
GLACIAL PHENOMENA AND SUPERFICIAL DEPOSITS. 219 
but they too, seem to be essentially superficial. They are generally 
of Laurentian rocks, but often of whitish, or yellowish limestone; the 
latter in some places being very abundant. 
497. The eastern front of Pembina Escarpment, is very distinctly 
terraced, and the summit of the plateau, even at its eastern edge, thickly 
covered with drift. The first, or lowest terrace, which is about one-third 
from the prairie level toward the top of the escarpment, is the best 
marked ; but in different parts of the escarpment does not seem to pre- 
serve exactly the same altitude. On the Boundary-line, its height above 
the general prairie level, was found to be about 90 feet, a second terrace 
260 feet, and that of the third level, or summit of the plateau, about 360 
feet. The surface of the first terrace, which is here wide, is strewn with 
boulders, as is also that of the second terrace and plateau above. 
There are chiefly of Laurentian gneiss and granite, but a fewsmaller ones 
of limestone occur. The banks of ravines cutting the top of the plateau, 
and draining westward into the Pembina River, show, in some places, 
a great thickness of light-coloured, yellowish, marly drift, with few 
boulders embedded in it. 
498. South of the Pembina River on the line of the trail from St. 
Joseph’s to Totten, only one well marked terrace level, besides that of the 
summit of the escarpment, was found. Its height was about 270 feet 
above the Pembina River, the summit of the plateau being about 747 feet 
above the same datum.* 
_ 499. The Pembina River, where it leaves Pembina Escarpment at St. 
Joseph’s, shows high banks of yellowish drift material. The pebbles in 
the river valley, derived from the drift, are very varied in aspect, 
including Laurentian, and other metamorphic rocks which may be 
Huronian ; also whitish limestone like that of Winnipeg, fragments of 
calcareous and gypseous nodules from the Cretaceous clays, and a single 
specimen of silicified wood, similar to that found so abundantly in the drift 
of some localities much further west. 
500. On the west side of Pembina River—beyond the escarpment, 
where its course is nearly north and south—many coulées and banks 
show yellowish and light-grey arenaceous or marly drift, often resting 
directly on the clays of the Pembina Mountain group, and then always 
charged with half-rounded pebbles of the underlying rock. The river 
valley, where crossed by the Commission Trail, is over a mile in width, 
_ * The measurements of terraces here given must be considered approximations merely, the weather 
being unsettled, and the readings from a single small barometor. 
