; Raa

there does not appear to be any large portion of it that would be available for
agricultural purposes even if the climate were suitable. A very large proportion
of the region has a rocky surfacé. Boulder clay is found frequently filling
depressions on the surface and here and there occur sand-plains or other accu-
mulations of glacial drift. The whole region has been subjected to intense glacial
erosion by which the surface has been worn down to the live rock and denuded
of its loose material which has been carried westward and deposited in the low-
land portion of the basin. South of Athabaska lake is a large area underlain by

_ horizontally bedded sandstone which on decomposition forms wide plains of
sand or gently rounded hills and ridges wooded with banksian pine.

In spite of its lack of soil, however, almost the whole region is wooded,
though sparsely, with a forest of spruce, banksian pine, tamarack, poplar, birch,
or willows. This forest becomes thinner towards the eastern and northern edge
of the basin and disappears entirely north of the east end of Great Slave lake
in the basins of Clinton-Colden, Aylmer, and MacKay lakes.. This is the only
part of the Mackenzie basin included within the great unforested region of
northern Canada known as the Barren lands.

Cordilleran Region

On the western border of the Mackenzie basin and extending throughout
its whole length is a lofty mountainous region constituting a part of the North
American Cordillera. It forms a belt varying in width from 20 to 200 miles
extending from the foothills which border the central lowlands to the height of
land separating the Mackenzie waters from those which drain westward to the
Pacific. The tributaries of the Mackenzie cut deeply into the ranges which
constitute this region and two of them, the Liard and Peace rivers, cut right
through, drawing much of their water from the western or back slopes of the
ranges and from the plateau region lying to the west of them. This memoir,
however, is not concerned with that portion of the Mackenzie basin lying west
of the summit of the Rocky mountains which is drained by the upper waters
of the Peace and Liard rivers. The Cordilleran province of the Mackenzie basin
as herein defined embraces the eastern slopes of the Rocky mountains, the Mac-
kenzie mountains, and Richardson mountains.

The eastern boundary of this province is a fairly definite line at which
the foothills of the mountains die out in the Great Central plain. Starting
in the south from a point near the intersection of latitude 53 degrees and
longitude 116° 30’, the line runs northwestward, crossing the Peace river near
Hudson Hope and striking the Liard river near longitude 125 degrees. Here,
the continuity of the Rocky mountains is interrupted and they appear to die’
away north of the river. Under the name Mackenzie mountains, however, the
Cordillera springs up again north of the river, but its eastern front is stepped
far to the eastward and abuts against the Liard river at Fort Liard. From this
point the eastern boundary of the Cordilleran province runs northward, touching
the Mackenzie river at the mouth of the Nahanni river and continuing thence
along the western side of the Mackenzie to latitude 65° 30’, where it turns in a
broad curve and swings westward round the headwaters of Peel river. The Mac-
kenzie mountains die out about the head of Peel river in much the same way as

“the Rockies north of the Liard river, but another lower range, known as the