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the extension of the 3-inch seam in the adit. Just outside the
adit are impressions of small tree trunks in black shale. The
coal itself to some extent resembles the material from Cowgitz
and Slatechuck valley, but instead of being dense and heavy, it is
porous and light, of a coky, rather than of an anthracitic nature,
and with a lustrous, jet black colour. Some of the coal shows
well marked columnar structure, the individual columns being
about the size of the lead in a pencil and arranged normally to
the bedding.

Camp Trilby, the other locality near Yakoun lake, was not
visited by the writer; but S. E. Slipper of the Geological Survey,
who visited it, states that the occurrence is similar in a general
way to that just described, though he was unable to carefully
examine the workings.

As in the case of the occurrences near Skidegate inlet, the
metamorphosed condition of the coal is ascribed to the heating
action of dykes and sills of the Etheline volcanics. Sills are
found in proximity to the seams and there are doubtless many
that are not visible. The coked appearance of the coal is strong
evidence that direct application of heat caused the metamorphism.

Structure. In general structure this coal basin seems to be
a close folded syncline, pitching north. The opening nearer the
lake is on the western limb of the fold, and the measures there
dip steeply northeast, while Camp Trilby is situated on the
eastern limb, and the rocks dip steeply southwest. This syncline
is in part covered by flows of Tertiary volcanic rocks.

Extent of the Coal-bearing Horizon.

The accompanying areal map shows the supposed outcrop
of the horizon of the Robertson seam, definitely located only at
Camps Robertson and Anthracite, and elsewhere traced by
means of its relations to the massive sandstone of the upper
Haida. Away from the high ground on which these two camps
are situated the outcrops are few and in certain areas lacking,
so that the location of the line representing the horizon on the
map is based, along portions of its course, more on inference than
on direct evidence. The line shows at least approximately,
however, the area which is underlain by the coal horizon. The

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