Landforms of British Columbia 1976 - Department of Geography

(15,300 feet) on the Alaska-British Columbia Boundary, the highest peak in British
Colmbia; Mount St. Elias (18,008 feet) on the Alaska-Yukon boundary; and
Mount Logan (19,850 feet) in southwestern Yukon, the highest peak in Canada
and second only to Mount McKinley (20,300 feet) in the Alaska Range, the highest
peak in North America.
In British Columbia the St. Elias Mountains extend along the Alaska-British
Columbia Boundary between Mount Fairweather and Mount Jette. Their boundary
with the Coast Mountains is along the Tatshenshini, Kelsall, and Chilkat Rivers.
Within British Columbia they comprise the Fairweather Ranges, Icefield Ranges,
Alsek Ranges, and the Duke Depression.
The mountains along the Alaska-British Columbia Boundary southwest of a
line drawn from the head of Tarr Inlet along Melbern Glacier to the Alsek River
cuhninate in Mount Fairweather (15,300 feet) (see Plate I), and constitute the
Fuirweuther Ranges. The ranges lie in a coastal belt of heavy precipitation and are
very largely covered with glaciers and snowfields. Much of the height of the Fair-
weather Ranges is due to Pleistocene and Recent uplifts totalling as much as
5,000 feet.
The valley of the Alsek River (see Plate IIA) , the only breach in the mountain
front between Cross Sound and the Copper River, serves as the southeastern and
eastern boundary of the Icefield Ranges, which extend northwestward from the
Alsek River to Mount St. Elias and Mount Logan and for the most part lie within
Yukon Territory. These ranges, too, are very largely covered with glaciers and
snowfields and, together with the Fairweather Ranges, constitute one of the least
explored sections of the Province.
The AZsek Ranges extend southeastward from the Alsek River and lie to the
east of the Fairweather Ranges. They are separated from the Coast Mountains on
the northeast by the Kelsall and Tatshenshini Rivers. In contrast to the Fair-
weather and Icefield Ranges they are considerably lower in general summit level,
about 6,500 to 8,500 feet in elevation, and they carry a much smaller mantle of
snow and ice. Their serrate peaks have been sculptured by cirque action, and the
major valleys especially have been modified strongly by the movement of ice
along them. The creeks and rivers are heavily charged with sediments from
melting glaciers, and most streams are aggrading; they flow in intricate and ever-
changing courses over their valley trains (see Plate 11~). The valley flats of the
lower Alsek and Tatshenshini Rivers are more than a mile wide and present
formidable barriers to travel by foot.
The low timberline and general lack of vegetation in many parts, coupled
with many evidences of stagnant and receding ice, give the appearance of a land
just emerging from its glacial cloak.
The Duke Depression, a physiographic unit more prominently developed in
the Yukon, is a belt of broad smooth slopes, almost plateau-like in character.
The general trend of the depression is parallel to the Kluane Ranges, which lie along
its northeastern side and which are separated by it from the main mass of the
St. Elias Mountains. However, the extension of the Duke Depression into British
Columbia is only a very minor feature and is represented by the uppermost reaches
of the Tatshenshini River valley at an elevation between 3,000 and 4,000 feet.
[References: Watson, K. dep., “ Squaw Creek-Rainy Hollow Area,” B.C.
Dept. of Mines, Bull. No. 25, 1948; N.T.S. Sheet 114~, Tatshenshini River.]
[Photographs: B.C. 687:58, 76; B.C. 688:13, 31, 35, 82; B.C. 691:26.]
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