir Panjal, but for the greater
part the formation is an unvarying succession of thick massive unfossiliferous limestone. It is this limestone which builds the range of
high hills and precipices so conspicuous by their colouring in the Vihi
and the Islamabad districts.
A broad and continuous belt of barren, light and dark grey, Upper
Trias dolomites and limestones stretches from north of Pailgam,
through the head-waters of the Sind, to beyond Gurais. At the latter
locality the Kishenganga river has excavated through this hmestone a
broad U-shaped valley bounded on both sides by an imposing line of
precipices, towering 4000 to 6000 feet above the flat scree-strewn
bottom. The Lower and Middle Trias are missing in Gurais, the
upper flows of the Panjal trap showing a conformable passage into the
Upper Trias. In Tilel the lower part of the Trias is scantily developed
in the south slopes of the valley.
Around Baltal the Upper Trias builds the mountains surrounding
Kolahoi (17,799) and exhibits a great deal of complex folding. In
424
GEOLOGY OF INDIA
some of tte-major synclinal flexures of this series, between Baltal and
Zoji La, it is probable that. Jurassic strata, of Lias or Lower Oolite age
are exposed, containing a few ba,dly preserved ammonites and belemnites. The group of Amarnath peaks (17,290), with the sacred cave
on their southern flank, is composed of Upper Trias limestone and
dolomite, at some places altered to gypsum.
The Triassic limestone has furnished an abundant building material
to the architects of ancient Kashmir in the building of their great
temples and edifices, including the famous shrine of Martand.
Relation of the Kashmir and Spiti provinces during the Upper Trias
—The fauna of the Upper Trias is quite poor in comparison to that of
the Lower and Middle divisions. Cephalopods are almost absent.
The few lamellibranchs include Myophoria, Gervillia, Pseudomonotis,
Lima, Pecten, Pleurophora, Trigonodus. The brachiopods are Spiriferina haueri, Dielasma, Rhynchonella; Calamopliyllia is a common
coral; Crinoids; Marmolatellct, etc. The rarity of the zone fossils
Halobia and Daonella, -and the almost complete absence in Kashmir
of the cephaFopods that are so numerous and highly diversified in
the Spiti Upper Trias, suggest some sudden and eflective interruption
in the free intercourse and migrations "of species that had existed
between the seas of the two areas for such long ages. This intercourse appears to have been partly re-established during the
Jurassic, though not on the former scale, for the fauna, of the later
ages that has been discovered in Kashmir up to now, is quite scanty
and impoverished in comparison with the Spiti fauna.
JURASSIC
The Jurassic of Ladakh—In the Spiti area, which in reality is the
direct south-east extension of the Zanskar area of the Kashmir basin,
it will be remembered the following sequence of. Jurassic deposits is
known :
Giumal sandstone.,
Cretaceous.
Spiti shales.
TT- , ,•
,
V Tagling stage, including the Sulca- Jurassic.
I cutus beds.
I Para stage, including the Megalodon
I limestone.
Triassic.
Monotis shales.
A sequence, roughly similar in many respects to this, is traceable in
GEOLOGY OF KASHMIR
425
some outcrops in the Central and Southern par^iS of Ladakh, resting
conformably upon the Upper Triassic limestone. These outcrops form
part of a broad basin of marine Mesozoic rocks situated upon the inner
flank of the Zanskar range, and are connected with the Jurassic formation of Spiti by lying on the same strike. The lower parts of a
number of these outcrops, which include about 500 feet of dolomitic
limestone, recall the Megalodon limestone, both in their constitution
and in their fossil contents. At another locality this group is succeeded by light-blue limestone, which from its contained fossils is
referable to the Tagling stage. ^ The Tagling stage passes conformably up at several localities into the Spiti shales, that eminently characteristic Jurassic horizon of Himalayan stratigraphy. It is readily
recognised by its peculiar lithology, its black, thin-bedded, carbonaceous and'micaceous shales containing a few fossil-bearing concretions. The following fossils have been hitherto obtained from the
Jurassic of Ladakh.
Megalodon, Avicula, Pecten, Cerithium, Nerinea, Phasianella,
Pleurotomaria; some Ammonites, including Macrocephalus and
numerous fragments of Belemnites; with a few species of RJiynchonella and Terebratula.
With the exception described below, the Jurassic system has not
been recognised in the Kashmir province proper. It is probable that
the more detailed survey of the province, which is being prosecuted at
' the present time, will bring to light further outcrops of this system
from remoter districts.
Jurassic of Baiiihal—An outcrop of the Jurassic system is found on
the north sMe of the Banihal pass of the Pir Panjal in a tightly compressed syncline in the Upper Trias. A series of limestones, shales and
sandstones therein, rating on the topmost beds of the Upper Trias,have yielded a few Jurassic cephalopods and lamellibranchs.
It is probable that similar outliers of the Jurassic exist in association
with the extensive Triassic formation of the northern flank of the Pir
Panjal between Banihal and Gulmarg, under cover of the Pleistocene
glacial and Kajewa deposits, which have sheeted the long gentle
northern slopes of this mountain range.
As mentioned on page 424 the Upper Trias of Baltal appears to pass
upwards into dark carbonaceous and pyritous shales, calcareous shales
' The accuracy of this correlation, it must be realised, has never been sufficiently
ascertained. Revision of the Kashmir sequence is proceeding. I t is only when this
work is completed that a full account of the Jurassic of Kashmir can be given in any
detail such as we have given above of the Palaeozoic formations. The same is to be said
about the Cretaceous.
426
GEOLOGY OF INDIA
and limestones, containing some badly crushed and distorted ammonites and belemnites. These are probably of basal Jurassic, Lower
Lias, age. These rocks are well displayed in the synclinal folds of the
Upper Trias in the.magnificent series of bare cliifs on the north side of
the Sind above Sonamarg and in the Amarnath valley. They are well
exposed in the cuttings of the Zoji La road above Baltal.
CRETACEOUS
If the account of the Jurassic system of Kashmir is meagre, that of
the Cretaceous rocks is still more so. It is only at a few localities that
rocks belonging to this system have been discovered ; all of these lie
in a distant unfrequented part of Kashmir, either on the Great Himalayan range between the Burzil and Deosai or in the Zanskar range in
the Eupshu province. The great development of the Cretaceous
rocks of Spiti and its surrounding places, the Giumal sandstone, the
Chikkim limestone and the enormous flysch-like series, have not been
yet recorded in Kashmir, though from the fact of their occurrence in
the western province of Hazara, it is probable that these series might
have their parallels in^the Skardo and Ladakh provinces of Kashmir
in a few attenuated outcrops at least.
The Chikkim series of Rupshu-Zanskar—Two or three small patches
of Cretaceous rocks occur in Eupshu which correspond to the Chikkim
series in their geological relations. They are composed of a white
limestone, as in the type area, forming some of the highest peaks of
the range in Ladakh. No fossils, however, have been obtained from'
them hitherto.
Cretaceous Volcanic Series of Aster, Burzil aiid Dras ^
A highly interesting group of volcanic rocks-^Iaminated ash-beds,"
tuffs, agglomerates, coarse agglomeratic conglomerates and bedded
basaltic lava-flows, associated with marine Cretaceous limestones on
the one hand and with a varied group of acid and basic plutonic intrusives—granites, porphjTies, gabbro and serpentine on the other,
has lately been discovered during the geological survey of North
Kashmir. These rocks are folded into a synclinal trough lying among
the Salkhalas, extending from south-east of Astor to beyond Dras,,
traversing the Great Himalayan range at the head of the Burzil valley
in a 12-mile wide outcrop. The stratified volcanic series, several
' D. N. Wadia, Rec. 0:8.1. vol. Ixxii. pt. 2, 1937
GEOLOGY OF KASHMIR
427
thousand feet in thickness, contains numerous sedimentary layers and
lenticular intercalations of fossiliferous limestones and shales, carrying
foraminifera, bi-valves, gastropods, ammonites and corals, among
which the best preserved fossils are the Cretaceous foraminifer Orbitolina (of. 0. bulgarica).
Fully half the bulk of the Burzil outcrop is occupied by intrusive
hornblende-granite, which has penetrated the basic volcanics in
bathyliths, and in anastomosing sills and veins, while massive stocks
and bosses of pjoroxenite (converted to serpentine) and gabbro are of
local prevalence at various points in the outcrop.
It is evident that the belt of Burzil-Dras Cretaceous volcanic
series is in structural continuity with the wider development
of the Lower Tertiary volcanics of the Upper Indus valley of
Ladakh and Kargil and constitutes its north-west prolongation
along the strike.
The most interesting feature of the rocks we are now considering is
the injection of fossiliferous Cretaceous sediments by a granite, one of
the three varieties of common Himalayan granite, whose post-Cretaceous age is thus settled beyond doubt. This granite overspreads
a large extent of the country from Astor to the Deosai plateau.
Ladakh—Drew has recorded the occurrence of Hippurite limestone,
of Cretaceous age, in the Lokzhung range of mountains, on the furthest
northern boundary of this State. Another indication of a Cretaceous
formation in the Ladakh province is furnished by the discovery of the
Cretaceous fossil, Gryphea vesiculosa, at a place Sajna, on the road
from Leh (the capital of Ladakh) to Yarkand, from a group of cal, careous sandstones. Stoliczka has also recorded the occurrence of
Hippurite shells in some parts of the same province. It is probable,
therefore, that the detailed examination of the country by the Geological Survey which is at present in progress may disclose a wellformed Cretaceous series in these parts correlated to the Spiti and
Hazara Cretaceous.
Hazarai^In common with the rest of the Mesozoic systems the Cretaceous is extensively, though very thinly, developed in Hazara,
barely 120 feet in total thickness, belonging to the Gault horizon.
The Upper Trias, Jurassic and Cretaceous cover a. wide horizontal
extent of Hazara country in narrow well-defined bands, but their total
vertical extent is inconsiderable.
Middle and Upper Cretaceous sediments containing Orbitolina and
428
GEOLOGY OF INDIA
Hippurites are met with in Chitral underlying the Tertiary Reshun
conglomerate.
i
TERTIARY
Introductory--The Tertiaries of Kashmir call for no special notice
beyond the few local peculiarities which they exhibit. The Tertiary
band at Jhelum stretches eastwards through the Kashmir area, preserving all its geological characters and relations unchanged, to the
Ravi and thence to the Sutlej, where it merges into the much better
explored country of the Simla Himalayas. Structurally, however, one
feature of distinction emerges, and that is the gradual disappearance
of the Main Boundary Eault as a limit of deposition between the Murrees and successive Siwalik zones to the west of the Chenab ; the
more northerly fault-plane junctions, however, between the older Tertiaries and the still older Himalayan rocks yet preserve their boundary
nature. This tract of hilly country of low elevation, lying outside the
Pir Panjal, and bgtween the Jhelum and Ravi, is designated the
Jammu hills. The Tertiary outcrop is widest where it is crossed by
the Jhelum, but is much constricted at its eastern boundary at the
Ravi,i though the broad features of structure as well as of lithology are
readily perceived in the Dalhousie foot-hills.
The remaining account of the geology of Kashmir pertains to the
Jammu province, which is almost entirely composed of Tertiary rocks
with the exception of a small area of crystalline rocks in the Kishtwar
and of the Permo-Carboniferous (Sirban) limestone in the Riasi district. The few districts situated on the Pir Panjal belong geologically
to the Kashmir province.
Tertiaries of the Imier Himalayas—the Indus Valley Tertiaries—A •
most noteworthy event, already briefly hinted at, in the Tertiary geo- ^
logy of Kashmir, was the occupation of an area in Ladakh by the •
waters of the retreating Tethys. This sea has left a basin of Lower
Tertiary deposits, in a long, narrow tract in the Upper Indus valley
from Rupshu to Kargil and Dras. The existence of marine Tertiary
sediments to the north of the Himalayan axis must be regarded as a
very exceptional circumstance, for'except the Nummulitics of Ladakh
and Hundes and some outhers of the Eocene (Kampa) system ot
south-eastern Tibet, from Hazara t o the furthest eastern extremity ot
the Himalayas, sedimentary rocks younger in age than Cretaceous
aire not met with.
1 Rec. O.S./._vol. ix. pt. 2, 1876.
GEOLOGY OF KASHMIR
429
The Tertiaries of Ladakh rest unconformably over gneissic and
metaniorphic^rocks. The base is of coarse felspathio grits and conglomerates, followed by brown calcareous and green and purple shales.
The shales are overlain by a thick band of blue shelly limestone, containing ill-preserved Nummulites. This-nummuliferous limestone is
succeeded by a coarse limestone-conglomerate. On either extremity
of this sedimentary basin there is a large development of igneous rocks
of an acid as well as extremely basic composition. They include both
contemporaneously erupted d^rk basalts with ash and tuff-beds, as
well as dykes and sills of intrusive granite, quartz- and augiteporphyries together with peridotites and gabbros. In the northwest prolongation of the Kargil band of Eocene volcanics, in Dras,
.there is a close association of tuffs, volcanic ash-beds, lavas and augite
porphyries, with limestones containing Alveolina, Dictyocohoides,
Nummulites and gastropods.
.^ The sedimentary part of this group has preserved a few fossils, be.sides the Nummulites noticed above, but owing to the great deal of folding and fracturing which they have undergone the fossils are mostly
deformed and crushed beyond recognition. The following genera are
identified, with niore or less certainty: TJnio and Melania, in ,the
lower part (which bear witness to estuarine conditions), and Num,mulites, Hamites, Hippurites, Conus, etc., which yield very discrepant
evidence as to the age of the enclosing group, extending from the
Cretaceous to Oligocene or even later.
The Tertiaries of the Jammu hills—The systems of strata constituting the Tertiary zone of the Jammu hills are disposed in three or four
parallel belts conforming to the strike of the hills; the oldest of these
abut on the Pir Panjal, and constitute its south-west flank ridges,
while the newer ones occupy successively outer positions building the
low ranges of the Murree Siwalik foot-hills. Where the Chenab leaves
the mountains at Akhnur, there is a deep inflection of the strike of the
hill ranges ; the same feature is repeated, but on a far larger scale, at
Muzufferabad, at the emergence of the Jhelum. At this point the
strike of the^whole outer as well as inner Himalayan system undergoes a more profound bending inwards. The re-entrant bay thus produced is an acute-angled (40°) triangle with its apex thrust forward
nearly a hundred miles from the base-line. The significance of this
feature is dealt with on p. 314 where it is explained as probably due
to some crustal obstruction which has deflected the main axis of the
fold-systems and converged them in a knot (Syntaxis).
The accompanying table shows the relations of the Tertiaries of
430
GEOLOGY OF INDIA
Jammu hills to the corresponding rocks of the
parts of India :
1
Simla.
Jammu.
Upper Siwalik.
Upper Siwalik:
Boulder - Conglomerate stage.
Pinjor stage.
Siwalik . Middle Siwalik:
Middle Siwahk.
system. Dhok Pathan stage.
Lower Siwalik;
Lower Siwalik
(or Nahan). •
Chinji stage.
Kamlial stage.
Kasauli series.
Upper Murree:
Soft sandstones,
purple shales.
Lower Murree:
Dagshai series.
Hard, dark sandstones, red and purple shales.
Fatehjang beds:
Ossiferous sandstones.
^
Laki or Chharat
Subathu series.
series:
Nummulitics of Pir Shales and thin
limestones.
vPanjal, Riasi and
. Indus Tertiaries.
Coal-measures.
Pisolitic hmoLaterite (bauxite).
nite.
•
"•
Ranikot stage of Pir
Panjal.
-
Simla hills and other
Other parts.
SiwaUk of the E. Himalayas ; Irrawaddy
series: Upper
Manchar of Sind.
" Siwalik of the Potwar
plateau; Kangra,
- and the N.W. Frontier Provinces. Lr.
J Manchars of Sind.
Pegu series of Burma ;
Mekran system of
Baluchistan; Cuddalore sandstone of
the East coast.
Bugti beds ; Nari and
Gaj series of Sind.
Kirthar series of Sind,
Assam, Cutch.
Laki series of Sind,
Assam, Cutch, SaltRange.
9
Nummulitics of Gujarat.
Rock Salt and gypsum of Salt-Range.
Ranikot of Sind ; Bur^
ma, Salt-Range and
Hazara.
EOCENE
The Eocene of Kashmir exhibits a double facies—one analogous
with the Nummulitics of Hazara and N.W! Punjab and the other recalling the Subathu facies of the type area iii the Simla hills. The
former type is well developed in the south-west fiank of the Pir Panjal
wherein, along its whole length from the Jhelum to the Ravi, it constitutes a remarkably consistent and characteristic belt of altered,
obscurely nummulitic limestone of the " Hill Limestone " facies, overlain by a thick series of variegated shales with coal seams at the bas&
(Chharat Series). Its width vajies from a few yards to about i miles.
GEOLOGY OF KASHMIR
43I
Lydekker ascribed these rocks to an indefinite age between the Carboniferous and Trias, and named them " Ruling " and " SupraKuling " series; late work in the Pir Panjal range, however, has
established the Eocene age of these rocks beyond dojibt.^
The Subathu series of Jammu—The Sind facies of the Nummulitics
mixed with the Subathu type of the Eocene is met with in a number
of inliers exposed in the Murree zone lying to the south of the Pip
Panjal. The most important of these inliers occurs as a narrow rim
bordering the outcrop of an older unfossiliferous limestone, Sirban
limestone (p. 418), exposed as the core of an anticlinal near Riasi,
north of Jammu. Another is seen in Poonch exhibiting like relations.
The section given below illustrates the sequence of formations in
the Eocene :
Lower Murree
(Some thousand
feet),
Subathu
(300-600 ft.).
TPurple and grey sandstones and shales of great
-|
thickness underlain by ossiferous pseudoy
conglomerates.
,
Nummulitic limestone, thin-bedded, nodular, bituminous.
Olive shales, papery.
Nummulitic hmestone, up to 300 ft. thick.
• Grey and oUve shales.
Pjrritous shales.
Ironstone shales, carbonaceous.
Coal seams (6 in. to 10 feet) in pyritous shales.
Pisolitic bauxite and aluminous clays, 6 feet.
Dykes of ultra-basic intrusive.
Chert breccia, 6 ft. to 10 ft.
White cherty and silicified dolomitic limestone, unfossiliferous, thickness over 1000 ft., inter-
(
1,
1J
J
-ill
A
1
i-
1 i
CI
1
bedded with Agglomeratic slate, near bumlar
KotU.
These inliers are exposed as the cores of faulted anticlinals in the
Murree series, the north limb of which shows an apparently conformable passage of the Eocene into Murrees, while the south limb is
generally missing as the result of strike-faulting.
Eocene bauxite—The basal beds of the Eocene are highly interesting as containing .evidence of an extensive laterite formation, which
appears variably at different places, either as a pisolitic hmonite, as
highly aluminous clays, or as a pure bauxite. The laterite or bauxite
covers an old land surface of the pre-Tertiary limestone, and marks a
> D. N. Wadia, Mem. 0.3.1. vat. li'. pt. 2, 1928.
432
GEOLOGY OF INDIA
great erosional unconformity. In the valley of the Poonch, near
Kotli, the base of the Eocene rests, on the truncated edges of nearly
vertically inclined strata of the " Great Limestone ", but this dis^
cordant junction is not equally
apparent everywhere.
The pisolitic limonite and ironstone of Riasi and Poonch have
been largely drawn upon in the
past to support a -flourishing
industry of iron-smelting, while
the associated bauxite deposits
of these localities form large
potential reserves of a high-grade
ore of aluminium. At Riasi the
overlying coal-measures, containing seams of anthracite coal up
to 20 feet in thickness, have been
found to be workable and capable
of supporting remunerative mining, but further westward the
coal is excessively friable, and
distributed in very thin and inconstant seams which are severely
crushed and in part graphitised.
The nummiilitic limestone is
thin-bedded and .hlack-coloured;
it has a tendency to assume
greater proportion as it is traced
«/)
westward® of the Jhelum, in
which direction the constitution
of the whole series changed'
materially. The coal-seams become thinner and then disappear ; the pisolitic iron-ore and
bauxite are barely seen, while the
nummulitio limestone steadily increases in bulk, becoming a massive
monotonous formation of white or pale colour, whose aggregate thickness is over 1600 feet. The species of Nummulites so far identified in*
these rocks are : N. beaumonti, N. atacicus, Assilina granulosa.
Eocene of the Pir Panjal—The Eocene of the Pir Panjal probably belongs to a lower-horizon, thoaigh its base is not exposed anywhere.
GEOLOGY OF KASHMIR
433
The Kmestones are about 200-400 feet thick, generally thin-bedded
and lenticular, containing obscure tests oiNummulites and gastropoda ;
they show a general resemblance to the " Hill Limestone " of the P u n jab andJHazara (Ranikot age). A typical section shows :
Metamorphosed older Palaeozoic rocks, or Murree Series.
^
•
Thrust-plane.
Variegated red and green shales with quartzose sandstones,
800
Laki
Thin-bedded lenticular, black bituminous lime(Chharat). \
stones with Nufnmulites, Operculina, Assilina and Ostraea. 100
Coaly and pyritous shales with ironstone shales
and jasperitised beds,
50
rMassive, pale, grey-coloured, cherty, generally
Ranikot
|
thin-bedded limestones, with badly pre•
served Nummulites and gastropoda, - 300-400
Shale partings very ievi.
i
ft.
ft.
ft.
ft.
• Panjal Trap and Permian or Trias limestones.
I t is probable t h a t this limestone group extends in a continudus
outcrop along a general north-west direction from the northerly termination of the Panjal cliain near Uri, along the Jhelum valley to
Muzzaffarabad, and thence to Hazara, merging into the wider Eocene
zone of t h a t region.
MURREE SERIES
The Murree series is a thick pile of purple and grey, fine-grained,
indurated sandstones, very slab-like a n d compact in aspect, alternating with purple and red splintery shales and repeated bands of
concretionary clay pseudoconglomerates. This group everywhere
exhibits isoclinal t y p e of folding, and hence its true thickness is difficult to estimate, b u t it is probably not less t h a n 8000 feet. This great
thickness of often deeply ferruginous, unfossiliferous sediments points
to a lagoon mode of deposition, t o which fresh-water had no or very
rare access, and in which the concentration of the calcareous m a t t e r
in solution a t times reached the stage of precipitating beds of impure
limestone. The possibihty of a t e m p o r a r y return of clear water
marine conditions is suggested b y a series of fossiliferous bituminous
limestones and calcareous shales containing a fauna very like t h a t of
the Upper Chharat stage of Rawalpindi, which appear to be interstratified with Lower Murree beds in Poonch.
w.a.i.
2B
434
GEOLOGY OF INDIA
It appears probable that unlike the Siwaliks, which are derived
wholly from the denudation of the Himalayan granites and other
rocks, the Murrees have originated from sediments whose source was
the iron-bearing Purana formations of the Peninsular highlands to the
south.
Fatehjang zone—A few palm and dicotyledon leaf impressions and
silicified wood remains, with very rare mammalian bones, fish and
frogs, are all the fossils hitherto observed in the main body of the
group. At the base, however, some 100 feet of ossiferous sandstone
and conglomerate occur—the Fatehjang zone—containing AnthracotJierium, Teleoceras and Brachyodus, which indicate close affinities
with the Bugti beds fauna.
The Murree outcrop is over 25 miles wide where it crosses the
Jhelum, but it thins eastwards rapidly, and where it intersects the
valley of the Ravi it is only 3-4 miles across. At this point it merges
into the Dagshai series of the Simla region. On lithological grounds
the series is divisible into Lower and Upper stages of variable thickness :
Soft, brown and buff, coarse, sandy sandstones, with
inner cores of gray colour.
Eed and purple shales and nodular clays.
Numerous di- and mono-cotyledon leaf impressions.
'Indurated, deep-coloured, at times inky purple and red
sandstone, generally flaggy.
Splintery, purple shales and deep red clays, with abundLower Murree -j
ance of vein calcite.Numerous bands of pseudoconglomerates.
Unfossihferous, except at base, where a few beds are ossiferous. Derived Nummulites.
(
Structurally and in their field relations thie Upper Murrees present
aspects of Siwalik type—open, broad folds weathered into strike7
ridges and valleys with a succession of escarpments and dip-slopel',
while the Lower Murrees show a far. greater amount of compression,
fracture and dislocation, being plicated in a^series of tight isoclines and
overfolds with repeated local faulting. They weather in the fashion
of older rocks which are cleaved and jointtd, and with which the
lineation of spurs and ridges have no close relation to the prevalent
strike or " grain " of country.
The inner limit of the Murree group is as usual a great thrust-fault
where it abuts upon the older rocks of the Panjal range—a structural
feature which, as already referred to, is not repeated at its outer limit
—the junction of the Murrees with the outlying Siwalik group.
GEOLOGY OF KASHMIR
435
SIWALIK
Rocks of the Siwalik system are disposed in parallel folded zones
constituting the outermost foot-hills, which have a width of some
twenty-four miles. The Siwalik system of the Jammu hills does not
differ in any essential respect from that developed in the rest of the
Himalayas from Afghanistan to Assam. Structurally, stratigraphically, as well as palaeontologically, they exhibit similar characters,
broadly speaking, to those found in the better-surveyed areas of
Kangra to the east and Potwar to the west of the Jammu hills.
No detailed work or systematic collecting of fossils, however, has yet
been made in those hills, as has been the case with the same series of
deposits in the Siwalik hills, Kangra and Salt-Range, which have
jdelded relics of the highest value, bearing on the problem of the
phylogeny of Mammals.
°
The Siwalik group of theJ a m m u hills is classified into Lower, Middle
and Upper, but the respective limits of these divisions are not certain
owing to the meagreness of the palaeontological evidence. On the
whole, while the Upper and Middle Siwaliks of the Jammu hills show
a more or less close lithological analogy with those of the adjacent
Salt-Range and Potwar areas, the lower division exhibits marked
local variations, which relate them more nearly to the Murrees than
^0 the typical KamUal or Chinji facies. This persistence of Murree
conditions of deposition during Lower Siwalik time becomes more
marked nearer the Jhelum valley, in the Poonch area where, between
the Upper Murrees and the basal beds of the Lower Siwaliks there is
no difference whatever of rock-facies, save the local occurrences of
fragmentary bones of fresh-water reptiles and mammals in the latter
group.
Lower Siwalik—Petrdlogically the Lower Siwaliks are composed,
from the bottom upwards, of indurated brown sandstones liberally
intercalated with thick strata of red and purple semi-nodular clays
_ having a general resemblance with the Upper Murrees on the one hand
towards the west and the typical Nahans of the Simla hills towards
the east. The lower harder and more purple coloured beds, about
2000-3000 feet in thickness, possess a fauna of Kamlial age, though of
a very meagre description. The upper, scarcely less indurated, but
more shaly division, is of like vertical extent, and is characterised by a
newer fauna of Chinji type, in the few localities from which fossils have
been collected. Fossil plants and woody tissue are met with abundantly in the lower part, together with bones of a varied reptilian popu-
436
GEOLOGY OF INDIA
lation of Ghelonia, Orocodilus, GJiarialis,fishesand snakes, naixed with
gastropod shells and their opercula. The upper division has yielded
numerous Mastodon, Dinotherium, Microbunodon, Dorcatherium,
GirajfoTceryx, Aceratherium, sev6ral species of Anthropoid apes/ Antelopes, Giraffes, and several genera of the Suidae and Anihracotheridae.
Middle SiwaJik—Overlying this group there comes the Middle
Siwalik group of thick massive beds of coarse micaceous sand-rock, at
times too.incoherent to be termed sandstone. Clays and shales are
sparingly developed in these, and they have not the bright vivid
coloration of the shales of the lower division. The prevalent colour
of the sand-rock is pepper-and-salt grey. Its cementation is very unequal, much of the cement being concentrated in large, hard, fantastically shaped concretions which at times enclose fossil teeth, skulls
or bones, leaving the main part of the rock a crumbling mass of sand.
There is a well-marked Dhok Pathan stage, underlain by the Nagri
zone in the Udhampur Dun. Pebbles are found, and increase in
numbers and size, as the upper limit of the Middle Siwalik series is
reached, till they form enormous beds and lenticles of coarse bouldery
conglomerates. The Dhok Pathan stage is recognised by Hipparion,
Bramatherium, several suidae, e.g. Potamochoerus, Listriodon and
Tetraconodon; Tragocerus, Hippopotamus, Stegodon and Rhinoceras.
Upper Siwalik—The Upper Siwaliks consist lithologically either of
very coarse conglomerates, the boulder-conglomerates, or massive
beds of sand, grit and brown and'red earthy clays. The former occur
at the points of emergence of the large rivers—the Eavi, Tavi, Chenab
and Jhelum and of their principal tributaries—while the latter occupy
the intervening ground.. The clays in the upper part of the series are
indistinguishable from, the alluvial clays of the Punjab plains into
which they pass by an apparently conformable passage upwards.
Fossils are numerous in the Upper Siwahks at some localities.^This
area appears to have been a favourite haunt of a highly diversified
elephant population, as is evident from the profusion and wide distribution of their skeletal remains. Incisors of Elephas, Stegodon,
Mastodon, their molars, skull plates, mandibles, maxillae, limb-bones,
etc.,- are commonly found in the sands and conglomerates. Other
fossils are referable to Bubalus, Bos, Hippopotamus, Rhinoceros, Sus,
Equus, Germs, Apes, Gharialis and numerous Chelonian bones.
The precise boundary of the various Siwalik divisions described
above cannot be delimited in the absence of positive or sufficient fossil
1 From a, locality near Ramnagar village, 20 miles north of Jammu, species of
Sivapithecus and Dryopithecus- hSve.been found.
GEOLOGY OF KASHMIR
437
evidence, nor is more minute sub-division into stages and zones possible. The inner boundary of the Siwahks is, as stated above, a
faulted one only as far as the Chenab, beyond which, westwards, the
fault gradually diminishes and is replaced by an anticlinal flexure.
It is well-marked and typical at Udhampur, but has lost its significance at KotU, where Siwalik outliers are found inside the boundary,
in synclinal troughs of the Murrees. The parallel boundary faults
within the Siwalik zone of the eastern Himalayas (Kgs. 31 and 32),
are not observed in the foot-hills west of Udhampur ; the system of
strike-faults that is met with in this area is of the nature of ordinary
dislocations, which have no significance as limits of deposition.
Physiography of Siwalik country—The weathering of the Siwalik
rocks has been proceeding at an extraordinarily rapid rate since their
deposition, and strikingly abrupt forms of topography have been
evolved in this comparatively brief period. Gigantic escarpments and
dip-slopes, separated by broad longitudinal strike-valleys and intersected by deep nieandering ravines of the transverse streams—
surface-features which are the most common elements of Siwalik topography—give us a quantitative measure of the subaerial waste that
has taken place since the Pleistocene. The strike is remarkably constant in a N.W.-S.E. direction, with only brief local swerves, while it is
almost always in strict conformity with the axes of even the subordinate ridges and elevations. The only variations in strikedireCtiqn from this course are the ones already referred to.
Although the Siwalik strata are often highly inclined,' especially
towards their inner limits, they are never contorted or overfolded, as
is the case with the Murrees.
PLEISTOCENE AND RECENT
Pleistocene or post-Pliocene deposits of the nature of fluviatile, .
lacustrine or glacial, have spread over many parts of Kashmir and
occupy a wide superficial extent. Of these the most interesting as
well as conspicuous examples are the fresh-water (fluviatile and lacustrine) deposits, found as low fiat mounds bordering the slopes of the
mountains above the modern alluvium of the Jhelum. In these, reassorted terminal moraines of the glaciers from the higher ground have
furnished a large constituent.
Karewa series—These are known as Karewas in the Kashmiri
language. The Karewa formation occupies nearly half the area of the
valley ; it has a width of from eight to sixteen miles along its southwest side and extends for a length of some fifty miles from Shopyan
438
GEOLOGY OF INDIA
to BaramuUa. The earlier view regarded the Karewas as the stirviving remnants of deposits of a lake or series of lakes which once filled
the whole valley-basin from end ^o end. The draining of the lake or
lakes, by the opening and subsequent deepening of the outlet at
BaramuUa, has laid them bare to denudation which has dissected the
once continuous alluvium into isolated niounds or platforms. Taking
into consideration, however, the enormous thickness of the Karewa
deposits revealed on the north-east Panjal slopes, viz. 5000 feet, and
the alternating succession of coarse boulder and fine sand and clay
beds, some observers consider the lake theory of their origin untenable
except for the upper portion of these deposits, which were intermittently laid down'during warm interglacial periods of melting ice.
Middlemiss suggests that the lower part of the Karewas must have
had an origin similar to the Siwaliks and be as old as the Pliocene—
a local ty