I 
part 4 '.] McMaKon: The Simla Himalayas. 215 
I noted in my journal, when as yet I had formed no theory,—“ They are often carbonaceous, 
and closely resemble the slaty schists above the Blaini rocks.” 
From the Nogli to Rampur and beyond, there is au extensive intrusion of trap which 
has tossed the rocks about a good deal. From Rampur to Nirth the dip, at first westerly, 
changes to east, then to south, and then back again to west. 
Following the upper road from the Nogli to Narkanda, on rising from the Satlej, we 
come on white quartzite, then dark carbonaceous slates and schists, and in these, a little 
under Ivunisu, there is a thin bed of blue limestone. It is not crystalline. A little above 
Kumsu the “ central gneiss ” begins. Again on this road, just below the Sungri Bungalow 
(on the ridge near Shiinal of the map), on the northern side of the ridge, a blue sub-crystal¬ 
line limestone appears. The outcrop being in cultivated fields, the immediate “allure ” 
could not be made out. Elevation of Sungri, 8,675 feet. 
The facts to he stated further on have an important bearing on the question of the 
nature of the contact of the Ivrol with the older crystalline series, but I think it will he more 
convenient to discuss that question now. The view I have formed is that the Krol, Infra- 
Krol, and Blaini series were laid down on a denuded surface of the crystalline rocks, and that 
the line of contact has been masked— 
(a) . By the subsequent metamorphism of the younger rocks, at the point of con¬ 
tact, in the wet way; 
(b) . By the subsequent compression of the two series against each other. 
That the younger rocks often appear to he conformable to and to dip under the older 
rocks I fully admit, but is it possible that this conformity can be real P Are we to believe 
in an inversion extending along a great part of the line of the Himalayas P Or are we to 
believe that the “ central gneiss,” and at least 6,000 feet of mica schists on the top of it, 
are really younger rocks than the Simla slates ? If they are, by what means has the meta¬ 
morphism of the younger rocks been accomplished P Heat, the product of pressure from 
above, and heat, the result of plutonic action from below, seem to he put out of court, by 
the fact that the lowest rocks which ought to have been the most changed are the least 
altered.* Metamorphism in the wet way seems to me equally out of the question. Can we 
suppose that during the vast ages required for the gradual metamorphism, by the slow wet 
process, of the great thickness of strata we have to deal with, the Simla slates would have 
remained as unchanged as we see them at this day p 
But may not the observed facts he rationally explained in the way I have suggested P 
A glance at the map will show—and I hope to explain this in detail further on—that the 
dip of the older strata is often low, and at times perfectly flat. It does not seem to require 
a great demand on our imagination therefore to suppose that the younger rocks were laid 
down upon and against the flat strata of the older rocks; and if the plane of junction of 
the two series were often more or less steep, would not- the subsequent compression of the 
two together lead to the idea of conformity, especially if the younger rocks at their point of 
junction with the older had been considerably metamorphosed p That the Krol and Infra-Krol 
rocks have, as a matter of fact, undergone extensive metamorphism has been pointed out 
by others (l. c., p. 3-1); and that this metamorphism has been produced in the wet way is 
indicated by the fact that it is extensive in the porous top schists and stops short at the 
impervious clay slates. 
Heat, the local product of tangential pressure, seems to have been left out of court.—H. B. M. 
