Landforms of British Columbia 1976 - Department of Geography

highlands, but the main effects of ice occupation were the deposition of drift over
the plateau surfaces and the moulding of drumlins from it. With the wasting of the
ice, meltwater channels were occupied temporarily by large streams which long
since have disappeared or are greatly diminished in size. After the disappearance
of the ice, numerous depressions and blocked valleys were. left, which now are
occup’ed by the many lakes of the region.
[Reference: Reinecke, L., “Physiography of the Beaverdell Area,” Geol.
Surv,, Cmada, Mus, Bull. No. 11, 1915.1
COLUMBIA MOUNTAINS
The Columbia Mountains constitute a highly mountainous area 160 miles wide
and 380 miles long in the southeastern interior of the Province. They lie west of
the Rocky Mountain Trench, and on their western side are flanked by the highland
belt of the Jnterior Plateau. The boundary between the mountains and the trench
is distinctly marked by the clean-cut wall of the trench, but the western boundary
of the mountains is zm arbitrarily selected line because of the transitional nature of
the highlands (see p. 72). The boundary is drawn from the trench at Slim Creek
southward along Bowron and Spectacle Lakes, thence along Hobson and Clearwater
Lakes and along MurUe Lake to Blue River. From Blue River the boundary runs
down Adams River and across to Anstey Arm of Shuswap Lake, thence by way of
Craigellach:e and Three Valley to Mabel Lake, across by Tsuius Creek to Shuswap
River, then to Sugar Lake and by Monashee Pass to the Kettle River, which is
followed southward to the 49th parallel.
The Columbia Mountains include a varjety of rocks, ranging from Precambrian
metamorphic rocks, mostly of sedimentary derivation, through Paleozoic and
Mesozoic sedimentary and volcanic formations, all of which xe intruded by a considerable
number of granitic stocks and batholiths ~of varying size. Topographic
differences between individual ranges are in part due to altitude and in part due to
dif?erences in erosion of the rocks involved.
The Columbia Mountains are drained by the Fraser, North Thompson, Columbia,
and Kootenay Rivers and their tributaries. Valleys of severa of these rivers
divide the Columbia Mountains into their four major subdivisions-the Cariboo
Mountains, Monashee Mountains, Selkirk Mountains, and Purcell Mountains.
Cariboo Mountains
The Cariboo Mountains (see Plate XXVIJJc) occupy the northernmost part
of the triangular-shaped arex of the Columbia Mountains. They lie east of the
Quesnel Highland and west of the Rocky Mountain Trench and the through valley
occq+ed by the North Thompson River, Albreda River, and Camp Creek. The
mountains occupy an area 130 miles long between Blue River and Slim Creek and
a maximum of 70 miles wide.
Southward from Slim Creek the summit level gradually increases to Mount
MacLeod (8,500 feet) near Goat River, Mount Kaza (8,350 feet), Mount Matthew
(8,506 feet) east of Sandy Lake, and Mount Soranger (8,700 feet), The highest
peaks of the ranges are in the Premier Group, which lies south of T&e Jaune at the
heads of the North Thompson, Raush, and Azure Rivers. Of the several peaks
there in excess of 10,000 feet, the highest is Mount Sir Wilfrid Laurier (11,750 feet).
The mou@ns are drained by the Fraser and North Thompson Rivers and
their principal tributaries, the Bowron, C&boo, Goat, Clearwater, Azure, Raush,
and Canoe E&ers, flowing at elevations chiefly between 2,000 and 3,000 feet. The
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