Landforms of British Columbia 1976 - Department of Geography

eda Rivers on the west and the Columbia River on the east-occupy northerly
and northeasterly valleys crossing the topographic and geologic grain of the country.
The Monashee Mountains are underlain by sedimentary and metamorphic
rocks, largely gneissic rocks of the Shuswap terrain, by Paleozoic and Mesozoic
sedimentary and volcanic rocks, and by batholiths and stocks of Lower Cretaceous
and younger age. The Shuswap rocks are widespread between Shuswap and Sugar
Lakes; meta-sedimentary rocks of Proterozoic and Lower Cambrian age underlie
the northern ranges, while the southern ranges are largely underlain by intrusive
rocks and foliated gneisses.
The highest peak in the mountains near the north end is H&m Peak (10,560
feet), and the next highest is Gordon Home Peak (9,562 feet) northwest of Gold-
stream. South of Revelstoke there are seven peaks over 9,OOO’feet in the Gold
Range, of which Mount Odin (9,751 feet) is the highest and the southernmost.
To the south the peaks are progressively lower, with elevations of 8,791 feet at
Mount Fosthall, 7,400 feet at Whatshan Peak, and 7,440 feet at the Pinnacles. In
the Midway Range the extreme height is 7,390 feet at Mount Tanner, and from it
a number of peaks over 7,000 feet extend southward to Almond Mountain (7,604
feet), south of which the summit level declines to just above 5,000 feet. In the
Rossland Range the highest point is Old Glory Mountain, elevation 7,795 feet.
The mountains are drained by the North Thompson, Fraser, and Columbia
Rivers and their tributaries, flowing at elevations largely between 1,500 and 3,000
feet. The relief is greatest to the north, being 8,000 feet between Mount Odin and
the Columbia River, 8,600 feet between Hallam Peak and the Canoe River, about
5,000 feet in the Midway Range between Mount Tanner and the Kettle River, and
even less farther south near the 49th parallel.
The high mountains, especially those in the northern ranges, are mostly massive
and bold sharp peaks separated by deep, steep-sided valleys. Peaks above 8,000
feet projected through the Pleistocene ice-sheet and were subjected to intense cirque
glaciation wh:ch produced matterhorn-like peaks, Lower summits were covered
by ice at one sta2e and subsequently have been sculptured by cirque and valley
glaciers to sharp peaks and sawtooth ridges. It is only in the southern ranges at
elevations below 7,000 feet that rounded or only moderately pointed summits pre-
vati, The valleys, especially those parallel to the southerly moving ice, were intensely
glaciated, with considerable modification of their longitudinal and transverse valley
profiles. On the retreat of the ice a mantle of drift, deeper in the valley bottoms
than on the sides, was left everywhere.
A few cirque glaciers in the Gold Ranges and in the ranges north of Revelstoke
remain as reminders of the former extensive Pleistocene ice cova.
[References: “ Kettle River (East Half),” Geol. SLU-v., Cam&, Map 6-1957;
Little, H, W., “ Geology, Kettle River,” G&. Surv., Canada, Map 19-1961; Jones,
A. G,, “ Vernon Map-area,” Geol. Surv., Canada, Man. 296, 1959; Little, H. W.,
“ Nelson Map-area (West Half) ;’ Gtd. ,Surv., Canada, Man. 308, 1960.1
[Photographs: B.C. 489:60; B.C. 490:107; B.C. 804:94.]
Selkirk Momfaim
The. Selkirk Mountains (see Plate XXX) lie directly to the east of the Mona-
shee Mountains in an area about 220 miles long and 40 to 50 miles wide. They
lie within the big bend of the Columbia River and are flanked on the west by the
Monashee Mountains and on the east by the Purcell Mountains. The boundary
with the Monashee Mountains is along the valley which, south of Boat Encamp-
mat, is occupied by the Columbia River and the Arrow Lakes. The boundary
with the Purcell Mountains is along the through valley which extends southward
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