5

mately the same stratigraphic horizon. At the Island Mountain mine the
bed is about 600 feet structurally higher than a persistent band of argillite,
whereas the limestone at the Cariboo Gold Quartz mine is less than 500
feet structurally higher than the same band of argillite. This suggests that
unless the limestone beds are at the same horizon, the one at Island
mountain is structurally higher.

The lower part of the Baker member is penetrated by the underground
workings of the Island Mountain mine and of the Cariboo Gold Quartz mine.
Occasional outcrops expose the member northwest of Jack of Clubs lake, on
lower Lowhee creek, and about 2 miles southeast in the B.C. ditch. The
upper part is apparently cut by the Shamrock tunnel. The member out-
crops again on the Conklin mineral claim, at the head of Conklin gulch,
and on Grouse creek below the Kumangetit fraction claim. In some
places outcrops are continuous across the width of the member to the
overlying Barkerville formation and although along the strike long gaps
exist between outcrops the mapping of the member is believed to be correct.

Below the Baker member is a series of interbedded quartzites and
argillites called the Rainbow member. This member is cut by thousands of
quartz veins and it with the lower part of the Baker member constitutes
the most valuable part of the Barkerville gold belt. In the Island Mountain
and Cariboo Gold Quartz mines the beds of the Rainbow member form a
zone approximately 900 feet wide across the strike and are probably
between 500 and 600 feet thick. Beds or other small lithogical units within
this member can be traced for very short distances only. Because of per-
sistent members below and above, however, the member can be followed with
some assurance from Island mountain southeastward to Barkerville, and
with less assurance to Grouse creek. The breadth of outcrop appears to be
much greater at Grouse creek and may exceed 1,500 feet.

At the Island Mountain mine the beds are much shattered and
apparently rather intricately folded. They consist of argillites with some
quartzites, and a few thin beds of limestone. Some beds of clastic sedi-
ments are quite limy. The clastic sediments are sheared so that locally they
are fissile. The member could not be subdivided into divisions traceable
throughout the mine workings.

In the Cariboo Gold Quartz mine the member was subdivided into four
units. The uppermost or No. 1 unit is about 300 feet wide across the strike
and consists of interbedded black argillites, argillaceous quartzites, and
grey quartzites, all somewhat sheared. The next or No. 2 unit is 100 feet
to 200 feet wide and consists of grey quartzite, locally schistose, and a thin
bed of limy quartzite. Below this No. 3 unit is 200 to 300 feet wide and
consists of interbedded grey quartzites and black argillites all somewhat
sheared, and a few thin beds of impure limestone. No. 4 unit at the base of
the Rainbow member is 100 to 200 feet wide, consists of fine-grained, grey
quartzites, somewhat sheared and fissile, and a thin bed of impure hme-
stone. Attempts to trace the beds, a few feet thick, of quartzite or of
argillite throughout the workings of the Cariboo Gold Quartz mine failed,
but showed that such beds change rapidly in their nature along the strike
and dip. Several examples showed a change from northwest to southeast,
from argillite to argillaceous quartzite, and finally to grey quartzite. No