102

“Overlying the dark grey, fissile, marine shales of Lower Cretaceous
age on Petitot River are grey, banded sandstones and interbedded, dark
grey, chunky shale transitional from the marine shale to the overlying
medium-grained, grey, buff weathering sandstone. ‘Thirty feet of the
transitional beds are exposed at this locality. Above them the section is
only partly exposed to where the uppermost 250 feet of conglomerate and
coarse, grey, crossbedded sandstone form continuous outcrops along the
banks for 4 miles through the canyon. A section in the partly exposed
interval shows 130 feet of beds composed of dark grey shale interbedded
with medium- to fine-grained sandstone overlain by medium- to coarse-
grained sandstone beds and a 15-foot bed of loosely cemented pebble-
conglomerate. Carbonaceous fragments were observed along some of the
bedding planes. The upper conglomerate member contains pebbles of
quartz, quartzite, grey, green, and black chert, and grey and black argillites.
These are as much as an inch in diameter, and are fairly well sorted. The
sandstone associated with the conglomerate is coarse grained and cross-
bedded.”

Age and Correlation

The only fossils yet found in the Fort Nelson are a few leaves collected
by Kindle from the upper part of the formation on Liard River, and they
are not diagnostic. Williams (1944), Kindle (1944), and Hage (1945) all
propose a correlation with the Dunvegan formation of which they consider
the Fort Nelson to be a northern extension.

SMOKY GROUP
Definition

The Smoky group embraces all strata between the Dunvegan formation
below and the Wapiti group above. In northeastern British Columbia
it contains considerable sandstone, but in most places is predominantly
shale. On the Plains, it consists mostly of shale, with the exception of a
sandstone near the middle. The group is entirely of marine origin.

‘Smoky River’ was first used as a formation name by Dawson in
1881, for the ‘Upper shales’, “well seen” by him on Coal Creek and the
lower part of Smoky River. On Smoky River, two thick shales are separ-
ated by the Bad Heart, or in the broad sense, Bighorn sandstone. The
lower shale unit has been called Kaskapau member (McLearn, 1919). The
upper shale has not been named, and can probably be called Wapiabi
(Gleddie, 1949). It is now the practice to treat the Kaskapau, Bad Heart,
and Upper shale as formations, and the Smoky as a group (McLearn and
Henderson, 1943; Crickmay, 1944; Gleddie, 1949). The Smoky has a
shorter downward range than the Alberta group.

Very little has been published on the Smoky group of northeastern
British Columbia, and few sections have been examined carefully.