Landforms of British Columbia 1976 - Department of Geography

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lighter and where, approaching the Fraser River, the slopes are openly timbered, with
little or light undergrowth.
[Reference: Burwash, E, M. J., “ Geology of Vancouver and Vicinity,” Uni-
versity oj Chicago Press, 19 18 .]
[Photographs: B.C. 398:66; B.C. 457:68; B.C. 496: 30, 35, 5’7; B.C.
498: 40, 109; B.C. 499: 82, 111; B.C. 528: 64; B.C. 551: 60; B.C. 554: 116;
B.C. 566: 55; B.C. 983: 88; B.C. 994: 36, 52; B.C. 996: 60; B.C. 999:31; B.C.
1051: 37; B.C. 1402: 23, 40; B.C. 1406: 67.1
The Chikotin Ranges (see Plates XIA and XIB) lie along the east side of the
Pacific Ranges and are a subdivision of them. They extend southeastward from the
head of the Khnaklini River to Lillooet. They are very largely composed of non-
granitic rocks and lie east of the eastern contact of the Coast Intrusions. On their
east the Chilcotin Ranges are flanked by the Fraser Plateau and, southeast of Chum
Creek, by the Camelsfoot Range, which lies within the Fraser Plateau. The bound-
ary between plateau and mountains is sharply defined (see Plate XIB) by a narrow
transition zone. Between the Klinaklini River and the north end of Taseko Lakes
the generalized line of the 5,500-foot contour serves as a boundary, and between
Taseko Lakes and the head of the Yalakom River the boundary is more or less along
the 6,000-foot contour. The Yalakom River, which follows the Yalakom fault
northwest of Moha, separates the Shulaps Range of the Chilcotin Ranges from the
Camelsfoot Range of the Fraser Plateau.
High points in the ranges include Mount Tatlow (10,058 feet) west of Taseko
Lakes, Taseko Mountain (10,047 feet) east of Taseko Lakes, and Big Dog Moun-
tain (9,391 feet) and Shulaps Peak (9,446 feet) in the Shulaps Range.
The Chilcotin Ranges are underlain by a great variety of non-granitic rocks.
The ranges between Tatlayoko and Taseko Lakes consist very largely of north-
easterly striking Mesozoic volcanic and sedimentary rocks. Between Taseko Lakes
and the Fraser River, Paleozoic and Mesozoic sedimentary and volcanic rocks are
intruded by small granitic stocks, and Big Dog Mountain and Shulaps Peak are the
highest points of an intrusion of peridotite of Triassic age,
The Chilcotin Ranges rise progressively higher in approaching the granite
ranges to the west. For the most part, they display a combination of high serrate
peaks rising above lower rounded summits and gently sloping areas of undissected
upland. Glaciation has scalloped the northern slopes and modified the valley pro-
files. Timberline is between 6,000 and 6,500 feet. The ranges experience a rainfall
of 40 inches or less, and, as a result, timber is only moderately heavy and under-
growth is relatively sparse.
[References: DoImage, V., “ Chilko Lake and Vicinity,” Geol. Surv., Canada,
Sum. Rept., 1924, Pt. A, pp. 59-75; Dolmage, V., “Gun Creek Map-area,” GeoZ.
&rv., Canada, Sum. Rept., 1928, Pt. A, pp. 78-93; Leach, G. B., “Geology and
Mineral Deposits of the Shulaps Range,” B.C. Dept. of Mines, Bull. No, 32, 1953;
Cairnes, C. E., “ Geology and Mineral Deposits of the Bridge River Mining Camp,”
GeoZ. Surv., Canuda, Mem. 213, 1937; Duffell, S., and McTaggart, K. C., “Ash-
croft Map-area,” Geol. Surv., Canuda, Mem. 262, 1952; Tipper, H. W., “ Taseko
Lakes,” Geol. Surv., Canada, Map 29-1963.1
[Photographs: B.C. 393: 53; B.C. 457: 79; B.C. 550: 107; B.C. 566: 68, 85,
108; B.C. 567:30; B.C. 656:47; B.C. 922:5; B.C. 982:80; B.C. 983:53.]
CASCADE MOUNTAINS
The Cascade Mountains constitute a large physiographic unit of the north-
western United States. They extend northward from the northern border of Cali-
fornia, through Oregon and Washington, and extend a prong northward into British
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