granitoid areas. 31 



2. — The Granitoid Areas. 



To the granitoid group belong all the highest elevations in the 

 gneissic area, e.g., the Kanigiri Drug hills, the Podile and Chimakurti 

 hills, the Bogala Konda, the Yenema Konda and Yerra Konda (near 

 Kommalapadu), the Kotappa Konda, the Kondavidu hills, and lastly the 

 Bellam Konda. A great number of smaller hills also consist of granit- 

 oid gneiss ; but of these only four groups need be named, the Vinu 

 Konda hills, the Darisi hills, the group around Ramakur to the north- 

 east of Addanki, and the small hills around Nadella (Nadendla) to the 

 south-west of the Kondavidu hills. 



Three several forms of ternary granitoid gneiss were observed the 

 Varieties of granite hornblendic, the micaceous, and the epidotic, to 

 gneiss " state them in the order of their relative importance 



and frequency of occurrence. Very frequently, however, the rock 

 appears to be binary in its composition, only quartz and felspar being 

 visible, and the closest search failing to show the third ingredient, 

 unless a freshly fractured surface extending far beyond the weathered 

 surface of the rock is obtainable. This is especially the case in but 

 slightly micaceous varieties. Owing to this difficulty the exact nature 

 of the rock was not obtainable in a large number of eases in which no 

 quarries existed to afford really fresh sections, it being quite beyond the 

 power of an ordinary geological hammer to break up the great rounded 

 weathered masses sufficiently. 



In some few instances the granitoid rock contains both hornblende 

 and mica, but then one or other of the two is to be looked upon as a mere 

 accessory mineral. 



Though in very many cases beds of the two principal ternary varieties, 



the hornblendic and the micaceous, are met with together in alternate 



Areas of predominance strata, one or the other generally predominates 



of hornblendic rocks. over a certain area . such areas f or the hornblendic 



variety are the environs of Pedda Allavalapad and Cherlupally, the 



( 31 ) 



