]2 SUB-HIMALAYAN ROCKS OF N. W. INDIA. [CHAP. I. 



The lithological elements introduced in the top beds of the Subathu 

 rocks increase, till they predominate, to the entire exclusion of any others ; 

 they characterize the indefinite middle sub-group, and are typically 

 displayed on Dugshai hill, and on the ridge to the north of it, through 

 which the tunnel for the Tibet road is being carried. The deep red 

 colour of the clays, and the corresponding dark purple of the sandstones 

 of the middle portion of the Subathu group are useful, general charac- 

 teristics. I used frequently in my note-book to designate the whole 

 group as the " Red Rocks," as contrasting with the paler clays and gray 

 sandstones of the upper groups of the series. As we ascend in the group, 

 the arenaceous element increases to the almost total exclusion of any 

 other. This is well seen in the steep cliffs that form the summit of 

 Kasaoli ridge on the south-west. In these top-beds, both at Kasaoli and 

 elsewhere, I have found some well-preserved impressions of land-plants, 

 — leaves, seeds, and stems of various species. Among rocks so disturbed 

 as these are it is necessarily hazardous to assign thickness ; I do not think 

 3,000 feet is an over-estimate for the whole group. In separate sections 

 each of the sub-groups shows a thickness of at least 1,000 feet. What- 

 ever duration it may be found necessary from fossil or other evidence to 

 give to this group, or if even it should prove desirable palseontologically to 

 separate more positively its upper and lower members, it must, I think, 

 remain as a well-defined petrographiccd whole, an uninterrupted period 

 of some order. Although there is a total and a very marked difference 

 in the composition of the deposits, showing of course an equivalent change 

 in circumstances, yet this change was, or at least may have been, a change, 

 as it were, of natural growth, not involving the interruption of the 

 formative process. The series seems to represent one uninterrupted 

 sequence of formation, the deposits of tranquil and deeper waters 

 being transitionally succeeded by accumulations of sand, in the upper- 

 most of which we find unmistakeable evidence of the immediate proxi- 

 mity of land. The absence of conglomerates or even gravels among 



