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gravel deposits were observed along Prophet River east of Klingzut Moun-
tain. The overlying till in all instances contains a large percentage of
pebbles and boulders of igneous and metamorphic rocks, including various
types of granite, schist, and gneiss. Along the banks of Prophet River this
boulder clay deposit is several hundred feet thick. The lower till appears
to have a source different from the overlying one and, as the pebbles and
boulders contained in it are similar to the rocks outcropping in the
immediate vicinity to the west, it seems reasonable to conclude that the
glacier that deposited this material moved down the valleys from that
direction. The source of the upper till containing the igneous and meta-
morphic pebbles and boulders may have been the Precambrian Shield to
the northeast.

“The character of the surface till varies considerably at different localities.
South of Sikanni Chief River granite boulders are present, but they are not
numerous; north of the river igneous boulders are more numerous; and
along Buckinghorse River and other streams farther north they are plentiful.

“The major stream valleys are pre-Glacial in age. In Prophet River
Valley, for example, the present stream follows the old valley very closely,
and it is only here and there that it has cut into the old river bank to expose
outcroppings of the bedrock. Because of the thick deposit of glacial material
in this old drainage channel, outcrops along the present stream are few.”

Hage (1944) records a great thickness of glacial till in the vicinity of
Fort Nelson as disclosed by the drilling of three deep water wells at the
Fort Nelson Airport. The first well, Fort Nelson No. 1, reached a depth of
521 feet and was wholly in glacial drift; the second well encountered the base
of the drift between 720 and 730 feet; and the third well apparently reached
bedrock at a depth of about 700 feet. Another well drilled for water at mile
237 passed through 50 feet of glacial drift before entering dark grey shale.

When the Commotion Creek well was drilled in the valley of Pine
River, the surface deposits were found to be 1,081 feet thick (Hume, 1944).
A 100-foot test hole sunk on the sand plain about 5 miles due east of the
north end of Bullhead Mountain is reported to have penetrated only sands
and gravels without reaching bedrock (Beach and Spivak, 1943).

As pointed out in the first part of this chapter, the pre-Glacial gap
between Portage and Bullhead Mountains was closed by a great terminal
moraine during the wane of the Ice Age. With melting of the ice, waters
of Peace River Valley flowed over the crest of a saddle on the west side of
Portage Mountain and the diverted water ran south some 10 miles to join
the Johnson Creek drainage. The latter, a northeasterly flowing stream,
joined Peace River a few miles east of Portage Mountain in pre-Glacial
time. The diverted waters of Peace River excavated a gorge some 700
feet deep, linking the course above the gap with the valley of Peace River
east of Portage Mountain by way of this southern route. The slow cutting
of Peace River Canyon necessitated concomitant slow erosion of the drift
deposits occupying the valley upstream and made possible the production
of a series of terraces along the valley of the Peace (See McLearn, 1940;
Beach and Spivak, 1943).

MceLearn (1920) states that the main and tributary valleys of the Peace
above the canyon are bordered with terraces carved in fluvioglacial gravel,
sand, clay, and boulder clay.