CirAr. IV. 1.] METAMOIIPIIIC HOCKS. 79 



cases are of horublendic schist of black or greenish-black colour. The 

 accomj)anying' sketch (Fig. 2) shows a portion of the bed in question^ with 



Fig. 2.— Quasi-conglomeratic gxeiss, nkau Ciiittanuk. 



several included fragments^ the largest of which measures about 1 foot 10 

 inches in length. The same pseudo-conglomeratic nature of the gneiss 

 beds may also be well observed at Arkadu^ wdiere the rocks come 

 doAvn to the bank of the Punniar river in a well-marked ridge ; also at 

 Puragil^ on the banks of the Teringee Aur^ a small river rising near Trino- 

 malli and entering the Punniar opposite to Tirukovilur. Lastly, we have 

 to enumerate a very clear exhibition of included blocks at Seganankottei^ 

 about half way between Tirukovilur and Tiagar. Owing to the peculiar con- 

 stitution of the greater part of the rocks just described, the greater part 

 of the area occupied by them is covered by a very sandy soil, generally 

 of very pale colour, but here and there passing into decided red soil. 

 Cotton soil occurs no where but at the southern extremity of the por- 

 phyritic rock districts. The sandy soil consists mainly of silex, with 

 a smaller proportion of decomposing felspar, and not unfrequently a few 

 small lateritic pellets. Owing to the very sandy nature of the soil and 

 the o-eneral flatness of country, most of the rain falling on it is absorbed, 

 and in consequence there are but few well-defined water-courses to be 

 met with over this sandy region. 



The tendency of the granitoid rock to weather into tors has already 

 been adverted to. They are very common in many parts, and form very 

 conspicuous objects in the landscape from the boldness of their position 



( oOl ) 



