Notes on the Physical Geology of the Upper Punjáb
Authors: Wynne A. B. 
Published: October 2009

From the foregoing notes it will be seen that the geological history of this part of the world extends back to very remote times, and that through nearly all the extra-Himalayan formations there are found some indications of land, probably lying to the south, even perhaps connected with the old tropical continent (Lemuria) supposed to have joined the present peninsular India with Africa as late as the Tertiary period.

In the region between this old land and that where the Himalayan elevations afterwards took place, a state of things existed at two widely-separated periods (pre-Silurian and Eocene) which resulted in the formation of enormous deposits of rock-salt, and in association with the oldest of these there are traces of volcanic energy having been displayed.

In the Himalayan area the marine deposits older than Tertiary present fewer indications of terrestrial conditions. Still that denuded land did exist in those regions, between the Silurian and Triassic ages, is shown by the unconformity at the base of the infra-Triassic rocks, and again indicated by a bed of Mesozoic limestone-conglomerate enclosing rounded lumps of coral-limestone.

In this Himalayan or Western Himalayan region it has been shown that there was again land (probably mountainous) from an early post-Eocene period, if not earlier, also that this elevated ground continued to supply detritus to be carried southwards from the Tertiary period till the present time.

As this later elevation gave the first direction to the drainage-system of which that of the region under notice forms a part, and as the river Indus is one of the drainage-channels, it would appear that the elevation was earliest or greatest in the region where the Indus, the Satlej, and the Brahmapootra rivers rise among the central portions of the Himalaya Mountains.

That glacial conditions prevailed in the Western Himalaya during the post-Tertiary period, either to a greater extent or nearer to the Ráwal-Pindí plateau than they do at present, is to be inferred from the distribution of the large erratic blocks noticed, their transport to where they now rest being attributable to flotation by ice, for want of other evidences of glacial action such as moraines or glacial striæ, to the preservation of which, however, the climatic conditions are not favourable.

It would also appear that another and an older glacial period may have affected part of the formerly existing land to the south-ward; this is shown by the striated boulder of a red granite, unknown in the Himalaya, found by Mr. Theobald on the Salt Range, and fairly presumable to have been enclosed among the pre-Tertiary (or Cretaceous ?) Boulder-clay of that country. Should its striation have occurred since it was removed from this boulder-bed, the glacial period would have been later, probably post-Tertiary, and would account both for the presence of such blocks as the one near Khewra, and for the distribution of the numerous small boulders of the same granite in the country near the east end of the Salt Range. It must be remembered, however, that the clay and boulder-bed whence this block is supposed to have come answers very closely to the description given of the ice-scratched boulder-bed of the Talchir* group described by Mr. Fedden†.

In connexion with the subject of this Cretaceous (?) boulder-bed it may be mentioned that such boulder-shales or clays, first found in the Talchír rocks of central peninsular India by Mr. W. T. Blanford‡, are now known to occur in other places as well. He has recently described an earthy boulder-bed near Lowo and Pokran, in the Sind desert §, older than the Jurassic beds of that country, older even than rocks supposed to be of Vindhyan, and consequently of Palæozoic age. These occur under circumstances which render it possible that they have been transported by ice; so that it appears there are different horizons, sometimes widely apart, in the Indian geological series upon which ice-borne crystalline blocks are found, usually enclosed in soft earthy deposits. Hence the very oldest of the Salt-Range Boulder-clays resting upon the salt-marl may yet be found to contain ice-scored blocks, and all may indicate a recurrence of glacial periods in India, dating from very early geological ages.