Auriferous veins, of which those on Burns Mountain, the Foster Ledge veins on
Oregon Gulch, and on the Acme group are the main representatives, occupy north-
north-easterly striking and steeply westward-dipping fractures which belong to a
regional system of jointing. Not all fractures of this system are mineralized with
quartz, and of the quartz veins not all are mineralized with gold.

The fracture system, widely developed as it is and cutting across all folded rocks
regardless of their pitch, may have accompanied the formation of the generally parallel
but east-dipping major faults. On the Acme group there is a second set of east-
striking vein-filled fractures which together with the north-north-easterly striking
ones might constitute a conjugate fracture system associated with the near-by Last
Chance-Nelson Creek fault. The relationship of a group of east-north-easterly striking
veins on Burns Mountain to the north-north-easterly trending veins there is not known.
Elsewhere no other associated fracture directions have been observed. Moreover, it is
not possible to state with assurance that the regional fracturing is more abundant as
the major faults are approached. The origin of the fracturing has not been definitely
established. Consequently, the genetic association of auriferous veins and north-
easterly striking faults, such as exists in the Barkerville Gold Belt, cannot be closely
established, despite the fact that the gold-bearing veins on the Foster Ledge and on
the Acme group are close to, and just east of, the Last Chance-Nelson Creek fault, and
that the Perkins veins on Burns Mountain are fairly close to, and just east of, a fault
projected between Butcher Bench and Burns Creek.

AGE OF GOLD MINERALIZATION.

The gold-bearing quartz veins occupy fractures, many of which belong to the
regionally developed joint system. These fractures cut across all the folds in the Cari-
boo series. If these fractures are genetically related to the major faults, thought to
be Jurassic in age or younger (see p. 24), then the period of gold mineralization neces-
sarily must be of comparable age, rather than pre-Mississippian as previously con-
sidered (Johnston and Uglow, 1926, p. 191). Such an age would link the gold min-
eralization of the Central Cariboo with that of the gold-bearing veins on Cedar Creek
and in the Little River area and with the mineralization that presumably was the
source of the gold placers on Stewart, Cafe, and Big Valley Creeks, where the Slide
Mountain series outcrops, and on Mosquito Creek and Quesnel River where rocks of
the Quesnel River group outcrop.

PLACER DEPOSITS.
GENERAL CHARACTER OF PLACER DEPOSITS.

Placer deposits in the Stanley area have been mined from Lightning Creek, Slough
Creek, and certain of their tributaries. Few deposits now remain unworked and only
a few placer operations still persist.

The gold-bearing gravel lay largely on bedrock. In many instances it was at
considerable depth below creek-level and was overlain by glacial material. In others
it rested on bedrock benches along the sides of and above the level of the present creeks
or, in some tributary creeks, lay at shallow depth on bedrock in the creek-bottom. It is
thought that the gold was initially concentrated in preglacial time in the bedrock
gravels of streams flowing in the same valleys as the present, but at somewhat higher
elevations. In preglacial or possibly in interglacial time renewed downward erosion
on Lightning and Slough Creeks lowered the creek-bottoms and reconcentrated the
gold from the earlier channels, remnants of which were left along the sides. The area
was covered with ice during the Pleistocene, but little bedrock erosion and dispersion
of gold in the creek-bottoms took place. The valley slopes were covered with glacial
drift up to several tens of feet thick and the creek-bottoms filled with drift to heights
of several hundred feet above the valley-bottom. Since the disappearance of the ice,
creeks have reoccupied the old valleys and have cut down through and excavated much

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