164; SUB-HIMALAYAN ROCKS OF N. W. INDIA. [CHAP. VI. 



to periods anterior to the movement in question. And, as far as I have 

 been able to examine any of the great river gorges, — of the Ganges, the 

 Jumma, the Tonse, the Sutlej, the Beas, or the Ravee, — there is little or 

 no evidence for referring them to transverse fissures, and certainly there 

 is none since the beginning of the Sub-Himalayan period. 



2nd. The more open character and greater importance of the 

 longitudinal fissures in the centre of the area, as evinced by the 

 direction of rivers on the Thibetan table-land. — The very existence of 

 these longitudinal fissures in Thibet rests upon no evidence whatever 

 that I have ever heard of beyond the fact of there being great longitu- 

 dinal river valleys : and the inference from such evidence is by no means 

 necessary. It is inconceivable to me what could be the nature of 

 fissures so great as those supposed, yet which could be produced without 

 disturbing in any degree the great valley deposits, to explain the 

 elevation of which these imaginary fissures are brought in as evidence. 

 But this is not the only case in which this difficulty is introduced. 

 The author explains the separation of a patch of superficial deposits, 

 observed south of the Niti pass, from the main mass of those deposits, 

 in Thibet, by the dislocations which accompanied the upheaval. 



3rd. The existence of an important line of fissure along the outer 

 margin of the Himalayan slope. — The conditions of the rocks along 

 the south base of the Himalaya might easily be interpreted to suit this 

 theory. But the most considerable movements of upheaval (that of 

 the Subathu group,) in this zone can be shown to be anterior to the 

 time of the supposed great elevation ; I have also shown, that there 

 is no great uninterrupted line of fissure. However, by the admissible 

 assumption, that the Thibetan tertiaries are of Sivalik age, or at least 

 anterior to the disturbance of the Sivalik strata, and by setting aside 

 some plain probabilities, the evidence of this disturbance might be 

 interpreted to fix the limits and amount of this last Himalayan 

 elevation. 



