On the Age and Correlations of the Plant-bearing Series of India, and the former Existence of an Indo-oceanic Continent

Abstract

T he Peninsula of India (by which term I denote the whole of the country lying to the south of the Indo-Gangetic plain) has but little in common, in point of geological structure, with the ranges that encircle that plain on the north, or, indeed, with any of the neighbouring countries beyond, as far as these are known. The marine fossiliferous formations of Palæozoic age which are known to be largely developed in the Himáalaya and the Salt range of the Punjáb, have no assignable representatives to the south of the Ganges; and the Neozoic marine formations of the same mountains, of the western ranges, and those of Eastern Bengal are represented in the Peninsula only by the Jurassic and Tertiary rocks of Cutch, the small Cretaceous formation of Trichinopoly, the somewhat older deposits of Bagh, &c. on the Lower Nerbudda, and the Nummulitic conglomerates of Broach and Surat. With these exceptions and the probably estuarine deposit of Rajamundry (of the date of the Deccan traps), and some recent coast-formations, the peninsula is formed exclusively of crystalline (chiefly metamorphic) rocks of high antiquity, of volcanic rocks, and great sedimentary formations, which are either unfossiliferous, or which contain the remains of plants and animals such as, with rare exceptions, indicate a freshwater origin and the immediate proximity of land. The oldest of these, termed by the Geological Survey the Vindhyan and Infra-Vindhyan formations, have hitherto proved quite unfossiliferous; and their age is consequently unknown. But overlying these (very unconformably), and occupying much