Chap. VI.] general structure of hills. 165 



4fth, The occurrence of two lines of least rupture, parallel to the 

 margin of the area, and intermediate between it and the axis. — It is 

 only regarding the southernmost of these, the area, I have spoken of 

 as the Lower Himalaya, that we have any information whatever. The 

 contortions and dislocations of the strata of this area, being demon- 

 strably connected with the more ancient phenomena of disturbance, 

 it can, of course, be assumed that none of them are connected with the 

 elevation in question* 



These are the facts, or supposed facts, upon which Colonel Strachey 

 bases his account of Himalayan upheaval. But the prima facie 

 evidence against the supposition upon which the necessity for such 

 an hypothesis of upheaval rests, seems to me very strong. As far as one 

 can judge from written descriptions, (and the opinion has been advanc- 

 ed by some observers,) those Thibetan tertiaries are deposits of great 

 valley-lakes. If the presence of large mammalian remains (of the rhi- 

 noceros and his associates) should be thought an objection to the 

 supposition lately made by Mr. Jamieson, (Quar. Jour. Geol. Soc, Lon- 

 don, Vol. XIX., 1863,) that these lakes were caused by the damming up 

 of the valleys by glaciers, it may be possible to find a suitable and 

 admissible explanation in the moderate dislocations and changes of level, 

 for which independent evidence can be found. The explanation I have 

 given of the disturbance of the Sivalik rocks involves conditions pre- 

 cisely such as would produce great lakes in the central mountain region. 



Before indicating the few conclusions I am able to arrive at regard- 

 ing the structure of the Himalaya, I will here just mention some iso- 

 lated observations of much interest. We have. already (page 88 and 

 Nummulitic rocks in note > P a g e 92) discussed some surmises as to the 

 aaya * existence of nummulitic strata among the rocks 



of the Himalayan series, along its southern limits, in what I have 



* Colonel Strachey gives a fifth article of evidence, which however does not appear to bear 

 on the question of upheaval now under discussion. 



