Landforms of British Columbia 1976 - Department of Geography

feet at Nadina Mountain. These are monadnocks on the late Tertiary erosion sur-
face, resulting from the resistance to erosion of granitic stocks and their aureoles of
altered (hornfelsed) rock.
There arc numerous outliers of the Nechako Plateau lying within the Fraser
Basin. These are remnants of the plateau surface which were not destroyed during
the dissection of the plateau and the erosion of the Fraser Basin below the higher
level.
A smal1 area of plateau on the eastern margin of the Nechako Plateau, and
lying between the offset ends of the northern and southern sections of the Rocky
Mountain Trench, is designated the McGregor P~&YIU (see Plate XXV). Along its
eastern side is the valley of the upper Parsnip River and of McGregor River; on its
western side is the valley occupied by the~crooked River between Summit Lake and
McLeod Lake. On the southwest it is cut off by the valley of the Fraser River, and
on the southeast it is cut off by the cross-w&y between the McGregor River and the
Torpy River.
This plateau lies above 3,000 feet elevation, and in the northern part mostly
below 4,000 feet, but in the southern half it rises to a maximwn height of 6,866
feet east of Longworth. Northwest of the McGregor River the surface is an east-
ward extension of the Nechako Plateau, which was separated from it by the ancestral
Fraser River flowing northward through the McLeod Lake gap. South of McGregor
River the terrain is similar to the Fraser PIateau between the Fraser and Bowron
Rivers, though it is somewhat n~ore completely dissected by the Torpy River.
[References: Armstrong, J, E., “ Fort St. James Map-area,” Geol. Swv., Can-
ada, Mem. 252, 1949; Duffell, S., “ Whitesail Lake Map-area,” Geol. Surv., Canada,
Mem. 299,1959; Tipper, H. W., “ Nechako River Map-area,” Gml, Surv., Canada,
Mem. 324, 1963; Mu&r, J. E., and Tipper, H. W,, “ McLeod Lake: Geol. Sure.,
Canada, Map 2-1962.1
[Photographs: B.C. 468:33; B.C. 523:61, 80; B.C. 763:40; B.C. 766:9.]
Fraser Plateau
Most of the Fraser Plateau (see Plate XXVIA) lies west of the Fraser River.
It includes the Chilcotin country, and the road from Williams Lake to Anahim Lake
crosses the central part of it, The part east of the river is cut into by the Fraser
Basin along the Quesnel River and San Jose River. The plateau extends south from
the West Road River to a boundary with the Thompson Plateau that is determined
by the southern limit of the largely undissected flows of late Miocene plateau basalt.
It is flanked on the west by the Coast Mountains (see Plate XIB), abuts the Nechako
Plateau on the north and the Thompson Plateau on the south, and on the east is
flanked by the Quesnel Highland.
The Fraser Plateau is a flat and gently rolling country having large areas of
undissected upland lying between 4,000 and 5,000 feet. To the southeast the upland
surface rises gradually to 6,000 feet along the margin of the Chiicotin Ranges and
west of and south of Canim Lake.
The boundary with the Coast Mountains is sharply transitional, but in places
it may be a belt that is severa miles wide. From Taseko Lakes northwest it is drawn
along a line roughly at the S,OOO- to 5,500-foot contour running between the north
end of Taseko Lakes and One Eye Lake From Taseko Lakes east the boundary is
drawn roughly at the 6,000-foot contour because the plateau surface is warped
upward in this vicinity. On the east the boundary between the Fraser Plateau and
Quesnel Highland has been arbitrarily drawn along the 5,000-foot contour. There
is no definite division between the two because of the gentle eastward rise of the
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