of Salem and Barramahal. 163 



shewn that the blocks shew no signs of disintegration nor 

 erosion, and that where traversed by quartz veins, (on which 

 the weather has no action,) these will never be seen in any 

 case projecting more than two inches above the surface of 

 the block, and in almost all cases do not project at all. 



Further examination would have disclosed the fact, that 

 the original structure of these granite hills is formed by 

 a series of spheroidal masses, embedded in a friable mass of 

 crystalline grains of quartz and felspar, mixed with arenace- 

 ous earth, and some mica ; arranged with their angles fitting 

 and conforming, and evidently perfectly undisturbed and 

 in situ. This, which may be aptly termed " primary gravel," 

 fills the interstices between blocks, and embedding these, 

 rests upon the central nucleus of granite, which appears 

 generally as a crag at the top. Where the spheroids of 

 granite are near to each other, the interstices are often 

 filled in these hills with coarse kaolin earth, an instance of 

 which may be seen at the fort-gate of Royacottah. There 

 is no possibility of this kaolin having been lodged as a de- 

 tritus, nor derived from the decomposition of the granite ; 

 for it is intersected often by vertical and horizontal veins of 

 cracked quartz, with corresponding angles, (as described 

 in the Mysore red marie formation.) 



At the junction between the masses of granite and the 

 primary gravel and kaolin, the division is always perfectly 

 distinct and sudden, the granite being unaltered in texture, 

 composition, or mode of aggregation ; the only visible change 

 being a very slight indication of scaliness. The gravel and 

 kaolin present also no change of appearance, and the slight 

 alteration described between the kaolin and granite in 

 Mysore, I have* never observed in granite hills. Among the 

 irregular crags and masses of granite, other evidences of the 

 form being original may be constantly observed, if attention 

 is given to the examination; for it may be seen that the 

 chinks and apparent fissures have not been produced by me- 



