Association for the Adva?icement of Science. 477 



ture of the district, reference was made to the maps. In the Ner- 

 budda district the series was less interrupted, and there also the 

 same general results were obtained. The southern boundary of 

 this great field was for a large part of its couise produced by a 

 great fault, having, quam proxime, the same general direction as 

 that of the faults bounding the Talcheer field. The age, geologi- 

 cally considered, of these Damoodah rocks was briefly referred to. 

 A large series of drawings of the fossil plants from them were ex- 

 hibit<;d, and the fact of the general oolitic facies of this group, es- 

 pecially of those from the upper beds, pointed out. The difficulty 

 of the question was alluded to, especially in connection with the 

 discover)', on the one side, of several species identical with those 

 found in these Indian rocks in the Australian coal-fields, associated 

 with numerous animal remains distinctly referable to the lower 

 carboniferous era, and, on the other hand, to the discovery in 

 Cuth of other species, also identical with some of these Indian 

 forms, in beds associated v. ith animal remains, undoubtedly refe- 

 rable to tile oolic epoch. It must, however, be borne in mind 

 that the latter forms, or those which the evidence of associated 

 animal remains would show to be oolitic, are only found 

 in the upper beds of the Damoodah series, while those which are 

 common to the Australian fields are those chiefly found in the 

 lower beds. Unfortunately, no animal remains whatever have 

 been found with these plants in the districts examined, excepting 

 some annelide tracts u.seless as distinctive forms. He preferred, 

 under these circumstances, waiting for further evidence before 

 giving any definite opinion as to the age of this widely- extended 

 and important group of rocks. Mr. Oldham then stated that 

 there seemed good reason for separating altogether from the 

 several groups of rocks to which he had referred the whole of the 

 great thickness of sandstones which formed the great Vindhyan 

 range, extending almost entirely across India, from the mouths of 

 the Nerbudda to the Ganges at Monghyr. These appeared to be 

 of prior date, and there was a probability that there was a great 

 line, or a group of lines, of dislocation passing along the general 

 line of the valley of the Nerbudda, and the effects of which might 

 be traced over a very large area, extending towards the north-east 

 possibly even into the Valley of Assam. Besides the examination 

 of these districts, which together included an area of more than 

 30,000 square miles, the geological survey had been able to add 

 to the knowledge of the structure of the country in other ways. 



