100 EOOTE : GEOLOGICAL STRUCTURE OE THE EASTERN COAST. 



The sheets of this tufa, which is very hard, close-grained, and of yellow- 

 ish-white colour, show a lenticularly concretionary 

 At Kovur. 



structure, which gives rise to holes and depressions 



in the surface ; no trace of any organism could be found in it. At Kovur 

 (Covoor), 2 miles to the west, it is seen to rest upon shales of Rajmahal 

 age, but the section is too poor to show the real relation of the beds. It 

 is the densest and most massive tufa I am acquainted with, and but for 

 its concretionary structure, I should regard it as a sedimentary limestone, 

 in which case it would doubtless belong to the Rajmahal series. 



Blown Sands. 

 These iEolian accumulations are more commonly developed in the 



southern part of our area than in any other 

 Blown Sands. . _ . . 



equally large district that I am acquainted with. 



But though so commonly met with, they are mostly of very moderate 

 dimensions, and, except in a few cases, of no particular interest. 

 Three sets of blown sands may be recognized : lstly, the coast dunes and 

 flats ; 2nclly, the river-side dunes ; and Srdly, the inland dunes uncon- 

 nected with any river beds. 



Of the coast dunes but very little need be said; those lying be- 

 tween Ramapatam and the southernmost part o£ 

 Coast dunes. 



the Kistna Collectorate attain to no height, though 



the spreads of loose sand are often more than a mile across. Of those 

 in the Kistna district only a very small part in the extreme south, at 

 Pedda and Chinna Ganjam, and those immediately to the north-east 

 of Masulipatam, were visited. The remainder were for the present left 

 untouched, but they had already been mapped by the officers of the 

 Madras Revenue Survey, whose representation of them has been adopted 

 and shown in the map accompanying this Memoir. It was considered 

 unnecessary to devote to geological features of such very minor im- 

 portance the considerable period of time that would have been requisite to 

 travel over such a difficult country as the sandy and swampy sea edge of 

 the delta of the Kistna. The sand hills at Chinna Ganjam and near 

 ( 100 ) 



