120

best, on the basis of present knowledge, not to include this map-unit in the
Asitka group, although it is recognized that in part the two units are
probably correlative.

Similarly, the meagre paleontological data provide evidence for
correlating at least part of this map-unit with the Cache Creek group of
Permian and partly Pennsylvanian age. The relations between the Cache
Creek group and either the Asitka group or the map-unit here under
discussion are not known; the Cache Creek group is probably mainly
younger, but the ages of all three units may overlap considerably.

On the basis of their geographic position and general lithology the
banded tuffs of the southern mountain group appear to be in part a
continuation of some of the volcanic and sedimentary rocks that have been
mapped as the lower part of the Takla group of Upper Triassic and later
age in the Takla and Manson Creek map-area (Armstrong and Thurber,
1945; Armstrong, 1946b). However, the rocks of this unit in Aiken Lake
map-area contain abundant fragments of corals, which are not known in
the definitely Upper Triassic rocks of the map-area to the south, and do
not contain the molluses typical of the Takla beds.

In summary, this map-unit is thought to be entirely or almost entirely
of late Paleozoic, probably mainly or entirely Carboniferous, age, and to
include beds that correspond with beds of the Asitka group, and possibly
also with beds of part of the Cache Creek group.

CACHE CREEK GROUP

DISTRIBUTION

Rocks assigned to the Cache Creek group are exposed in the south-
eastern part of the map-area, south of Osilinka River, east and west of
Wasi Lake. A few outcrops, part of a large body of Cache Creek rocks
exposed in the adjoining McConnell Creek and Takla map-areas, are
found in the extreme southwest corner of the map-area, southwest of
Omineca River.

LirHoLoGy

ROCKS IN THE SOUTHEASTERN PART OF THE AREA

The Cache Creek group rocks in the southeastern part of the map-area
fall into three main divisions: one predominantly massive limestone, one
composed mainly of volcanic rocks, and one consisting mainly of argillite,
with slate, chert, minor volcanic rocks, and limestone. The divisions are
arranged from east to west in the order named.

Limestone Division

The dominant rock in this division is massively bedded, blue-erey
weathering, light grey and dark grey limestone. Most of it is free from
clastic material, finely crystalline, and of a compact uniform texture,
with a smooth conchoidal fracture. In places, units up to 100 feet thick
are creamy to white, buff weathering, and relatively coarsely crystalline.
Some beds, best exposed on the slopes of Osilinka River Valley just east