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The Maude formation is at least 3,800 feet thick and the
lower part is composed of thin, flaggy, fossiliferous argillites and
black slates, which, generally, are strongly impregnated with
bituminous matter. The upper part of the formation consists
of fine, even-grained, grey-green sandstones, with some tuff and
agglomerate intercalations. The character of the strata making
up the formation, varies somewhat in different localities; and
on Langara island, and on the northwest extremity of Graham
island there are sandstones and coarse conglomerates which are
thought to belong to this formation.

Conformable on the above described rocks is the Yakoun
formation, consisting of agglomerates and some flows of basalt,
and containing in its lower part greenish-grey tufaceous sand-
stones, which are in many places fossiliferous, and lithologically
resemble the sandstones of the Cretaceous Queen Charlotte
series.

These two formations, comprising the Vancouver group,
have been strongly folded, the general direction of the axes of
the folds being north 30 degrees west, but locally varying.
Faulting on a minor scale is common and is especially noticeable
in the well banded argillites of the Maude formation.

The rocks of the Vancouver group have been intruded by
stocks of granodiorite and associated rocks, which are exposed
on the southwest corner of Graham island, and are reported to
occur also in the valley of the Tlell river in the eastern part of
the island. Dioritic rocks also form the larger portion of
Langara island.

On the rough, denuded surface of these older metamorphic
and igneous rocks, a series of conglomerates, sandstones, and
shales were laid down unconformably. These sediments are
called the Queen Charlotte series and, in their lower portion,
contain one or more coal-bearing horizons. The time of their
deposition was during the Upper Cretaceous. The surface
on which they were deposited was hilly, and in many places
very uneven. The general topographical conditions surround-
ing the basin probably resembled to some extent those found
in the vicinity of Skidegate inlet to-day.