12 poote: geological structure oe the eastern COAST. 



This fault, however, does not everywhere form the boundary between 

 the gneiss and the Kadapa rocks in this corner, as after following 

 the fault for about 25 miles northward, the boundary line diverges from 

 it and follows the eastern side of a patch of the basement beds of the 

 Kadapa series, which here rests on the gneissic mica schist. 1 Further 

 north, however, the faulted boundary recurs and extends with only 

 one break up to the Kistna. 



The most westerly set of mica schist beds, which may be called 



the Gotlabailu (Gotlabyloo) series, forms several low but very rough 



jungle-covered ridges which coincide with the 



strike of the bedding. The quartzite beds above 



referred to run in a line nearly north and south through the centre 



Sitarampuram quartz- o£ the miCa ScMst area ' The q^tzite becomes 



ites - in places so micaceous as to pass into true mica 



schists. These beds may be conveniently called the Sitarampuram 

 (Sheetarampoorum) quartzites. 



The second set of mica schists forms the base of the Bairawudi 

 _ . ,. K , Konda, a considerable mountain mass capped by the 

 schist series. largest and most important outlier of the Kadapa 



rocks eastward of the Vellakonda mountains. The mica schists are 

 well seen along its flanks, and the unconform ability of the two* 

 rock series is very conspicuously displayed in the great ravine at 

 the south end of the mountain, after which the series may be suitably 

 named the Bairawudi Konda schist series. The prevalent colours 

 of these schists are dark greenish-grey and a dull dirty yellowish- 

 brown. 



Quartz veins of small but irregular thickness are extremely numerous 

 here as in most mica schists, and the surface is extensively and thickly 

 covered with quartz debris, which frequently hides the rocks over a large 

 extent of ground. 



1 The fault is apparently continuous along the hase of Jthe . Vellakondas, the western 

 side of the patch of basement beds being itself faulted unconformably against younger 

 beds of the same series. 



( 12 ) 



