12 R. D. Oldham — Esmys in Theoretical Geology. 



to the south-west there is no indication of the original limit of 

 deposition ; and the small outlier in the Singhe La, between Zanskar 

 and the Indus Valley, is described by Mr. La Touche as consisting 

 of a foetid limestone, resting directly on the Secondary quartzites 

 without the intervention of any beds of a littoral or shallow-water 

 origin.^ From this it is evident that the land-surface must have 

 been far to the southwards, and it may be that the sea extended 

 over the whole of the Himalayan area between this and the outcrops 

 of the Subathu group, as it certainly must have done over a con- 

 siderable portion of it. 



Having briefly reviewed the geology of the Himalayas so far as 

 is necessary to make what follows intelligible, we must now enter 

 into a detailed consideration of the evidence. It is not, however, 

 intended to give here anything resembling a complete account of 

 the geology of the Himalayas, for such would be impossible in the 

 space available, but merely to notice such points as have a special 

 connection with the age and elevation of the Himalayas. 



The first, most important, most palpable and unmistakeable point 

 that stands out is that, at the commencement of the Tertiary period, 

 the Himalayas did not exist as a distinct mountain range, or at 

 least that, if the Himalayan system of disturbance had commenced, 

 it had not extended north-west of a line, drawn transverse to the 

 range, through the debouchure of the Ganges. This is amply 

 proved by the occurrence of marine nummulitics in the heart of the 

 Himalayas, in the Upper Indus Valley and in Zanskar, at heights of 

 19,000 to 20,000 feet above the level of the sea. 



But besides this the nature of the contact between the Nummu- 

 litic and pre-Tertiary beds points to the same conclusion. In the 

 Upper Indus Valley the Nummulitics rest directly on an eroded 

 surface of, presumably, Archaean gneiss ; in the outer hills, however, 

 they rest on limestones or slates, and Mr. Medlicott has noticed how, 

 both near Subathu and in the Jamu Hills,^ wherever the boundary 

 is one of original contact, there is no perceptible divergence of dip 

 between the Tertiary and pre-Tertiary formations. The same appears 

 to be the case with the outliers in Garhwal, and this shows that, 

 though the older rocks had been denuded before the Nummulitics 

 were deposited, they had not at that time been seriously disturbed, 

 and that their position was practically one of horizontality. 



It is true that, in his recently published memoir, my colleague, 

 Mr. Middlemiss, has shown good reason for believing that, at the 

 commencement of the Tertiary period, the pre-Tertiary beds were 

 not everywhere so slightly disturbed as the contact with the 

 Nummulitics would indicate.^ But the Himalayan area is a large 

 one, and it would be unnatural to suppose that there had been no 

 disturbance of any part of it before the commencement of the 

 Tertiary period ; while the evidence produced by Mr. Middlemiss 



^ Rec. Geol. Surv. India, vol. xxi. p. 161. 



* Rec. Geol. Surv. Ind. vol. ix. p. 54. 



^ Mem. Geol. Surv. Ind. vol. xxiv. p. 184. 



