15

occur along the east side of Spectacle lake, and along Swamp river, to the
east of the map boundary, and a search for fossils in these localities was
also without result. Even the shaly partings appeared to be unfossiliferous.

Pleasant Valley Formation

Distribution. These rocks conformably overlie those of the Barker-
ville formation, and, like it, occur in two narrow belts trending north-
westerly across the eastern part of the area. They are poorly exposed,
except in the gorges of some of the creeks. Excellent sections of parts of
the formation may be seen at the junction of Pleasant Valley and Grouse
creeks; in the pit of the New Waverly Hydraulic Mining Company; in
Antler creek near the junction with Quartz gulch; and particularly along
Shepherd creek and the Downey Pass Creek road.

Lithology. The members of this formation are essentially argillaceous,
the dominant type being a clay slate, varying in colour from grey to pale
brown to black, and possessing a well-developed cleavage. Other rock
types occurring in this formation are:

Caleareous slate, in which beds of argillaceous material, a fraction of an inch thick,
alternate with thin beds of limestone

Phyllite, grey, brown, purplish

Knotted sericite schist, slate, and phyllite, in which the knots are cordierite

Chlorite schist

Quartz slate, greyish to brownish

Schistose amygdaloidal metabasalt

Schistose basic voleanic flow breccia

Greenish schistose tuff

Black graphitic slate impregnated with cubes and grains of pyrite and prominently
cross-seamed with paper-thin veinlets of pyrite

Greyish-green, schistose tuff-agglomerate, with a greyish matric containing grains
of quartz, elongated or angular fragments of blackish limestone, and of a rock resembling
quartz porphyry

Black, knotted, glistening, pencil-like schist

Silver-white, knotted sericite schist

Limestone, fine-grained, grey-blue, slaty

Thinly bedded quartzite, sericitic

Veinlets and lenses of quartz occur abundantly throughout the
formation, and the oxidation of disseminated pyrite and ankerite or siderite
has produced a prominent brownish colour.

PROSERPINE SILLS AND DYKES

Distribution. A large number of brownish weathering sills and a
few dykes occur cutting the various members of the Cariboo series. They
are usually not more than a few feet thick, but in two or three places ¢
thickness of 30 or 40 feet was observed. Owing to the covering of glacial
drift and vegetation it was impossible to follow them along their strike,
except for very short distances. For these two reasons, the locations of
only a few were indicated on the geological map. They were not found to
occur in the Slide Mountain series, but pebbles of a similar lithological
character occur in the Guyet basal conglomerate.

20285—2}