
62 B. N. A. BOUNDARY COMMISSION. 
green, or red, close-grained slaty rock. These slate conglomerates are 
not uncommon at several horizons in Series C., and fragments of them 
have been recognised among the drift deposits far out on the plains, 
129. The crest of a remarkably bold peak on the north-west side of 
the pass, at this place, is composed of thick limestone beds, forming Series D. 
of the general section. They weather light-brown, and fawn-colour 
on exposure, and are found to enter largely into the composition of all 
the mountains of this region. When, as in this instance, they form the 
summits of a peak or ridge, disintegration proceeding most rapidly along 
vertical lines of fracture, produces extremely picturesque and rugged 
outlines. When, however, merely exposed in the side of a mountain, and 
still covered by other beds, they form steep terraced slopes or perpendi- 
cular cliffs quite different in aspect. The upper beds, are generally more 
frequently divided by horizontal planes than the lower. The entire 
thickness of the series must be about one thousand feet. 
130. About four miles beyond the division of the valley, or Kast Fork 
of the trail, a thick bed of contemporaneous trap appears on the tops of 
the mountains on the north-west side, overlying the limestone. This bed, 
which is designated in the series by the letter E., must here be over fifty 
feet thick, though any very precise estimate could not from its position 
be obtained. Great blocks of the trap have fallen into the valley below, 
and increase the difficulty of the trail. The rock is a dark-coloured and 
very compact diorite, but has numerous amygdaloidal cavities. Series F. 
and G. occur overlying the trap in this part of the pass, but were not here 
examined. 
131. A deep transverse valley, filled in some placés with fine spruce 
woods, lies along the eastern base of the actual ridge of the water-shed, 
and from the brook flowing in it, to the summit of the water-shed, an 
ascent of 1,022 feet is made by the trail; which here becomes exceedingly 
steep and hardly practicable for heavily laden pack animals. The rocks 
of the water-shed ridge apparently belong, in this place, entirely to Series 
C., but other beds may also be represented, as the exposures are not very 
good. From the evidence, I have been induced to indicate a fault on the 
weneral section, as separating these from the last described westerly- 
dipping beds of the valley, though their relation was not actually 
observed. 
132. The height of the water-shed where crossed by the trail, as 
indicated by the mean of three closely corresponding readings, taken on 
as many different days, and compared with Mr. Fish’s nearly simul- 

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