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of Redfern Lake to 15 miles south of Muncho Lake, and is high and
very rugged. It contains many peaks with elevations of more than 9,000
feet, according to present information, and is crowned by Churchill Peak,
10,500 feet high. Within it are many ice-fields and alpine glaciers, none
more than a few miles in extent, the largest observed being those east of
Quentine, Hamworth, and Chesterfield Lakes. This central area is largely
composed of great thicknesses of massive strata, probably limestone, and
the big peaks resemble those of the more southern areas. No intrusions
have been reported in this northern part, but copper occurrences east of
Fort Grahame suggest the presence of intrusions not far below the surface.

“The border zone surrounds the central area for a width of 15 miles or
more. It consists of lower and less rugged mountains and contains no
glaciers. In general the elevations of its summits decrease from the central
area outwards. North of Sikanni Chief River, these summits in places
retain remnants of an old erosion surface that truncates their tops. In
the northern part of the zone, as the elevations decrease, areas in which
the old erosion surface, here a rolling upland, remains, become more and
more common as the boundary of the mountains is approached.

“At the north end of the border zone, the Rocky Mountains are cut
off sharply by Liard Valley. Southwest, from nearly opposite the mouth
of Smith River to Kechika River, the northern ends of the mountain ridges
disappear more gradually, and the boundary between them and Liard
Plain is less distinct, though viewed from a distance at an elevation of
20,000 feet a general belt is apparent where the ridges increase their eleva-
tion southward more rapidly to become mountains. Between Rabbit and
Kechika Rivers the outer ridges of the mountains continue northwest
along the side of the Rocky Mountain Trench, with summits at 4,000 to
5,000 feet or more, as far as the fifty-ninth parallel where they finally
merge with Liard Plain. Terminus Mountain, 6,250 feet high, forms the
northwest corner of the truly mountainous country.

“In the northern and northwestern parts of these border zone mountains
the general parallelism of valleys and ridges is less marked. From Rabbit
River a large valley extends obliquely to join that of Gataga River 25
miles above its mouth, and continues into the mountains as an outstanding
valley feature that sends deep branches through the central area, joining
with the valleys draining to Toad and Muskwa Rivers.

“Yarther south the border zone adjacent to the Rocky Mountain
Trench consists of parallel ridges and valleys. As the trench is approached,
the elevations of the ridges decrease, and the intervening valleys become
broader, that next to the trench being nearly as large as the trench itself.

“An area of less relief than usual lies in the border zone mountains
around the head of Sikanni Chief River and south of the head of Graham
River, and the boundary between it and the Foothills is indefinite. Farther
south the boundary follows Nabesche River, but in this whole northern
area the mountains of the border zone greatly resemble those of the Foot-
hills.”

LIARD PLATEAU
__ Liard Plateau is an area of broad, even-topped hills that rise in their
higher parts to about 4,500 feet above sea-level and include a few ranges of
mountainous character. In the central and southern parts of the plateau