302 Notes on the South Mahratta Country, fyc. [No. 160. 



scribed. There is frequently an intervening bed of gravel or of the older 

 kunker, in which the remains of a mastodon have been discovered, 

 near Hingoli, Nizam's country. I have not met with gravel beds in 

 the South Mahratta country. The diamond is found in the gravel 

 beds below the Regur in the Cuddapah district. My ideas regarding the 

 origin of those deposits have been elsewhere stated. 



Age of the Plutonic and Trappean Rocks. — Granite. From the ra- 

 rity of sections, it is difficult to ascertain the relative age of the granite 

 by the tests usually resorted to by geologists in fixing the ages of 

 plutonic rock, viz. : 



1st. Intrusion and alteration. 



2nd. Included fragments. 



3rd. Relative position. 



4th. Mineral character. 



Christie evidently views the granite of the South Mahratta coun- 

 try as primitive, according to the Wernerian theory ; but states that 

 there is a granite at Gairsuppa, in Canara, " not so old as the common 

 granite of India," which, from mineral character and association with 

 the gneiss and other hypogene rocks, he classes with them, in the 

 transition series of this school. But within the last half century it 

 has been ascertained that this granite, considered formerly as the 

 oldest of rocks, sometimes belongs even to the tertiary period, and 

 its presence at Gairsuppa, and in the southern portions of the South 

 Mahratta country, intruding into, disturbing and altering as it does, 

 these crystalline schists, plainly proves its posterior origin. 



But there is no proof adduced of any other granite of India being 

 anterior to the granite of Gairsuppa, and there is every reason to be- 

 lieve that the granite of Gairsuppa and the Western Ghauts must rank 

 among the oldest granites of India, until the age of the rocks they have 

 altered and intruded into be satisfactorily proved to be posterior 

 to the other hypogene rocks that prevail so extensively^ over its 

 surface. 



There is, moreover, a granite more modern than the common gra- 

 nite of the Western Ghauts, Gairsuppa, and indeed of India, which is 

 seen to penetrate the latter in veins and dykes, a fact proving its pos- 

 terior origin, — and which, although it has not hitherto been discovered 



