ELLS GRAHAM ISLAND 45 B
pany, may not exist. Owing, however, to the difficulty of obtaining outcrops over
the greater portion of the district, such exploration to determine the pres-
ence of coals in workable quantity can only be economically carried on by
means of boring, in which case the eable drill will possess some features
Superior to the diamond drill, owing to the comparative cheapness with
which it can be operated in such a wilderness country,

The only place where the Cretaceous rocks were seen outside of the
principal area which extends across the eastern centre of the island was an
isolated patch on the southeast corner of North island. Here, shales and
sandstones with conglomerates, precisely similar to the sediments seen
along the north side of Skidegate channel in the vicinity of the Honna
river, are exposed along the shore for nearly a mile. They dip generally
S. 50° HE. < 30°-40° with a roll midway to where the dip is changed for
100 yards to N. 60° E. At the northern end of the basin the shales pass
beneath a mass of coarse greyish conglomerate which exactly resembles that
at the Narrows west of Honna, and which there marks the base of the upper
series of shales and sandstone of Richardson. These conglomerates con-
tain pebbles of granite, hard fine-grained diabase; hard altered slate, quartz,
ete., with interstratified beds of coarse grits. These beds extend south-
eastward to the eastern entrance of the main channel between the two is-
lands, but here they are badly mixed up with the later Tertiary eruptive
rocks. In this area their distribution has been defined by Dr. Dawson,
(Rep. 1878-79.) No trace of coals was seen in this area, which is very
limited, and apparently of no economic importance.

IGNEOUS ROCKS.

The rocks of the west coast, and in fact of the greatest portion west of
a line drawn from the mouth of the Honna to Masset, are included under
the head of Igneous. These are divisible into two classes, viz., those of
Pre-Cretaceous and those of the later Tertiary. The former are the ex-
tension of the coast rocks of Vancouver islands and the greater part of the
southern islands of the Queen Charlotte group, named by Dawson the
‘*Vancouver series.’? They comprise large areas of green, generally fine-
grained, diabase, felsitic rocks, sometimes porphyritic, agglomerates, etce.,
with which in places are limestones which contain traces of fossils, though
generally of but little value for determination of horizons. These igneous
rocks are the oldest known on this part of the coast. They certainly under-
lie the Cretaceous rocks which have just been described and may, theretore,
be regarded as older than that series. They are penetrated by dykes and
sometimes by large masses of granite, as well as by blackish green diabase
rock which is more recent than the Cretaceous shales,

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