63

lake and beyond Camp Robertson. It is complicated by several
smaller folds (as illustrated in the sections accompanying the map)
and the folding is more severe in the western than in the eastern
limb. The portion of the syncline underlying Skidegate inlet
is an irregularly warped sheet of sediments of variable thickness,
in which strikes at all azimuths, and dips up to vertical are
found. The main extension of the Skidegate Inlet basin is
found in the syncline occupying the Honna and Slatechuck
valleys and other territory northward beyond Camp Robertson
and covered to the west by Tertiary volcanic flows. This
syncline is on the whole a broad open fold hereafter termed the
Honna basin. The western part of the Honna basin, in the
Slatechuck valley and around Yakoun lake, is severely folded,
in places overturned, and also faulted. The more severe folding
is doubtless due to the proximity of the underlying massive
rocks of the Vancouver group, which formed a buttress against
which the softer sediments were compressed. Westward from
Camp Robertson the rocks lie flat or in undulations, but to the
eastward there are severe local folds, accompanied by faults.
The structures at Camp Robertson are illustrated in the sections
given in connexion with the description of the coal seams there.
These sections give evidence that the beds have been affected by
intense folding with slight faults, probably due to the soft and
yielding nature of the coal seams and associated beds.

The Haida formation occurs in the vicinity of Camp Wilson
in the Yakoun valley in a basin-shaped syncline, warped into
several open folds complicated by minor crumplings and some
faulting. The detailed structure of this basin has not been
deciphered owing to the obscurity of the evidence given by the
meagre outcrops.

Further details in regard to the faults affecting the Queen
Charlotte series will be found in Chapter VI.

IGNEOUS INTRUSIONS.

Dykes of the Etheline volcanics are found cutting the
Queen Charlotte series in great numbers. They are particularly
common in the Haida formation, especially in the Honna basin.