14

Boulder Creek

Boulder creek rises at the base of King mountain, the highest peak in
this part of Cassiar district, and flows 8 miles in a northerly direction to
Muddy river. For approximately 3 miles above its junction with Muddy
river the creek occupies a narrow canyon 50 feet to 100 feet deep at the
lower end. There it falls 75 feet over limestone cliffs into the flat-bottomed
valley of Muddy river. Above the canyon the creek occupies an open,
V-shaped valley.

Boulder Creek canyon is cut in sedimentary rocks of the Dease series
for about one mile above the falls and in serpentine throughout the
remainder of the canyon. Cemented and stratified stream gravels outcrop
in the creek bottom on Shea’s lease at the head of the canyon. These
gravels fill an old stream channel which had a somewhat lower gradient
than that of the present creek. In addition to fragments of sedimentary
rocks and serpentine, the cemented gravels contain rounded cobbles of
granite, andesite, and basalt; that is, rocks that do not outcrop in the
drainage basin of Boulder creek and, consequently, must have been carried
there by Pleistocene glaciers. The gravels are covered by glacial drift in
some places, indicating that they were deposited before the last advance
of the ice.

Placer gold was discovered on Boulder creek in 1932 when Carl Johnson
recovered about 24 ounces of gold from small test pits in the lower part
of the canyon. J. W. Wheaton purchased the Johnson lease in 1938 and
during the summers of 1934 and 1985 he and F. Bobner built a dam and
a diversion canal and also did a small amount of ground-sluicing. Accord-
ing to Mr. Wheaton, approximately 100 ounces of gold has been recovered.
This figure is very encouraging, for work below the diversion dam has
been restricted to the western edge of the creek channel where a band of
schistose rocks has provided a series of natural riffles.

Depth to bedrock in the lower part of the canyon is from 4 feet to
7 feet. Large boulders up to 7 feet or 8 feet in diameter must be broken
and removed by hand. ‘Consequently, the work preparatory to sluicing
is slow and arduous.

Percy Peacock and Mr. and Mrs. V. Shea have placer leases on
Boulder creek 1 and 2 miles above Wheaton’s lease. In the summer of
1935 they were constructing dams preparatory to ground-sluicing.

The gold particles taken from Boulder creek are flat and fairly coarse.
The source of the gold is not known. The present concentrations on bed-
rock in the creek bottom and around the edges of large boulders in the
present stream gravels are post-glacial in age and may have been formed
by the reworking of pre-glacial placer deposits or by the re-concentration
of gold in glacial drift.

Future Possibilities

It should be borne in mind when prospecting for placer gold deposits
in Cassiar district that the region has been heavily glaciated in compara-
tively recent geological time. Most of the main valleys were filled with
moving ice to a depth of several thousand feet and pre-glacial placer
deposits in these valleys may have been scattered and destroyed.