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CRETACEOUS AND TERTIARY—PEMBINA ESCARPMENT. 81 
mantle of drift, it is impossible at present to fix this group as exactly 
contemporary with that defined by Meek and Hayden. TI shall therefore 
refer to it in this Report merely as the Pembina Mountain Group ; a name 
to which it may well be entitled, from the numerous good exposures 
which occur in the ravines of that escarpment, and which expresses its 
intimate connection with this great feature of the physical geography of 
the plains. 
185. In the valley by which the Commission Trail ascends Pembina 
Mountain, ten miles north of the Boundary-line, and not far from the 
wooded projection known as Point Allard; rocks of this division were met 
with for the first time, in a bare hill-side, which is too gently sloping and 
crumbled by the weather to yielda good section. The rock is a rather dark 
greenish-grey clay-shale, in which no organic remains appear. It holds 
at least one, and probably several, layers of clay ironstone an inch or two 
in thickness, dark brown fragments of which strew the face of the bank. 
The exposure must represent at least 30 feet of the strata, which appear 
to be quite horizontal. The ironstone is very poor, the iron in a sample 
examined amounting to only 19:14 per cent. Itis almost wholly in com- 
bination with carbonic acid, and is associated with much clayey matter, 
like that of the surrounding beds. 
186. Seven miles further west, on the second prairie plateau, of 
which Pembina Mountain forms the front; the Calf Mountain, so called, 
though only about thirty feet in height, forms a somewhat prominent 
feature on the plain. It appears to be an outlyer of a gently sloping 
ridge which runs northward from it, and may be due to the surface 
contour of the drift, but more probably indicates the line of outcrop of a 
bed of the Pembina Mountain group somewhat more resisting than the 
rest. ; 
187. Where the forty-ninth parallel cuts the base of the Pembina 
Escarpment, rocks of this series are well shown in the almost precipitous 
banks of a small stream. Some feet of the upper part of the section 
consist of drift material, in which fragments of the underlying shale 
are mingled with gneiss and granite boulders. Below this, about forty 
feet of Cretaceous clay-shale are exposed, much resembling that already 
described, and of the same dark greenish-grey colour when freshly broken, 
but weathering to a lighter shade. It crumbles into little rectangular 
fragments by the action of the frost and weather, and the bank, even 
where freshly exposed, is penetrated in all directions by cracks with 
rusty surfaces. Several large lenticular septarian nodules occur in the 
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