20 SUB-HIMALAYAN ROCKS OF N. W. INDIA. [ClIAP. I. 



deposits and the actual positions of the great river courses : both in 

 quality and 'quantity the immense accumulations of boulder conglo- 

 merates, forming the top of the Sivalik group, correspond with the 

 actual debouchures of the great rivers from the main mountain mass, 

 thus proving the great antiquity of even the details of the actual con- 

 figuration. This is indeed a view to which one is predisposed by the 

 contemplation of the prodigious results of atmospheric denudation in 

 excavating the deep winding valleys through the mountains ; but as this 

 process has been variously impugned on the score of inadequacy, it is 

 satisfactory to have the stores of geological time thus clearly opened to us. 

 This same point has even a more important application than that just 

 indicated. These immense accumulations of coarse detritus have under- 

 gone very great disturbance : they are often deeply faulted, sharply folded, 

 vertical, and even inverted ; yet all this has been effected without sensi- 

 bly affecting the details of contour in the adjoining mountain region. 

 The bearing of observation in this direction upon the theories of moun- 

 tain formation, and upon theories of disturbance in general, cannot fail 

 to be very important. The most interesting example that I can mention 

 of the fact here brought to notice is the case of the Sutlej at Bubhor, 

 because at this place this mighty torrent has already for many miles 

 flowed through rocks of Sub-Himalayan formations. Just north of 

 Bubhor the river cuts through a ridge of massive boulder beds stand- 

 ing nearly vertical. The materials of this deposit are precisely such 

 as we now find in the bed of the river immediately above. Within a few 

 miles on either side the low ridge formed by these rocks gradually 

 disappears, the rock itself having passed into a pebbly sandstone. 



I regret that I shall have but little to say in connection with more 

 recent surface phenomena. As one of the most interesting observations of 

 this kind I may here mention the occurrence of what I believe to be 

 glacial deposits in the Kangra Valley, along the flanks of the Dhaola- 

 dhar, at a present elevation of not more than 3,000 feet. 



