110 KHASI HILLS. 



shall hereafter refer) being composed of granites and of metamorphic 

 rocks, presenting on the whole a gneissose character, with a few inter- 

 calated beds of slates and quartz rock, and dykes of greenstone ; the 

 bedded rocks occurring at every angle of inclination and being much 

 disturbed : the Southern portion, on the other hand, is composed of 

 sandstones and limestones with associated beds of coal and shale, which, 

 as a whole, rest horizontally on the older rocks. 



In addition to these, basaltic and greenstone-like volcanic rocks are 

 well exposed in some places. These are of still more recent age than the 

 sandstones with which they occur. 



After this very brief sketch of the general aspect and structure of the 



hills, it remains to describe a little more in detail 

 Eocks, &c. . , , . , . , ,. . 



the various rocks which occur m the district ex- 

 amined, and their mutual relations. Taking these in the order of their 

 relative epochs, the metamorphic rocks demand the first place. Of 

 the igneous rocks, which have so materially modified the aspect, 

 position and structure of these mechanical deposits, we shall speak 

 afterwards. 



Metamorphic eocks. (Gneiss, micaceous slates, clay slates, horn- 

 blendic slates, quartz rocks, &c.) — A very large area in the Khasi hills is 

 composed of slaty and gneissose rocks, presenting for the most part a highly 

 crystalline character, and traversed throughout their entire estent by nu- 

 merous veins of granite, and here and there by dykes and bursts of green- 

 stone. With slight interruption, these rocks stretch from the most 

 "Westerly portion of the hills, which I have examined, to the most Easter- 

 ly. They occur at Nungklow, on the Northern verge of the hills immediate- 

 ly over the valley of Assam, and here form the entire escarpment of the 

 hills down to the Boripani river ; from Nungklow, they extend South to 

 the Kullono- rock (where a great mass of granite protrudes through 

 them), and from thence to near Mow-phlang, where they become 

 covered up by the sandstones. They seem to wind round the Northern 



