
264 B. N. A. BOUNDARY COMMISSION. 
the valley separating the sources of the Qu’Appelle and River That 
Turns, has not been heightened very considerably by the accumulation in 
it of debris from its sides, the South Saskatchewan must have cut 
down its present bed, since its occupation, about eighty-five feet. Prof. | 
Hind also believes that the Souris River flowed southward at one time 
through the great depression now occupied by the Back Fat Lakes, and 
joined the Pembina River, a fact which may assist in explaining the for- 
mation of the great valley of the latter. Such changes of bed may have 
arisen from some general alteration in the inclination of the country, and 
itis perhaps worthy of remark, that both the instances cited, show change 
from courses easterly and southerly, to north-easterly ; and such as would 
be brought about by a slight elevatory movement of the transverse 
watershed in the vicinity of the forty-ninth parallel, or an increase of | 
depression northward. 
610. One of the most remarkable instances met with of this sort 
of change, is that of the disused second valley of the Souris, near its first 
intersection with the Line. The old valley lies to the east of the present 
one, and is separated from it by about two miles of prairie. They are 
about equally wide, and depressed about 90 feet below the general sur- 
face, though from a barometric comparison, the valley of the present 
stream appears to be from ten to eighteen feet below the disused one. In 
the old valley, the course of the stream is still discernable, and is occupied 
in some places by small, and somewhat saline pools. 
611. Another striking instance is found in the Great Dry Coulée, 
which joins the valley of the Milk River, a few miles north of the Line, 
and, according to Palliser, extends north-westward to the junction of the 
Bow and Belly Rivers. About equidistant from the Milk River and the 
latter locality, the valley contains a large saline lake, known as Peekopee. 
It would appear that the waters of the Bow and Belly must at some time 
have passed thus to the Milk River, and if this is the case, a northward 
diversion of the water must have taken place here also. 
612. The so-called Riviere des Lacs, which crosses the Line at the 227 
mile point, also seems to occupy the bed of a former stream. This sheet 
of water, where it*is intersected by the Line, must be nearly three quarters 
of a mile wide, and is not fordable. It occupies the bottom of a valley, and 
is over fifty feet below the prairie level. Northward, it extends about 
four miles, becoming gradually narrower, and ending in a broad, dry 
coulée, which shallows and dies away in a strip of boulder-covered ground, 
which stretches northward toward the Souris River, five miles distant, 
