126 GEOLOGICAL & MINERALOGICAL STRUCTURE OF 



The nodular wacken or basalt, is one of the most common forms of 

 trap in the extensive districts, composed of the rocks of this family, south 

 of the Nennadd. 



It occurs perpetually in the extensive and lofty range of mountains, 

 situated between the Puma and Tapli rivers, and appears to form their 

 principal mass. It is found equally abundant throughout the whole 

 of Berar, part of the provinces of Hyderabad, Beder, and Sholapiir, and 

 appears to form the basis of the great western range of trap hills, which 

 separate the Konkan from the interior of the DekJiin. 



It is probably one of the main sources, when decomposed, of the 

 black diluvial soil, to which Hindsuthan owes so much of its fertility. 

 The valley or extended plain of Berar, that of Hasanahad, of Seronj, 

 of Nandidla, south of the Krishna, of the Pcilndd, bordering the Krishna, 

 and numerous others, all lie near the course of rivers, which at some 

 former period have covered these plains and formed their extensive depo- 

 sits of alluvium. Whether the deposition originated in some sudden and 

 partial inundation, or whether it was owing to the gradual subsidence of 

 the waters of the great deluge, I think may be determined by cautious 

 investigation ; I am at present inclined to think that the most probable 

 cause was the latter. 



.au t it; ■ ■ 



The hill of Sitabaldi offers favorable opportunities, if the quarries 

 are extended, of ascertaining positively whether the basalt is merely a su- 

 perficial deposit, or is deeply connected with a mass beneath. It is sur- 

 rounded on all sides by gneiss, or slaty granite, which is found at the 

 base of the hill a few feet deep. Perhaps Nagpur affords more opportu- 

 nities than any other part of India, of studying the geological history of 

 these rocks, as it is situated near the junction of the primary and over- 

 lying 



