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NOTES ON CRETACEOUS FOSSILS FROM AFGHANISTAN AND KHORASAN. BY THE LATE H. S. BION, B.SC., F.G.S., Assistant Superintendent, Geological Survey of India. WITH AN INTRODUCTION BY J. COGGIN BROWN, O.B.E., D.SC., Superintendent, Geological Survey of India.
(J. C. B.)
MONGST the papers left by the late Mr. H. S. Bion at the time of his lamented death in June, 1915, were a number of notes on Cretaceous fossils from Afghanistan and neighbouring regions, which it was his intention to bring together into a paper for publication in the Records of the Geological Survey of India. Parts of the notes were typed out and finished, others were in manuscript, while in one or two cases merely the identification of the fossil itself had been made. Before proceeding to give a list of the forms recognised by Mr. Bion, together with such notes on them as he had prepared and his conclusions drawn from a study of the fauna, it is necessary to point out that the bulk of the collection was made by the late Mr. C. L. Griesbach during his deputation with the AfghanBaluch Boundary Commission. To these were added a few forms obtained by the late Sir Henry Hayden during his sojourn in Afghanistan, and one or two more collected by the late Dr. W. T. Blanford from the neighbourhood of Dera Ghazi Khan in the Punjab.
In 1887, Griesbach, as a result of the extensive traverses undertaken in earlier years, was able to demonstrate that rocks of Cretaceous age are widely spread over Afghanistan and Central Asia. They form a large part of Afghan Turkistan, and, to the west and north-west, extend in strips through the Herat province into NorthEastern Khorasan, where apparently all horizons from the Neocomian to the Upper Cretaceous Exogyra limestone are represented. Elsewhere, the lower portions of the system are missing. Griesbach found Cretaceous strata in great force between the Hindu Kush
and Peshawar, in the south-western prolongations of the Central Afghan ranges, and in the Sulaiman Range. In Khorasan and Northern Persia, Cretaceous rocks form great ranges and play an important part in the structure of the mountain ranges which skirt the northern frontiers of Persia. In Central Asia proper, the Upper Cretaceous covers a large area and hides nearly all the older formations, which appear only in isolated patches where the overlying mantle has been denuded away. To Griesbach, already acquainted with the Central Himalayas and Kashmir, where Cretaceous rocks are comparatively rare, their vast expanses in the regions mentioned were at once arresting and remarkable. His terse descriptions of their prominent features are scattered through a series of papers published between the years 1885 and 1887 under the general title of "Afghan Field Notes." In the first of these, a short report on the geology of the Herat province,1 there are brief preliminary notices of the Tir-band-i-Turkistan beds. In the second, which deals with the Herat valley in more detail, and in addition with Eastern Khorasan, Griesbach divides the Cretaceous rocks of the latter region into a lower and upper group and traces their distribution generally. The third paper describes reconnaissances carried out between the confines of Afghan-Turkistan and the district of Bamian in Afghanistan, which includes the areas north of the Tir-band-i-Turkistan and the Koh-i-Baba to the Oxus valley. Herein we find the Cretaceous system divided as follows:
White chalk with flints. Inoceramus Tir-band-i-Turkistan Range and anti-
Main mass of the Kara Koh and folds between Saighan and Tashkurghan.
(Clays, shales, shell limestone, and beds Middle course of the Astar-ab and of
Detailed descriptions of the various sections are given, together with the following comment on the fauna :- The commonest fossils found in this group are Exogyra sp. and Janira quinquecostata besides numerous others which have not been determined yet." Mr. Bion's investigations were concerned mainly with these then
1 Rec., Geol. Surv. Ind., Vol. XVIII, pp. 57-64 (1885).
3 Ibid., Vol. XIX, pp. 235-267 (1886).
undetermined remains. In the fourth paper,1 Griesbach considers the geology of the country crossed by the Afghan Boundary Commission on its return to India across the Hindu Kush and through Kabul, while in the fifth 2 and last note, we find his general conclusions accompanying a geological sketch map of Afghanistan and NorthEastern Khorasan, as well as a table in which the Cretaceous rocks of Khorasan, Herat, Turkistan and South-Western Badakhshan are correlated with these displayed in the sections from Sibi to Kandahar and in the vicinity of Kabul.
A quarter of a century later, Sir Henry Hayden's memoir on the "Geology of Northern Afghanistan was published.3 Sir Henry in his introduction to this work, wrote:-"What little we know of Afghan geology is due chiefly to Mr. Griesbach's own work in that country between the years 1880 and 1888, the scientific results of which were published in the Records of the Geological Survey of India, Vols. XVIII, XIX, XX and XXV. Since that time nothing has been published on the subject, and the small amount of purely scientific work that I was able to do during a short tour undertaken primarily for the investigation of economic questions has tended to confirm on the whole, and to some extent to amplify, Mr. Griesbach's conclusions."
Describing the Cretaceous system, Sir Henry wrote "This comprises by far the most widely distributed group of rocks in Afghanistan to the north of the Koh-i-Baba and the Hindu Kush, From these ranges northwards to the plains of Afghan Turkistan, the whole area was formerly covered by a sheet of Upper Cretaceous limestone, which was deposited unconformably on all older formations." At the base of the series in the neighbourhood of Ishpushta, "there is a well-marked overlap, representing the great Cretaceous transgression which affected such a wide area in Central Asia and which is usually attributed to the Cenomanian period. Although fossils are fairly numerous in the beds above the basal limestone, I was unable to collect more than a very few, and these are all rather badly preserved. In Upper Saighan some shaly marls and arenaceous limestones yielded echinoids and ammonites, which my colleagues, Messrs. E. Vredenburg and G. H. Tipper, have been kind enough to examine for me." Mr. Vredenburg determined the
1 Rec., Geol. Surv. Ind., Vol. XX, pp. 17-26 (1887). Ibid., Vol. XX, pp. 93–103.
Geol. Surv. Ind., Vol. XXXIX, pp. 1-97 (1911).
echinoderms as Micraster sp. and Cyphosoma sp., and pointed out that this was the first occurrence of the genus Micraster in Asia, and proved that the rocks from which it was derived could not be older than Middle Cretaceous, and probably not older than Cenomanian. Mr. Tipper referred the ammonites to the genus Hoplites. small fragment of Scaphites sp. and a brachiopod very closely allied to, if not identical with Terebratula semiglobosa D'Orb., also occur at the same horizon. The limestone overlying these beds is full of lamellibranchs, among which the genus Exogyra is very common and led Mr. Griesbach to call the rock, "Exogyra limestone." Gryphaa vesicularis Lam. occurs in this limestone at about 150 feet above the horizon of the ammonites and Pecten (Neithea) quinquecostata Sow. The limestones, therefore, are perhaps not older than Senonian, whilst the underlying marls may be as old as Cenomanian."
Such was the state of our knowledge of the Cretaceous faunas of these regions when Mr. Bion commenced his study of the fossils which Mr. Griesbach and Sir Henry Hayden had deposited in the collections of the Geological Survey of India in Calcutta.
Mr. Griesbach's specimens come from various localities in Khorasan and Afghan Turkistan, those collected by Sir Henry Hayden from the Saighan district of Afghanistan, while the few specimens which Dr. Blanford collected are from the Sulaiman Range in the Dera Ghazi Khan district of the Punjab.
List of the Forms identified by Mr. Bion.
Micraster præcursor Rowe.
Serpula filiformis Sow.
Terebratula sella Sow.
Terebratula obesa Sow.
Terebratula biplicata Sow.
Exogyra ostracina Lam.
Pecten (Neithea) quinquecostata Sow.
NOTES ON THE FOSSILS.
(H. S. B.) Cyphosoma sp.
There are two specimens representing this well-known Upper Cretaceous genus, but the preservation is too imperfect to allow of specific identification.
Locality.-K.11-328. Cretaceous marls near the base of limestone cliffs between Begal and Khárgin dara, Saighan, Afghanistan (lat. 35° 11' long. 67° 29′).
Micraster præcursor Rowe.
There are six specimens available for description, all more or less damaged. Five of these were collected by Sir Henry Hayden
in the Cretaceous marls near the base of the limestone cliffs between Begal and Khárgin dara, Saighan (lat. 35° 11′ : long. 67° 29′). The cliffs alluded to are composed of the Upper Cretaceous Exogyra limestones, which are in great part of Campanian age. The exact locality from which the fossils came is marked on the photograph reproduced in Plate 3 of Hayden's memoir.
In the same memoir (p. 36) there is a short note by Mr. Vredenburg to whom the generic identification is due. The note is as follows:-"The four specimens of a spatangoid echinoderm are too crushed and too incomplete for specific determination. Nevertheless the generic characters are perfectly recognisable; the specimens belong to the genus Micraster, the extremely short ambulacral petals recalling forms from the Cretaceous of Europe. So far as I am aware, this is the first Cretaceous Micraster obtained in Asia. None, at least, is known from India or Persia. The rocks containing