H. E. BLANEOKD ON THE PLANT- BE APvING SEKIES OF INDIA. 519 



39. On the Age and Cokkelations of the Plant-beaking Sekies of 

 India, and the former Existence of an Indo-oceanic Continent. 

 By Henry E. Blaneokd, Esq., E.G.S. (Read December 16, 



1874.) 



[Plate XXV.] 



The 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 neigh- 

 bouring countries beyond, as far as these are known. The marine 

 fossiliferous formations of Palaeozoic age which are known to be 

 largely developed in the Himalaya and the Salt range of the Punjab, 

 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 Penin- 

 sula 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 Wummulitic conglo- 

 merates of Broach and Surat. With these exceptions and the pro- 

 bably estuarine deposit of Eajamundry (of the date of the Deccan 

 traps), and some recent coast-formations, the peninsula is formed 

 exclusively of crystalline (chiefly metamorphic) rocks of high an- 

 tiquity, 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 Yin- 

 dhyan and Infra-Vindhyan formations, have hitherto proved quite 

 unfossiliferous ; and their age is consequently unknown. But over- 

 lying these (very unconformably), and occupying much of Central 

 India and the north-eastern part of the peninsular region, come the 

 formations sometimes designated as the great Plant-bearing Series, 

 the age of which and of their fossil contents has frequently been 

 discussed in the pages of the Society's Journal and elsewhere. The 

 latest general and comprehensive discussion of this subject is that 

 given by Dr. Oldham in the second and third volumes of the ' Me- 

 moirs of the Geological Survey of India ;' but later notices of parts 

 of the series have appeared in the ' Memoirs and Records of the 

 Geological Survey ; ' and several excellent papers on the geology of 

 other countries have been published, chiefly in the Society's Journal, 

 which help to throw light on the correlations of the Indian rocks. 

 Having lately had occasion to investigate this question, with the 

 help of this later evidence, I venture to submit the results to the 

 Society, and at the same time to put forward some speculations 

 respecting the ancient physical geography of an adjoining region, 

 which, though not entirely original, have not, I believe, as yet been 

 published in a definite form. 



