1840.] 



of the Great JOasaltic District of India. 



61 



southern Mahrattas, a country covered -^th a rich basaltic soil, and 

 abounding in schistose limestone, sandstone, granitic rocks, and basalt, 

 it enters the granitic platform of the Deckan, the limits of -which in 

 this direction are unkno-wn. The limestones and sandstones, how- 

 ever, soon reappear on descending the river, and extend across to the 

 basin of the Pennar, and as far as the ascent to the granitic plat- 

 form of the Mysore. It is on the banks of the Kistnah that the richest 

 diamond mines occur, and that the sandstones acquire their greatest 

 elevation, amounting to more than 3000 feet ; the river passing through 

 mural precipices of this rock and of the schistose limestones to be pre- 

 sently described. It then enters the plains of the Carnatic, -where the 

 same rocks occur, sometimes a little elevated above the level of the sea, 

 at others forming the caps of granite mountains, or broken up by varieties 

 of greenstone and basalt. Thence, passing through a narrow gorge in 

 the gneiss hills of Bezwarrah, it enters the alladal plains continuous 

 Vrith the delta of the Godavery. Its -waters, hovrever, are more loaded 

 with mud than the last-mentioned beautiful river, and the deposit of new 

 land may be seen, by the inspection of a common map. to be proportion- 

 ably great. 



The Pennar is comparatively a small stream, but of much geological 

 interest, the greater part of its -waters being derived from the districts in 

 which the diamond sandstones and the argillaceous limestones, on which 

 they rest, are exhibited in their most characteristic forms, and where 

 they are most easily investigated. To describe these strata in detail 

 would be out of place here ; but a few of the leading facts must be stat- 

 ed, that the identity of the formations with those of the fossiliferous 

 district, more immediately the object of this paper, may be rendered 

 manifest. Like all the rivers of Southern India, gi-anite' is frequently 

 seen in the bed of the Pennar, more especially in its southern branches, 

 where the passes of Eyachottee lead to the granitic table land of Mysore, 

 having an elevation of 3000 feet above the sea, or 2-500 above Cuddapah, 

 ti3e principal town of the Pennar basin, With these exceptions, and the 

 occasional appearance of trap through the stratified rocks, the rest of 

 its course, till it approaches the sea, is over rich plains of black and 

 saline alluvium, derived from the decomposition of basalt and of the 

 stratified rocks so often referred to. From these plains numerous table 

 lands, insulated eminences, and ranges of hills, having for the most part 

 a direction nearly N. E. and S. W., rise abruptly, presenting mural pre 

 cipices of difficult access, around the base of which the roads often make 

 extensive circuits. The Nulla MuUa hills extending from the Mvsore 

 frontier to the basins of the Kistnah and Godavery, and the minor ranges 



