14

Marmot river. Farther northwest, in the mountain sides east of Portland
canal, the contact seems to have been displaced by a fault. At Stewart,
because of a tongue-like projection of the batholith extending east from
mount Dolly on the Alaska boundary, the contact swings abruptly to a
northeastward course which it follows for 2 miles to where it turns
through north to a westerly course which it follows back to Bear river.
At Bear river the contact is offset north by a fault, beyond which it fol-
lows a westerly course and passes out of the area into Alaska on the
southern slope of mount Dolly.

Except for the sharp swing round the tongue of the intrusive extend-
ing eastward from mount Dolly, the line of contact is fairly straight and,
in general, is nearly concordant with the strike of the beds of the intruded
rock. On Marmot river the contact dips northeastward at nearly the
same angle as that of the dip of the adjacent strata, but the strikes of the
line of contact and of the adjacent strata make a small angle, so that
argillites at the contact in the south are entirely cut away by the batho-
lith farther north. On mount Dolly the contact and the adjacent beds of
voleanic rock have the same strike and dip 60 degrees northeast. The
sharp swing of the contact at Stewart and the tongue-like projection of
the intrusive extending east from mount Dolly appear to be due to a local

upward bulge of the upper surface of the batholith as depicted diagram-
matically in Figure 1.

Figure 1. Diagram illustrating how an upward bulge of the Coast Range batholith
might give rise at the surface to a tongue-like projection as in the
Vicinity of Stewart, B.C,

The rock of the batholith is, on the whole, massive, but locally has
been slightly sheared. It is grey, medium to coarse-grained, and appears
to be a normal granodiorite. The predominant dark mineral constituent
is hornblende. Biotite is usually present, but in minor quantity only.
The plagioclase feldspar is oligoclase-andesine. Orthoclase and quartz