56 KING : NELLORE PORTION OF THE CARNATIC. 



an inch in diameter to less than gth of an inch. I noticed in one or two 

 places in quartzo-micaceons schists, mica appearing to replace garnets, 

 having at least assumed their crystalline form." 



CHAPTER V.— GRANITIC AND TRAPPEAN ROCKS. 



The massive metamorphic rocks of the Kalahasti and Venkatagiri 

 regions are only slightly marked by seams of hard binary granite of 

 pink and white felspar and dull grey quartz running with and across 

 the foliation ; but the gneiss is so frequently granitoid itself, that it is 

 difficult to decide whether these are really intrusive or that they are 

 mere segregations. 



The most noticeable development of granite is, however, among the 

 The Ogili and Gudur foliated gneisses, and here again the reefs are 

 g ranite - nearly always running with the foliation, so that 



they must, if they are igneous, be considered extravasated veins, though 

 they also appeared to me to be the result of segregation. These occur 

 on or alongside the main northern road between Ogili and Gudur as a very 

 crowded system* running generally in a north-north-west to south-south- 

 east direction among hornblendic, micaceous, and quartzose schists. From 

 Gudur northwards granite is frequent at intervals all along this belt 

 of gneiss right up to the northern edge of the field. The rock is mainly 

 a very coarse binary aggregate of quartz and felspar (orthoclase), the 

 ordinary ternary form with mica (muscovite) being, however, frequent 

 at places. 



At the Calingula or weir of the Karevadu tank, the micaceous and 

 hornblendic gneiss is intruded on by veins, 3 or 4 feet wide, of 

 coarsely crystallized granite which run between the beds and along the 

 east-west joints. The rock in this neighbourhood is of flesh-coloured 



1 I found it difficult to represent the reefs of Gudur granite on the map as they are so 

 numerous and yet not large enough to allow of their being separately mapped on the 4-inch 

 scale. I have therefore delineated hands in one colour, which are to he considered as areas 

 of stronger development. In the same way I have represented areas of trappeau outburst 

 in one colour, though the real condition of things is often a confused plexus of dykes 

 mid trap masses among hornblende schists. 



( ici ) 



