164 NERBUDDA DISTRICT. 



great Puchmurri Hills, of which the accompanying sketch, (Plate IV), 

 presents a view. The sandstone of the escarpment when looked at, as in 

 this view, from the valley below, presents a character not only different 

 from, but strongly contrasted with, that of the rocks of the low ground 

 (in this place flags and shales of the lower Damuda series), and still the 

 difficulty of determining the position of the line of demarcation between 

 the two formations exists even in the best exposed sections. Few, how- 

 ever, of these are found free from the talus which generally hides all 

 rocks in place along the base of the hill. 



It is superfluous to state that in order to measure the thickness of the 

 highest member of the lower Damuda' s sub-division (f), its upper limit 

 must be definitely fixed, and thus we are here again reduced to unsatis- 

 factory approximations and estimates which, however cautiously they be 

 made, must remain uncertain and to a great extent conjectural. 



There is no positive evidence that this member of the lower Damu- 



da-group is now represented by a thickness of more 

 Thickness estimated. _^ P -ri i • n -, 



than 400 or 500 feet. It has, as being found at 



or near the top of the series, suffered much from denudation, and may 



once have attained to very much greater dimensions. It is indeed this 



portion of the series which more especially swells to such wide proportions 



in the Johilla sections, and it may hereafter appear, that very considerable 



portions of the sandstone masses of the Gondwarra hill district, which 



must be for the present included within the Mahadeva boundaries, in 



reality are outstanding and undenuded portions of the lower Damudas.* 



Summing up what has been already stated on the subject of the 



thickness of the rocks of the Tawa valley district, we have for 



The Talcheer group (a,) (5,) (<?,) 600 



Lower Damuda ditto (d,) (e,) 700 



Ditto ditto ditto (/,) 450 



1,150 



A minimum thickness in total, of 1,750 feet. 



* As a possible case of this we may mention the massive sandstones of the Kangla pas?. 



