Geology: India

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Extracted from:

THE IMPERIAL GAZETTEER OF INDIA

THE INDIAN EMPIRE

HENRY FROWDE, M.A.

PUBLISHED UNDER THE AUTHORITY OF HIS MAJESTY'S SECRETARY OF STATE FOR INDIA IN COUNCIL

OXFORD

AT THE CLARENDON PRESS

1909

PUBLISHER TO THE UNIVERSITY OF OXFORD

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Introduction

Peninsular To those who support as well as to those who deny the and extra- doctrine of the permanence of oceanic basins and continental India!" plateaux, India, the land of paradoxes, provides striking illustra- tions of these diametrically opposed opinions, a circumstance which suggests that the real truth lies somewhere between the extreme positions t#ken up by two classes of equally sincere naturalists. Those who think that the main orographical features originally developed on the solidified crust have never been seriously modified recognize in the main Pen- insula an example of solid land which has neither been folded nor disturbed since the earliest geological times. Those who hesitate to recognize any limits to the mobility of the earth's crust quote the Himalayas as an example of an area in which marine deposits containing Nummulites, and therefore no older than the London Clay, have been raised to an eleva- tion of 20,000 feet within the Tertiary period.

Within the limits of the Indian Empire we have, therefore, two utterly dissimilar areas, unlike in geological history and equally unlike in the physical features which are the direct outcome of the geological past. In the Peninsula we have one of the few masses of land which have withstood all ten- dencies to earth-folding for as long as the palaeontological record stretches back. In the Himalayan region, on the other hand, the folding of the crust has produced, during the latest geological epoch, the ^grandest of our mountain ranges.

The stable peninsula

The stable Except in marginal strips which show temporary and local Peninsula, trespasses of the sea on the coast, not a single marine fossil is found throughout the whole extent of peninsular India. The features of geographical area are the outcome of the differential erosion of an old land surface, where the shallow open valleys, with rivers near their base-level of erosion, and the gently undulating plains are due to the toning down of the rocks by long exposure to the weather.

The folded extra peninsular area

A very different state of things is disclosed in the land lying The folded to the west, north, *nd east of the great Indo-Gangetic alluvial belt : in Sind, Baluchistan, the Himalayan belt, Assam, and area. Burma we have abundant evidence of repeated immersions beneath the ocean. In this area the directions of the mountain chains are determined by comparatively young rock-folds, while the region having been but lately elevated, its rivers are swift and torrential, cutting down their beds so rapidly that the valley sides are steep, with loosened material, always ready to slide off in destructive landslips,

Correlation of Indian strata with the European scale

In attempting to express these two distinct geological stories Correlation in European terminology we find that our simplest and most easily translated characters are preserved in the marine fossili- strata with ferous strata, while it is practically impossible to correlate European directly the land and fresh-water formations which are so largely sca i e . developed on the Peninsula with their equivalent stages in the European standard scale.

Variable rate of evolution in isolated land areas

The reasons for this contrast are simple. Conditions of life Variable are much more uniform, and facilities for migration much evection more perfect, in the ocean than on land. On land areas there in isolated is a greater variety of physical features, and a greater diversity, areas, therefore, of climate and other conditions which affect the distribution of living beings. Consequently, when such areas are cut off from one another by impassable physical barriers, the intermingling of plants and animals is prevented, and evolution proceeds at independent rates in the separated areas, attaining corresponding stages at quite different times. As an example of the errors which would arise if we compared the fresh-water and land fossils of widely separate areas with one another, we have, in the existing indigenous mammalian fauna of the isolated Australian continent, a stage of evolution about equivalent to that which characterized Europe in Jurassic times. TWIs want of correspondence during the same period of living forms in widely-separated land areas is one of great importance to the Indian ^geologist, who has had the point most strikingly brought home to him in his attempt to deter- mine the age of the great coal-bearing system in India. The luxuriant growths of ferns, horsetails, cycads, and conifers which flourished in the great river-valleys of the old Gondwana continent did not make their appearance in Europe until well on in the Mesozoic era, yet, from other evidence, we know that the lowest coal measures in India were being formed during Upper Palaeozoic times.

Comparative uniformity of life in the ocean

On the other hand, among marine fossils, especially such of f ree ty migrating forms as cephalopods, we have in general life in the a tendency to wide geographical distribution with a very limited ocean. vertical range. The recognition, therefore, of the species of marine fossils in Indian formations permits a more precise correlation of Indian strata with those of Europe than is possible in the case of the freshwater strata. The marine formations enable us to fix the chief landmarks in Indian geological history, and, having established these, we can con- sider the associated fresh-water and unfossiliferous rocks. Want of Before settling down to the description of the Indian rocks, tenipora-" there }S one more stratigraphical principle of which the reader neity in should be reminded : it is necessary to explain how it is that, geological j n Qur a ^ ern pt s t o express Indian stratigraphy in European terminology, we never attain full success.

In consequence of the way in which most areas have been alternately immersed below the sea to receive deposits of sedi- ment, and raised to the denuding action of atmospheric agents, the sedimentary record in any country is marked by inter- ruptions at irregular intervals in the scale. These interruptions or * breaks ' are not on the same horizons for all parts of a large area, for one part may be below water and receiving sediment when another is exposed and being cut into by the weather. Thus the dominant breaks in the Indian stratigraphical scale can only by an infinitesimal chance be strictly contemporaneous with those in Europe. In employing such breaks in the succession to define the upper and lower limits of stratigraphi- cal units, we obtain series of strata which cannot correspond precisely to the units in the European scale ; and for these Use of series we are driven, therefore, to employ, in the first instance, localstrati- j oca j names w hich may cover parts of two or more European names. units. In Southern India, for instance, we have a series of strata answering generally to the Upper Cretaceous of Europe ; but the four natural subdivisions in India do no! correspond precisely with the European subdivisions. The lower part of the Utatiir stage of Southern*" In^ia corresponds to the cenomanian of Europe, while its uppermost beds contain a turonian fauna. The lower beds of the next succeeding stage, the Trichinopoly beds, are turonian, while its higher beds are senonian ^see Bibliography, paper No* I ! ). This circumstance,

1 Figures in parentheses and printed in antique type refer to the papers quoted in the Bibliography at the end of the chapter. which increases the difficulties of correlation, is no more than one expects from the teaching of physical geography. The changes which occur during the processes of sedimentation are local : one area is receiving the fine detritus carried out by a large river, another is covered with sand brought down by a swifter stream, while a third is being buried in foraminiferal ooze, or supports a coral reef in the deeper and clearer water of the ocean. All have their characteristic forms of life, and these differ again, in both lithology and fossil-contents, from the beds produced contemporaneously in lakes and river- valleys. The commencement and end of sediment in one area do not coincide with those in another; and, as a final difficulty in the way of precise correlation over large areas, many animals migrate from one region to another, their remains being found in one area and those of their descendants in another at a higher horizon in the stratigraphical scale. When the reader, therefore, finds the Indian geologist hesi- tating over the naming of his stratigraphical systems in India, he should remember that the hesitation is not due always to imperfect knowledge, but to consciousness of the fact that no unit in the stratigraphical formations of India corresponds exactly with the stages defined in the European scale. Never- theless, our nearest approach to precision in correlation will be among the marine formations, and these, consequently, are used as reference horizons in our attempt to express the data of Indian geological history in terms familiar to European students.

Classification of Indian strata

The datum line in stratigraphy is the base of the Cambrian Classification system, the so-called Olenelhts zone, characterized in various n parts of the world by remains of this genus, or its near relations, strata, belonging to the extinct order of Crustacea known as trilobites. The datum Below this line there are many thousand feet of strata without tigraphy. determinate fossil remains, and generally quite unfossiliferous ; above it are piled the great fossil-bearing systems preserving the record* of evolution among animals and plants through the Palaeozoic, Mesozoic, and Cainozoic eras to the present day.

The olenellus zone

Fortunately in India W have a trace of this datum line The Olenellus preserved in the Salt*Range of the Punjab, where, although ellus zone% the Trilobites preserved are not exactly like the well-known OlenelluS) there are forms which must have been close relations of it, and we can safely t assume that these beds, referred to in more detail below as the Neobolus beds, are equivalent to the Lower Cambrian of the European scale.

Pre-Cam-brian unfossiliferous rocks

Fossiliferous deposits

Four resultant main groups

Archaean group

Purana group

To the ages preceding the date at which the Ntobohis beds were formed we refer : (a) The great mass of crystalline schists which are exposed over half the Peninsula, forming the old floor on which the unaltered sediments were laid down ;

The great thicknesses of unfossiliferous strata known by such local names as Gwaliors, Cuddapahs, and Vindhyans.

The ages following the Lower Cambrian period have left their records in India in two groups :

(c) During the Palaeozoic era deposits were formed in the extra-peninsular area with fossil remains referable to one or other of the well-known systems of Europe from the Cambrian to the Carboniferous. No records of this era have been pre- served on the Peninsula.

(d) From Permo-Carboniferous times to the present day we have a double history : a record of life and events on the stable Peninsula, and a series of deposits formed in the adjoin- ing ocean whose bed was afterwards upheaved to constitute the extra-peninsular parts of India.

Indian rocks thus fall naturally into four great groups : two below the Olenellus datum line without fossils, and two above the horizon at which the oldest recognizable fossils occur. The arrangement and chief divisions of these four groups are shown in the accompanying table (p. 55).

The oldest is a group of highly folded and foliated, im- measurably old, crystalline schists, gneisses, and plutonic rocks having the typical characters of the Archaean group of Europe and America, with which they can be correlated with sufficient safety to warrant the employment of the same group name.

The next is a great group of unfossiliferous strata lying with marked unconformity on the Achaean gneisses and schist, separated from the latter by a great physical ' break/ which is un- mistakable throughout the Peninsula. This group is here distinguished as the Purana (o\d)jSind it includes such isolated systems as the Cuddapahs, the Gwaliors, and the Vindhyuns in the Peninsula rocks which are sometimes locally folded, but never foliated, and often practically undistvrbed. To what extent the Purana group is represented in the unfossiliferous systems of the outer Himalayas it is impossible to say ; for the only correla- tion data being lithological, the records have been mutilated by the folding of the Himalayan range, fhis group corresponds to much of what in America has been known as the Algonkian rocks which lie between the base of the fossiliferous Cambrian

ALGON- KIANARCHAFAN.

Approximatc age in European and American equivalents.

Keweenawan Animikie

HuronianLaurenti an Keewatin Coutchiching

Fresh-water formations. Vindhyans, Kurnools, Upper Cuddapahs, Kaladgis, Pakhnls, BhTmas Lower Cuddapahs, Gwaliors, Bijawars, and Penganga series ........

Great Eparchaean interval.

Eruptive gneisses and granites: charnockites and norites of Southern India; anorthosites of Bengal. Schistose gneisses, often with intruded pegmatites like those of the mica-mining areas Oldest gneisses Recent alluvium Older alluvium Upper Siwaliks, Lower Manchha Kasauli

Marine formations.

Trichinopoly, and Baluchistan Cutch ; Hsipaw f Lite formations of Productus shales and limestones, Central Himalayas and Salt Range.

Upper Palaeozoic unconformity. Fenestella shales of Central Himalayas; Zewan beds of Kashmir ; Limestones t &c., in Burma Chitral limestones, Maymyo limestones Silurian of Central Himalayas and Upper Burma Haimantas in part of Central Himalayas .

Neobolus bed and associated Cambrian in the Salt Range. Olenellus zone or base of the Cambrian system .

Raised beaches ; coral banks Cnddalore sandstones * Makran series .... Gaj, Yenangyaung, and Prome series Nari Kirthar, RanHtot, Sabathu .

Cardita beaumonti beds Chikkim series ; Bagh beds ; Ariyalur Utatur beds. Spiti shales; massive limestone c Uftia. Katrol, Chan, and Patcham series of serUe. Trias of Central Himalayas ; Cera Salt Ranee.

and the eroded edges of the Archaean schists. Whether the younger stages of the Puruna group were formed before Cam- brian times is not known ; for on the Peninsula, where the Upper Vindhyans are the youngest strata in the Punina group, they come into relation with no fossiliferovs rocks older than the Permo-Carboniferous of Europe.

Grouping of the fossiliferous strata

Grouping The nomenclature and grouping of the fossiliferous strata f lifer- re( l u ^ re explanation. In Europe the corresponding fossiliferous ous strata, scale is divided very unequally into the Palaeozoic, Mesozoic, and Cainozoic groups, the inferior and superior limits being fixed at positions showing pronounced physical and palaeonto- logical ' breaks.' As the evolution of animals and plants has been continuous since life first appeared on the earth, palaeon- tological breaks have obviously only a local significance, and the chief gaps in the European scale do not correspond to those which are noticeable in Indian strata. If the scale had been divided into groups according to Indian data, the lowest group would have its superior limit at an horizon corresponding ap- proximately to the Permo-Carboniferous of Europe, for at about this stage there was a pronounced revolution in the physical The features of the Indian area. The second stage would com-

The upper Palaeozoic break

Palaeozoic nuance the conglomerate which was formed in a period of break. great cold, giving rise to ice-sheets which have left their marks in a boulder-bed below the Productus limestone formation of the Punjab Salt Range, and in the Talcher series which forms the lowest stage of the great coal-bearing GondwSna system. There is no break at a higher stage so pronounced and wide- spread as this Upper Palaeozoic gap. Local changes in the physical geography of the extra-peninsular area are recorded in many localities, but there is a fairly continuous history of evolu- tion from the time when the remarkable brachiopod Productus invaded the Indian seas to the coral banks and oyster beds of Pravidian modern times. The Indian fossiliferous strata thus fall naturally and Aryan j nto two g reat g rou p s w hich are approximately equal in value. The lower and older group, which may be conveniently distin- guished as the Dravidian, is about equivalent to tkat portion of the European Palaeozoic which includes the Cambrian, Ordovician, Silurian, Devonian, and Carboniferous systems; while the upper and younger, distinguished as the Aryan group, includes all strata from the Permo-Carboniferous system to the present day.

The Dravidian group in extra peninsular india

There is no trace of any fossil iferous f strata on the Peninsula of India which can be referred to the Dravidian group; and such unfossiliferous strata as the Cuddapah and Vindhyan systems are, in the absence of fossil evidence, grouped with the Purana strata, and regarded as more ancient than the Cambrian. In theTheDravi*. extra-peninsular area we have members of the Dravidian group ? and soil in extra- peninsula the Salt Range, where there are strata of about the same age peninsular as the Cambrian o Europe ; in the Central Himalayas, where lndia * Cambrian, Silurian, Devonian, and Carboniferous rocks are preserved ; and in Burma, where representatives of the Silurian and Devonian have been definitely recognized by characteristic fossils.

Fresh water deposits in the Aryan group

The younger or Aryan group is represented on the Peninsula Fresh-water by the great fresh-water Gondwana system, which was followed c ! p ? lts m by marginal encroachments of the sea in Upper Jurassic and Lower Cretaceous times ; and by the deposition of subaerial and lacustrine formations in the Upper Cretaceous, with the great outflow of basic lava, covering the Deccan by volcanic eruptions, which continued until the commencement of the Tertiary period.

Marine deposits in the Aryan group

In the extra-peninsular area there is a great development of Marine de- fossili/erous rocks, ranging through Permian, Mesozoic, and Positsin Tertiary times. Most of these are of marine origin, for the great central sea, Tethys, extended from Europe over most of this area throughout the Mesozoic era. It was only in the Tertiary period that the Himalayan region emerged and gradually drove back the ocean, until, in miocene times, it was restricted to Baluchistan on one side and Burma on the other. It was driven back still farther in pliocene times, when the mastodon and other mammals now extinct roamed through the jungles of Burma and the Himalayan foothills, leaving their bones to be buried in the rapidly accumulating river sands.

Pre-Cambrian History of India

In dealing with the unfossiliferous rocks formed in pre-Cam- brian times, the geologist is in a predicament similar to that in which the historian finds himself when dealing with legendary periods for which no written records exist. The subject de- mands cither a full description of the numerous difficulties which arise from want of yrecise data, or the briefest of state- ments consistent witfl the paucity of definite conclusions to which type the geologist is able to point.

The archaean and purana eras in the Cambrian history of India

In the pre-Cambrian history of India there are two great and The Ar- well-marked divisions, jthe records of the Archaean being im- cj^ean and measurably older than those of the Purana era. Among the Tra?^ the Archaean group are rocks which were presumably formed by

The great Eparchaean break

Archaean era.

Area of the

Archaean rocks.

Origin andnature of the funda- mental complex.

the ordinary processes of mechanical sedimentation, yet after their formation there was time enough for them to be folded into great mountain ranges, and then cut down to a base-level of erosion, before the Purana sediments were laid down on their upturned and denuded edges. f

What this * break ' represents in the geological time-scale we have not the slightest idea ; but it is probably no exaggeration to say that the lapse of time since Olentllus flourished in the Cambrian seas is small compared with that between the forma- tion of the lava-flows which are now folded up in the Kolrlr gold- field, and the deposition of the basement sediments of the Cud- dapah area. In gauging geological time the intervals of no record are as important as those of continuous sedimentation ; and if there is one break in strat (graphical history that is uni- versal, it is this which cuts off the Archaean crystalline schists from all subsequent rock groups. This Eparchaean interval in peninsular India is as well marked as it is in the Great Lakes region of North America, both areas having escaped folding movements since the deposition of the old unfossiliferous rocks. In these two areas, therefore, the circumstance of folia- tion alone is sufficient to mark off the Archaean from the Purana group. But in areas which have been highly disturbed since Purana times the old and the very old rocks have all been foliated, and it is now impossible to distinguish one from another. This summary permits only of brief reference to the chief characters of the two great groups, which are here taken in order of age.

More than half the area of the Peninsula is occupied by ex- posures of the old crystalline rocks, which must have obtained their present characters at great depths, being afterwards ex- posed to the surface by denudation of the superficial rocks. The crystalline rocks now exposed at the surface form only a fraction of the whole, for large areas are covered by the mantle of younger sediments and lava-flows ; and it is in conse- quence of its position with regard to the ordinary sedimentary rocks that the old crystalline group is sometimes spoken of as the 'fundamental complex.'

The fundamental complex in Injjia agrees in essential re- spects with that of other countries, for instance America, where this group, on account of its great age greater than that of any known fossiliferous rocks was first named Archaean. Some of the rocks forming this complex are masses of deep-seated igneous origin; others presumably originated as sandstones, shales, limestones, lava-flows, and other forms of superficial

deposits, which became metamorphosed by close-folding, by depression to great depths in the crust, and by further injection of igneous material.

Orthogneisses and paragneisses

In some cases the gneisses and schists present so markedly the chemical anc^ mineralogical characters of igneous rocks that one does not hesitate to regard them as merely plulonic gneisses. masses deformed by pressure and movement. These are often spoken of as ' orthogneisses ' and ' orthoschists/ Others retain the essential chemical characters of well-known sediments, and differ from them merely in mineral character and texture due to metamorphism. These are known as ' paragneisses ' and 1 paraschists.' But there is a considerable fraction of the Mixed Archaean group in India, as elsewhere, whose precise origin K nelsses - is doubtful : some of these indeed appear to be the result of the intimate mingling of igneous injections and pre-existing rocks.

The Archaean group in India may thus be divided conve- Chief divi- niently as follows:-

4. Dharwarian. group.

Eruptive Unconformity.

3. Granites of Bihar (' dome-gnerss '), granites of North Arcot in Southern India, anorthosites of Bengal, char- nockite series of the Madras Presidency, norites of Coorg, pegmatites, c.

2. Schistose and

i. Gneissose rocks.

Among the gneisses and schists it is practically impossible to distinguish a succession in time, even locally ; and we are reduced to a system of classification which separates the dis- tinctly eruptive types from those of doubtful origin, and from the masses in which there are signs of the commingling of eruptive and probably sedimentary material in a way far too intimate for differentiation. The following main divisions represent the chief types noticeable in the field :

(i) Wejl-banded gneisses and schists, among which are alternations of bands of dissimilar lithological types, presenting the characters which one lyould expect from the metamorphism of a formation consisting of shales, sandstones, limestones, and lava-flows. The areas in which the mica-bearing pegmatites of Nellore and .Hazaribagh occur form good illustrations of this division of the Archaean group (2).

(?) More massive gneisses, *such as might result from the more complete metamorphism of gioup (i), and the inclusion

of more eruptive material which has absorbed and become intimately mixed with the pre-existing rocks.

(3) Definite eruptive types, deformed by earth pressures, with a foliation structure often in conformity with the associated gneisses and schists of groups (i) and (2). f The rocks of this group generally show a family character over considerable areas. As examples we have the elaeolite-syenites and associated rocks of Coimbatore (3), the great granite masses of North Arcot and Salem, the norites of Coorg, the anorthosites of Bengal, the charnockite series which forms the larger hill masses in Southern India (4), and the so-called 'dome-gneiss 1 which rises as bosses in the midst of group (i) in the mica-belt of Bihar (2).

The rocks of group (3) are in general younger than those of the two preceding groups of crystalline rock, having attained their present position by eruptive transgression. As to groups (i) and (2), not only are we unable to determine their relative ages, but we are by no means certain that they are older than the Dharwars.

The dharwarian system

The rocks of the Dharwar system are generally quartzites System ( j f iss ji e schists, chloritic, talcose, micaceous, and hornblendic. The quartzites often include much iron ore, and all grades are found between a quartzite with a few crystals of magnetite or hematite, and beds of almost pure micaceous iron-ore. Among the chloritic and talcose schists there are at times beds of pot- stone, and even the finer grades of steatite, indicating, probably, the derivation of some of the material from the alteration of the ferromagnesian,peridotic rocks of igneous origin. Similarly, too, among the hornblendic schists relics of true diabasic structures are often preserved, and many of the beds are doubtless the result of the alteration of basic lava-flows, while others suggest ash- beds. In fact, all through these beds there is abundant evidence of igneous action, which is no more than one would expect to have been the case in the earlier days of the earth's history. Limestones are comparatively rare in the Dharwar system, but they occur occasionally, and so, too, do true conglomerates which, notwithstanding the difficulty with which they are distinguished from autoclastic or crush conglomertes, may be taken as evi- dence of real water action in Dharwar titftes (6).

The Dharwars have attracted a special interest on account of the valuable minerals they include : iron ores in great rich- ness and purity in the Central Provinces and Bellary, copper ores disseminated at a particular horizon in Singbhum, and gold in the quartz reefs of Kolar are examples well-known.

The purana era

Upon the weathered surfaces of the highly folded Dharwars and the associated gneisses and schists of the Archaean group, Ehuibu- enormous thicknesses of sediments were deposited in peninsular tion of the India. These rocks being devoid of fossils, isolated occurrences Purana cannot with certainty be correlated, and consequently local names have been freely used to distinguish them. In Southern India we have the Cuddapah system, amounting to 20,000 feet in thickness with several unconformities, covered, also uncon- formably, by a thin series of strata distinguished as the Kur-^ nools. Other examples of rocks of this class occur near Kaladgi in the Southern Maratha country in the valley of the Bhima, near Pakhal in the Godavari valley, in the valley of the Penganga, in parts of the Mahanadi valley, and in Chota Nagpur. Farther west, in Central India, are series of old rocks distinguished as the Gwalior and Bijawar series, and finally there is the great Vindhyan system, ail being unfos- siliferous.

Lower aifcl upper divisions of the purana group

A general survey of these old rocks reveals a lithological Lower and contrast between the lower beds, in which ferruginous jaspers

and porcellanites are common, and the higher beds in which Purana the rocks are shales, limestones, and sandstones, more nearly g rou P- resembling materials formed by later common processes of sedimentation. The lower beds are also remarkable for the inclusion of basic lava-flows, which are conspicuous in the Gwalior series and in the Chey t ar division of the Cuddapahs. The older division is thus represented by the typical Bijawars, the Gwaliors, and the lower half of the Cuddapahs ; while the younger division includes the original Vindhyans, the Bhima series, the upper part of the Cuddapahs, and the Kurnools. Local difficulties must naturally occur in drawing a line between the older and the younger systems, and in the precise classifi- cation of isolated exposures of rocks belonging to the Purana group; but such difficulties are the natural result of the conditions of sedimentation generally, deposition in one area, with a continuous record of beds, being contemporaneous with erosion and consequent unconformity in an adjoining district.

The cuddapah and Kurnool system

In Southern India a groat development of the Purana strata The Cud- has been preserved in the Cuddapah and Kurnool Districts, a P ah an(1

Kurnool forming a basin of sedimentary rocks that cover some 14,000 systems. square miles. The strata within this basin have been divided into two very unequal groups, on account of a marked unconformity between the lower 20,000 feet, distinguished as the Cuddapahs, and the upper 1,200 feet, known as the Kurnool series. The

Cuddapahs are divided into four series, separated from one another by unconformities ; and it is highly probable that the lowest series in the Cuddapahs, in which we find the peculiar ferruginous jaspers and porcellanous beds, are the equivalents of the so-called Bijawars and Gwaliors in Central India, while the upper series of the Cuddapahs and the associated Kurnools, in which normal sedimentary rocks occur, correspond generally with the Vindhyans.

The vindhyan system

The The Vindhyan system is conspicuously displayed along the g rea j. escarpment of the Vindhyan range from which the rock system derives its name, stretching from Ganurgarh hill in Bhopal territory east-north-eastwards to the ancient fort of Rohtasgarh (24 37' N. ; 83 55' E.). The rocks of this system are prominently sandstones, with subordinate bands of shale and limestone. Three of the massive sandstones, known as the Upper Bandair, Upper Rewah, and Upper Kaimur respec- tively, stand out conspicuously and determine the leading features of the main Vindhyan area. The system has been divided very unequally into a lower and an upper division ; and the lower division includes large quantities of material that appears to have been ejected from volcanoes, producing beds of siliceous materials which, when very fine-grained, have a characteristically porcellanous aspect, and when in coarser fragments resemble some of the old European greywackes. The Vindhyan system, notwithstanding the apparent suitability of some of the shales and limestones for the preservation of fossil remains, has so far yielded no recognizable structures of organic origin, and its subdivisions are based on purely lithologicai characters (6). The system is remarkable for including rocks in which diamonds are found. These have been obtained in a band at the base of the Rewah stage in the State of Panna, the horizon being apparently about the same as the Banganapalle beds in the Kurnool series of Southern India. The most important product of the system is, however, its resources in lime and building stone, which are referred to in the chapter on Mines and Minerals*(Vol. Ill, chap. iii).

The Unfossiliferous sedimentary rock* occur in Upper Burma Purina below the Lower Silurian of the Northern Shan States. Their a ^ e * s un ^ nown '> but they had been folded and greatly denuded before the Lower Silurian beds were deposited on their up- turned edges, and their general strike o folding coincides with the schists which underlie them in the Ruby Mines District. The schists in their turn pass into gneisses with which are

found various forn\s of granulites and crystalline limestones ; and this apparently gradual succession is similar to the order so frequently seen in the Himalayas, an association of beds among which it is almost impossible to make out a time-scale to distinguish upper from lower, or older from younger.

The unfossiliferous rocks which occur so prominently in the Possible outer hills south of the crystalline, snow-covered peaks of the existence Himalayas, illustrate the difficulty of distinguishing between p ur ana upper and lower in a group of highly folded, often inverted, group in _ unfossiliferous rocks, and the impossibility of correlating one j a y as ima " area with another, which combine to throw doubt on any systematic grouping of these strata.

Attempts have been made to distribute the various occur- rences of these rocks over the recognized stratigraphical scale. Slates and quartzites in the Dhaola Dhar region have been referred to as Silurian, while associated volcanic rocks have been classed as Carboniferous, Permian, and Triassic. The well-known Blaini boulder-bed of the Simla area has been regarded as the equivalent of the Talcher and Salt Range boulder-beds of Permian age, while the strata apparently above and apparently below have been relegated to higher horizons on the one hand and to the Carboniferous and lower on the other. The weak points in the arguments for and against these correlations are freely admitted by their authors, and they must be regarded, consequently, as mere attempts to draw the simplest natural inference from a few significant features in lithology and succession. There is one important feature, however, which has not received its full share of recognition : the fact that only unfossiliferous rocks occur south of the snowy range and crystalline axis, while fossiliferous beds varying from Cambrian to Tertiary extend along the whole length of the range on the Tibetan side, suggests an original difference between the two areas. Those on the south have a significant proximity to the peninsular unfossiliferous Purana group, whc^se age is regarded as pre-Cambrian, mostly or wholly. That such old rocks extended far beyond their present peninsular limits is highly probable, and they may be represented in the enormous thicknesses of pre-Cambrian Vaikritas of the Central Himalayan and Tibetan zone of the range. Had the unfossiliferous rocks of the outer Himalayas been formed during Palaeozoic and Mesozoic times, it is hardly likely that they would have uniformly escaped the inclusion of fossils which are so abundant in the rocks of

corresponding age in the Salt Range, on the north-western frontier, in the Central Himalayas, and in Burma. It seems far more natural to suppose that a northern extension of the Purana group has become involved in the Himalayan folding, while the beds of the Peninsula have regained undisturbed : the relations of the younger Gondwanas of the Darjeeling area to those of the Peninsula are precisely parallel to this. The suggestion is thus offered that the great masses of unfossiliferous rocks, well-known in hill stations like Simla and Nairn Tal, the Attock slates farther west and the Buxa series farther east, should be referred to the Purana group instead of being correlated with Palaeozoic systems.

Cambrian and Post- Cambrian History of India A. THE DRAVIDIAN ERA The The oldest fossiliferous strata we know in India are found

o^thc'salt in the Salt Ran 8 e of the pun J al) > where beds are exposed Range. with fossils whose nearest relatives occur in the lower division of the Cambrian, the oldest fossiliferous system of Europe.

The undoubtedly Cambrian beds are found lying on a for- mation of peculiar marl with beds of rock-salt and gypsum, possibly of Tertiary age, similar to the salt deposits of the Kohat area which will be referred to in describing the Tertiary system of India. The occurrence of such old beds, lying over masses of much younger material, is due possibly to the former having been thrust bodily over the salt-marl formation during the process of earth-folding.

The Cambrian strata of the Salt Range may be conveniently divided into the following series, which overlie one another in conformable sequence :

4. Bhaganwalla, or Salt-pscudomorph scries. 3. Jutana, or MagneMan sandstone scries, a. Khussak, or Neobolus beds, j, Khewra, or Purple sandstone series,

Turple The purple sandstones are quite devoid of recognizable

sa " d ?J one fossils, but they frequently reveal the ripple-marks originally

bolus beds, produced on the sandy shore on which they were formed.

They graduate into the overlying dark-coloured shales and

cream-coloured dolomitic rocks of th$ Neobolus series, which,

by the fossils they contain, indicate the prevalence of a deep

sea. The Neobolus series nowhere exceeds 150 feet in thick- ness, but where best developed it is capable of subdivision into five zones, in the uppermost of which the principal fossils have been found. Besides the brachiopod genus Neobolus, which has given its name to the series, the most interesting form is a new genus of the peculiar Palaeozoic crustacean sub-class of trilobites recently distinguished by the name Redlichia. This form was until lately mistaken for the well-known Olemllus, a trilobite characteristic of the lowermost Cambrian (georgian) strata of Europe and America. The nearest relatives of Redlichia, as well as of the associated animal remains, occur, however, in the Lower Cambrian elsewhere, and the Neobolus beds may consequently be regarded as the homotaxial equiva- lents of these old rocks (7).

The next series above is a sandy dolomite with intercalated Magnesian argillaceous layers, and among the few and imperfect fossils san . clston ^ they contain is one resembling the peculiar mollusc Slcnotheca, salt Salter, found in the Lower Cambrian rocks of America. These pseudo- beds gradually pass into the next higher, and uppermost, of zon r e . the Cambrian strata preserved in the Salt Range, which are remarkable for the preservation of sandy models of v cubic crystals, evidently pseudomorphs of salt crystals left by the evaporation of salt water before -the deposition of succeeding layers of sediment. Here closes the first chapter in the geological history of the Salt Range ; and between these rocks of Cambrian age and the next higher, which are not older than Upper Carboniferous, we have no record of sedi- mentation in this area, though the interval was wide enough for the deposition of three great systems of strata elsewhere, and for the evolution of several new classes of plants and animals.

For an imperfect record of Indian geological history during Palaeozoic the great interval between the Cambrian and the Permo-Car- of the boniferous rocks of the Salt Range we must turn to other areas, \\\^, the best known being a zone of folded strata in the Central la\as. Himalayas, near the frontier of Tibet in the border tracts of Spiti and I^umaun.

The earlier records in this zone have been obliterated by The Vai-

metamorphism : but the great thicknesses of metamorohosed kritas and ,,...., . %. .. . , * Haimantas

rock distinguished as fhe Vaikrita system pass gradually up (Upper

into less altered strata, in the higher levels of which imperfect Cambrian), fossil remains have escaped destruction. These less-altered old strata are, on account of the snow-clad mountains which they form, named the Haimanta (snowy) system. The base of this system is fixed at an horizon of conglomerates which is exposed only in the Kutnaun end of the zone. The conglo- merate series is overlaid by greenish phyllites, slates, quartzites, and grits with obscure fossils. In places these are altered by granitic intrusions. The uppermost division of the Haimantas consists of alternating beds of quartzite and shale, with narrow bands of dolomitic limestone, which become more important at the summit. The shaly beds include several trilobites of the family Olenidae^ indicating an Upper Cambrian (Pots- damian) age. The dolomitic limestones are covered by red slates and reddish-brown dolomites, over which a conglomerate marks the unconformity separating the Cambrian from the succeeding Ordovician strata.

Gothlandian(Silurian)

The Ordovician is represented in the Kumaun area by landian a cora i limestone, while in Spiti this stage is probably not preserved, the lowest of the Silurian beds being red grits and quartzites, with overlying shales and limestones, which contain fossils, like the coral Halysites catenularia, Lmck., indicating an Upper Silurian (Gothlandian) age. The Gothlandian beds are overlaid by a grey limestone, which becomes reddish-brown on weathering, but has not yielded fossils sufficiently well- preserved to determine its exact age, though from its posi- tion it is probably Devonian. Then follows in conformable succession a formation which first develops into a red and then shades off into a white quartzite, named the Muth quartzite.

Conform- Over the Muth quartzite, where the complete sequence is able sue- displayed, as in the Lipak valley of Eastern Spiti, we find, in ession to the Car- order, grey limestones with numerous brachiopods of Upper boniferous Carboniferous age ; alternating beds of limestone, shale, and quartzite, with a thin band of conglomerate; and a thick covering mass of limestone with flaggy sandstones and shales, containing brachiopods and fragments of a trilobite belonging to the genus Phillipsia, Portl. ; finally, shales distinguished as the Fencstclla shales, with numerous specimens of this and other Bryozoa resembling some from the Zewan beds of Kashmir, and thus probably of uppermost Carboniferous or Permo-Carboniferous age (8).

With these beds we approach^ the close of the second chapter in the geological history of iVorthern India; for at about this horizon, corresponding to the Upper Carboniferous of England, there is an important break in the deposition, and new conditions are introduced by a widespread conglomerate which forms the base of the division of marine sediments distinguished as the Aryan group.

The only other areas within British India where fossiliferous Devonian rocks of older Palaeozoic age have been found are in Chitral of Chltral - to the west and in Burma far away to the east. In Chitral Devonian fossils have been found in a limestone exposed on the right bank oft the Chitral river, immediately opposite Reshun, where it seems to overlie a red sandstone and a still lower conglomerate. The best preserved of these fossils include corals and brachiopods, of which the corals show affinities with forms found in the Upper Silurian of England, while the brachiopods include forms like Orthis striatula, Schloth., Spirifer extensus. Sow., S. disjunctus, Sow., Athyris concentrica, v. Buch., and Atrypa aspcra, Schloth., which have Devonian affinities, some of them resembling Devonian brachiopods found in Southern China (0).

A similar series of rocks, amounting to more than 2,000 feet Infra-Trias in thickness in Hazara, has, on account of its relations to the of Hazara ' Triassic rocks in that area, been generally referred to as the infra-Trias. These beds are, however, almost certainly identi- cal with the rocks just described in Chitral : the succession in both areas consists of a coarse conglomerate at the base, resting unconformably on a great slate series and overlaid by red or purple sandstones and shales, with limestone above as the principal member of the series. Fossils have not, however, been found in the Hazara rocks.

Rock formations of Lower Palaeozoic age cover considerable Older areas in the Shan States and in Karenni. They are, however, P so thoroughly covered with a coat of decomposition products, Burma/ and often so concealed by the thick undergrowth of jungle, that precise information as to their structures and palaeonto- logy is not easily acquired. But some calcareous shales and limestones have yielded Echinosphaerites, Wahl., one of the peculiar stalked cystoids so characteristic of the Ordovician system in Europe and America. In higher beds Ortfwceras^ trilobites, and graptolites have been found, and, with the last- named, a form of Ttntaculites closely resembling the Ordo- vician form* 7! elegans, Barr.

Devonian beds have also been recognized containing, with other fossils, the unmisyikable and characteristic coral, Cakeola sandalina, Ulm. The predominating rock in this system is a limestone, distinguished as the Maymyo limestone, which extends, almost without interruption, from the neigh- bourhood of Maymyo to the Salween river in the Northern Shan States.

THE ARYAN ERA

the Cen- The changes in physical geography which occurred towards ie Carboniferous period are marked by a wide- cession, spread conglomerate in Spiti and the Bhot Mahals of Kumaun. This conglomerate forms the basement bed of a great series of strata which were laid down successively, without a sign of interruption or break, throughout a period corresponding to the whole of the Permian period and the succeeding Mesozoic era of Europe. The beds thus formed have been preserved in a zone lying to the north of the crystalline snowy peaks of the Central Himalayas near the boundary between Tibet and North-western India. Recent observations in Tibetan territory to the north of Sikkim show the eastward continuation of the younger fossiliferous strata of this series, which rest abruptly on the northern flanks of the crystalline axis, and probably cover the older beds which happen to be exposed in Spiti and Kumaun.

Trespass of The form of physical revolution which gave rise to this great central^ ser * es f strata appears to have been an eastern trespass of the ocean. Eurasian ocean, whose southern shore apparently coincided with the present line of snowy peaks, while an arm stretched into the Punjab as far as the Salt Range. Thus commenced what may conveniently be distinguished as the Aryan era in Indian geological history. The great central ocean above referred to, known to geologists as Tethys^ flowed over a belt stretching across Central Asia, leaving deposits in which the fossil contents of places so widely separated as Burma, China, the Central Himalayas, Siberia, and Europe show the marked affinities due to free migration in the ocean.

The very complete scale of conformable strata preserved in the Central Himalayas attains a thickness of some 7,000 feet from the basement conglomerate below the Permian calcareous sandstone to the top of the Chikkim shales of Cretaceous age. The Permian 'Productus shales 'pass up gradually into beds which introduce Triassic conditions through successive sones characterized by the genera of ammonites, Otoceras, Ophiceras, and Meekoceras. These are followed by beds with fossils so unmistakably characteristic of the Trias that the different stages recognized in Europe can be approximately defined and divided into zones. The Triassic rocks are followed by about 2,800 feet of Jurassic strata, among which occur the well-known Spiti shales, now known as far west as Hazara and as far east as Sikkim. The Spiti shales are covered by the Giumal sandstone and the unfossiliferous Chikkim series, which resembles the flysch deposits so frequently found in Cretaceous and Lower Tertiary formations (9).

One of the most interesting features in connexion with the Exotic geology of the Central Himalayas is the occurrence in the Blocks in Kumaun section of numerous blocks of older rocks, mainly tra i limestones, lying on the Spiti shales and the Giumal series layas. without apparently any regularity of distribution. They are weathered into picturesque crags, rising in abrupt pinnacles with precipitous walls, and on account of their composition (often brightly-coloured, semi-crystalline limestones) they stand in striking contrast to the more sombre shales and sandstones forming the undulating country around. At first sight they recall the Klippcn and lambeaux de rccouvremcnt, or blocs xotiqucS) of the Alpine regions in Europe whose origin has been the subject of much controversy. In Europe these exotic blocks have been supposed to obtain their abnormal positions by being shorn off from highly crushed anticlinal folds, or by the removal of all but these fragments of enormous recumbent folds, or by faulting (10). Whether any or all of the theories employed to account for the Alpine exotic blocks are satis- factory appears to be far from settled; but the Himalayan examples seem to admit of a very simple explanation. They are always associated with igneous rocks, which are often amygdaloidal and otherwise generally agree in character with igneous rocks of surface (volcanic) origin. In these lava-flows the exotic blocks are buried by the hundred and are of various sizes. They are not only older than the Jurassic and Cre- taceous strata they rest on, but belong to a facies either palaeon- tologically or lithologically foreign to the rocks of the same age in the Central Himalayas. They have thus come from a distance ; and there being no signs of volcanic necks in the neighbourhood, the basic lava-Hows in which they are em- bedded must have come from afar, like the flows characteristic of the so-called fissure eruptions, carrying with them their load of stratifiec^ rocks torn off from various horizons of the forma- tions occurring in the area of eruption. It is assumed, for several reasons which need not be discussed here, that these exotic blocks belong tft formations occurring farther north in Tibet, but political reasons have hitherto prevented the explora- tion of that country, and as a consequence this theory of the origin of the exotic blocks must remain for a time unverified : to establish it firmly it would be necessary to trace the blocks to their source, and to show that the fragments of basic lava in Carboniferous of the Pun- jab, the North- West Frontier Province, and Burma The Salt Range. Permian boulder-bed. which they are embedded are outliers of lava-flows farther north. As a first simple inference, however, from the facts so far available, the explanation just offered is, among the theories which have been considered, the one that offers least difficulty. . f

the central Himalayan succession

The Central Himalayan area is exceptional in possessing such a complete and unbroken succession of strata. As a general rule we find the Permian and Triassic rocks linked together, as in the Salt Range, on the North-western frontier, and in Kashmir, while in other areas the Upper Jurassic and Cretaceous rocks are associated with one another. It will therefore be convenient to notice the other occurrences in approximately natural sub-groups, beginning with the Permo- Trias of the Salt Range, where we have the nearest approach to the remarkably complete succession of the Central Himalayas.

The salt range

The first chapter in the geological history of the Salt Range closed, as already explained, in the Cambrian period, between which and the uppermost Carboniferous no traces of sedimen- tation have been preserved in that area (11). The second chapter opens with the remarkable boulder-bed which rests unconformably on the Cambrian strata. In its essential characters, as well as in its stratigraphical position, this boulder-bed corresponds to, and is probably contemporaneous with, the Talcher boulder-bed at the base of the Gondwana system in the Peninsula. On it, therefore, we have two great systems of strata developed : that in the Peninsula was formed in the river-valleys of the old GondwSna continent, while the beds in the Salt Range, now to be described, represent the deposits which were laid down at about the same time in the adjoining ocean.

The boulder-bed of the Salt Range, like that of the Talcher series, has the peculiarity of being composed of a fine-grained silty matrix with included boulders of varying size up to several cubic feet. Many of these are faceted and striated in a manner which agrees with the general characters of the formation in pointing to a glacial origin ; and several of them prove to be identical with the peculiar felsitic lavas we find in the Mallani series, on the western tlanlrs of the ArSvalli range, about 750 miles to the south. The glacial origin of the beds is shown also by the exposure of typically ice-scratched surfaces on the rocks they rest upon.

The fossils found in the beds immediately associated with the boulder-bed show a Carboniferous facies, having noticeable affinities with forms occurring in the Upper Carboniferous marine beds of Australia, to which area the same great ocean apparently extended. Among the identical species in these two widely separated areas are Eurydesma globosum^ E. ellipti- cum^ E. cordatum^ Conularia laevigata^ C. tenuistriata^ Pleuroto- maria nuda^ and Attartinopsis danuini.

The beds overlying the boulder-bed introduce a change in Speckled the physical geography which commenced with the retreat of the Australian ocean, the development of an area of internal drainage unfavourable to life and to the preservation of organic remains resulting in the deposition of about 400 feet of red and purple sandstones and shales with gypseous bands. These beds are known as the Speckled Sandstone series.

Further developments in the local physical geography re- Productus suited in the gradual encroachment of a western ocean which l in ^ estonc opened up marine communication with the European area, and gave rise to the formation of a system of fossiliferous rocks, mainly limestones, which, on account of the abundance of a genus of brachiopods, is known as the Productus Limestone. The lower beds are sandy and coaly in the east, but become more calcareous towards the west, that is, as we pass out to the deeper sea ; and as we ascend in the series we find the encroachment of the sea more completely established, with the production of purer limestones. This lowest division of the Lower Productus limestones is distinguished as the Amb series ; and J. r some of its fossils show great affinities with those of the Gshe- lian stage of Russia and the Fusulina limestones of the Carnian Alps, strata which are regarded as Upper Carboniferous in age. Many of the species are found also in the Artinskian (Permo- Carboniferous) and in even younger stages in Europe ; but the fact that most of the fossils belong to the class of brachiopods, whose species, on account of their stationary habits, have a wide vertical range, prevents the more precise correlation which would have been possible if the animals had belonged to migratory forms like the cephalopods, which we shall find to predominate in the Triassic beds overlying the Productus limestones* Among the brachiopods characteristic of the Amb beds, or Lower Productus series, are Productus lineatus, Waag., P. cord) d'Orb., P. sfirah's, Waag., P. semireticulatus, SchL, Athyris roysii^ Leo., Spirifer marcouii, Waag., S. alatus, Schl., Martinia glabra y Mart., Reticularia lineata. Mart., Orthispecosi:^ Marcou, and Richtoftnia sinensis^ Waag., the last-named being one of the peculiar aberrant forms of brachiopods which also characterize beds of this age in Southern China, an area to which this great Eurasian ocean extended in Permo-Carboni- ferous and Permian times.

Middle products limestones

Middle The middle division of the Productus limestones forms a Productus large and conspicuous fraction of the whole formation, being characterized by the prevalence in it of more exclusively Permian fossils. Its younger age is also marked by the appearance of forms, like the lamellibranch Oxytoma^ Meek, not known elsewhere below the Trias, and of Nautilus pcre- grinus, which has a near relative in the Jurassic strata of Europe. There are three well-marked palaeontological zones in this middle division. The lowest of these. is characterized by the survival of the foraminiferal genus Fusulina y Fisch., which, with its relative Schwagerina, Moll., attained an enor- mous development in Carboniferous and Permian limestones elsewhere. The central zone is distinguished by including the peculiar brachiopod Lyttonia nobilis^ Waag. The occurrence of the cephalopod Xenodiscus (Xenaspis) carbonarius in the uppermost zone of this division of the Productus limestone for- mation indicates a greater affinity of the series with the Triassic beds than would be supposed from the fossils mentioned above, and it is possible that a re-examination of this interesting series of beds will place it on a level with the Zechstein of Europe.

Upper productus

Upper The upper division of the Productus limestones shows still Pioductus more t h e a pp roac h of the conditions characteristic of Mesozoic limestones.times by the appearance of several forms of true ammonites with complicated sutures. Prominent among these species are Cyclolobus Oldhami) Waag., Medlicottia Wynnei, Waag., and Euphemus indicus, Waag., which predominate in successive zones from below upwards in this order,

Gradual passage from from Permian to Triassic

Gradual As in the Central Himalayas, so in the Salt Range, there is passage a perfectly gradual passage from strata which are unquestion- Permian a k' v Permian up to beds which contain an essentially to Triassic. Triassic fauna. To draw a line, therefore, exactly correspond- ing to the base of the Trias in Europe is as difficult as it is unimportant : the main point to establish is the fact that the perfectly conformable passage is accompanied by t'he gradual replacement of typical Palaeozoic forms by characteristic Mesozoic fossils. Within a few fefbt of the beds containing the highest remains of the genus Bcllerophon, we meet with limestone containing traces of ammonites ; and from this horizon up for over 200 feet, in a typical section near the village of Chideru -(32 33' N. ; 71 50' E.) in the western part of the Salt Range, we find beds in which the character- istic Triasste ammonite Ceratites^ Haan, occurs so abundantly that its name has been employed to distinguish the whole series (12).

According to the predominating rock, this series can be divided into four tyhological stages and five palaeontological zones, as follows:

5. Upper Ceratite limestones . Zone of Stephanitcs superbus.

4. Ceiatite sandstones . . Zone of Flemingitts flemingianus.

3 )Zone of Koninckites voltttus. a. ) ( Pnonolobus ro'ttndatus.

I. Lower Ceratite limestones . Zone of Ccltites sf^

Of these, zones i and 2 are characterized by the frequent occurrence of the genus Meekoceras, Hyatt, and zones 3, 4, and t i n s rma ~ 5 by the abundance of fossils belonging to the genus Hcdenstroemia* Waag. Palaeontologically, therefore, the beds are capable of division into two stages which correspond approxi- mately to the beds in the Trias of the Central Himalayas, where Meekoceras is found associated with Ophiceras and Otoceras in a series of limestones and shales, which are in turn covered by further beds in which Ceratites is well represented with, as in the Salt Range, Flemingites flemingianus, Waag. With the Ceratite beds, which are approximately equivalent to the Lower Tiias of Europe, the second chapter of the Salt Range closes; and all younger records, representing the Muschelkalk, the Upper Trias, and the two lower divisions of the Jurassic system, have, if they ever existed, been completely removed.

Permo carboniferous of Burma

Exposures of beds belonging to different parts of the Permo- Permo- Trias so well displayed in the Salt Range occur at different T ria v S T on t. . , ' J to the North-points farther north. In the Bannu District, for instance, a western boulder-bed with scratched and faceted boulders, like the well-known occurrence of the Salt Range, occurs covered with limestone containing fossils of Permian age. In this area the Triassic Ceratite limestones also follow in conformable succession, while the Trias is likewise represented in Hazara. Permian limestones with fossils like those of the Productus limestone series have been found in Chura and the Ba/JIr valley, but the Palaeozoic rocks are apparently covered up by younger formations sourii of*the Safed Koh (13).

The Permo-Triassic series of Kashmir have a special interest, on account of the occurrence of remains of the Lower Gondwana plant Gatigamopteris associated with those of typical Pei mo-Carboniferous fishes and labyrintho- donts (10).

the trias of hazara

The Trias Perhaps the nearest approach to the remarkably complete of Kama, succession which we have in the Central Himalayas is furnished in Hazara, where a sequence, complete but for a local uncon- formity between the two lowest systems, extends from Triassic through Jurassic and Cretaceous to the great Nummulitic or eocene formation. The Triassic rocks of HazSra rest un- conformably on the Devonian or so-called //ra-Trias, consisting of some 50 to 100 feet of acid felsitic material (pro- bably of volcanic origin and associated with a pisolitic hematite) at the base, followed by a limestone formation of from 500 to 1,200 feet containing Megalodon and other characteristic fossils (14),

permo carboniferous of Burma

In the Tenasserim Division of Southern Burma there are Carbon- limestones from which a few fossils have been obtained, having of Burma, affinities with the Carboniferous limestone of Sumatn^and less intimate relations to some forms occurring in the Productus limestone of the Salt Range. So far as they go, the fossils indicate approximately a Permo-Carboniferous age. These limestones are associated with a series of shale and sandstone beds, distinguished as the Moulmein series, which have a total thickness of about 5,000 feet and rest on another series, the Mergui series, which consists of some 12,000 feet of unfossili- ferous sandstones, grits, and shales. Limestones similar to those which are fossiliferous in Tenasserim are found east of the Salween river, and farther north in Karenni, where they have yielded a number of fossils, chiefly brachiopods, like Athyris, Productus^ and Spiriferina^ belonging to species closely related to forms known in the Productus limestone of the Salt Range. South-west of Hsipaw (Thlbaw) also, in the Northern Shan States, limestones have been found with the form Fusulina, which is so common in the Carboniferous and Permian formations elsewhere. This area, only recently visited by the Geological Survey, promises a geological record which, from its geographical position between the standard strati- graphical scale of Northern India and the Palaeozoic formations of Sumatra and adjoining areas, will be of unusual value as an index to the physical geography of the Indiah region in Palaeozoic times.

In the gorge of the Subansirf*riv$r in Assam numerous boulders of limestone and sandstone have been found, in- cluding fossils of Lower Productus limestone affinities, but these may possibly have been brought from the Tibetan plateau (16).

the Jurassic of Baluchistan and the frontier province

The Jurassic system is well represented in parts of Western and North-western India. The so-called * massive limestone of Baluchistan, which is several thousand feet thick and forms tan and the many conspicuous peaks, such as the Takatu north of Quetta, Frontier and the Takht-i-Sulaiman, is of about the same antiquity as the oolite of England, tne fossils from its uppermost strata being of callovian age. The massive limestone rests conformably on a great thickness of shales and limestones corresponding in age to the Lias of England. A somewhat similar succession is characteristic of the North-West Frontier Province, where, too, there are coverings of Cretaceous and Tertiary strata, with generally unimportant interruptions in the stratification.

A traverse of the country between All Masjid in the Khyber Pass and the British frontier at Shinawari covers representatives of ever/ system from the Tertiary to the Carboniferous, and some older altered rocks of probably Lower Palaeozoic age. From the Bara valley south to the Samana range, the Palaeozoic rocks are covered, the beds exposed being either Mesozoic or Tertiary in age, thrown into a series of folds with a tendency to inversion over to the south. This gives the northern slopes of the ranges a comparatively gentle inclina- tion, while their southern scarps are steep and rocky. An example is furnished by the Cretaceous and Jurassic rocks which form the heights of Dargai, rendered famous by the engagement of October 20, 1897, when the British suffered the tactical disadvantage of having to carry the scarp face (13).

In Northern Hazara there is an exposure of beds precisely similar in lithological character and fossil contents to the remarkable Spiti shales of the Central Himalayas, and they are covered, too, by flysch-like beds identical in character with the Giumal sandstones of Spiti and Kumaun (14). On the other hand, Jurassic rocks in Southern Hazara present a facies quite unlike that of the Spiti shales, being more calcareous and sandy, and generally more like the Jurassic rocks of the Salt Range (14).

Jurassic of cutch

Remains of formations deposited in Upper Jurassic and Jurassic Lower Cretaceous times are found exposed in the region west of Cutch. and north-west of the^ Antvalli range in Cutch, in the Raj- putSna desert near Jaisalmer and Bikaner, and in the western part of the Punjab Salt Range. These have been most com- pletely examined in Cutch, where they attain a development of over 6,000 feet, ranging from a stage about equivalent to the bathonian (Middle Jurassic) of Europe, through the Upper

Jurassic, to the neocomian, without any decided unconformity. These rocks have been divided into four series distinguished by local names as follows :

Umia .... Fortlandian to N^ocoroian.

Katrol , . . . U. Oxfordian and Kimmeridgian.

Chari .... Callovian and L. Oxfordian.

Patcham . . . Bathoniau.

Jurassic of jaisalmer

The great mantle of sand which has spread over R5jputSna Curing recent times effectually conceals large areas of rocks, patches of which here and there peep through ; but, being isolated, they cannot be grouped with certainty except where they are fossihferous. In the neighbourhood of Jaisalmer, however, there are highly fossiliferous limestones whtch'include many forms identical with those characteristic of the Chari series of ditch, and these are overlaid by other series consist- ing of sandstones and limestones which have yielded fossils resembling those of the Cutch Katrol series. We thus have proof that the sea extended so far eastwards during Upper Jurassic times.

Jurassic of the salt range

Jurassic From Jaisalmer to the Salt Range, where we find marine Ranee * J urass ^ c rocks again, is about 350 miles due north, the whole country between being completely covered with recent alluvial accumulations. In the Salt Range, we have, as already de- scribed, an uninterrupted succession from the Permo-Carboni- ferous to Lower Triassic times ; then an interruption occurs, and the next formation preserved is of Middle or Upper Ju- rassic age. These strata are developed in the western part of the Salt Range extending to the Indus, being exposed again farther west to the Chichali (Maidani) hills (32 51' N. ; 71 n' E.) and in the Sheikh Budm hills (32 18' N. ; 70 49' E.). Small patches of coal occur near the base of the series ; and for the rest it consists of an alternation of conglomeratic sand- stones, shales, and limestones, the last-named being especially developed in the western exposures. Two less usual for- mations are a bed of hematite and layers of a peculiar golden oolite, similar to that well-known in Cutch. So far as they have been examined, the fossils correspond with those of the Chari and probably also of the higher series of Relics of Cutch. the great The narrow encroachments of the sea which took place in man trans- J urass i c times on the Peninsula were extended during the Cre- taceous period, and especially in cenomanian times, when pro-

found changes occurred in the physical geography of the earth. Relics of this Cretaceous transgression of the ocean, preserved on the Coromandel coast of Madras and in the Narbada valley, are well-known examples which may be conveniently selected for special notice, t

coromandel cretaceous

The best studied of these marine formations is that represented by three patches' on the Coromandel coast, where, by a very narrow accident of relative level between sea and land, we find highly fossiliferous rocks which have made a contribution of inestimable value to our knowledge of marine zoology in Upper Cretaceous times. Situated as a sort of half-way stage between the Pacific and the Atlantic areas, this coast, which was immersed to a very small depth, formed a home and final resting-place for many animals which migrated under stress of competition from one region to the other, marking out their route, like the old East Indiamen, by wrecks on the southern coast of India, in Natal, and on the west coast of Africa. The fossil remains include many forms which appear to have flou- rished from Brazil right around the oceanic belt to British Columbia, together with others which modified themselves to develop species peculiar to the conditions in various parts of the Cretaceous sea. Supposing a few feet of elevation in Creta- ceous times, and no shells would have stranded on the shelving beaches of the Coromandel coast ; a similar amount of depres- sion in recent times would have hidden the deposits beyond the reach of the geologist. As it is, the small patches of strata on the eastern coast of Madras form a little museum of Creta- ceous zoology, in which nearly a thousand species of extinct animals have been recognized ; and, by the inclusion of many cosmopolitan forms, they permit the correlation of these rocks with those in many parts of Europe ; Syria ; the north-western borders of India ; North, West, and South Africa, and Madagas- car ; Brazil ; the Eastern, Central, and Western States of the American Union ; British Columbia; Japan; Sakhalin; Bor- neo ; and Australia (1).

The trichinopoly area

The highjy fossiliferous Cretaceous rocks of the Coromandel coast form three small patches separated from one another by the alluvium of the VellSr and Penner rivers, and by the sub- recent Cuddalore sandstones. The largest of the three patches is in Trichinopoly District ; the other two are west of Cudda- lore and north-west of Pondicherry respectively. They rest on the eroded surface of the old gneiss, or unconformably on the Upper GondwSna beds.

The fossils show a range in age from the lowest beds corre- spending with the upper greensand (cenomanian) to the danian. The strata are divided as follows into four stages : NlNNlYUR STAGE . Large specimens of Nerinta, iVantilus, &c., with wany Foraminifera, etpecially Or- biloides, filling the hard ma- trix of large shells.

Nautilus danicus, Schloth.

Danian.

ARIYALUR STAGE .

Trigonoarca galdrina^ d'Orb., very abundant. Other com- mon forms are Nerita divari- cata^ d'Orb., RosteUaria pal- liata, Forb., Exogyra^ and Alectryonia.

Upper Senonian.

TRICHINOPOLY STAGE

ft Zone of Placentictras fa- mulicum y Blauf.

(a} Zone of Fachydiscus aff. fframftus, Mant.

Lower Sen onian. Turonian.

UTATUR STAGE . .

(c] Zone ofAfammttes concilia- tus, Stol.

() Zone of Acanthoceras man- telli, Sow.

(a} Zone of Schloenbachia injlata. Sow.

Cenomanian.

TheUtatur stage.

The lowest of these stages, distinguished by the name Utatur, is only partially covered by the younger beds, and is exposed as a wide band along the western border of the Tri- chinopoly Cretaceous patch. Its base is generally a coral-reef limestone ; but the principal part of the series consists of fine silts, calcareous shales, sandy clays, sands, grits, and some conglomerates. The fossils include fragments of cycadaceous woods, often bored by molluscs, with a rich assemblage of marine forms generally indicating, by their nature and mode of preservation, a littoral habit Near the base of the Utatiir stage occurs the common lower cenomanian ammqnite Schloen- bachia inflata, Sow., a species characteristic of this horizon in Europe, West Africa, Brazil, Australia, California and else- where ; but more especially of the Cretaceous rocks of the Atlantic province. The majority of the fossils are, however, near relatives of, or identical with, those found in the Pacific province. In the higher beds there is a rich Acanthoceras fauna, including the world-wide form A. rhotomagensc, Brong., found also at various places in Europe, Syria, the Caucasus,

Persia, and the regions bordering the north-west of India, Japan, South, West, and North Africa, and Madagascar : in this zone, also, Turrilites costatus^ Brong., and Alectryonia carinata, Lam., agree in indicating a middle and upper ceno- manian age.

The uppermost zones of the Utatur stage mark the com- mencement of turonian conditions by the appearance of the characteristic lamellibranch Inoceramus labiatus^ Schloth., and of ammonites related to the European form Mammitts nodosoides.

There is a slight break between the Utatur and the next The Tri- overlying Trichinopoly stage, shown by a stratigraphical un- c h |n conformity, as well as by a considerable change in the fauna. Among the Trichinopoly beds there occur typical relatives of Pachydiscus pcratnplus> Mant, an ammonite characteristic of the lower chalk of England, and of the corresponding horizon in many other parts of the world, ranging over the Atlantic province, and in the Pacific area as far as Japan. The higher Trichinopoly beds mark the incoming of a lower senonian fauna among the gastropods and lamellibranchs as well as among the ammonites. Thus the genus Schloenbachia, Neum., represented in the lowest Utatur beds by S. inflata, Sow., is here represented by the tricarinata type.

Then follows the Ariyalur stage, covering a large area on the The Ariya- east side of the Trichinopoly patch. A point of peculiar in- terest in connexion with this series is the occurrence in it of a tooth and some ill-preserved bones of the dinosaurian Megalo- saurus, resembling M. Bucklandi, a well-known form from the Stonesficld slate, belonging to the bathonian stage or great oolite of England, and thus much older than these rocks in Southern India. As this genus is not known above the neo- comian in Europe, we have another example of the class, so well illustrated by the Gondwna fossils, showing v the different rates of development which occur in widely separated land areas, cut off by sea or by other physical barriers from one another. The most important cephalopods in the Ariyalur beds are the upper senonian species of Pachydiscus and Bacu- lites, B. vagina, Forb., being especially characteristic. Ap- parently this series is aUo represented in the Pondicherry area, where, as in Trichinopoly, the next and highest stage is also preserved.

The Ninniyur beds are intimately related to those of the ThcNinni- Ariyalur stage, but contain a fauna sufficiently characteristic >'" r to permit their correlation with the danian stage of the Upper Cretaceous in Europe. Thus the disappearance of ammonites and other characteristic Mesozoic forms foreshadows the faunal characters which distinguish the approaching Tertiary period. The characteristic form, Nautilus danicus^ Schloth., makes its appearance, and the only other genus that* requires mention to ensure the Mesozoic character of the beds is the gastropod Ntrinta, Defr., whose name is used to distinguish the highest beds in the Pondicherry area. Thus closes the most complete fragment of Mesozoic history in peninsular India, the only record we have of the life in the seas washing the Coromandel coast when the Mesozoic era was approaching its close in Europe. The Cretaceous sea, which left such perfect samples of its inhabitants on the Coromandel coast, also stretched north-eastwards as far as Assam ; and there, on the margin of a mass of old rocks which formed a part of the peninsular crystalline gneisses, it deposited limestones, sandstones, and shale beds, containing numbers of fossils identical with the more completely studied formations in Southern India.

Dagh beds. The rocks of corresponding Cretaceous age on the western coast are known as the Bagh beds, which occur in the Narbada valley and separate the Deccan trap-flows from the underlying Archaean gneisses. Some forty species of marine animals have been identified in these beds, including a few cosmo- politan forms which show a specific identity with those in the Coromandel beds, but many of them are distinct types mani- festing a greater affinity with Cretaceous fossils from Arabia, Palestine, and Europe, areas which were covered by the same great ocean. In Kathiawar some sandstones in the neighbour- hood of Wadhwan resemble the Bagh beds in lithology, in the few imperfectly preserved fossils which they have yielded, and in their position unconformably below the Deccan trap-flows.

The Gond- Above the youngest member of the Vindhyan system there sys>- j s a g reat g a p Q f un k nown width in the geological history of peninsular India ; and it is probable that much of the record has been destroyed by denudation, for its next chapter commences with a formation deposited on a land surface when India was part of a large continent exposed to the weather.

The oldest rocks after the Vit^dhyans are distinguished as the Talcher series, which form the lowermost stage in a great system of sub-aerial and fresh-water deposits known as the Gond- w3na system. In Gondwana times India, Africa, Australia, and possibly South America, had a closer connexion than they appear to have at present. Although probably at no time forming a continuous stretch of dry land, they were suffi- ciently connected to permit of the free commingling of plants and land animals. At different parts of this great southern Bouldw- continent there occur peculiar boulder-beds whose special beds in _ characters appear to be best explained as the result of ice wana " action. The boulders of this peculiar formation of the Talcher series vary from mere pebbles to blocks weighing many tons, generally well rounded and rarely scratched, lying often in a matrix of fine silt, a matrix which would not exist if the boulders had reached their present positions by rolling in rapid streams. The formation in New South Wales which is taken to he the equivalent of the Talcher boulder-bed has a similar structure, with large and sometimes striated boulders embedded in a fine, silly matrix ; and in this case the tranquil conditions under which the formation was laid down are shown by the inclusion of numerous delicate Fenestellae and undisturbed bivalves lying in the silt. The age of the Australian formation is fixed by the associated Upper Carboniferous marine beds, and this testimony agrees with that of the boulder-bed of the Salt Range already referred to (ante, page 70). In Kashmir, beds have been found containing Ganganwfteris (a typical Lower Gondwana plant), associated with fish and labyrinthodont remains related to those of the Permo-Carboniferous in Europe (16). The lowermost beds of the Gondwana system are thus fixed Age of the

by indirect evidence as Upper Carboniferous or Permo-Car- Gondwana

J r system.

boniferous in age. Later on it will be shown that the upper-

most stages of this system are associated with marine deposits of oolitic, or possibly neocomian, age. We thus have a great system of strata ranging from the Carboniferous, through Permian and Triassic times, to the period during which the well-known oolites of Europe were formed. The fossil contents of this system give a record of the natural history of the great southern continent of Gondwana, which differs in a remarkable and most interesting way from that of the northern hemisphere. Allusion has already been made to this in the Introduction ; and after a brief description of the subdivisions of the Gond- wana formations, the question will be referred to in greater detail, though the few pages tcj which this chapter is necessarily limited are insufficient fof a full discussion of a subject which possesses such an important bearing on palaeontology. The reader who wishes for more information is referred to the memoirs cited at the end of the chapter.

The Gondwana rocks are preserved as small patches l down, mostly by faulting, into the great crystalline mass of Gondwana* the Peninsula. Originally they must have covered a much wider area ; but as the Peninsula has been exposed ever since to the free action of weathering agents, the GondwSna forma* tions have been cut into like the older formations, and the coal* measures thus preserved in India now form but a fraction of those that once existed. Isolated patches of GondwSna rocks, including coal beds, have been involved in the folded extra-peninsular area, in the Darjeeling District, and in Northern Assam. The string of Gondwana patches which determines the direction of the river Damuda includes our most valuable deposits of coal. Their faulted, parallel boundaries *!and general east-west alignment suggest the action of the same earth movements as occurred in structural lines parallel to the subterranean ridge of high specific gravity running across India to the south of this line the great depression of the Gangetic valley and, farther afield, the main axis of folding in the Hima- layan region. All these phenomena are probably connected, though not necessarily contemporaneous.

The Tal- The lowest subdivision has already been referred to as the cher senes * Talcher series. The rocks of this series are . generally soft sandstones and peculiar silty shales, often of a greenish hue, which break up in a most characteristic way into small angular fragments. The peculiar characters of the Talcher rocks permit their ready recognition ; and though a compara- tively thin formation, probably not exceeding 800 feet in thickness, they are developed, with all their peculiar char- acteristics, over an enormous area on the Peninsula.

In the upper layers only a few plant remains have been found ; but the Talchers generally, notwithstanding their litho- logical suitability for the preservation of delicate fossils, are remarkably devoid of signs of life, a feature which is consistent with the evidences of great cold indicated by the glacial boulder-beds near the base of the series.

Damuda The next younger beds are grouped together under the scries. name Damuda series, and these are subdivided in Bengal into the following stages :

3. Ranlganj stage.

2. Ironstone shale stage.

i. Barakar stage. *

Barakut The Barakars are recognizable in many other areas ; but the

stage * upper stages cannot be identified with certainty, and local

names like Kamptee, Bijori, and Motur are used to distinguish

the Damuda beds above the Barakars in other coalfields. It is in the Damuda series that the most valuable Indian coal-seams occur. The associated rocks are all sandstones and shales, which sometimes attain a thickness of 10,000 feet The iron- stone shale stage is so called on account of the lenses of clay- ironstone which, as in the Ranlganj coalfield, sometimes occur in sufficient abundance to supply a valuable iron-ore. All these stages are in general conformity with one another, though the upper may be found to overlap the lower.

There is generally, however, a slight unconformity between Panchet the uppermost stage of the Damuda series and the next, which senes * is distinguished as the Panchet series. The Panchets are characterized by the absence of coal-seams, being composed of micaceous sandstones, often of a greenish colour, with bands of red clay. The series is well-known on account of the reptilian and amphibian fossil bones it has yielded, besides a few fossil plants which show more pronounced affinities with those of the Damudas than with the higher beds.

The whole of the foregoing series Talcher, Damuda, and Pflnchet make up the lower division of the Gondwana system, being cut off from the Upper Gondwanas by a marked strati- graphical break, accompanied by a contrast in fossil contents. The plants of the Lower Gondwana beds include many equi- setaceous forms, while those of the Upper Gondwanas show a prevalence of cycads and conifers ; the species of common genera of ferns, as well as other orders, are quite distinct in the two divisions.

The Upper Gondwanas have a lower series, distinguished as Uppei the Rajmahal series in Bengal and as the Mahadevas in the Gondwanas. central parts of the Peninsula. The Mahadevas attain a thick- ness of 10,000 feet in the Satpura area, most of the rocks being sandstones and unfossiliferous. The Rajmahals, on the other hand, have yielded a number of fossil plants, and are interest- ing, too, on account of the great sheets of basaltic lava interstratified with the shaly and sandy sediments, attaining a thickness of over 2,000 feet. The Rajmahal lava-flows are Rajmahal

often amygdaloidal like those of the Deccan trap series, the 5 nd Ma ! la " ...,,. , ,. ,. . , , , \ deva series.

cavities yielding agates and zeolites of considerable variety

and beauty.

Rocks of Upper Gondwana age occur at various places Marine along the east coast of tlte Peninsula. In some cases marine u eds e f fossils have been found associated with the plant-bearing Gondwana beds, and these have helped to fix the position of the Upper a s e - Gondwanas in the standard scale of marine strata. More pronounced evidence as to the age of the upper limit of the Gondwanas is afforded by the occurrence of plant-bearing beds in the so-called Umia series of Cutch, whose age has been already referred to as about equivalent to the neocomian of Europe (ante, page 76).

The Kota- A series between the Rajmahal horizon and the Umia series Maleri deserves special mention on account othe animal remains which it has yielded. Its beds occur in the Godavari valley, and have been named the Kota-Maleri series from two villages near which they are developed. In the lower or Maleri stage fossil remains of the remarkable fish Ceratodus, species of which are still living in Australian waters, and of the reptilian genera Hyperodapedon and Parasuchus, have been found with numerous coprolites ; while in the Kota stage a greater variety has been found, including the crustacean Estheria, and several forms of fish and reptiles, with plant remains which indicate the position of these beds in the Gondwana sequence. Characters At the time when the Glossopteris flora flourished on the G ndw" a & reat southern continent of Gondwana-land, Lepidodendron^ fossil Sigillaria, and Calamites were conspicuous among the forests plants. o f t h e nor thern hemisphere. But the separation of the two great continents was not sufficiently complete to prevent the southward extension of some members of the Lepidodendron flora to Africa and South America ; and the fact that typical members of the Upper Palaeozoic Lepidodendron flora, as it is known in Europe and North America, have now been found associated with the Glossopteris flora in South America and in South Africa proves beyond question that the two were co- existent (25).

The Gloss- The predominant flora of the Lower Gondwana system, in flonTof which Glossopteris and Gangamopteris are prominent genera, Gondwana- has much closer affinities with the Mesozoic plants of Europe land. t k an w j t k t h e pi an |- s o f the Upper Palaeozoic coal-measures. This fact at first seemed inconsistent with many other evidences pointing to an Upper Palaeozoic age for the Lower Gondwanas ; but the explanation offered by the earlier members of the Geological Survey of India, though for many years a stumbling- block to European palaeontologists, has received conclusive support in recent times. A flora closely resembling that of the Indian Gondwanas was found represented also in Australia, South and East Africa, Argentina, ind Brazil. In most of these places, too, the formations in which the fossil plants occurred were associated with a boulder-bed having the peculiarities of that at the base of the Indian Gondwanas, and regarded as the result of ice action by the Indian geolo- gists. With a boulder-bed of Permo-Carboniferous age at the base, and a marine intercalation of Jurassic and neocomian forms near the summit of the Gondwana system, we have an inferior and a superior limit of the time-scale over which to distribute its various series. A considerable fraction of the lowest beds must represent the Per mo-Carboniferous, Permian, and Triassic periods ; and yet the plants they contain show, when compared with European fossils, a predominating Rhaetic and Jurassic facies. The remarkable agreement between the Glossoptcris (Gondwana) flora of India and the fossil plants of similar formations in Australia, Africa, and South America can onfy be explained on the assumption that these lands, now separated by the ocean, once constituted a great southern continent

That India and the southern and central parts of Africa Existence were once united into one great stretch of nearly continuous f an old . dry land is proved by overwhelming evidence (17). In the can con ti. first place, besides the remarkable correspondence among the nent. plants which flourished during Upper Palaeozoic times in India, South Africa, and the portions of East Africa which have been explored, there is an agreement between the peculiar generalized labyrinthodonts and reptiles of which remains are found in the Panchet series of India and in corresponding beds in South Africa. So far as this evidence goes, it points either to a complete land connexion, or to an approximation sufficiently close to permit free migration of land animals and plants.

A study of the distribution of Jurassic cephalopods indicates Evidence

the existence of a tropical sea to the north-west of this supposed fron ? J u " .... t _ * , , , , TO . rassicfos-

land barrier, and of a cold sea to the south-east. The separation s ii s .

was not, however, sufficiently complete to prevent the migration of species from the Cutch area, which we presume to have been on the north-west side of the barrier, to the Lower Goda- vari, which was probably on its south-eastern shores. But a shallow strait in Upper Jurassic or Lower Cretaceous times would be sufficient to account for the small amount of com- mingling thus indicated by the occurrence of identical species on opposite sides of India.

The Upper Cretaceous fosgils demonstrate the existence of Evidence the land barrier more <*ompletely. The marine Cretaceous om the beds near Bagh, in the lower Narbada valley, contain fossils deposits, which, especially the echinoderms, show striking resemblances to those of the Cretaceous beds of Syria, North Africa, and Southern France, all patches of rocks deposited in the great ocean of which the modem Mediterranean is a shrunken relic.

Persistence of the old continental ridge.

Effects of the old continent on the modern distribu- tion of animals.

But the .Bagh beds differ in facies from the Cretaceous beds of the Trichinopoly area, since in the latter, though there are many forms that had a world-wide distribution in Cretaceous times, types related to the fossils of the Pacific province preponderate, as shown by numerous correspondence! with South Africa, Borneo, Japan, Sakhalin, Chili, California, Vancouver, and even as far as Queen Charlotte Islands. We have thus a contrast between the Mediterranean-Atlantic Cretaceous province and that of the Pacific, and this contrast is preserved in the Bagh beds on the west of India and the Trichinopoly formations on the east coast The evidence goes even farther, for in Assam, Trichinopoly, and South Africa the Cretaceous beds show a distinctly littoral character, indicating the fact that the old Mesozoic coast-line on the east was not far from a line joining these places.

There is still another piece of evidence as to the existence of the old Indo- African continent, all the more striking because it belongs to an entirely different field of observation. It is found that between the Seychelles, which are connected by comparatively shallow waters with Madagascar and Africa, and the Maldives, which are on the Indian continental platform, there exists a submarine bank, preventing the ice-cold Antarctic currents that characterize the greater depths in the South Indian Ocean from extending into the Arabian Sea, which has thus a higher temperature than the water at correspond- ing depths to the south of this bank. We have here the remains of the old continent, depressed sufficiently to cut off India from South Africa, but still enduring as a bank between the great abyssal depressions to the north-west and the south-east.

Finally, the modern distribution of animals is explained by this occurrence of a Mesozoic Indo-African continent, and in turn furnishes further evidence in favour of the conclusion already based on palaeontological data. Within the part of India south of the Gangetic plain are numbers of genera and species not found in other parts of the Indo- Malayan region, which have near relatives in Madagascar and South Central Africa. These, distinguished as, the Dravidian constituent of the Indian fauna, are comparatively iSw forms, mostly reptiles, batrachians, and invertebrates, with only one mammalian genus, Platacanthomys. The likeness between the Dravidian fauna of the Indian Peninsula and some forms in Madagascar can only be accounted for by this supposition of an ancient land communication, while the amount of divergence they show is no more than would be expected from independent evolution, since the separation occurred in early ^Tertiary times (18).

The great revolutions in physical geography, which took The break- place towards the end of the Cretaceous and during early Tertiary times, resulted in the break-up of the old Gondw&na land, continent, and were followed by the rise of the Himalayan range. These orogenic movements appear to have been caused, or accompanied, by igneous action on an unusually grand scale. The great masses of basic lava covering more than 200,000 square miles in peninsular India remain as a fragment of the enormous flows which must have spread over that area, and probably over a very much larger portion of the old Gondwana continent to the west and south, now buried under the Indian Ocean or removed by denudation. Among similar phenomena Igneous in other parts of the world, at or near the same period, may be outbursts mentioned the great basaltic flows of North-western Europe O f Meso- with their associated granites, gabbros, and other intrusive zoic times, rocks, and the Laramie series in the United States which very closely parallels the case of the Deccan trap of India. Besides the Deccan trap, other intrusive and extrusive igneous rocks made their appearance at about the same time in parts of extra-peninsular India. Burma contains intrusives of basic and ultra-basic rocks cutting through the early Tertiary strata, and now remaining as conspicuous masses of serpentine. In the North-western Himalayas similar rocks, accompanied by volcanic ashes and probably also by lavas, were formed during and subsequent to lower eocene times, while in Baluchistan even more extensive series of eruptions have been detected. Finally, with this great period of earth-movement we must connect much of the granite which is so prominent in the Central Himalayas and contributes to the great core of the range.

The most extensive and best known of the instances of The Dec- eruptive activity which characterized the close of the Mesozoic, can tra P* and the opening of the Cainozoic, era is naturally the Deccan trap. The great lava-flows which make by far the chief part of this formation constitute the plateau of the Deccan, con- cealing all older rocks over an area of 200,000 square miles, filling up the old river ^dle^s, and levelling the surface of the country. Subsequent denudation has carved these lava-flows into terraces and flat-topped hills, with, as in the seaward face of the Sahyadri or Western Ghat range, steep scarps, rising to about 4,000 feet and indicating a part only of the original thickness of the accumulated lavas, ashes, and beds of interstratified marl. The trap-rock is usually a form of olivine basalt or augite-andesite, rarely porphyritic, but often vesicular with amygdala of beautiful zeolites, calcite, and agate. The La- At the base of the flows are beds in which limestones of metasenes. i acustr ; ne origin predominate. These |j>eds, known as the Lameta series, were laid down unconformably on all the older formations, even on the youngest members of the Gondwana system, while they were themselves exposed to local denuda- tion before the lavas spread over and protected them from the weather.

Among the few fossils which have been found in the Lameta series are the bones of a large dinosaur, Titanosaurus indicus, Lyd., allied to some Lower Cretaceous and Upper Jurassic reptiles in Europe. The occurrence of this form in strata which are certainly not older than Upper Cretaceous agrees with the evidence of the Mcgalosaurus from the Ariyalur stage of Southern India, in pointing to the backward state of evolu- tion among Indian reptiles in Upper Mesozoic times one more among the many evidences from Indian geology to prove that correlation of strata by land animals often contradicts the evidence of marine forms.

Age of the In making an attempt to fix the position of the Deccan trap Deccan j n t h e European stratigraphical scale, the chief point to guide our judgement is the fact that we are limited below by the cenomanian (Bagh) beds and above by the Nummulitic rocks of Cutch, while in Baluchistan what appears to correspond to the base of the series is associated with marine strata of about senonian age, and in Sind the upper flows have spread out over beds regarded as equivalent to the oldest Tertiary in Europe. The eruptions thus probably began at about the time of the formation of the upper chalk of England, and finished before the remarkable foraminiferal genus Nummulites made its appearance and spread throughout the great Eurasian central ocean. During this interval, which geologically is a very short one, there was time for the accumulation of lava- flows which amounted to not less than 6,000 feet in thickness in some places, with intervals of rest sufficient for lakes, stocked with fresh-water mollusca, to form on the cold surfaces of several of the lava-flows. So this remarkable tccumulation of volcanic materials has remained until to-day, with its original horizon- tality of bedding but slightly disturbed. Except on its north- western fringe, where it was bent down with the subsiding land to the north to suffer the encroachment of the early Tertiary sea, it has remained exposed to the weather, which has carved the great lava-flows to produce the characteristic scenery of the Deccan plateau.

Until the Deccan trap has been dissected out by the weather Ultra-basic in the way in which the Tertiary basalts of North-western Europe have been cut up, we shall have very little visible trap, evidence of the masses of ultra-basic rocks which almost certainly lie below. But it is just possible that portions of these ultra-basic rocks have been squirted into the early Tertiary rocks of the North-western frontier; and the numerous masses of olivine-rock exposed in Mysore and the Madras Presidency may even have had a similar origin, though it is also conceivable that the latter are as old as the Cuddapah lava-flows which, like the Deccan trap, once extended far beyond their present limits. These dunite-masses in Madras Dunites of can be dismissed with a very few words. The majority them are almost pure olivine, though at times they contain enstatite and chromite, and locally pass, by concentration of other minerals, into various forms of picrite. But the chief feature of interest in connexion with these rocks is their frequent, almost constant, decomposition into magnesite with- out ordinary serpentinous alteration. The original olivine-rocks must have been attacked by water and carbonic acid of deep- seated origin, probably originally contained in the magma ; and, with the formation of magnesite, chaladonic silica is also separated. The so-called Chalk Hills near Salem (n 39' N. ; 78 10' E.) form a well-known instance of these peridotite eruptions, being so named because of the abundance of dazzling white magnesite.

Passing on to Burma, we find numerous and large masses of Serpentines peridotite which were erupted in early Tertiary times. Unlike ^ J ~ those of Madras, whose age, it should be remembered, is Burma* unknown, the Burma peridotites are always much serpentinized. One instance, interesting because of its connexion with the valuable mineral jadeite, may be taken as an example. In Upper Burma, in the vicinity of Tawmaw (25 44' N. ; 96 14' E.), serpentinous rocks are found piercing strata of miocene age. Microscopic examination of the rock shows that large quantities of the original olivine have escaped hydration, but most of the mineral b#s Been altered to serpentine. The jadeite occurs in the masses of serpentine, standing out, when exposed, by its white colour against the dark-green serpen- tine (91).

Serpentinous masses, presumably of the same age as that intrusive in the miocene rocks of Upper Burma, are found also

Tertiary gabbros andgrano phyres.

ThcTcr- passage Tertiary,

as irregular bosses and dikes at various places mainly on the eastern side of the Arakan Yoma, where they are intruded into rocks of the Chin series. The serpentine, with chromite, found in the Andaman Islands probably belongs to the same series of eruptions. t

Baluchistan was the scene of the grandest and most inter- esting manifestations of igneous action during this period. With the beds of volcanic ash which are found below the hippuritic limestone (Cretaceous), and at different stages to the middle eocene, there are certain basic intrusions which, with the ash beds, were formed before the folding of the rocks, and have consequently suffered the usual deformations. Either as cause or ^ an accompaniment of the folding movements, great intrusions of granophync rock granites and more basic types were forced into the Nummulitic limestone and asso- ciated rocks some time after the close of the eocene period. Then followed the injection of dikes and sills of dolerite before the pliocene strata were deposited. But this did not close the volcanic action in this interesting area : lavas and ashes were ejected and further material injected into the pliocene (Siwalik) rocks, while eruptive activity persisted on to recent times in Baluchistan as well as in Persia, and some of the volcanoes are still active, though showing signs of senility (20).

With a brief remark on the granitic rocks, because of their possible connexion with the Himalayan granite, we must leave this attractive section of Indian geology. It is interesting to note that the granites found cutting the limestones, which are full of Nummulites, often show the peculiar granophyric struc- ture so characteristic of the similar early Tertiary rocks of North-western Europe, that they pass in the same way into more basic types also with micrographic structures, and that they are similarly traversed by basaltic dikes. But besides these peculiar features they are in places porphyritic, and otherwise recall some granites in the Central Himalayan zone.

While the Deccan trap was being poured out on the Peninsula of India, at the time when the typical Cretaceous fauna of Europe was gradually giving* way to the forms which mar k t* 16 distinctly Tertiary formations, deposition was going on in the seas washing the west coast of India ; and as a result we have preserved, in parts of Sind and Baluchistan, sediments which contain fossils with affinities both to the Cretaceous and to the Tertiary types. The exact side of the dividing line on which a particular formation should be placed can be decided only by detailed examination of its fossil contents.

In one of these cases, which alone there is space to mention, Cardita we have a series of beds in which some highly fossiliferous olive-coloured shales contain large quantities of a peculiar globose species of lamellibranch, Cardita beatimonti^ which gives its name to the formation. Associated with this form are reptilian remains with Mesozoic affinities, besides corals and echinoids of mixed Cretaceous and Tertiary types which have yet to be critically examined. The association, as an interbedded flow, of amygdaloidal trap with the Cardita beaumonti beds gives one fixed point for the age of a portion of the Deccan trap.

The Tertiary system which forms the southern fringe of the Himalayas is divided as follows :

! Upper Siwalik. Middle Siwalik. Lower Siwalik or Nahan stage,

t Kasauli stage ) Murree

Sirmur series . . < Dagshai stage ( beds. ( Sabathu stage.

A review of these Tertiary deposits shows a general passage Himalayan from marine beds at the base to the great river deposits of the Tertianes. Siwaliks, which are essentially similar in origin to the modern alluvia deposited by the rivers emerging from the Himalayan valleys on to the plains of Hindustan.

The lowest or Sabathu stage of the Sirmur series consists of Sabathu a highly disturbed set of grey and red gypseous shales, with stage, layers of limestone and sandstone, in which the fossils indicate a marine origin and an age equivalent to the Nummulitic beds.

The Dagshai stage, with its hard, grey sandstones and Dagshai bright-red clays, follows conformably above the Sabathu beds, sta e - and in turn passes up into the Kasauli stage, which is essen- tially a sandstone formation in which the clay beds are distinctly subordinate in quantity.

On reaching the Kasauli^ stage all evidences of marine action Kasauli disappear, and the deposits seem to have been formed in sta e * fresh water, the sea having then permanently retreated from the plains of Northern Hindustan, while the conditions favour- able to the formation of the great thicknesses of sandstones, clays, and conglomerates which mark the Upper Tertiary, or Siwalik, series were developed.

Wide ex- Marine conditions prevailed in Lower Tertiary (Nummulitic) Nummuli- ^ mes a ^ on g the foot of the Himalayas, as far east at any rate as tic stage. Garhwal, and the deposits of marine Sabathu beds can be traced at intervals north-westward to Jammu, while Nummulitic rocks occur also in the Salt Range ; over various parts of the North-West Frontier Province, covering up large tracts of older rocks ; at the back of the zone of crystalline, and now generally snow-covered, peaks in the far parts of Kashmir and Ladakh ; on the Tibetan border in Spiti and Kumaun ; and away to the far east in the region of Tibet north of Sikkim. Still farther east, in Assam and Burma, Nummulitic rocks occur in numerous places. Within the limits of this chapter it is possible to refer to a few only of the remarkable features of this widespread series of deposits. The guiding line through- out is generally the occurrence of the remarkable foraminifer Nummulites, which, on account of the way it spread itself throughout Europe and Central Asia in early Tertiary times, is as useful in marking a stratigraphical horizon as the freely migrating cephalopods of the Mesozoic group.

In Sind, where the Tertiary marine rocks have attained an exceptional development, the following subdivisions are recognized :

Sind Ter- tiaries.

Manchhar . Gaj . Kari

Kirthar Ranikot

Miocene to Pliocene.

Miocene.

Oligocene.

Priabonian.

Lutetian.

Ypresian.

Sparnacian.

Cardita beaumonti beds Montian.

Tertiaries in Baluchistan.

The lower portion of the Ranlkot stage is poor in fossils, consisting of pyritous and carbonaceous shales and soft variegated sandstones with gypsum. The upper beds, how- ever, are rich in marine fossils, among which in the two uppermost zones are Nummulites of different species which persist thence, through the Kirthar, to the Lower Nari stage.

The great thickness of beds represented by the Ranlkot and Lower Klrthars has not been preserved in Baluchistan, where a series of beds distinguished by the name Ghazij rest directly, and with . distinct unconformity, on the Cardita beaumonti beds. The Ghazij passes locally into flysch-like material (the Khojak shales), which apparently accumulated with raoiditv and oroduced a ereat thickening of the beds without much change in their fossil contents. Above the GhSzij-Khojak stage we find a limestone formation, known as the Spintangi stage, which is represented in parts of Baluchistan, and caps the scarp of the Kirthar range between Baluchistan and Sind. The gfeat thickness of Khojak, Ghazij, and Spintangi beds in Baluchistan represents merely the Upper Kirthar of Sind. Between the middle eocene Spintangi beds of Baluchistan and the Lower Nari (upper eocene) there is a distinct unconformity, corresponding approximately to the bartonian of England. But this gap is not apparent in Sind, the yellow or brown Nari limestone following the white limestones of the Kirthar stage with seeming conformity. With the Lower Nari end the Nummulites, and the limestones in which they occur are succeeded by a great thickness of comparatively barren sandstones.

Representatives of the Nummulitic series, which are so well developed in Sind and Baluchistan, occur also in Cutch and Kathiawar, in Surat and Broach.

The Lower Tertiary rocks of the Kohat region are remark- Rock-salt able for the valuable deposits of rock-salt which occur at their * n the base, and which, in default of contradictory evidence, are tiaries. assumed to be of Tertiary age, though the base of the salt- bearing series is not exposed. The salt, and its associated gypsum, shales, and sands, in the Kohat region present certain characteristics which distinguish the formation from the salt- marl occurring so mysteriously below the Cambrian beds of the Salt Range in the Punjab. The colours are generally grey instead of reddish, and the potash and magnesium minerals of the Salt Range are not found in the Kohat area.

The Lower Tertiary rocks of the Kashmir and Ladakh area Lower deserve special mention on account of the associated peridotites Ternaries and basic igneous lavas and ashes a set of rocks which, placed m \ Ty ^ in this stratigraphical position, suggests a genetic connexion dakh, and with the great Deccan trap eruptions and some of the basic eruptives of Baluchistan of about the same period.

The Nummulitic rocks of Assam are of importance on account of the economic value of their limestones, coal-beds, and mineral oil, which are referred to in detail in the chapter on Mines and Minerals(Vot. III).

In miocene times the sea was driven back, and marine Miocene of strata of this age are consequently restricted to areas nearer v the present coast lines. In Sind there is a fine display of marine miocene beds in the Kirthar range, where the series is cut through by the Gaj river and is named the Gaj series in consequence. In Cutch beds of corresponding age are well developed, while far away on the other side of the peninsular mass there are relics of the miocene sea in Upper Burma, distinguished as the Yenangyaung series. Tertiary The earliest records of the Tertiary history of Burma are still sealed up in a great thickness of flysch-like shales and limestones which, occurring in the forest-clad and almost inaccessible Arakan hills, have only been superficially examined. Above these, on both flanks of the zone of older rocks which stretches from Cape Negrais northwards to Manipur, we find marine beds, the Bassein series, of upper eocene age, showing that a great part of this area was covered by a shallow sea. This sea became, in lower miocene times, silted up by sand and mud, with included organic remains, which afterwards gave rise to the thin coal-beds and petroleum-bearing sands of the Prome stage. Then followed a further inroad of the miocene sea, with its corals, echinoderms, molluscs, Crustacea, and fish, many of whose direct descendants are living to-day in the Indian and Pacific Oceans. These, and the deposits formed in the estuaries of the rivers which poured their contents into the miocene sea of Burma, constitute the Yenangyaung stage. Then followed the changes which, after a local denudation of the Yenangyaungian sediments, resulted in the deposition of 20,000 feet of sandstones in river valleys that formed the home in pliocene times of many remarkable mammals and reptiles, contemporaneous with, and in many cases similar to, the animals whose remains have made the Siwalik series so famous. The folding of these pliocene rocks, distinguished as the Irrawaddy system, into a north and south series of anticlines and synclines introduced the modern physical conditions of Burma, and determined the disposition of the great valleys of the Irrawaddy, Sittang, and Salween, whose sediments are in places burying, while in others the rivers are cutting away, the deposits produced by the great rivers which drained this area in pliocene times. The southerly extension of the Irrawaddy series is buried under the delta of the river, and possibly even under the Andaman Sea, where a longitudinal depression forms the submarine con- tinuation of the Irrawaddy basin, and comes to the surface in the Andaman and Nicobar Islands, where, besides unfossilifer- ous rocks similar to those of the Chin series of the Arakan hills, there are younger soft limestones, clays, and coral sands whose precise age is not known.

FormationsOriginAge.

IRRAWADDY SYSTEM. 20,000 feet.

Upper series. Yellow, friable sandstones with bed* of brown clay. No fossil bones, iossil wood scarce.

Lower series. Yellow, friable sandstones and conglomerates. Much fossil wood and bones.

Terrestrial andFluviatile.

Pliocene.

TEGU SYSTEM.

Yenangyanng series. 2, 400 feet. Glauco- nitic sandstone and olive-green clays.

Prome series. 3,100 feet. Petroliferous sandstones, blue clays, and coal-seams.

Estnarine and Marine.

Miocene.

BASSKIN SYSTEM. 1,200 feet. Sandstones and shales capped by Nummulitic lime- stones.

Marine . .

Eocene.

CHIN SYSTEM. Over 10,000 feet of unfossi- liferous shales and limestones.

Undeter-mined.

The Chin series has not, so far, yielded any fossils, and Chin series, beyond Nummulites very little has been obtained from the Bassein series ; but one of its fossils, Velates Schmiedtliana^ Chemn., is a gastropod of great interest on account of this further evidence of its wide distribution and consequent value as a means for determining the geological horizon. From France, this gastropod ranges through Italy, Egypt, Persia, Cutch, Sind, and Western Burma, being a widely distributed inhabitant of the great Mediterranean sea which stretched as a belt across this area in early Tertiary times.

But the chief interest to the student of natural history lies Yenang- in the rich molluscan fauna of the Yenangyaung series of the miocene Pegu system. These beds, well exposed in the anticline near Yenangyat (21 6' N. ; 94 51' E.) and south- wards to Minbu (20 10' N. ; 94 53' E.), have yielded 167 species of Felecypoda and Gastropoda, of which 30 per cent, are either identical with or closely related to species now living in the Indian Ocean, and 19 per cent, have near relations still living in the Western Pacific. While no species among this assemblage of molluscs is identical with any found in the series. miocene beds of Europe, 14 per cent, have their nearest relatives in the well-known eocene beds near Paris. These facts indicate an easterly migration of many of the molluscan animals during Tertiary times, the descendants of the eocene sea of Europe living in the miocene sea Jn India and Burma, and contributing, by further movement eastward, to the fauna now living in the seas of Japan, China, the Philippines, and Australia. The miocene beds of Burma have thus yielded forms which constitute connecting links between living forms in the Pacific and closely related extinct species which lived in the eocene sea of Europe. In some of these cases the living species are, so far, only known east of Singapore, having apparently, during the continuation of this easterly migration after miocene times, become extinct as far as the Indian Ocean is concerned, while their descendants have passed on to the Pacific (21).

The Siwalik series

he name Siwalik, now applied to the fringing foothills lik series. o f ^ Himalayas in the United Provinces and the Punjab, is also used to indicate a great system of river deposits remark- able for its wealth of vertebrate fossil remains. The deposits of sands, clays, and conglomerates are essentially similar to those formed in modern times by the Himalayan rivers ; and their relations to the modern alluvium show that they were produced in the same way, and were then caught up in the folding movements by which the Himalayas, rolling out as a mighty rock-wave towards the south, rose as the greatest mountain range in the world.

The most interesting and, for stratigraphical purposes, the most important among the fossil remains found in the Siwaliks are those of vertebrate animals, especially of the mammalian class. The exact horizon of many of the specimens was not recorded by the collectors ; and it is consequently not certain whether the apparent mixture of forms having relatives in the oligocene, miocene, and pliocene strata of Europe correctly represents the life in the jungles of the Himalayan foothills, or whether the order of succession was the same as in Europe. The general facies of the fauna, however, shows predominating pliocene affinities, on the whole newer than the fossils of the Manchhar beds in Sind, for which an upper miocene age is accepted on stratigraphical as well as palaeontological evidence. A remarkable feature in connexion with the Siwalik verte- brate fauna is the abundance of the larger mammals, and the predominance of true ruminants over the artiodactyle ungulates. Out of sixty-four genera of mammals which have been identified among the Siwalik fossils, thirty-nine have species still living, while twenty-five are now extinct. Among the reptiles only two out of twelve genera are extinct, while all the birds and fishes whose remains have been examined belong to living genera. The impoverishment in variety of large mammals since pliocene times is a feature of considerable interest, as it is not peculiar to India and is supposed to be due to the effects of the glacial epoch. We have now but a single species of elephant in India to compare with the eleven species which lived at the foot of the Himalayas in pliocene (Siwalik) times, while the two species of Bos now living in India are all that are left of the six which formerly lived in the Siwaliks.

Very pertinent evidence as to the age of the Upper Siwaliks The Irra- is obtained in Burma, where the basin of the Irrawaddy way contains a great system of beds, chiefly composed of yellow sands, which attain in some places a thickness of 20,000 feet and rest, with slight unconformity, on marine beds whose miocene age is placed beyond doubt by their fossil contents. Two features of special interest in connexion with these beds Fossil may be mentioned : one is the common occurrence at various woodt horizons of pieces of silicified, exogenous wood ; the other is the abundance in the two lower zones of vertebrate remains agreeing very closely in character with many of the remarkable forms which have made the Siwaliks so famous.

The vertebrate fossils are, from the geological point of view, the more interesting. The specimens so far collected appear to belong to twenty-six species, of which only thirteen have been specifically determined, and eleven of these are identical with forms known in the Upper Siwaliks. The undetermined species belong to genera which are all known in the Siwaliks ; so there is a sufficiently complete correspondence to justify us in regarding the Irrawaddy system as the equivalent of the Upper Siwaliks. As the stratigraphical position of the Irra- waddy system shows it to be of pliocene age, we thus have a confirmation of the conclusion which has been arrived at by a comparison of the Siwtilik fauna with the pliocene fossils of other lands.

It is probable that the rock known as the Tipam sandstones Tipam in North-eastern Assam are of the same age as the Siwaliks sandstones and the Irrawaddy series, but no unquestionable fossils have ssam * been found in them.

Since pliocene times, when the Himalayas finally rose as Post-Ter- a great barrier between India and the rest of Asia, considerable l | ary de " changes have taken place in the ohvsical ereolotrv of the vc opmen ' Recent country. In the two great areas of folding which meet the volcanic eas t e rn and western extremities of the Himalayan range volcanic action has persisted down to recent times. On the east we have Barren Island, Narcondam, and Puppa, repre- senting the northern extension of the lint which in the region of Sumatra, Java, and the Sunda Islands has been so remarkable for its volcanic activity, while on the west, in the Iranian region of folding, we have volcanoes like Koh-i-Sultan, Koh-i-Tafdan, and Basman Koh now settling down to the solfataric stage. Earth- Earthquakes tend generally to be more frequent in the

quakes. regions of extra-peninsular India, where the rocks have been recently folded, than in the more stable Peninsula; and the areas which have recently come into prominence in this con- nexion are the Province of Assam and the K5ngra valley in the Punjab Himalayas. In the former tract the most violent earthquake on record occurred on June 12, 1897. The known extent of the area over which the shock was distinctly felt was about 1,200,000 square miles. Within the epifocal area of 10,000 square miles, which was situated in Western Assam and Eastern Bengal, alterations have occurred in the heights and relative positions of the hills, in addition to the usual phenomena of earth-fissures, sand-eruptions, small faults, and the destruction of building^. The violence of the movements is shown by the fracture of upright stones, indicat- ing, in the case of short stones which were broken and over- turned, a modified form of projection, while in others there was distinct rotation by the action of a vorticose motion in the ground. In the alluvial areas the effects were especially con- spicuous, vibrations being noticed in the distant and detached alluvial area of Ahmadabad, though the earthquake was not noticed over the rocky ground to the east for about a hundred miles. In the Assam-Bengal alluvial area the river channels were narrowed, railway lines were bent into sharp curves and bridges compressed, while fissures and sand-vents opened in myriads. Ever since the great earthquake of 1897 the same area has been disturbed by small shocks, more than 5,000 being recorded during the following year (22).

Earth quake

The Kangra earthquake occyrred on April 4, 1905, at an early hour in the morning, in consequence of which it resulted in a great loss of human life, estimated at about 20,000* Its epifocal area lay about a curved NW.-SE. line, some 1 60 miles long, extending from the neighbourhood of Kangra, through Kulu, to near Mussoorie. This line corresponds to a fault or chain of faults, which, emerging near the surface in

the Kangra valley, caused the greatest destruction near the north-west end of the line, with an intensity of shock diminish- ing to the south-east, where the focus was deeper below the surface. The area of extensive damage to masonry buildings was only about 5, Soot square miles, as compared with 150,000 square miles of similar damage in the Assam earthquake of 1897. But on account of the great depth of the focus at its south-easterly end, the waves spread out over a wide area, and serious damage was caused over about 27,000 square miles, while the shock was sensibly felt over an area nearly as large as that disturbed in 1897, being recognized as an earth- quake as far west as Quetta, as far south as Surat in Bombay and False Point in Bengal, and as far east as lakhimpur in Assam.

Within India proper there have been local changes in the Recent relative level of land and sea within recent geological times, ris s . and in some cases connected with earthquakes, as in the case of the dences of earthquake of Cutch in 1819 when a part of the Rann was sub- the land * merged, and in the Assam hills, among which alterations of level and horizontal distance were detected by measurements after the great earthquake of 1897. The Andamans and Nicobars have been isolated from the Arakan coast by sub- mergence at a probably recent date.

On the east side of Bombay Island trees have been found imbedded in mud about 12 feet below low-water mark, while a similarly submerged forest has been described on the Tinnevelly coast. On the other hand, there is evidence to show that a part of the coast of Tinnevelly has risen and driven back the sea in the neighbourhood of Kayal. Again, the accumulations of thick masses of old alluvium in the rocky basins of the Narbada and Tapti rivers indicate changes in the relative levels of the upper or eastward, and lower or westward, parts of these basins.

The clays and sandstones of uppermost pliocene or of Pleistocene pleistocene age which are found in the Narbada valley have sometimes been referred to as the older alluvium of the bada and Narbada a misleading expression, as, although they were Godavari formed under fresh-water conditions, they could not have been va eys * deposited in their present pQsition in a rock basin by the Narbada river as it now exists. They include remains of mammalia specifically, and sometimes generically, distinct from forms now living, and among them bones of a hippo- potamus now represented only in Africa. The molluscs in these deposits belong to known living species of fresh-water habit ; and the rocks therefore cannot be older, probably, than pleistocene, though some of the mammals are identical in species with those in the pliocene Siwalik series.

Recently, among the older alluvium of the higher part of the GodSvari valley, in the Nasik District of Bombay, remains of extinct vertebrates have been found, including a skull of EUphas namadicus, Falc. and Caut, of exceptional size. Re- mains of Hippopotamus and Bos namadicus have recently been obtained in wells 80 feet below the bed of the Ganges near Allahabad. These, like the vertebrate remains found many years ago in the Jumna valley, indicate a pleistocene age. Porbandar One of the most interesting among sub-recent and recent stone. formations is the calcareous freestone, largely used for building purposes in the Bombay Presidency, which is quarried from deposits that occur near Porbandar and other places on the Kathiawrir coast. The rock consists largely of the remains of minute foraminifera, with small quantities of sand grains which have been transported by the wind from the sea-shore. Depo- sits of this nature attain thicknesses of 200 feet, showing their characteristic false-bedding, near Junagarh, which is 30 miles from the coast ; but the foraminifera are carried much farther inland, being found as far as Bikaner in the RajputJina desert. The rounded and small shells of the foraminifera which make up such a large part of the Porbandar stone are often mistaken for oolitic grains, which also occur in the deposit (23). The Indo- The most important and extensive among the deposits of G*ngetic ver y y OUn g a g e j n India are the great alluvial accumulations on the confluent plains of the Indus, Ganges, and Brahmaputra. Throughout the great Indo-Gangetic alluvial area a sandy micaceous and calcareous clay forms the prevailing material, the older alluvium being distinguished by the nodular segre- gations of carbonate of lime, called kankar, used largely as a source of lime and as road metal. These alluvial deposits have been penetrated by borings in two places below the sea level. The boring at Calcutta reached a depth of 481 feet without signs of either a rocky bottom or marine beds, while fragments of fresh-water shells were found as low as 380 feet below the surface, and coarse pebble beds were met through- out the lowest section of the borehole, showing that the present site of Calcutta was near the margin of the river valley which has undergone depression accompanying the accumulation of alluvial material. The boring at Lucknow extended to nearly 1,000 feet below sea-level, with no further sign of an approach to the bottom than that shown by the appearance of coarse sand near the end of the hole.

Besides the deposits formed by the great rivers on the plains Upland of India, Assam, and Burma, there are interesting river deposits at higher levels, like those of the upper Sutlej valley in Hundes, which have yielded numerous vertebrate fossil remains; the karewa deposits of fche upper Jhelum in Kashmir; the so- called tanr lands of Nepal, in which beds of peat and phos- phatic clay occur ; and the similar deposits in Manipur and farther east in the Chindwin valley of Burma.

The sand-dunes of the coast of Orissa, the teris of Tinnevelly Wind- and Travancore on the coast, the accumulations of blown sand on the banks of the Kistna, Godivari, and Cauvery, the great gravel slopes which form the daman fringes of the Baluchistan hills, the finer loess of the plains, the extensive accumulations of the Potwar, the great desert sand deposit of Rajputana and Sind, and the peculiar black soil or regar so widely distributed over the Deccan must be passed by with a mere mention.

The rust-coloured caps which frequently cover the rocks in Latent* moist tropical climates, and have been known for a century under the name lateriU^ have long been a puzzle to geologists. In its typical form this material has a vesicular or scoriaceous appearance, on which account it has been supposed by some to have a volcanic origin. Occasionally it has a pisolitic struc- ture, and is often mottled through irregular distribution of the ferric hydrate stain. There is hardly a doubt about the fact that most, and probably all, real laterites are formed by the subaerial decomposition of the rocks on which they lie, and that the peculiar structures they show are the result of molecular segre- gation among these products. For a long time laterite was regarded as merely a ferruginous clay, formed by the decompo- sition of the aluminous and ferromagnesian silicates in the rocks which are attacked by the weather ; but analyses recently made show that much of the silica has been removed during the process of rock decomposition, and that the alumina, instead of being retained as a hydrous silicate such as we get in a clay, is often present as a simple hydrate of alumina, being stained red with the corresponding hydrates of iron, and mechanically mixed with other substances set free during the processes of rock- weathering. * Analyses show a great variation in composition ; but there is a general tendency among later- ites to differ from the rocks from which they are derived by the concentration of alumina, iron oxide, and titania, while the silica, alkalies, and alkaline earths are carried away by the atmospheric waters. The fact that this peculiar form of rock- weathering is characteristic of, and practically confined to, moist tropical climates has given rise to the suggestion that the alteration of the fresh rock is effected by the action of some organism, which grows at the surface of the rock and possesses the power of breaking up the rock silicates. The separated silica is removed in solution, while the hydrated alumina and iron oxide remain behind, and, by their segregative power, cement the other products into a mass with the peculiar structures which characterize laterite (24).

Laterite may become broken off and carried to lower levels by the action of streams, and when re-deposited at lower levels may become cemented again into a compact mass by the segre- gative action of the hydrates, including sand-grains of quartz and other minerals. Thus there are high-level laterites, resting on the rocks at whose expense they have been formed, and low- level laterites, formed in the usual way of detrital deposits. Lateritcsof Laterites are not merely modern formations; several old past ages. j an( j sur f aces s h o \v traces of lateritic deposits. On the old surface of India, for instance, which was overwhelmed and covered by the Deccan trap in uppermost Cretaceous times, laterites existed, and are sometimes now exposed where the weathering agents have cut away the protecting layer of trap. At the base of the Tertiary rocks north-east of Surat, and at a few other places, are rocks having such a perfect resem- blance to modern laterite that there is little or no doubt that the conditions for the formation of this peculiar material existed in early eocene times, and it is probable that many of the bauxites of Europe and America have a similar origin.

BIBLIOGRAPHY

For all papers published on the geology of India before 1893, references will be found in the second edition of the official manual (Manual of the Geo- logy of India] published in that year. Results of importance which have been obtained since, and which are noticed in this chapter, will be found more fully discussed, with reference* to previous literature, in the papers named below. In addition to these papers, certain conclusions and changes in nomenclature are adopted in this chapter, which have not yet been made public. These, however, have been discussed by all the officers of the Geological Survey of India, and have been accepted as representative of their views.

i. F. Kossmatt.On the importance of the Cretaceous rocks in Southern India in estimating the geographical conditions during later Cretaceous times. Records, GeoL Surv. /</., vol. x*viii, p. 39 (1895). The Cretaceous deposits of Pondicherry. Ibid., vol. xxx, p. 51 (1897),

a. T. H. Holland. The Mica deposits of India. Mem. Geol. Surv. Ind. 9 vol. xxxiv, p. n (1902).

3. T, H. Holland. The Sivamalai scries of Elaeolite-Syenites and Corundnm-Syenites. Mem. Geol. Surv. fnd., vol. xxx, p. 169 (1901).

4. T. H. Holland. The Charnockite series, a group of Archaean hyper- sthenic rocks in Peninsular India. Mem. Geol. Sutv. Ind., vol. xxviii, p. 119 (1900).

5. R. Bruce Foote. -The Geology of the Bellary District, Madias Presi- dency. Mem. Geol. Surv. Ind., vol. xxv (1896).

6. R. D. Old ham. Geology of the Son valley in the Rewah State and of parts of the adjoining Districts of Jabalpur and Miizapur. Mem. Ceol. Su~v. Ind., vol. xxxi, pt. i (1900).

7. K. Redlich. The Cambrian fauna of the Eastern Salt Range. "alaeontologia Indica, New Series, vol. i, pt. i (1899).

8. H. H. Hayden. The Geology of Spiti. Mem. Geol. Surv. Ind., vol. xxxvi, pt. i (1904).

9. C. A. McMahon and W. H. Hudleston. Fossils from the Hindu Khoosh. Geol. Mag., decade IV, vol. ix, p. 49 (1902).

10. A. Von Krafft. Notes on the Exotic blocks of Malla Johar in the Bhoot Mahals of Komaon. Mem. Geol. Surv. Ind., vol. xxxii, pt. 3 (1902).

u. T. Tschernyschew. The Upper Palaeozoic deposits of Eurasia. Rec. Geol. Surv. Ind., vol. xxxi, pt. 3 (1904).

12. F. Noetling. Beitrage Zur Geologic der Salt Range. Ntues Jahrb. fur Min., etc., band xiv, p. 368 (1901).

13. H. H. Hayden. On the Geology of Tirah and the Bazar valley. Mem. Geol. Surv. Ind., vol. xxviii, pt. I (1898).

14. C. S. Middlemiss. Geology of Hazara. Mem. Geol. Surv. Ind., vol. xxvi (1896).

15. J. M. Maclaren. The Geology of North-East Assam. Rec. Geol. Surv. Ind., vol. xxxi, pt. 4 (1904).

1 6. A. Seward and A. S. Woodward. On some Permo- Carboniferous (Gondwana) plants and veitcbrates from Kashmir. Pal. Indica, New Series, vol. ii, pt. r, p. 40 (1904).

17. W. T. Blanford. On the ancient geography of Gondwana-land. Records, Geol. Surv. Jnd., vol. xxix, p. 52 (1896).

18. W. T. Blanford. The distribution of Vertebrate animals in India, Ce)lon, and Burma. Phil. Trans., vol. cxciv, p. 335 (1901).

19. M. Bauer. On the Jadeitc and other rocks from Tarn maw in Upper Burma. Rec. Gtol. Surv. Ind,, vol. xxviii, p. 91 (1895).!

20. E. Vredenburg. A geological sketch of the Baluchistan desert and part of Eastern Persia. Mem. Geol. Surv Ind., vol. xxxi, pt. 2 (1901).

a i. F. Noetling. Fauna of the Miocene beds of Bui ma. Pal. Ind., New Series, vol. i, pt. 3 (1901).

22. R. D. Oldham. Report on the Great Earthquake of June 12, 1897. Aftm. Geol. Surv. Ind., vol. xxix (1900). After-shocks of the Great Earth- quake. Ibid., vol. xxx, pt. i (1900), and vol. xxxv, pt. 2 (1903).

23. J. W. Evans, Mechanically formed Limestones from Junagarh (Kathiawar) and other localities. Quart. Journ. Geol. Sec., vol. Ivi, p. 559 (1900).

24. T. H. Holland. On the constitution, origin, and dehydration of Laterite. Geol. Mag., decade IV, vol. x, p. 59 (1903).

25. A. C. Seward. On the association of Sigillaria and Glossopteris in South Africa. Quart. Journ. Geol. Soc., vol. liii, p. 315 (1897).