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of the formation in the south may-be of non-marine origin, like the tar sand:
of the Athabaska at the same horizon. At the great horseshoe bend the thicknes=
is 400 feet (estimated) and to the south in the oil wells, 1,100 feet. The Loon
River formation is correlated with the McMurray and Clearwater formations of
Athabaska river.

Peace River Formation. The rocks of the Peace River formation outcrop
on both sides of the valley from a point about 14 miles above Carcajou point
to Peace River. Where they are typically developed and exposed, they form steep
valley-walls, the “ Ramparts of the Peace.” The formation consists of two sand-
stone members, with an intervening shale member, and where all three outcrop,
the sandstone components give rise to two cliffs, separated by a bench on the
shale. In its southern development the upper sandstone is made up of massive,
white-to-cream, crossbedded sandstone. The few concretions present are thin
and horizontally extended. A discontinuous lignite seam is found near the top at
some localities. The surface of the cliff walls weathers into an arabesque of
hollowed and bossy sculpture. The thickness of this upper sandstone in the
south is 180 feet, but due to replacement by shale above, it thins northward and
near the mouth of Cadotte river is only 90 feet thick. At this locality the upper,
massive, crossbedded, freshwater sandstone of the south is replaced by bedded
sandstone and shale with marine fossils. Both the thickness and arenaceous
content continue to decrease northward until the entire member is replaced by
shale; so that the contact with the St. John shale descends stratigraphically in
that direction.

The middle shale member is made up of blue black, friable shale without
fossils, but probably is of marine origin. The thickness is 30 feet.

The lower sandstone member differs considerably in structure and lithology
from the upper. At the top it is characteristically massive and crossbedded and
contains large spherical concretions similar to those of the lower part of the
Grand Rapids sandstone of the Athabaska section. This passes down into bedded
sandstone and shale. The shale is thin-bedded at the base and carries marine
fossils. The top may be subaerial, but the lower part is certainly marine. The
contact with the Loon River shales is arbitrarily chosen, being marked by a
gradual transition from bedded sandstone and shale to shale below. South of
Brown’s trading post the thickness is about 160 feet, 7 miles below the mouth of
Battle river it is 80 feet thick, and to the north it is only about 20 feet thick.
Both this formation and the Loon River have a common fauna and this is now
being studied. The affinities of this fauna are Lower Cretaceous and pre-Dakota,
taking Cenomanian as the base of the Upper Cretaceous. The formation is
correlated with the Grand Rapids formation of Athabaska river. As to Dakota
there are three possibilities; it is represented by the top few feet of the Peace
River sandstone; the lowest beds of the St. John are its marine equivalent; or
there was no deposition in Dakota time. |

Bull Head Mountain Sandstone. The Bull Head Mountain formation con-
sists of a thick series of strata of freshwater origin lying between the Triassic
shale below and the St. John shale above. It appears first in the canyon midway
between Deep and Johnson creeks and continues to the west as far as Twenty-
mile creek. As a result of the preliminary examination, this series of rocks may

be divided into two members, The upper member consists of sandstones, shales,

and coal beds and is well exposed in the canyon and on Gething and Johnson
creeks. The lower part is made up of massive, coarse, crossbedded sandstones