

GENERAL PHYSICAL GEOGRAPHY. 3 
is the remarkable fact, first clearly pointed out by Dr. Hector, that the 
rivers flowing into Hudson’s Bay and the Arctic Ocean have their sources 
further back among the mountains as we proceed northward. Near the 
Boundary-line, the tributaries of the Missouri and South Saskatchewan, 
rise in the abrupt eastern vallies of the first range. The Kananaskis 
’ River, one hundred miles to the north, rises in the first longitudinal 
valley, or at the foot of the second range; Bow River from the third 
range; the North Saskatchewan from the fourth range; the Athabasca 
from the fifth, and the Peace River still further to the west. 
4. The interior region of the continent, slopes gradually eastward 
from the elevated plains lying at the base of the Rocky Mountains, to the 
foot of the Laurentian highlands; and though the inclination is more 
abrupt on approaching the mountains, it is not so much so as to attract 
special attention. Between the fifty-fourth and forty-ninth degrees of 
latitude, however, along two lines which are in a general way parallel, 
and hold a north-west and south-east course across the plains, very 
remarkable step-like rises occur. These escarpments form the eastern 
boundaries of the two higher prairie plateaus, and the most eastern of 
them overlooks the lowest prairie level, or that of the Red River Valley, 
from the west. The three prairie steppes thus defined differ much in age 
and character ; they have been impressed on the soft formations of the 
plains by the action of sub-zrial denudation, of the sea, and of former - 
great lakes, and though the precise mode of their formation is more fully 
discussed elsewhere, they deserve notice here, as being among the great | 
primary features of the country. 
5. The actual increase of elevation accounted for in the two escarp- 
ments, however, is but slight compared with that due to the uniform 
eastward slope of the plains. The direction of their greatest inclination 
is towards the north-east, and a line drawn from the intersection of the 
forty-ninth parallel and the mountains, to a point on the first prairie 
level north of Lake Winnipeg, will be found to cross the escarpments 
nearly at right angles, and to have an average slope of 5:38 feet to the 
mile. From the same initial point, in a due east line to the lowest part 
of the valley of the Red River—a distance of 750 miles—the plains have 
an average slope of 4:48 feet per mile. 
6. The first or lowest prairie level, is that of which the southern part 
lies along the Red River, and which northward embraces Lake Winnipeg 
and associated lakes, and the flat land surrounding them. A great part 
of its eastern border is conterminous with that of Lake Winnipeg, and 
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