Landforms of British Columbia 1976 - Department of Geography

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from the Rocky Mountain Trench and contains the Beaver River, Duncan River,
Duncan Lake, Kootcnay Lake, and Kootenay River.
The mountains comprise a number of individual ranges which in the south trend
northeastward, at and north of Nelson trend northward, and in the north trend
northwestward. They form a cnrve convex to the east, which is the topographic
expression of the Kootenay Arc, a major structure of the underlying bedrock.
In the northern Selkirk Mountains the bounding valleys of the Columbia River
north of Goldstream and the upper Duncan and Beaver Rivers cut across the topo-
graphic and geologic trends of the mountains, Although those valleys provide the
physical basis for separating the northern Monashee, Selkirk, and Purcell Mom+
tains, the northern ranges of all three mountains are, geologically and topographi-
cally, very much alike.
The Selkirk Mountains are underlain by a variety of rocks: by Proterozoic
and Lower Paleozoic sedimentary and metamorphic rocks, by gneiss of both
sedimentaT and igneous origin, by late Pakeozoic and Mesozoic sedimentary and
volcanic rocks, and by granitic stocks and batholiths of Cretaceons and early
Tertiary age, The Proterozoic zmd Lower Paleozoic rocks include prominent
quartzite and limestone members which are resistant to erosion and form many of
the highest peaks, Canes Peak (10,000 feet), Mount Moloch (10,198 feet), and
Mount Sir Sanford f 11,590 feet) are limestone, as are the highest peaks in the
Badshot Range north of Trout LakGMmmt Badshot, Mount Templeman, and
Mount Abbot,
The sedimentary rocks are complexly and as a rule isoclinally folded about
axes that regionally have an arcuate trend, convex to the east, which is reflected in
the trends of individual ranges.
The Proterozoic and Lower Paleozoic sedimentary and volcanic rocks form
most of the mountains north of Trout Lake. Triassic sedimentary rocks (Skxan
Group) occupy an east-west belt between Nakuso and Kale, and, with Jurassic
rocks, form a broken irregular area southwest of Nelson. The Kuskanax batholith
occuoies a large area south of Trout Lake, and most of the area between Silverton
and Trail is underlain by the Nelson batholith and associated gneiss. Differences in
the underlying rocks provide topographic differences between the various ranges,
The Selkirk Mountains contain some very high and very rugged mountain
country, North of the Illecillewaet River there are a number of lO.OOO-foot peaks,
and the highest pezk in the mountains is Mount Sir Sanford (11,590 feet) in the
Sir Sanford Rance at the head of Gold River. Between the Illecillewaet River and
the Trout Lake-Lardean River valley there are many 10,000.foot peaks and three
over 11,000 feet, of which Mount Dawson (11,123 feet) in the Dawson Range
at the head of Incomappleux River is the highest. The highest peak in the Slocan
Ranges is Kokanee Peak (9,200 feet); in the Valhalla Range, Gladsheim Peak
(9,275 feet) ; farther south the summits are below 8,mO feet.
The northernmost mountains we the highest, and in the Selkirks and adjoining
mountains it would appear that the greatest amount of late Tertiary uplift was in
the area extending from T&e Jaune on the north to Windermere on the south.
The area is drained by the Columbia and Kootenay Rivers and their tribe-
taries. The nlecillewaet River cuts transversely across the nortern Selkirks, and
the Trout Lake-Lardeau River valley crosses them mainly parallel to the individmd
ranges and the geologic structure, Slocan River, Slocan Lake, atid the throngh
valley to Nakusp serve to separate the Slocan Ranges ~II the east from the Vdhalla
Ranges on the west. The Salmo River separates the Nelsoti Ranges, west of south
Kootenay Lake, from the Bennington Ranges, which lie east of the Columbia River.
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