IV. 



The Geology of the Central Himalaya/ 



THE physical structure of the Himalaya must always be a sub- 

 ject of great interest to geologists, since our knowledge re- 

 specting the birth and growth of great mountain-systems is derived 

 very largely from this region ; and the imagination is stirred by 

 learning that the main disturbance which brought the rocks to their 

 present elevation took place after the deposition of the London Clay. 



For more than fifty years information has been accumulating on 

 the geology of the Himalaya, but no systematic survey had been 

 attempted of the region now described, until Mr. Griesbach 

 commenced work among the higher mountains in 1879. 



We can understand how unintelligible the geology appeared at 

 first, the slopes being covered with masses of debris, and the peaks 

 being, most of them, inaccessible. Pushing on, however, from one 

 tract to another, the author found many areas where the rocks were 

 exposed, and in course of time the comparisons that could be made, 

 enabled him to piece together the evidence and establish the sequence 

 of rocks. 



In the first part of his memoir, Mr. Griesbach deals with the 

 Physical and Stratigraphical Features, and in tTie second he gives 

 particulars of the sections, and a summary of results. The first part 

 and the summary are naturally the more readable portions of the 

 volume. Attention is drawn to the work in the same or neighbouring 

 regions of other geologists, amongst whom we note R. Strachey, 

 Stoliczka, H. H. Godwin- Austen, McMahon, Middlemiss, and 

 Lydekker. 



The highlands of Central Asia comprise the great Tibetan 

 plateau, tablelands traversed by some mountains, and bordered on 

 the north by the Kuen-Luen range, and on the south by the Hima- 

 laya. On these tablelands we find the head-waters of a few of the 

 great rivers which intersect the mountain-belt of the Himalaya, and 

 thence find their way to the sea across the plains of India. Thus, 

 the Sutleej rises in the southern part of this plateau, in the region 

 known as Hundes. 



1 Memoirs oj the Geological Survey of India, vol. xxiii The Geology of the 

 (!enlral Himalayas, by C L C.riesbach, C.I.li., Supeiiiuciidcnt of the Geological 

 Survey of India. iSyi. Pp. i.-x., 232, and i.-xix. (index). 



