15

With the exception of McDame creek, the productive creeks in the
region are in valleys that lie transverse to the direction of ice movement
and, consequently, did not suffer the full effects of glacial erosion. These
valleys are commonly V-shaped in contrast with the marked U-shape of the
glaciated valleys.

Practically all of the valleys in Hotailuh mountains head in glacial
cirques and are U-shaped. Consequently, the possibilities of finding any
extensive gold placer deposits in these valleys are poor.

The productive creek valleys in Cassiar district are in the sedimen-
tary and volcanic rocks on the north and south sides of the Cassiar batho-
lith. Streams flowing entirely through areas underlain by granitic rocks
have not been found to contain commercial placer deposits. Therefore,
prospectors would be well advised to avoid the central parts of Cassiar
and Hotailuh mountains, which are largely made up of granite.

In conclusion it may be said that the areas to the southeast and north-
west of Dease lake warrant careful and intelligent prospecting.

LODE DEPOSITS

The gold quartz deposits near Quartz City occur as vein fillings in
fissures in a band of volcanic rocks of the McLeod series. The veins are
roughly parallel to one another and form a well-defined belt about 3 miles
wide. They strike north 30 degrees to 60 degrees east, and cut across the
northwesterly trending volcanic rocks at right angles.

Development work has been confined to a few open-cuts and surface
pits. The veins are largely drift covered, so information regarding their
nature is rather meagre. The known gold-bearing veins vary in width
from a few inches to 4 feet. Other bodies of quartz that are in the gold-
bearing vein belt but are not known to contain gold are as much as 50 feet
in width. Many of the veins are over 500 feet long and as exploration
proceeds may be found to be much longer. Information regarding the
persistence of veins at depth is limited to a natural cross-section seen on
a high cliff near the head of Quartz creek. Here, veins which have a
maximum width of about 3 feet persist down the dip to a depth of several
hundred feet. Those with a maximum width of 1 foot have a vertical
length of about 100 feet and narrow stringers extend downward a much
shorter distance. In other words, the persistence at depth of the veins
appears to be roughly 100 feet for each foot of width. ;

Pits and open-cuts are not numerous and have not been sunk through
the oxidized zone, but they show that the gold in the veins is practically
restricted to an inch or two on one or both walls. The interior parts of
the gold-bearing veins do contain some fine gold, but do not return com-
mercial assays. Pyrite is practically the only sulphide, but occurs in very
small amounts and appears to be mainly along the vein walls with the
gold. Specimens from the walls of the better veins exhibit many par-
ticles of gold somewhat smaller than grains of rice adhering to rust in
cavities in the quartz. The shapes of the cavities suggest that they were
filled originally by ankerite and pyrite.

Some of the gold-bearing veins were sampled in the summer of 1935,
but the assays, in general, were quite low. It should be borne in mind,