146 NERBUDDA DISTRICT. 



vious observers had confined their labors to one or other of the rock 

 areas, without comparing these with each other, accounts for the fact 

 that the separation of these rocks, as a distinct group, had not been made 

 previously to the visit of the Geological Survey in 1855. This separa- 

 tion was subsequently announced to the Asiatic Society, Calcutta, by 

 Professor Oldham, after his visit to Central India, in 1856. 



§ 5. (a) Talcheer Group. 



(ti) Lower Damuda Group. 



If we take together the sub-divisions § 5, § 6, and § 7 of our list, 



„ , „ ,, it will be seen from the map that rocks belonging 



General area or the r a » 



newer sandstone. to these groups, form the ranges which bound 



the Nerbudda valley on the south, as the Vindhyans do that which 

 bounds it on the north. • 



Nowhere have the Vindhyans been seen in contact with any of these 

 rocks, and between the boundaries which respectively limit the two groups 

 a long narrow strip of country lies, which maybe considered as occupied 

 by the crystalline rocks, these being however, for the most part, covered 

 by the more recent ossiferous sands, and gravels, and surface clays. 



The area occupied by the rocks of our groups, § 5, 6 and 7, lower 



and upper Damuda and Mahadeva collectively, is 

 N. boundaries. . '. . 



limited on the north by a very straight line run- 

 ning along the base of the ridge which bounds the Nerbudda valley on 

 the south. Looking at the map, pi. II, and commencing at Lokurtullye, 

 at the extreme west of it, this line will be seen to hold a very rectilinear 

 direction, throughout the whole of its length, to the Re wall country on 

 the east, and it is believed to keep the same course down the south side 

 of the Sone valley. Bounded by this line on the north, the rocks above 

 referred to may be seen to occupy a considerable area to the south of it. 

 They are covered by the trap to the south, and west of Lokurtullye. 



