Table Lands of South India. 303 



The Petralogical characters of the above rocks cannot be 

 entered upon here ; but hereafter will be given under their 

 respective heads ; for although I consider the identification 

 of particular rocks to be of the greatest consequence to 

 perspicuity in local descriptions, yet as the subject of this 

 paper is more Geological than Petralogical, I shall postpone 

 the minutiae for the present. 



The beds in which these rocks are arranged are very irregu- 

 lar, and are very seldom continuous for any distance. They 

 seldom exceed a few feet in thickness, and almost always 

 fine out at both ends when both can be seen ; sometimes 

 one bed is found embedded in another; sometimes parallel 

 beds, in violent contortions, may be traced for some little 

 distance, and soft masses in concentric layers are common 

 in the friable gneiss and hornblendic rocks. 



The beds of the various hornblendic rocks form a very 

 large proportion of this formation, and are constantly divided 

 by rhomboidal partings, both vertical and horizontal, the 

 separations of which are filled with kunkur. In a soft rock 

 which may be called friable trap or wacke, seams of kunkur 

 dividing it into rhomboidal masses three or four feet square 

 are common. 



Massive beds of milk quartz are common, but they never 

 take the appearance of veins, while small tortuous veins of 

 quartz, both compact and sometimes friable, frequently 

 only an inch or two thick, occur very commonly between, 

 or crossing and cutting through several beds, and these 

 veins, as in the Mysore red marie, fine out perfectly, and are 

 never connected with the larger beds. 



In the friable gneiss and pegmatite, contorted streaks or 

 veins similar to those described in granite are very common ; 

 and also similar nests of sienite, which are not harder than 

 the embedding rock occur, apparently half melted and drawn 

 out into streaks which mingle in the mass. 



Generally the rocks nearest the granite are the hardest, 



