160 KHASI HILLS. 



With reference to the mechanical rocks described above under the seae- 

 ral head of " metaiuorphic," I have already stated 



Metamorphic rocks : xi i i . , , 



two groups of. that, SO lar as they have been examined, they are 



entirely and completely azoic ; no trace of either 

 animal or vegetable remains having been found in them. The distinct 

 age of the two groups to which I have above referred is shewn by their 

 unconformability as well as by their different litliological character ; but 

 I have not attempted on the accompanying map to separate them, my 

 examination of the hills having been too brief and too limited to enable 

 me to trace their boundaries exactly. Of the still more recent sand- 

 stones, I have already briefly spoken above. There is a well-marked 

 group of sandstone and shaly beds greatly altered, very much disturbed, 

 and pierced by veins of granite, totally distinct from any of the more 

 recent beds, but the age of which cannot be determined in consequence 

 of the absence of organic remains. In lithological aspect, they greatly 

 resemble many of the highly altered beds of Central India and the 

 Nerbudda ; but this resemblance may be very deceptive. Possibly in 

 the absence of any evidence of their age, it may be the most convenient 

 way to consider them simply as secondary, without attempting any distinc- 

 tive classification, thus indicating their intermediate position between the 

 . metamorphic rocks below and the tertiary sandstones, &c., above. I was 

 at first disposed to view them as an upper group of the metamorphic rocks 

 themselves — a classification justified by their very highly altered condition. 

 But this would to a great extent mask the real circumstances of the case, 

 and they have therefore been set down as secondary. Their age is 

 to a certain extent very well marked by the intrusion of the granite 

 veins in them, while these are totally absent in the tertiary beds above ; 

 and also by their highly inclined and greatly disturbed positions. 



The group of sandstones, limestone, coal, &c., occurring along the 

 Southern escarpment of the hills, is of much 



Nummulites. . . . 



greater interest. In these, many organic remains 



