in width, but most of them are less than a foot wide. In general they are less than
150 feet long and rarely exceed 200 feet. Diagonal veins are less numerous; most
are less than a foot wide. They are somewhat longer than the transverse veins, but
rarely exceed 300 feet. Both vein-types are vertical or steeply dipping. Strike-veins
or formational quartz veins occur more frequently than the others, and several strike-
veins outcrop for lengths of more than 1,000 feet, but most are short.

The quartz veins are not related to the contact-zone of any exposed batholith,
though a granitic intrusive may be buried at some unknown depth beneath the region.
Veins do, however, lie along a belt that extends south-eastward from Island Mountain
to Roundtop Mountain, and also at two other points; i.e., Burns Mountain and Yanks
Peak.

The belt lies along the line of occurrence of the richest gold placers. Moreover,
detailed geological mapping shows that the belt coincides with the outcrop of certain
rock members (the Rainbow and middle Hudson) that occur near the top of the Rich-
field formation.

A detailed study of the belt between Island Mountain and Grouse Creek has shown
that the Rainbow member holds most of the quartz veins. Evidently quartzite such
as constitutes the Rainbow member has fractured more readily than other types of
rock. Similarly, at the Cariboo Hudson mine the middle Hudson member is the one
that has fractured most readily. The physical character of the rock, taken in conjunc-
tion with that of the adjacent rocks, appears to be the controlling element in the
localization of the quartz veins. Secondarily, the development of local faults has
localized fracturing in parts of the favourable members. It is believed that the local-
ization of fractures within the belt is related to cross-structures, such as the Aurum,
Lowhee, Rainbow, and other northerly-striking faults.

The transverse and diagonal veins at the Island Mountain and Cariboo Gold Quartz
mines are well mineralized. Strike-veins are rarely well mineralized, and most of
them are barren. Veins occupying northerly-trending fault-zones are the best
mineralized in the Keithley Creek area. The reason why some veins contain minable
amounts of gold while others are poor or barren has not been satisfactorily explained.

The hypothesis of a second belt extending between Burns Mountain and Yanks
Peak has been proposed. It is based on the occurrence of gold-quartz veins at both
places, but no others are known, nor are there any placer creeks found between them.
It is possible that former gold placers were dispersed by glacial erosion, but that is
unlikely. The existence then of a second belt is less certain.

Gold-quartz veins at Burns Mountain and Yanks Peak are in rocks of various
kinds; they are not restricted to a mapped or recognizable member of the Richfield
formation. They are, however, close to the axis of the major anticline, and around
Burns Mountain appear to be associated with three northerly-striking faults that extend
between Slough Creek and Lightning Creek.

PROSPECTING POSSIBILITIES.

The most favourable prospecting ground in the Cariboo is considered to be along
the belt, particularly in the sections where the richest gold placers were worked.
However, Burns Mountain, Yanks Peak, and the entire belt from Island Mountain to
Roundtop Mountain have been staked; therefore, these sections contain very little
open ground.

The extensive drift-cover makes prospecting difficult, particularly when further
prospecting must rely on information gained from geological studies made in great
detail. It should be emphasized that previous prospecting involving the search for
quartz outerops has resulted in the finding of most exposures. Any further prospecting
must be directed towards the discovery of veins or vein-zones that do not outcrop,
either because they are blind or are covered by overburden. Consequently, further

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