of Salem and Barramahal. 181 



while the rock in which the mica is in considerable propor- 

 tion, and in which the mica is arranged conformably to the 

 lamination, I shall term " friable gneiss," following Dr. Benza, 

 who has so applied that term, in consequence of every In- 

 dian variety of such rock being always so finely lamillar as 

 to be fissile and soft. I have here anticipated further and 

 more complete explanations for the sake of preventing any 

 misunderstanding from a neglect, (but too common in writers,) 

 in not defining their terms, which is often productive of seri- 

 ous inconvenience ; as for instance, where we are informed by 

 Dr. Graham, that the common rock of Ceylon is " gneiss," 

 while we have reason to believe, that any extensive form- 

 ations of gneiss is as rare in Ceylon as in the Peninsula of 

 India. 



Outlying Boulders of Granite. 



Rounded blocks of granites may frequently be observed far 

 detached from any range, and embedded among the schist- 

 ous series of the formations of the plains, or even embedded 

 in red ferruginous soil. By many geologists these would be 

 considered as travelled boulders ; but although I have seen 

 many of them perfectly insulated among the matrix which 

 embeds them, yet they may in many cases be seen to be 

 in situ, by their being intersected by veins of white quartz, 

 which run completely through the blocks, and to some dis- 

 tance (for a yard or more) into the matrix. In the block 

 these veins are solid; but in the earthy matrix, they are 

 cracked into small portions with regular answering angles, 

 as has been several times before remarked. This interest- 

 ing fact, Mr. F. Burr, (a well known geologist at Madras,) 

 has informed me that he has also observed in the road be- 

 tween Cannanore and Bangalore; but whether he draws 

 from it the same inference as myself, I am not aware. 

 Wherever gneiss occurs as a formation near granite ranges, 

 large flattened spheroids of granite, sometimes three yards 



