49

places. The length is upwards of 4 miles. The location of most of the
mine workings and veins in that part of the fissure zone north of Glacier
creek is shown by Figure 12. Only veins wider than 2 feet are shown
on the plan and for simplicity some of the smaller mine workings are
omitted.

The fissure zone at Victoria Mines, Limited, which is its most
northerly known point, is in contact with the overlying Bear River
voleanics. Southward the zone departs gradually from the upper contact
of the sediments and passes through lower members of the Bitter Creek
formation. Where the zone crosses Glacier creek it is still near the over-
lying volcanics, but is a few hundred feet from them. The fissure zone was
not examined south of Glacier creek but there it appears to depart from
the voleanic contact at a more rapid rate until at its most southerly known
point it is well down in the Bitter Creek formation. The argillites strike
north and dip west at 45 degrees. The strike varies locally to northwest
or to northeast and the dip varies from about 10 degrees to 80 degrees.
Several dykes intrude the argillites.

Prior to the formation of the metalliferous veins the argillites were
subject to pressure which resulted in folding, shearing, and faulting. Shear-
ing was not uniformly distributed throughout the argillite formation, but
was restricted to a zone 1,500 feet or less in width known as the Portland
Canal fissure zone. The shearing in the fissure zone was localized in many
narrow, parallel zones along which considerable differential movement
probably took place, so that the narrow shear zones are faults accompanied
by shearing. The narrow shear zones follow rather closely the strike and
dip of the argillites, but in many places crosscut at small angles, but every-
where in the same direction, so that, whereas the argillites strike north,
the narrow shear zones strike a few degrees west of north. Less is known
about the dip of the shear zones, but in mine workings it is in some
places steeper and in other places less steep than that of the argillites.

Formed perhaps at the same time as the narrow shear zones are more
clean-cut faults. Two of these faults are known in the Portland Canal
fissure zone. The faults are parallel and their strike is north, approx-
imately the same as the average strike of the argillites, but the faults are
fairly straight and crosscut the argillites along the strike at all local curves
or bends in the strata. Local bends are common, so that the faults cross-
cut in most places. The dip of the faults is in general steeper than that
of the argillites.

The strike of the narrow shear zones and that of the faults, therefore,
intersect at a small angle which is in general less than 15 degrees, but is
as great as 45 degrees in a few places. The dip of the faults is in general
steeper than that of the shear zone.

The net result of the shear zone-fault combination is that the shear
zones on opposite sides of a fault are quite distinct from each other and
join the faults at small angles.

After the faults and shear zones were initiated, differential move-
ment still continued and took place along a few favoured shear zones
and along the faults past the shear zone-fault junctions. Thus in the