Oo  ————

160

Boulder clay largely occupies the sides of the valley above Stanley, but
very little is said to have been met in shafts in the deep channel above the
mouth of Van Winkle creek. Nearly all the deposits are gravels, except
where boulder clay partly fills the buried channels alongside the newer
channels. There is said to be some boulder clay in the valley bottom near
Stanley and the drilling records at La Fontaine mine 13 miles below Stanley
and 2 miles farther down (Figure 29), show pretty clearly that boulder clay
forms a part of the valley filling at these places. The morainic deposits,
the surface of which is characterized by undrained basins and irregularly
shaped knolls, are partly sands and gravels and partly boulder clay. They
extend nearly across the valley opposite the lower part of Davis creek and
probably form an impervious stratum above the bedrock gravels. It is
a debatable point how much of the gold-bearing gravel that was mined in the
deep channel was pre-Glacial or whether any of the gravels are pre-Glacial.
The gravels seen on several of the dumps of the old mines above Stanley are
partly the typical “flat wash” and show no evidence of glacial action. The
gravels, especially those in the bottom of the deep buried channels alongside
the newer rock canyons, are probably in part at least pre-Glacial. The
gravels in the bottom of the deep channel below Stanley, judging by those
seen on the dump at La Fontaine mine, appear to be glacial gravels. Unlike
Williams and Slough creeks, Lightning creek in the section above and below
Stanley for some distance does not appear to contain any interglacial
pay-streak. It may be that the drift filling the channel was partly eroded
out and the channel deepened somewhat by stream erosion during a tem-
porary retreat of the ice. The wide part of the valley below Stanley may
have been deepened by ice erosion, although probably not to any great
extent, for some of the bedrock valleys of the tributary streams are graded
to the bottom of the main channel. The narrow bedrock channel of the
creek above the mouth of Van Winkle creek could hardly have been eroded
by the ice, because of the narrowness of the channel and because the
tributary stream channels are graded to the bottom of it. It must have
been formed by stream erosion before it received the glacial drift. Spruce
canyon is clearly post-Glacial in age and, unlike the somewhat similar
Black Jack canyon on Williams creek, it contained considerable gold, the
reason being that the canyon was cut partly through rock benches on the
south side, which carried concentrations of placer gold. The rich part of
the creek extended from the Vulcan ground just above Stanley to the
Lightning claim above the head of Spruce canyon. The deep channel of
the creek above the Lightning claim is said to have been unprofitable,
although there were rich spots in places as far up as the foot of Eagle canyon.
Considerable gold was found on Dunbar flat, a series of drift-covered rock
benches on the north side three-quarters of a mile above Spruce canyon, on
the famous Butcher bench on the south side near the head of the canyon,
and on Nason point just above the mouth of Van Winkle creek. The
Butcher bench is a gently sloping rock bench 60 to 80 feet above the stream,
and is a remarkable feature, for it appears to be a remnant of an old stream
channel of the creek when it flowed at a much higher level than at present,
and has been preserved in spite of downcutting of the stream valley of over
100 feet and in spite of glacial erosion. The bench is said to have produced
$122,000 in gold from an area of only a few square yards. The Dunbar