Landforms of British Columbia 1976 - Department of Geography

south end of Teslin Lake, which separates the Teslin Plateau on the west from
the Nisutlin Plateau on the east.
The Teslin Plateau (see Plate XIVA) consists of an upland surface which
rises to heights of between 6,000 and 7,000 feet and whose two highest summits
are Mount Barham (6,868 feet) west of Surprise Lake and Mount Snowdon
(6,987 feet) west of Teslin Lake. It is dissected into large isolated blocks by the
wide valleys of Atlin Lake, Surprise Lake, Gladys Lake, and tributary valleys of
the main rivers. There is a moderate relief within the region between the upland
areas and the levels ‘of Atlin Lake at 2,192 feet, Teslin Lake at 2,239 feet, and
Surprise Lake at 3,092 feet.
The widely flaring valleys and gently sloping upland surfaces have been
glaciated, and cirques have scalloped the north and east sides of peaks and ridges.
Ice moving northward along Teslin Lake valley eroded drumlin-like forms in
bedrock and moulded drumlins in the glacial materials on the west side of the lake.
Numerous small lakes occupy glacially formed depressions south and west of Teshn
Lake and along the valleys of Hall Lake, ~Gladys River, and Gladys Lake-Snafu
Creek. At one stage some ice evidently moved southwestward down the upper
valley of Nakina River and thence by the Taku River valley to the sea.
[Reference: Aitken, J. D., “Atlin Map-area,” Geol. Surv., Cunuda, Mem. 307,
1959.1
[Photographs: B.C. 681:67,87; B.C.‘691:111; B.C. 694:l.l
Nisutlin Plateau
The Nisutlin Plateau (see Plate XIVB) extends southward into British
Columbia between Teslin Lake on the west and the Cassiar Mountains on the east
as a prong about 40 miles long and about 20 miles wide.
Several high points in the area lying between 4,000 and 5,000 feet represent
an old erosion surface which is incised to the level of Teslin Lake (2,239 feet) by
the Jennings and Swift Rivers. Much of the country is low lying and covered
with glacial drift, and numerous small lakes occupy depressions in the drift. Ice
escaping outward from the Stikine Plateau moved northward and northeastward
across this part of the Nisutlin Plateau.
[Photographs: B.C. 893:40, 50; B.C. 954:12.]
LIARD PLAIN
The Liard Plain (see Plate XVA) is a low area of slight relief lying withm
the drainage area of the Liard River and its tributaries. The elevation of the Liard
River is just below 1,500 feet at the Liard Bridge (Mile 496) and is almost 2,000
feet at Lower Post. The surface of the Liard Plain is largely between 2,500 and
3,500 feet, but 4,000 feet is reached at a very few points. The plain is surrounded
on all sides by a ring of plateaus’ and mountains rising to considerably greater
heights. The only break in the ring is where the Liard River valley flows past
the northern end of the Rocky Mountains. In British Columbia the plain is
bounded on the west and southwest by the Dease Plateau, the boundary between
the two being along the 3,000-foot contour line. On the south the plain merges
in the Rocky Mountain Trench, and the two are arbitrarily separated at the
junction of the Turnagain and Kechika Rivers (2,000 feet elevation). On the
southeast the plain is bounded by the Rabbit Plateau, rurming along a line north-
eastward along Boya Creek past Fishing Lakes to the mouth of Smith River.
East of Smith River and north of Liard River it is bounded by the Liard Plateau.
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