TWENTYSIXTH SIR ALBERT CHARLES SEWARD MEMORIAL LECTURE

GROWTH OF PALAEOBOTANY IN RELATION TO BIOSTRATIGRAPHY OF INDIA

BY PROFESSOR A. K. GHOSH Department of Botany, University of Cl!culta, Calcutta-700 001, India

Published by BIRBAL SAHNI INSTITUTE OF PALAEOBOTANY LUCKNOW

ISSUED 1979 GROWTH OF PALAEOBOTANY IN RELATION TO BIOSTRATIGRAPHY OF INDIA

BY PROFESSOR A. K. GHOSH Department of Botany, University of Calcutta, Calcutta-700 001, India

Published by BIRBAL SAHNI INSTITUTE OF PALAEOBOTANY LUCKNOW

ISSUED 1979 TWENTYSIXTH SIR ALBERT CHARLES SEWARD MEMORIAL LECTURE

GROWTH OF PALAEOBOTANY IN RELATION TO BIOSTRATIGRAPHY OF INDIA

PROFESSOR A. K. GHOSH Department of Botany. University of Calcutta, Calcutta-700 001, India

INTRODUCTION the deep debt of gratitude that they owe LBERT Charles Seward was such to Seward. a distinguished palaeobotanist-cum­ When I was an undergraduate student A geologist that it is a privilege to be in Geology at the Presidency College, asked to deliver a lecture associated with Calcutta in the mid-twenties, I was for the his name. Judging from the galaxy of first time introduced to Sir Albert through scholars who have preceded me for this his monumental work 'Fossil Plants' in lecture ever since its inception in 1953, four volumes (1898-1919) by my teacher, I am fully conscious of the onerous respon­ the late Professor Hem Chandra Das Gupta. sibility imposed on me, and of my limi­ Seward was a histriographer par excellence tations in discharging the same. of palaeobotany and although his "Fossil Sir Albert Seward was born in 1863, and Plants " is in part out of date, it is still an joined the Cambridge University in 1890 essential book of reference in any palaeo­ as a Lecturer and rose steadily to be its botanical library, as is testified by a reprint Vice-Chancellor in 1925. For some times of the four volumes in 1963 by Hafner of he rendered double service to the University New York. and also as a Master of Downing College. As Seward was specially interested in A dominating personality in the world of palaeobotanical studies in general, and India science for nearly half a century, Seward in particular, both in time and space, I feel was elected President of the Geological that I may outline the" Growth of palaeo­ Society of London in 1922, President of the botany in relation to biostratigraphy of 5th International Botanical Congress held India" and choose this topic as the subject at Amsterdam in 1935 and President of the of my talk today. British Association for the Advancement of Science. EARLY HISTORY OF PALAEOBOTANICAL STUDIES IN INDIA Noteworthy, however, is his part in furthering progress of palaeobotany by helping Palaeobotanical studies in India was started young men to become active workers on in right earnest with the formation of the the subject and among those who under Geological Survey of India in 1851, and his guidance later became internationally its first Superintendent Thomas Oldham famous plant morphologists and biogeo­ initiated the Memoirs of the survey in 1856 chronologists, mention may be made of to which, he in collaboration with Prof. Birbal Sahni, Hamshaw Thomas, John J. Morris of London University, made Walton, Harry Godwin and Tom Harris valuable contributions in regard to the (the latter two of whom are still with us), Jurassic flora of Rajmahal Hills in the and it is through them that the present day series "Fossil flora of the Good wana palaeobotanists and biostratigraphers of India System" in 1863, being the volume I, Part I and other countries, realize and recognize of Palaeol'/tologia indica. 4- GROWTH OF PALAEOBOTANY IN RELATION TO BIOSTRATIGRAPHY OF INDIA

It was, however, left to the Austrian Seward's investigations on the flora of Palaeobotanist, Ottokar Feistmantel, who Afghanistan, Afghan-Turkestan, Assam and joined the survey as palaeontologist in 1875, Kashmir appeared in several issues of the to lay the foundation of Indian Palaeobotany. Memoirs and Records of the Geological His monumental works in the subsequent Survey of India. volumes of Palaeontologia indica, published At the request of Prof. Seward, the geo­ between 1877-1886, are well known. These logical Survey of India loaned some of the volumes contain detailed enumeration of specimens described and figured by Feist­ the plant fossils discovered till then with mantel for a restudy. Seward in the early accurate illustrations drawn by artists from stages of this work was only assisted by Bengal. It was Feistmantel, who for the Miss Ruth Holden, a graduate of Harvard first time applied palaeobotany to biostrati­ University and a resident at Newnham graphic classification in India with respect College, Cambridge who got herself inte­ to the Gondwanas and the classification rested in the study of cuticles of Indian of the Gondwana System as proposed by conifers, and Palaeozoic stems of India, him, has stood the test of time, as evidences published in t;le Annals of Botany. Strong addu~edby the scholars of this Institute sense of duty led her to join a British Medical have amply demonstrated Unit in Russia in December 1916 during After the retirement of Feistmantel in World War I where she died in April 1917. 1885 and till the return of Birbal Salwi from Birbal Sahni in the course of his asso­ Cambridge in 1919, there was an ebb in ciation with Seward took up along with activity in palaeobotanical res~archesin him the revision of the Indian Gondwana India, with only sporadic contributions by Plants and this work was completed by R. D. Oldham, H H. Hayden, E. W. Vre­ April, 1919 and was published in Palaeonto­ denburg and G, de P. Cotter of the logia indica in 1921. Prof. Sahni meanwhile GeologicalSurvey of India. returned to India to join the Banaras Hindu A redee.ning feature, however, was that University as a Professor of Botany, in 1920. within this period palaeobotany as a subject ft was thus not till after World War I, of study was introduced perhaps for the that the study of fossil plants was revived first time in India, in the curricula for the in India by Prof. Sahni, inspired by that M.A. degree in Botany and Geology of the doyen of Pal.~eobotanist,Sir Albert Seward. Calcutta University in 1895. 'Fossil Botany' by H. Graf Zu Solms Laubach, INITIATION OF THE APPLICATION OF PALYNOLOGY IN BIOSTRATIGRAPHY Professor in the University of Gottingen, published in 1887 and a revised and english In 1937, I joined the teaching staff of tIle translation of this book by Sir Isaac Bayley Botany Department of the Calcutta Univer­ Balfour of Edinburgh issued in 1891, was sity and inspired by Prof Sahni to take up recommended by the Calcutta University palaeobotany as my subject. Sahni's review as a text book. Feistmantel's researches on India's fossil flora in his presidential and other works on Indian flora available address to the Botany Section of the Indian till then were duly incorporated in this Science Congress in 1938, formed the basis book. of our teaching work on Indian fossil flora During the first quarter of the present both in its botanical and geological aspects. century specimens of plant fossils from At about this time, Miss Chenna Virkki India found their way abroad for study by (Mrs Jacob) was studying the Gondwana Arber, Seward and Walton in U.K., Zeiller Permian miospore complexes under Birbal in France and others. Sahni at Lucknow University. She extended GROWTH OF PALAEOBOTANY IN RELATION TO BIOSTRATIGRAPHY OF INDIA 5 her work in a monograph on spores from Though they are recorded from so many the Lower Gondwana of India and Australia formations. their application to biostrati­ thaI formed an important landmark In the graphic classification In India in early years history of Permian palynology. had been mostly confined in respect of the She instituted the genus Pityosporites Gondwanas and the Tertiary formations. sewardi Virkki in 1937 from the Lower For the Gondwanas, this is mainly due to Gondwana rocks above the Talchir Boulder the abundance of fossil plants and compa­ bed. rative paucity of other organic remains. 1t may be recalled, Seward instituted the In the oil fields, correlation of Tertiary genus Pityosporill!s in 1914, based on his horizons demanded a superior precision and studies on the Antarctic fossil plants, of the palaeogeograp' y was an important objective. British Antarctic (Terra Nova) expedition Palynological studies provided the answer. 1910 and referred to as Pilyosporites Qntarc­ The Burmah Oil Company Limited ticus Seward. sponsored a projeci under Prof. Birbal In 1940, Sahni emphasized" urgent need Sahni, with a view to find out whether the in fndia for a thorough study on a large study of microfossils could assist in the scale of the spores and cuticles of Indian correlation of the Tertiary succession of fossil plants, particularly of those from the Assam - Arakan basin, in quest for oil. Lower Gondwana which contain such a RecogniZing the importance of geochrono­ vast proportion of our most valuable coals." logical studies, and at the invitation of the HIS call for such study was widely welcomed Committee on Measurement of Geological and resulted in attracting attention in India Time in India of the Council of Scientific to their Importance In stratigraphy. and the and Industrial Research, for a sci eme to late Dr J. Sen, while yet a post-graduate organize, systematize and finance research student in the Calcutta Uni versi ty, work ing on the subject Professor Blrbal Sahni drew on palynology of Raniganj Coalfield, showed out a plan in J 946 for research on the perhaps for the first time in India t le appli­ determinatIOn of the age of Indian sedi­ cation of palynology In stratigraphical mentary rods containing microfos~ilsbut geology while correlating the Satpukhuriya, not megafossils. Ghusick and associated seams in 1944. A palaeobotanical research scheme \\3.S Further studies lead to a long controversy initialed by Prof. Sahnl in the Department about the age of the Salt Range Saline Series, of Botany of tbe Lucknow University and in which Sahni played the leading role. later in the Birbal Sahnl Institute of Palaeo­ Although the Saline Series is now in Pakistan, botany. our interest therein can not flag. The latest I may now proceed to review chronologi­ work on this problem is that of the German cally the progress made since then on pal2eo­ geologists o. H. Schindewolf and A. Seile­ botanical studies in relation to biostrati­ cher (l 955), who favour a Cambrian age graphy in India. purely on sedimentological evidence The microbotan ica I evidence pu t forwa rd in the PRE-CAMBRIAN SHIELD two Symposia in 1944 and 1946, sponsored by Sahni raised a host of geological and The absence of fossil occurrences in the palCleobotanical problems of a more funda­ ''irst few million years of earth's history mental character envisaging a new line of encompassing the Pre-Cambrian Era was approach. until recently an accepted fact. Plant fossils are known to occur from The Pre-Cambrian includes the earliest Pre-Cambrian to Sub-recent formations. seven-eight of the geologic time during f, GROWTH OF PALAEOBOTANY IN RELATION TO BLOSTRATJGRAPHY OF LNDLA which period pnmitive life originated a'ld and Bose as early as 1954 examined rock organized itself into multicellular life and specimens belonging to the Kumarmunda it IS here that vigorous search has been Stage of the Gangpur Series and the Kolhan made in recent year'i of their biologic acti­ Series. The microfossils recovered include vity. A lal'ge period of geologic time cover­ scalariform and apparently simple pitted ing the so-called Azoic is now conclusively wood elements together with four types of proved to contain undisputed imprints of spores amongst which monolete ones are life which necessitates a detailed palyno­ noteworthy. stratigraphic studies on the Azoic-Proterozoic The conclusions drawn by me that had sediments. not met with unanimous agreement had Tile Pre-Cambrian shield in peninsular always aroused interest and formed valuable India is widely distributed in Rajasthan, contributions to the discussions of important Orissa, Andhra Pradesh, Mysore a'ld ad­ problems of phylogeny and stratigraphy. joining regions. The rocks ranging in age Sahni and Srivastava (1962) recovered from Dharwars, Cuddapahs, Vindhyans, microspores of primitive vascular and non­ Cambrians have been palynologically Investi­ vascular plants from the Cuddapah rocks of gated by various workers, since [ had repor­ Madhya Pradesh which indicates that lycop­ teu the occurrence of microfossils from sids and sphenopsids were evolved as early as Vindhyans ill 1950 the Pre-Cambrian These studies have a Palae:Jb)tanical and palynological works great bearing and prospects or palynological hav~evolved around the acritarchal and 'itudies in solving the stratIgraphic problems algal renains from the Pre-Cambrian of of these ancient sediments. [nd ia. Gowda and Sreenivasa (1969) repor­ The Vindhyan sediments covering a large ted an assemblage of microfossils from the area in Central India remain to a great G. R. Format ion of Dharwa r, consisti ng of extent unfossiliferous. Search for remains the gl'Oup Acritarc/za Evitt, Denuffte & of life in these sediments centred around Downie. The organic fossils discovered lhe nature of the discoidal remains discovered come fro:n an age group of 2,00)-1,400 by Jones (1909). M R. Sahni (1936) reported million yors b,lsed on the homotaxial Fermoria minima and several investigators relationship. reported microfossils from different localities. Gowda (1970) discovered similar algal Maithy (1968) recorded Tasmanites from remains in the Chert members of Dodguni the Kaimur Series of Madhya Pradesh. Series in Chitaldrug Schist belt of 2,450 Tasmanites previously referred to acritarchs million years which are tile oldest fossils are now attributed to a group of unicellular recorded from India. marine alga, ParslOophyceae. This class [n the variety of material seen and in the was proposed as a result of discovery of excellent mode of preservation, the flora using electron microscopy. discovered in this Archean complex of Salujha et af. (1969-7l) recorded acri­ Mysore has become the most interesting tarchs and algal remains and conclude of the undoubted algal flora known from that Vindhyan sequence ranges in age from the late Pre-Cambrian deposits of the world. Pre-Cambrian - Early Silurian. The fossil Subsequently, Venkatachala and Rawat COntents of Bhimas and Kurnools arc similar (1974, described a diversified biota from to those recorded from the Lower Vindhyan Dharwar-Shimoga Schist belt containlllg (Early - Late Cambrian). acritarchs, and Cyanophyceae (Chroococa­ A recent tool in hand in biogeochrono­ lean) algae, spores, algal filaments, etc. [n logical studies is the stromatolite abounding search of microfossils from Dharwar, Ghosh in Pre-Cambrian shield. GROWTH OF PALAEOBOTANY IN RELATION TO BIOSTRATIGRAPHY OF INDIA 7

Dating as indicated by microfossils for by Curtes and others while studying the the Vindhyans is at variance with the radio­ KoobI Fora Formation of Kenya (1975). metric dating by Crawford and others. The first indications of recorded life are Extensive studies on the dating of Vindh­ thus about 2,000 million years old (blue­ yans and the Pre-Cambrian sediments on the green algae, acritarchs) and around 1,500 basis of potassium-argon method carried million years ago colonie~of algae' (stro­ out in Cambridge by Prof. S. N. SarkaI' matolites) appear to have made their debut indicate the age of Vindhyans, somewhere in the geologit:al ret:ord. between 1,100 and 900 million years. [n the light of this, the plant fossils recorded EARLY PALAEOZOiC FLORAS in the Vindhyans needs re-interpretation. Nor,lu t y we should expect geochronology The existence of land plants in the Spiti and palaeontology to give concordant results. Valley, Punjab Himalayas was alluded to Any large disagreement suggests a more by Sahni for the first time in J938, based critical examination of the evidences from on the collections made by Hayden and both sides and the apparent discrepancies, Von Krafts of the Geological Survey of by different methods need to be reconciled India. A posthumous paper by Sahni by the Co-ordination Committee on geo­ (1953) gave the details of the possible exis­ chronology under the Central Geological tence of Psilophytales in India. Programming Board. Gupta (1967) reported the existence of It is indeed encou ragi ng to see the estab­ Psilophylol1 princeps occurring in arenaceous lishment of a C-14 laboratory in. this insti­ shales lying between fossiliferous Up,)cr tute as a prelude to other similar methods Silurian shales and Middle Devonian quart­ needed at this time. zites of the Spiti Valley of Punjab Himalayas. On the available radiometric dating and [n recent years, A. K. Pal of the Geological contained protistids, a tripartite division Survey of fndia has been working on the of the Proterozoic of India is attempted. Pal.leozoic biostratigraphy of Kashmir Hima­ 1. The oldest member, the G.R. Formation laya. He discovered a series of plant beds of Dharwar Systems (2.5 <.IOl') contain in Devonian and Carboniferous of Kashmir primitive unicellular material, notably cysts, and the results suggest that Devonian-Car­ spores and protistan re,ting stages called boniferous of Kashmir represent a domi­ acritarchs 0;' unknown affinities. nantly continental facies with several marine 2. The Cuddapah (I.OAI09-2.0:~10!')transgressions (as opposed to the prevalent exhibiting sharply advanced biota is equated view of tbc:ir being entirely marine). (had to midd Ie Proterozoic. an opportunity to see some of his materials 3. Vindhyan (0.5 A lOll-LOx 10!l) indicates and photographs which are very convincing. the diversification of Thallophyte and deve­ The plant fossils are clearly of Northern lopment of multicellular organisms. Continent affinity and the possibility of This tentative division is based on study these horizons being in continuity with the of unicellular organisms, discoidal bodies Northern Continent may not be vel'y easy of fungal origin, spores, various algae and to rule out. These beds are followed by stromatolites. plant bearing horizon of the well known There is little doubt that absolute age Lower Carboniferous Rhaeopteris ovala Aora. determination with the help of various The northern record is rich and varied radioactive methods, represents ::J. major as compared to the southern. If the conti­ breakthrough tn the earth sciences although nents had already occupied in the Lower

cl()ubl~have been expressed on ils infallibility Carboniferous the rositiol1 postulated hy 8 GROWTH OF PALAEOBOTANY IN RELATION TO BIOSTRATIGRAPHY OF INDIA the drift theory, it is difficult to imagine not very far from the northern continent, that these delicate plants were able to survive postulating a major change from south to the physical barriers and different climatic norlh and supporting the theory of conti­ belts in migrating from the north to the nental drift. south or it is that the plants at this time Prasad and Bhatia (1975) reported tra­ had reached more or less the same stage of cheids, foraminifera, dinoflagellale algae, evolution in different parts of the world and ostracode and radiolaria from Blaini tillite as Plumstead suggested they were derived horizon of Simla Hills suggestive of a from similar ancestral stocks of algal origin Permo-Carboniferous age for the Blainis. and developed independently. Palaeontological evidence from the Infra­ Kapoor (1969) of the Geological Survey of Blaini sediments by Powar and Phansalkar India has recorded additional evidences of (1971), viz., remains of gymnosperm wood admixture of Lepidodendron, Lepidostroblls, from the phyllites of undifferentiated Chand­ etc. in the Mammal area of Kashmir. pur-Nagthat Formation of Kumaon of Post­ Earlier Tiwari (1965) reported Lepidos­ Devonian confirms Auden's views about trobus from the same horizon in Kashmir. Jaunsars being of Devonian age. These studies reveal the existence of early Various attempts had been made since Palaeozoic flora in India and its relationship long to fit in the stratigraphical position of with the contemporaneous flora of Europe. Krol Senes which is a thick group of massive Although Pre-Gondwana rocks of India blue limestone and shales, uncertain by consists of thick sedimentary deposits, the partly consolidated coarse sandstones and records of land plants are very few. The are exposed in the fOOL hill of Himalayas paucity of fossils calls for more extensive over the Blaini conglomerates and under search for the plant remains in these rock the Tal Formation. Ghosh and Srivastava formations. (1962) studied Infra-Krols, Krols and Tals of the Mussorie Syncline. They could get PALYNOSTRATIGRAPHY OF THE BLAINIS polospore which were quite helpful in AND KROLS setting the stratigraphical problem of this Up to 1974, when a symposium on Blainis senes. and related formations was held at Chandi­ On the evidence of Schizeaceous spores garh under the auspices of the Indian Geo­ Tals are considered as of Jurassic age. The logists Association, no fossil had been Krol with a preponderance of leptosporan­ reported from the Blainis themselves. A giate fern spores and coniferous pollen are rich assemblage of palynomorphs and acri­ indicative of Triassic age. On a reappraisal tarchs has been reported by Shrivastava of the data subsequently, Sah, Venkatachala and Venkatanman (1975) from shale samples and Lakhanpal (J 968) on the dominance of of Blaini Formation. The occurrence of nonstriate-bisaccate pollen confirmed the such short ranging sporomorphs as Denso­ Krols to be of lowermost Triassic, substan­ spor/tes sp., Tripartites sp., Triquitrites sp. tiated by such marker types as the abun­ and Latosporites sp. confirms a Lower to dance of Vo!triacaesporites and Triadispora. Upper Carboniferous age for the Blain! Gundu Rao (1970) on the other hand Formation. reported the Occurrence of oolites of algal Forms belonging to the Northern flora ongln and identified: Volvate!!a vadosa, have not been reported so far from the V. zona!es, Ambigorne!latus horridus, Vermi­ southern hemisphere. The presence of nor­ culites irregularis and Vesicularis bothrydio­ thern floral elements in the Blaini shales formis from Krol C member oflhe Krol For­ indicate that the basin of deposition was mation. The oolites are believed to be of GROWfH OF PALAEOBOTANY IN RELATION TO BIOSTRATIGRAPHY OF INDIA <)

Pre-Cambrian affinities and may be of Upper A possible relationship is noticed among Pre-Cambrian in age. the striate-saccate grains of Lower Gond­ Nalll1ofossiis of Jurassic affinity have wana, with the contemporaneous Eu­ been discovered from limestone and shales American flora, though there is evidences at the contact of Band C stages of Krols of a more serious obstruction to plant in the type area. The age of the Krols is migration from northern to the southern thus a matter of long controversy. hemispheres ll1 the Upper Carboniferous times. In Oklahoma (U.S.A.) the striate­ GO~DWANA saccate grains first Occur in the Des Moines Series (Middle Pennsylvanian) and become Palaeobotany has great signtfl.cance in coal abundant In the MiSSOUri Series. In exploration. Correlation of coal seams of Gearyan Series, they are almost as abundant different areas, exploration of extensive of as in the Lower Permian. There exists an coal-bearing strata and even discovery of intimate genetic relationship between the new coalfields have been achieved with the microfossils and the petrographic compo­ aid of palaeobotany. nents of coal. Palynopetrographic study MicroOoristic study on the Lower Gond­ is helpful to resolve the complex nature or wana deposits has been made extensively coal. An integrated approach involving in Lucknow and other centres. Bharadwaj palynological, petrographical and chemical and others attempted correlation of coal methods is envisaged. seams in the Raniganj, Korba, North Karan­ A re-appraisal of the fos~il110ra of the pura, South Karanpura, Singrauli, Chirimiri, Gondwanas in recenl times and since the Talchir, Bisrampur, Mohpani, Sohagpur classical \York of Feistl1lantel indicating its and Baraboni coalfields. tripartite division, biostratigraphically the Fr·.)m ,h~exhaustive analyses of the mi· Gondwanas are divisible into five assemblage crospores in six coal seams of South Karan­ zones, that could be divided into further punt CoalfIeld, two distinct biofacies could subzones. The assemblage zones are: be evaluated. Miospore genera tdicro!ovco­ !alispora, Verrucosisporilcs, fllclospora and Lahirites constitute upper facies showing close resemblance to the Raniganj Stage. GOllgomopleris NVl'ggewliliopsis­ Assen1blage Zone Parollo('/adlls subzone Miospore genera PlInctalisporites, Apicu!alis­ GOlld"'Qllidiull1·Buriadia porites, Didecitri!etes and Deu/elispora, subzone

Plicatipo!!enites, Cuneatipollenites, Gneta­ G/ossop/(:ri; 8~lrakariadichotoma­ ceaepo/lcnites and Welwelschiapiles repre­ Assemblage Zone Wa/komiella illdica subzone senti ng lower facies show resem blance to eye/Odelldroll subzone & miospore of dennite Barakat' Stage. Glossopleris relijem-G compicl/o subzone Although a beginning has been made, the nner sophisticated and dependable paly­ Labyrilllhodonl As~clllblageZonc nostratigraphic subdivisions of the entire Gondwana sequence is yet to be achieved. Dicroidil/III Asscmblagc Zone EO'orts should be made with support from biometric study to establish phylogenetic Pri/ophy/11I1/1 Dicl)'o:olllites-Pleroph.I·I­ Assemblage Zonc II/III SlIb70nc trends of certain significant taxa, which PIIgiopll)·/ItIlIl-!Jra('/lyph,l·/­ would obvioLlsly be the most depend­ 111111 Sli blonc Weichsc/ill-Ollychivpsi; ab!.:: time-lineages for widespread corre­ 'lIbzonc lation. III GROWTH OF PALAEOBOTANY 11" RELATION TO BIOSTRATIGRAPHY OF INDIA

Surange and his school on ClossofJreri,\ Intermediate tropical region in order to flora have critically investigated and sur­ explain the eXIstence of common elements veyed the vertical range and horizontal in the flora of Western Siberia and Ausrralo­ distribution of species in the Lower Gond­ New Zealandian regions. wanas, The investigations carried out by K R, Surange and 0, C. Bharadwaj and GANGA V ALLFY their school during the last One or two decades have resolved the various aspects On the basis of palynological studies, it of historical geology, stratigraphy, palaeo­ was suspected that the upper part of pre­ climate and palaeoecology of the Gond\\ana Siwalik sequence in the UJhani Well of Ganga seque;lce, Palynological evidence has been Valley in Uttar Pradesh belongs to Meso­ adduced to confirm the occurrence of t\\O ZOIC A re-study of the microflora from glacial phases in the older horizons of the rocks below the unconformity resulted in Lower Gondwana System of India and are the discovery of primitive trace fossil of the within the Karharbari Stage, Although fossils genus Diplocraterian along with spores and have not yet been obtained directly from pollen, the boulder bed, thel'e is some evidence to While the trace fossil in the pre-unconfor­ show that the flora almost co-existed with mity Pre-SiwalJk rocks are indicative of the Permo-Carboniferous glaciation in India. Palaeozoic age, no satisfactory evidence is forthcoming en the invalidity of spores MESOZOIC and pollen of post-Palaeozoic age in these beds, Like the Yindhyans and the KroJs, A significant contribution in the Mesozoic the Ganga Valley data needs reinvestigation, stratigraphic palynology is the recognition of three palynological zones, viz" Callialas­ porites segmcntarlls zone of Upper Jurassic, BAGH BEDS !vfierorarhr)'dit(!s an/arc/iells zone of Neo­ comian, and Coprospora callveriana zone of The fresh-water and marine sediments Aptian - Lower Albian ages in the subcrop of Upper Jurassic to Tertiary assigned to sediments of Cauvery basin. These are the so-called Bagh beds of the Narbada quite extensive assemblage zones of Meso­ Valley in West Central India are well kno\\ n ZOICS of India which might be recorded in in Indian stratigraphy for their rich faunal various basins, such as subcrop Godavari and floral contents, or the fossil Aora, Mesozoic or Rajmahal outcrop. algae are the most conspicuous in the Bagh Srivastava (1963) studied the flora of beds, These contribute considerably to the Lathi Formation of Rajasthan and com­ limestone and percentage of algae by pared with Rajmahal, Jabalpur, Salt Range, volume ranges from a low 2-3 per cent to Ceylon, Australia, South Africa, Western high about 30 per cenL The genera recorded Siberia and Canada and showed great simi­ are ParJ1oea!cu!lIS, Arabicodiurn, Archaeo­ larity with the microflora of Australia, South litholhamnilll1l, Disrichop!ax, Caycllxia, Africa and Western Siberia, differing from Halimcdia, BOII(!inia, Disoclad(!!ia, Oriopore­ that of the Rajmahal and Jabalpur floras lia, etc Cayeuxia !rucrilos(!, a Codiacean It has been indicated that the Jack of algae belong to Maestrichtian age, while Palaeobotanical data from the Mesozoic of Dislichoplax, an index fossil for Palaeoc~n<2 India and South [astern China does not calls for a revised biostratigraphy of the permit the establishment of the probable beds indicating seven biostratigraphic zona­ migration of the floral elements from some tion with extension into the Palaeocene, GROWTH OF PALAEOBOTANY IN RELATION TO BIOSTRATIGRAPHY OF INDIA 11

It is noted that several south Indian very close similarity of the bulk palyno­ Cretaceous forms are common in the Bagh logical assemblage of the two. This simi­ Group. It is suggested that the interming­ larity obviously leads to surmise a broadly ling of the Bagh groups of the Narbada Eocene age of the Neyveli Lignite (Deb, Valley and the Lower Cretaceous forms of Baksi & Ghosh, 1973). Venkatachala South India took place along the passage (1973) also supported this age independently. which opened between India and Mada­ The characteristic elements of the Miocene gascar along the coasts of Cape Comorin palynoflora known to date from other parts and Ceylon with the commencement of the of India are hardly represented in Neyveli Aptian-Senonian transgression. The occur­ Lignite. On analysis of the stratigraphic rence of several South Indian Cretaceous set up of this coastal basin, it is thought that forms in the Bagh Group suggests that the Cuddalore Sandstone is a time transgressive latter is homataxial with the former. unit covering a wide age-interval, in which A huge thickness of limestones having a Neyveli Lignite may be palynologically profusion of calcareous algae have a direct identified as Eocene. Numerous fossil logs bearing on the nature of the lime secreting that are known to be of post-Miocene age algae in relation to the genesis of the algal are thought to have occurred in the topmost limestones. part of the Cuddalore Sandstone. Palynostratigraphic zonations of the subcrop of Cauvery Tertiaries have been KUTCH established by Venkatachala ef al. (1971). Mathur and others (1970) established Lakhanpal (1974) attempted a broad palaeo­ five distinct palynological assemblages geographical reconstruction of India during ranging in age from Neocomian to late the Paleogene and Neogene times based Senonian at various localities in Kutch in on his study of the Tertiary flora. environments ranging from terrestrial to marine conditions. Presence or absence SUBATHU of Weichselia has been suggested as a cri­ terion for the demarcation of Jurassic-Lower The Eocenes of the Himalayan foot-hills Cretaceous biostratigraphy by Bose (1966). have assumed a great significance of inten­ sive oil exploration since similar rocks of same age are producing oil in the Potwar TERTIARY plateau. The sediments known as Subathu extend as a narrow zone along the inner NEYVELI liGNITE margin from Jammu in the north-west to as far south east as central Nepal. The age of Neyveli Lignite, which occurs While based on foraminifera the Subathus as a lenticular deposit within the Cuddalore could be divided into zones extending from Sandstone, has been so far held as Miocene Upper Palaeocene to Upper Eocene, occur­ along with the Cuddalore Sandstone. Not rence of Proxapertites sp. similar to that much work has been done to arrive at the obtained from JaJangi in West Bengal is age of this deposit. A critical comparison indicative of Lower Eocene. Besides, re­ of the palynomorphs based on published covery of hystrichosphaerids in the Bilaspur­ materials as well as on those recovered from Dadahu region indicated shallow marine the lignite with those from the well-dated environment. Eocene formations of different parts of India From further studies it is clear that Eocene has been made. The resu It thereof reveals sea did not extend in the present day plains 12 GROWTH OF PALAEOBOTANY IN RELATION TO BIOSTRATIGRAPHY OF INDIA

of Uttar Pradesh and Nepal and in the covery in this area in 1958 goes to Oil and outer foot-hills of Punjab. Natural Gas Commission. This was an event of tremendous importance as it led CAM BAY AND BENGAL BASIN to discover and develop a fairly large area of oil field, the most important of which is The geology of Bengal basin had re­ the Ankleshwar field (1959) and Bombay mained practically obscure because of the High. thick alluvial cover. Palynographic studies In all these works, the field geological on the cores recovered during deep drilling methods was backed up by petrological, under Indo-Stanvac Project helped the palaeontological and palynological support. establishment of Jurassic - Pleistocene suc­ Plants display remarkable specificities of cession in Bengal basin. The existence of environment. The flora in the Cambay Cretaceous-Lower Tertiary successions in basin (Kalal Formation) has been grouped Burdwan and Birbhum have also been into 15 plant communities, namely, montane, substantiated by the Geological Survey of inland, freshwater, xerophytes, fern, palm, India under All-India Ground Water Explo­ low salinity, pro-haline tidal mangrove, ration Project. algal (Pediaslrum - Oudhkusumiles & Bo­ Palynology has helped remarkably In Iryococcus), fungal, shallow marine. poly­ recent years in Our biostratigraphic study, aperturates and reworked plant complexes. specially the groups nannoplanktons, dino­ Fou rteen transgressive and regressive flagellates, acritarchs, diatoms, silico­ pulses have been interpreted. A f1uvio­ flagellates, etc. It is now evident that spores estuarine, littoral and near shore environ­ and pollen are not lagging much behind ment are envisaged. the other long-reputed traditional animal The results of palynological studies on the microfossil, like foraminifera. Recognition subsurface Tertiary sediments from the of seven distinct palynological assemblage Bodra Well no. I of the Port Canning Project zones characterizing late Cretaceous, Palaeo­ indicate that the sediments are divisible cene, Early Eocene, Oligocene, Miocene, into 3 distinct palynological zones with their Mio-Pliocene and Plio-Pleistocene in the contained microflora comparable with the subcrop-Cretaceous-Tertiary sediments of Upper Tertiary microflora of Assam and Bengal basin and their correlation with the West Bengal. The presence of two-winged rock units of the area seem to be a valuable conifer pollen and spores of the genus Cera­ contribution. lopleris and Aneimia in the Bodra Palyno­ With the establishment of the Oil and logical Zone Ifl recalls the microflora of Natural Gas Commission at Dehra Dun in Simsang Palynological Zone IV of Assam 1956, my interest switched on mostly with and also of the lower zone of Debagram Tertiary palynology in age determination, Formation of West Bengal - these com­ correlation and other biostratigraphic pro­ parisons indicate a Miocene age of Zone HI. blems connected with oil exploration in Microflora of Bodra Zone II and Zone I Punjab, Himachal Pradesh, Saurashtra and may be compared with that of upper zone Assam. By palynological studies, it was of Debagram Formation being represented possible to determine the age and correlate by the dominant Dicksoniaceae and com­ the p'roducing wells at Ankleshwar and mon Cyperaceae, Graminae and Coni ferae. Rudrasagar in Assam. Cambay basin is Dicksonia spores are restricted to Zone I a long alluvium covered by semi-graben while Graminae and Cyperaceae pollen oc­ separating the main Indian Shield from the cur only in Zone IT. Zone II and I may Saurashtra peninsula. The credit of dis- be slqted to range in age from, Pliocene GROWTH OF PALAEOBOTANy IN RELATION TO BIOSTRATIGRAPHY OF INDlA 13

LO Quaternary. The Miocene-Pliocene boun­ of large anticlines, most other favourable dary falls between depths of 3,315 and factors are present for accumulation of oil 3,456 m. in the subsurface Eocene rocks in the South Post-Miocene prospective area - Bodra, Shi Ilong plateau. Bakultala, Diamond Harbour-silt-clay sand A well drilled at Baghmara near the border of marginal marine environment of Mio­ between India and Bangladesh revealed the Pliocene age constitutes about 5,000 m of presence of algal limestones. Palaeogene thick sedimentary sequence of this basin. rocks are exposed and covered by younger Detailed litho-and biostratigraphic break­ Kopilis. down of this thick Mio-Pliocene sequence Discovery of oil at Kharsang of Aruna­ is yet to be achieved. chal Pradesh at 2,850 m which belong to Abundant microplankton, rich vegetation, Tipam group of Miocene. carbonaceous shales, carbonates and evi­ It is of interest that indications of oil dences of reducing environment of the have been found ill even younger wells Pliocene-Miocene sequence of this pros­ (Namsang beds) in a well drilled beyond pective basin induces to drill more wells the Digboi-Jaipur line of folding. for oil. Apart from correlation of wells, palyno­ logical data obtained from Cretaceous to Sub-Recent times has thrown new light on CORRELATION OF BIOSTRATIGRAPHY OF tht> distribution of flora during the Tertiary S[WALlKS AND ASSAM times and its bearing on the evolution of the present day flora. Lower Siwalik & Gin!jan Clay Stage­ The microfloral composition of the lower Siwalik and Girujan Clay Stage are closely QUATERNARY comparable by their common elements. Within a thickness of over a thousand feet of quaternary deposits, there are three GARO H[LLS or four glacial horizons, corresponding to those in the Pleistocene of Europe. Vast In the southern foothill of Shillong plateau thickness of sediments indicated as Quater­ of Garo hills whose prospective sediment of nary in Indian Geology without any fossil Palaeocene-Pliocene age are exposed, the evidences, are areas where we may divert sequence contains Rewak shales (source our attention. It needs a multidisciplinary rocks) and Boldanguri sandstone (reservoir approach. A beginning has been made rocks). and it would be interesting to know more The stratigraphic framework proposed about our immediate past. have stood the test of time for the Oligocene Who knows if the present age is nothing - Miocene part of the succession but some but the phase of an interglacial period? revision have been necessary in the rocks I express my sincere thanks to the autho­ below and above this range. rities of the Birbal Sahni Institute of Palaeo­ The work done so far has indicated that botany to have given me this opportunity palynological data have considerable poten­ to pay my respectful homage to the memory tialities to a deeper knowledge of the Assam­ of Sir Albert Charles Seward and the founder Arakan Geology. Apart from the existence of this Institute Professor Birbal Sahni,