324 KHASIA MOUNTAINS. Chap. XXX. 



highly inclined stratified metamorphic rocks, through which 

 the granite has been protruded, and the basalt and syenite 

 afterwards injected. After extensive denudations of these, 

 the sandstone, coal, and limestone were successively depo- 

 sited. These are altered and displaced along the southern 

 edge of the range, by black amygdaloidal trap, and have in 

 their turn been extensively denuded ; and it is this last 

 operation that has sculptured the range, and given the 

 mountains their present aspect ■ for the same gneisses, 

 slates, and basalts in other countries, present rugged peaks, 

 domes, or cones, and there is nothing in their composition 

 or arrangement here that explains the tabular or rounded 

 outline they assume, or the uniform level of the spurs into 

 which they rise, or the curious steep sides and flat floors of 

 the valleys which drain them. 



All these peculiarities of outline are the result of denu- 

 dation, of the specific action of which agent we are very igno- 

 rant. The remarkable difference between the steep cliffs on 

 the south face of the range, and the rounded outline of 

 the hills on the northern slopes, may be explained on the 

 supposition that when the Khasia was partially submerged, 

 the Assam valley was a broad bay or gulf; and that 

 while the Churra cliffs were exposed to the full sweep of 

 the ocean, the Nunklow shore was washed by a more 

 tranquil sea. 



The broad flat marshy heads of all the streams in the 

 central and northern parts of the chain, and the rounded 

 hills that separate them, indicate the levelling action of a 

 tidal sea, acting on a low flat shore ; * whilst the steep flat- 



* Since our return to England, we have been much struck with the similarity 

 in contour of the Essex and Suffolk coasts, and with the fact that the tidal coast 

 sculpturing of this surface is preserved in the very centre of High Suffolk, twenty 

 to thirty miles distant from the sea, in rounded outlines and broad flat marshy 

 valleys. 



