172 Reviews — Geological Survey of India. 



quantities. In some places the ground is broken up and irregular, 

 in others it is shaped into innumerable hills, with only the 

 scantiest vegetation ; sometimes it is covered with jungle, at others 

 stony and barren. The form of the trap hills distinguishes them 

 from inlying hills of sandstone, and the vegetation of each is also 

 sufficiently distinct ; a very characteristic difference is the abundant 

 supply of teak saplings on the Trappean hills, which are quite 

 uncommon on the sandstone. 



Petrology. — Both the Upper and Lower Vindhyan series consist of 

 alternations of Limestones, Shales, Sandstones, and Conglomerates, 

 (distinguished in many cases by local names), but the strata of the 

 Lower series are as a whole calcareous and argillaceous, while those 

 of the Upper are arenaceous and argillaceous ; and while, in great 

 part of the Upper series, the beds are thick-bedded and massive, 

 flagginess is a prominent characteristic in the Lower. Lateral 

 alterations are often observed, by which limestones in one locality 

 change to shale in another. Wherever the junction of the two series 

 is seen in section, they are found to be conformable, but there is 

 reason to suppose a slight unconformity really exists. That the 

 Lower was more or less denuded during the formation of the Upper 

 is amply proved by the abundant fragments of its strata frequently 

 observed in the bottom beds of the upper series. The Vindhyan beds 

 have therefore been separated into two divisions. 



The thicknesses of the beds vary much in different places, partly 

 from original conditions of deposition, and partly from the effects of 

 subsequent denudation. In the neighbourhood of Eewah, the full 

 thickness of the Upper Vindhyans is about 2,500ft., while in the Dhar 

 forest it has been estimated at 10,000ft. At Eotasgurh the Lower 

 Vindhyans are about 2,000ft. thick. 



As yet no reliable fossils have been found in either the Upper or 

 Lower Vindhyans. 



Age. — Their age, relatively to the stratified formations newer, 

 cannot be determined by the test of superposition, as no more recent 

 deposits anywhere overlie them, except such as are known to be 

 vastly younger. They rest, with marked unconformability, on the 

 older rocks. 



The Vindhyans are in the Indian scale mediate between the Bijawurs 

 and Grwaliors on one hand (the relative age of which to each other is 

 yet uncertain), and the Talchirs on the other. This latter is the first 

 formation beneath the lowest coal as far as is yet known. 



"With regard to their age, according to the European standard, little 

 can be said. In a previous volume of the Memoirs, Dr. Oldham 

 pointed out the probability of the Damuda system, representing in 

 part the Permian and Upper Carboniferous periods, which would 

 indicate for the Vindhyans, therefore, some age older than the Upper 

 Carboniferous. Mr. Mallet remarks that it would be curious if they 

 were to turn out of Old Eed Sandstone age, as to this period they 

 were referred, in 1825, by Dr. Voysey, for no other reason than 

 their lithological similarity. 



Denudation. — The Vindhyan area, especially in the eastern districts, 



