104 Report on the Progress of the Magnetic Survey. [No. 2. 



are not a deposit by rivers, but a deposit in a large basin of water, 

 which very probably was fresh water ; they are in no way to be 

 considered as fluviatile deposits by the Ganges or Jumna ; the 

 material for their formation has been brought down from the Hima- 

 layas as well as from the ranges of Buudelkund, and I am quite 

 convinced that the very extensive denudation and excavation of 

 the sand-stone ranges of Bundelkund, Gwalior, &c, has contri- 

 buted in a very considerable degree to the formation of the deposits 

 in the plains of Hindustan. 



The formation of hunker is evidently generally due to a process 

 of segregation of the whole deposit, but besides this concretionary 

 /cunJcer, there occurs in some places a different formation of black 

 hunker, which extends horizontally sometimes to very great dis- 

 tances ; it occurs not very far below the surface and is generally 

 merely covered by drifted sands ; its origin has been connected with 

 the drying up of old lakes (jheels) similar to those found at present 

 in some parts of Hindustan. 



2. To the Southward of Agra, in Bundelkund and Gwalior, 

 occurs a formation of sand-stone with shales absolutely identical 

 with similar rocks, which cover a great extent of surface in India. 



I shall venture to offer a few general remarks upon these rocks. 

 The formation occurs in Bundelkund, in various parts of the 

 environs of the Nerbudda valley, in many places of the Nagpore 

 territory, and in the Eastern Ghauts throughout their extent : it 

 is there apparent in parts in extensive masses as in the Cuddapah, 

 Bangapilly, and Kurnool districts. In other places only occasional 

 masses or strips of sand-stone shales are met with, and the forma- 

 tion has been broken up and destroyed to a great extent by the 

 granitic outbreak of the Ghauts. The formation can be traced, 

 though often interrupted by the granitic masses in the Eastern 

 Ghauts, to the south of Madras. 



I met sand-stones and marls undoubtedly identical with the 

 Nagpore rocks and containing faint vegetable remains as Streper- 

 matoor, 30 miles west of Madras, on the Bangalore road, where 

 they crop out in some places around the tank. 



Another interesting locality which I had the opportunity of visiting 

 was at Trivacery or Teruvacery, a village 18 miles west of Pondi- 



