THE QNEISSIG SEEIES. £3 



There is more variety in the rocks of this band than in the red 

 More varied than the gneisses, but the more prevalent form is a massive 

 red gneiss. rather rough gneiss of quartz felspar and horn- 



blende, arranged more or less distinctly in a laminar manner, the laminae 

 or irregular folia being seldom continuous for any extent, unless they are 

 thick, and then they are mainly of quartz or felspar. Foliation of this 

 kind can generally be distinguished over a tolerably large surface of the 

 rock, but with difficulty, and it is occasionally so obscure that the syenitoid 

 character is then very striking. This form is never so essentially syeni- 

 toid, that is, hornblendic, as the mountain gneisses of Southern India, 

 nor is it so well laminated or schisted as is often the case in the 

 low country between these mountain masses. 



In the neighbourhood of Kalahasti, or on the western edge of the 

 belt, there are frequent outcrops of a more laminated or foliated rock, 

 with fair hornblendic strings and nests, and towards Venkatagiri and to 

 the north of that place this begins to show in greater force until about 

 Rapur. In the southern part of this band the syenitoid variety is often 

 more compact, rather pasty and full of small rounded or bean-shaped 

 masses of pale grey or white felspar, thus assuming rather a porphyritic 

 character. In the neighbourhood of Kalahasti and northwards from the 

 Swarnamukhi, it becomes more crystalline and coarse, the minerals occur- 

 ring in larger masses. 



The long bay of gneiss running southwards between the Kalahasti 



Porphyritoid gneiss of *'^ a » d the kl 'g er Kamb& mU ^ sh ° WS aW 

 Kalahasti. <j an t, outcrops and masses of this compact por- 



phyritoid rock, with kernels of white felspar ranging through it in north- 

 north-west to south-south-east laminae, in the long hog-backed hillocks 

 and ridges in the neighbourhood of Royagunta or in the flatter-rounded 

 exposures among the villages 4 or 5 miles west of Kalahasti. At that 

 town itself, on the right bank of the river, a more granitoid form of this 

 gneiss shows under the small hill to the north. The porphyritoid variety 

 also forms a short width of the low country on the eastern side of the 



Kambak range. 



( 131 ) 



