11

Skeena river! The sedimentary strata representing the Nass formation
with, in places, the associated volcanic member, continue to Skeena river.
Along Skeena river, southwest from the mouth of Kitsumgallum river,
volcanic rocks are exposed. They there belong to the Kitsalas formation
which McConnell? “ placed tentatively in the Triassic.’ The Kitsalas
volcanics, involved in intrusive granitic bodies, appear at intervals for
some distance northeastward along Skeena river to where they are suc-
ceeded by sedimentary strata of the Hazelton group which continue east-
ward and then southward along Bulkley river. Where the southern edge of
the Hazelton strata cross Skeena river they overlie volcanic rocks classed
by McConnell with the Kitsalas.

As a result of the different pieces of work done in the region and
referred to in the preceding paragraphs, an assemblage of sedimentary
and volcanic rocks has been definitely traced with only one gap from Skeena
River-Bulkley River district, to Salmon River-Bear River district. The one
gap—it is 12 miles wide and lies east of the Salmon River-Bear River
district—is known to be largely occupied by a sedimentary series. There
can be no doubt that the various component formations, known locally by
different names, correspond as a whole to the Hazelton group of Bulkley
River district. Wherever throughout this region a volcanic member
appears, it is conformably overlain by sediments; in some places but not
all, the voleanic member is underlain conformably by a sedimentary series.
It seems probable that the volcanic members are all at the same horizon,
that the Bear River formation of Salmon River-Bear River area, the Dolly
Varden formation of Upper Kitsault River area, and the Kitsalas forma-
tion on Skeena river are correlatives. If this be so, then the sediments
overlying the Kitsalas on Skeena river are equivalent to the Nass forma-
tion. The name Hazelton group was originally proposed to include all
these strata, sedimentary and volcanic, and it seems desirable to retain
the name with this implied meaning. ©

In the districts bordering Bulkley river the Hazelton group is divisible
into four members.> These, in descending order, consist of:

Upper Sedimentary division.
Upper Volcanic division.
Middle Sedimentary division.
Lower Volcanic division.

Fossils from the Middle Sedimentary division are of lower Middle
Jurassic age. It seems probable that the Lower Volcanic division is the
volcanic assemblage repeated at intervals to the northwest and known
as the Bear River formation in Salmon River and Bear River areas and
that the overlying Nass formation corresponds to the three upper divisions
in the south. If so the Nass formation is, in part at least, of lower Middle
Jurassic age. The underlying Bear River volcanics are presumably of
early Middle Jurassic or late Lower Jurassic age. The Bitter Creek sedi-
ments may be Lower Jurassic or even Triassic.

Geol. Surv., Canada, Sum. Rept.
e: Sum.

S 1909, p. 63.
Rept. 1924, pt. A, p. 26; Sum. Rept. 1925, pt. A, p. 104.