39

Sustut group. The Omineca intrusions cut Jurassic, Takla rocks in the
adjacent Takla map-area, and supplied pebbles to Sustut conglomerates
in McConnell Creek map-area. However, no marked angular unconformity
was noted where members of the Sustut group and upper, Jurassic division
of the Takla group were found in contact; the strata were essentially
parallel in strike, and dips did not vary more than 5 or 10 degrees. This
apparent slight discordance in dip is not necessarily significant, because
the available exposures did not lend themselves to precise observation.
Nevertheless, some angular discordance is inferred because of the emplace-
ment of the Omineca batholith during the intervening erosion period, for it
is improbable that this could have taken place without some folding.
Furthermore, the widespread, extremely gentle dips of the Sustut formations
in the vicinity of Thutade Lake are not, so far as known, duplicated any-
where within the Takla group, and it seems highly probable that a marked
angular unconformity exists in places.

The Sustut formations were not found in contact with strata assigned
to the lower division of the Takla group or to the Asitka group. However,
they were found nearly in contact at several places in the general vicinity
of upper Niven River, and there the discordance in attitudes leaves little
doubt that the Sustut strata rest with marked angular discordance on these
older rocks.

Fossil Collections

Fossil plant remains were seen in nearly all areas of Sustut rocks, but
the most diagnostic collections! came from the vicinity of Thutade Lake
and Niven River.

The following collections came from the lower division of the Sustut
group:

F34. Geol. Surv. Cat. No. 3485
Locality: 14 miles north-northeast of the mouth of Pilot Creek.
Angiosperms
Platanus latiloba Newberry
Ficus sp.
Viburnum ? integrifolium Newberry
Age: See remarks below
F35. Geol. Surv. Cat. No. 3484
Locality: 14 miles north-northeast of the mouth of Pilot Creek, and about
450 feet stratigraphically below F834.
Ferns
Cladophlebis striata ? (Presl.)
Cladophlebis frigida (Heer)
Angiosperms
Laurophyllum sp.
Ficus ef. protogaea Heer
Age: See remarks below
F36. Geol. Surv. Cat. No. 3486
Locality: 9 miles south of Thutade Lake at longitude 127 degrees.
Conifers
Elatocladus (Sequoia?) rigida (Heer)
Angiosperms
Dewalquea smithi Berry
Ficus cf. stephensoni Berry
Dicotylphyllum grandifolio-cretacea (Lesquereux)
Age: See remarks below

1 All identifications, age determinations, and comments are by W. A. Bell, Chief, Paleontological Section,
Geological Survey of Canada.