26 foote: geological structure of the eastern coast. 



characteristically displayed. They are so very distinct petrologically 

 from any other members of the gneissic series known to the geological 

 surveyors in Southern India, that they should be recognised as a 

 well-marked sub-group, to which Mr. King, Deputy Superintendent, 

 Geological Survey of India, and I, have given the name of Bezwada 

 Series after the small but important town of that name where the 

 Kistna is dammed back by the anicut, or weir, which forces the water 

 to flow into the series of great irrigation canals traversing the Delta. 

 The anicut is built of the stone quarried at the south and north ends 

 of the Bezwada and Sitanagaram ridges respectively, between which the 

 anicut is situated. 



At a cursory glance much of the stone used might be mistaken for 

 a coarse and much weathered quartzo-felspathic grit, but closer inspec- 

 tion shows its truly metamorphic character, and moderately weathered 

 masses show the micaceous ingredient of the schist quite distinctly. 

 In the southern half of Sitanagaram ridge the beds show a dip of 65° 

 close to the bank of the canal leading to Kommamur. In the Unda- 

 valli ridge the beds appear to have a rather higher dip, which increases 

 to as much as from 70° to 80° in the eastern spur of the Mangalagiri 

 hill, in which the beds make an acute curve, from 

 north by 5°-6° east, to east-by-north. The eastern 

 limb of this great curve disappears after a course of about 1J miles under 

 the alluvium of the delta. The greatest elevation of the Bezwada 

 beds south of the Kistna is attained in the Mangalagiri hill, the tri- 

 gonometrical station on the summit having an elevation of 889 feet above 

 sea level. As seen from this point the several ridges and hills 

 forming the highest points of the Bezwada series show a very remark- 

 ably level outline, as if the flat tops, speaking approximately, were 

 remains of a former great plain of marine denudation. That such 

 Plain of marine de- a P^ am did once exist appears quite certain from 

 nudation. Mr King J s examination of the country north of 



the Kistna, where he found this feature largely developed. The remark- 

 ably level character of the ridge tops, and their near approximation in 

 ( 26 ) 



