40 FOOTE : GEOLOGICAL STRUCTURE OF THE EASTERN COAST. 



Kadapa series came the second period of great east-to-west pressure, 

 which crumpled the eastern half of the Kadapa basin into huge synclinals 

 and anticlinals, several of which are locally inverted. These upheaved 

 and contorted strata were in their turn exposed to denuding agencies, 

 and underwent considerable waste before the series of rocks, called by 

 Mr. King l the Karnul series, began to be deposited. The completion 

 of this series was followed by another period of disturbance and up- 

 heaval, during which most probably a great fracture of the earth's crust 

 took place a little to the east of the line of greatest contortion of the 

 Kadapa rocks. This fracture formed the set of faults now seen to exist 

 along the greater parts of the eastern boundary of the Kadapa basin, 

 and coinciding nearly everywhere with the eastern foot of the Vellakonda 

 range. 



This fracture was accompanied by great displacement of the rocks on 

 either side, and those on the eastern side were greatly upheaved. Sub- 

 sequently to this, denuding agencies attacked the upraised area with 

 intense energy and removed the superincumbent Kadapa rocks almost 

 entirely, leaving in our area only a few outliers, namely, the Baira- 

 wudi Konda quartzites and slates, and the same set of beds in the 

 unconformable patch east of the great fault at foot of the Gali Konda 

 (Gauly Conda) in the south, and the Biravallipaya and Atchammapett 

 " faulted domes " 3 in the north-east. To the south of our area are the 

 very striking .outliers forming the Udayagiri Drug and the Korise 

 Konda. The Yerra Konda and Durgamma Konda, still further to the 

 south, are doubtfully of Kadapa age. None of these gives any clu e 

 as to the limit of the former eastward extension of the Kadapa basin 

 over the crystalline rocks. 



1 The names of Kadapa and Karnul series were given by Mr. King of the Geological 

 Survey of India to the two great series of submetamorphic rocks occurring in the Madras 

 Presidency. 



2 The northern end of the eastern boundary of the Kadapa basin is characterised by 

 a singular series of elliptical anticlinal domes, six in number, extending from Vinukonda 

 nearly up to the Kistna. The two northern ones are true outliers faulted into the gneiss 

 on all sides. 



( 40 ) 



