152

drainage area supplies about 140 miner’s inches. Water from Burns creek
was formerly brought to the ditches by a ditch to the small lake a short
distance west, but the Burns Creek water has been used for the past few
years at the Ketch mine near the mouth of Devils Lake creek. The
elevation of the ditch at the pressure box is 4,033 feet or 153 feet lower
than the Point ditch. The ditch cannot be extended much farther and
cannot be brought onto the Point ground because of the high, steep bank
of the hydraulic pit. It was proposed at one time by the Point Company
to bring water from Lightning creek, by way of the pass at the head of
Devils Lake creek, but the project was abandoned as being too costly.

The deposits overlying the bedrock on the benches consist of Glacial
drift and vary in thickness from a few feet to over 100 feet near the inner
edge of the benches. The rock benches are fairly flat, but have numerous
small irregularities and are cut through in places by stream channels, which,
however, are only a few feet deep and are not graded to the bottom of
Slough Creek valley. The bedrock at the inner edge of the benches, where
it is exposed near the upper and lower ends, rises steeply, and it probably
rises fairly steeply all the way along the inner edge of the benches. An
outcrop along the Point ditch near its end limits the width of the benches
at this point and shows that a steep rock slope must exist. The rock
benches are much wider in some places than in others and the inner edge
has been reached at only a few places. The deposits overlying the benches
in the central and eastern parts consist mostly of gravels. In the western
part they consist mostly of glacial silt and boulder clay. The clay, however,
is overlain and underlain by gravels. On the western part of the Point
claim and on the lower claim there are, in places, two boulder-clay sheets
separated by a few feet of deeply weathered, rusty, and partly cemented
gravels, indicating a period of inter-glacial weathering and erosion, and
probably also some concentration of placer gold. The gold is thought by
the hydraulic men to occur mainly on bedrock, and especially in draws
in the bedrock, but it is difficult to tell just where the gold occurs, for during
hydraulicking it tends to settle to the bedrock. There is probably some
gold scattered through the upper gravels and in the gravels overlying the
lower boulder clay. Some gold is also said to have been found on the
high “points” of rock. The gold is mostly fairly coarse, much flattened, and
monn and is similar to what is referred to in this report as glacial gravel
gold.

The mode of origin of the bedrock benches and the placer gold on
them is not very clear. The rock benches were probably formed partly
by stream erosion previous to the cutting of the deep valley of Slough
creek and were later modified by glacier ice erosion. The bedrock on the
benches shows no definite evidence of glacial erosion, although the rock
is sufficiently hard in places to have preserved glacial strie. On the
other hand all the deposits overlying the bedrock appear to be glacial in
origin. It is probable, therefore, that the ice eroded the bedrock, at least
to some extent, and removed or mixed with the glacial drift the old stream
gravels, if such occurred, on the benches. The benches must have been
formed before the deposition of the glacial drift and the fact that some
ofthe higher benches slope upstream seems to show that they were formed
by a system of drainage waters different from the present system and from