General Geology

Although several of the identified species range from Paleocene to early Miocene,
the assemblage as a whole correlates it with the flora contained in the Kitsilano
formation of the Vancouver area and in the Bridge Creek deposits of the John
Day Basin. Although Berry considered the Kitsilano flora to be either late Eocene
or Oligocene, an Oligocene, probably late Oligocene age, now seems to be the

more probable.

If the sedimentary rocks are of late Oligocene age, the overlying volcanic rocks
must be late Oligocene and Miocene or younger. This accords with the age of
the group as stated by Armstrong—Oligocene or later (Armstrong, 1949, p. 76).

Correlation

The Endako Group as defined in the Fort St. James area, appears to be a
fairly distinct stratigraphic unit. The group as mapped in the Nechako River area,
is comparable in age, lithology, and structure with minor exceptions. Recent work
by the writer in the Anahim Lake and Quesnel map-area (Tipper, 1957; 1959b)
has shown that there are three or more mappable units that may be correlated in
whole or in part with the Endako Group. Furthermore there are two or three units
that closely resemble rocks of the Endako Group but are older or younger. In
reconnaissance mapping, it is difficult to separate these various units and it is pos-
sible that some of these units have been erroneously included with the Endako
Group. For this reason any attempts at definite correlations are inadvisable until
the group is more closely defined and its upper time limit established.

Intrusive Rocks

Serpentinized peridotite outcrops on Sinkut Mountain in Prince George map-
area to the east and extends 2 to 3 miles into the northeast quarter of the Nechako
map-area. These rocks are intruded by the Topley granitic rocks on the northeast
side and probably on the southwest side. As the rocks here exposed lie mainly in
a contact zone, they are varied. The central part is a serpentinized peridotite with
talc schists, anthophyllite schists, and serpentinites near the granitic contact. They
are poorly exposed and only a brief examination was made.

The age and correlation of this unit is uncertain. In Nechako River area the
ultrabasic rocks are cut by the presumably Lower Jurassic Topley Intrusions. In
the adjoining Prince George map-area, the ultrabasic rocks are younger than
Upper Permian limestone. It can be concluded then that the ultrabasic rocks are
late Upper Permian to early Lower Jurassic in age and most probably are Triassic.
The Trembleur Intrusions (Armstrong, 1949, pp. 79-92) to the northwest appar-
ently occupy the same stratigraphic position.

Topley Intrusions

The name Topley Intrusions was given to “a group of acidic intrusive rocks
of probable pre-Jurassic age. They were first recognized in the Topley area. . .”

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