
84 ) B. N. A. BOUNDARY COMMISSION. 
194. South and east of this locality, where the Boundary-line crosses 
the Pembina Valley, it is still more gorge-like and abrupt, and shows 
several sections of the Pembina Mountain beds. One of those must be 
over 100 feet in height, and though the softer fish-bearing shales probably 
occur at its base, they appear to be completely covered by the falling 
down of debris from the crumbling upper beds. No nodules or bands of 
ironstone appear. Several of the ravines cutting deep into the prairie 
west of the river valley, and south of the Line, show more or less perfect 
sections of the same hard upper clay-shales. 
195. About forty miles west from the foot of Pembina Mountain, 
exposures of beds belonging to the same group again occur in the banks 
of the valley of Long River and in neighbouring coulées. A cliff on the 
west side of Long River, some miles north of the Line, shows a consider- 
able thickness of shale near the water level, underlying a great accumula- 
tion of drift. It is also seen at intervals for ten or twelve miles south 
along the river valley. It appears, as usual, to be quite horizontal, and as 
it is found at various levels from that of the bed of the river to the general 
surface of the prairie, it must still have a thickness of fully one hundred 
feet. The clay-shales here present exactly the physical characteristics of 
those of the upper part of the Pembina River sections, and also resemble 
them in the paucity of their organic remains. The curious rusty mark- 
ings, which may be the remains of small annelid burrows, or of fucoids, 
are still very common; and also other obscure rusty impressions more 
nearly parallel to the deposition surfaces. The mould of a small fragment 
of Inoceramus, which showed the prismatic structure of the shell, was 
found; also the flattened impression of a small naticoid shell, and 
other forms resembling broken portions of a ribbed cephalopod. 
196, Obscure markings, like these, indicating the former positions of 
calcareous fossils, are frequently found in some layers of this clay-shale 
both here and at Pembina Mountain. The fossils themselves, have, no 
doubt, been removed by the action of sulphuric acid, formed by the 
decomposition by surface waters of iron pyrites, contained in these 
little consolidated beds. The acid so produced, has attacked the calcic 
carbonate, converting it into the sulphate, and this has been redistributed 
and deposited in the fissures and more porous layers of the beds as 
selenite. The clay, at the time of this action, must have been so soft 
as to close in on the cavities formed by the abstraction of the shells. 
197. From this point, for over 350 miles westward, I have found no 
exposures of Cretaceous rocks in the vicinity of the forty-ninth parallel. 



