18 king: nellore PORTION of the carnatic. 



This general sub-division of the crystallines is quite clear in the northern 

 part of the Carnatic : in the south-west corner of the present field, that 

 is, in the Venkatagiri and Kalahasti country, the rock is a hard massive 

 granular crystalline gneiss, of pale-flesh and grey colours, with little or no 

 foliation, while on the other hand schistose gneisses are in great force all 

 over the middle of the field, in eastern Kalahasti and the taluqs of Gudur, 

 Nellore, Rapur, Kavali, and Udayagiri. 



These gneisses also appear to be associated in a fairly serial order, 

 though, as is usually the case in South India, 



Succession of tliGSG. 



no good boundaries are recognisable, the change 

 from one to the other group or sub-division, often within a narrow width, 

 being nearly always gradual. Such want of definition would necessarily 

 occur between the more highly granitoid or irregular crystalline aggre- 

 gates and the less distinctly foliated masses, the metamorphie action 

 having been presumably more intense in these rocks : but as the more and 

 more distinctly foliated gneisses are met with, as here and further north 

 in the Kistna and Godavari districts, it seems to me that boundaries are 

 becoming more evident, and will ultimately be recognisable down south 

 when more time can be devoted to the examination of these rocks. 



A distinguishing feature of the Nellore gneisses is that they do not 



„,, , . . number among them a good representative of 



The mountain gneiss ° ox 



of Southern India not the massive grey syenitoid or hornblendic rock 



represented. 



which is so persistent in the mountain ranges of 



South India, and which shows in diminishing force nearly as far north 



as Madras, but which, by its absence here, may perhaps be indicative of a 



much more important separation of the gneisses of Yenkatagiri and 



Gudur than is evident in the field. 



The Nellore foliated rocks may then be considered under the great 



A classification of the sub-divisions of the Massive and the Schistose 

 Nellore gneisses. Gneisses .— 



4. Micaceous, talcose, and hornblendic schists, with few ■) 

 quartz-schists or quartz-rocks 



3. Foliated gneisses, with frequent quartz-schists or 

 quartz-rocks ...... 



2. Grey gneiss (sometimes porpbyritoid) . 



1. Red granitoid gneiss ..,.., 



( 126 ) 



> Schistose Gneisses. 

 | Massive Gneisses. 



