72 KING NELL0BE PORTION OP THE CAftNATTC, 



I have already referred to the two low plateau hills of Rasanur and 

 a source of the ferru- Guralur or Kota in the southern or Swarnamukhi 

 ginous element in the iron t £ ^e g e ] c ] as De j n g capped by laterite, which 



stone beds of Rasanur. * ° 



I take to be decomposed gneiss, and to belong to 



this sub-division of the recent deposits. There are other, but very small, 

 elevated patches of the same kind occurring among the Potagunta and 

 Gelacapad ridges, which are even more obviously the result of the decom- 

 position of trappoid and hornblendic rocks, which give quite sufficient iron 

 to allow of this form of oxidization and consequent cementation. The 

 Rasanur and Kota hills are themselves of hornblendic rocks, and close by 

 is the very strong and remarkable outcrop of ironstone schists which no 

 doubt were the source of much of the ferruginous matter distributed 

 through the Cuddalore sandstones of this part of the Coromandel, and 

 which, in its excess here, may have given the group the decidedly more 

 lateritic aspect and constitution which it presents. 



The ferruginous constitution is also found to extend into the great 

 talus of quartzite debris, and shingle spread along the base of the Veli- 

 gondas and the other hill masses ; in fact in the Kalahasti group and 

 about Yarepet and the Venkatagiri country, the passage of a portion of 

 the talus debris into good lateritic conglomerate and breccia is very 

 evident. A considerable portion of the talus deposits must therefore be 

 included in this sub-group, though T think it is quite clear that this 

 talus must have been in process of formation long before this period, 

 while it is still receiving increments of material from the mountain-wall 

 by the curious stream-like strings of debris which tail up some of the 

 steepest gullies or furrows, and down which the debris is slowly and 

 imperceptibly descending. 



(4) . — Recent Deposits. 



The most important of these are the alluviums and blown sands, 

 there being no very marked display of particular soils. Of the former 

 a kind of distinction can be recognised between those of the rivers and 

 those of the back-waters or lagoons. 



( i»o ) 



