Chapter IT
PHYSIOGRAPHY AND GLACIATION

Physical Features

The area is drained by streams flowing to the Pacific Ocean. Prior to the
construction of Kenney Dam, Nechako and West Road Rivers and their tributaries
drained most of the area eastward into the Fraser drainage system but now the
area above Kenney Dam is drained to the Pacific Ocean through Kemano tunnel.
Only a small part of the southwest quarter is drained westward directly to the
ocean through Dean River drainage system.

Compared with most of British Columbia, the area is not mountainous (see
Pl. IL). Two distinct, though not rugged, ranges, Nechako and Fawnie, occur in
the central part, but even these rise gradually and gently from broad valleys to
mountain crests. Elsewhere in the area the topography is characterized by groups
of rounded hills with no particular arrangement into distinct ranges. Elevations
range between about 2,500 and 6,300 feet, but the local relief rarely exceeds
2,500 feet. The major valleys, such as Ootsa Lake, Entiako, Chedakuz, Nechako
and West Road, are broad and uneven and merge imperceptibly into the flanking
hills and mountains. The complex drainage pattern forms a disjointed network
of shallow V-shaped valleys cut into the broad irregular valley bottoms.

The topography shows a marked relation to the underlying rocks. The north-
west trend of Fawnie and Nechako Ranges reflects the northwest trend of the
folded, Jurassic rocks. The rounded hills of the northern quarter of the area
reflect the absence of pronounced trends in either the early Tertiary volcanic
rocks or the Topley granitic rocks of the Nulki Hills. The flat, swampy areas are
almost invariably underlain by flat-lying late Tertiary basalts.

Physiography

The physiography of the Canadian Cordillera north of latitude 55 degrees
has been studied extensively by Bostock (1948). His system of physiographic
subdivisions is here extended to include Nechako River area (see Table I, Fig. 2
Map 1131A).

Nechako River map-area is entirely within the Interior Plateau, which
Bostock divided into two secondary subdivisions—Fraser and Nechako Plateaux
—and placed the boundary “about the fifty-third parallel” (1948, p. 42). The
impression gained is that the division was based on convenience rather than on
a distinct difference in the two parts. However, if the boundary is more closely
defined as West Road River to its source and thence westward to the Coast
Mountains, the two areas are distinctly different both geologically and topo-

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