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As all the magnetite deposits examined are related to the contacts
of the diorite and granodiorite with the rocks of the Vancouver group,
the following detailed information concerning the petrography and structure
of these rocks, taken from the latest report by Dolmage, is embodied herein.

“VANCOUVER GROUP

“The oldest rocks of the district are those of the Vancouver group
and these are also the most widely destributed . . . . throughout
the island. The group consists almost entirely of volcanic rocks, chiefly
andesites, but contains also many intercalated beds of tuffaceous argillite
and limestone—some of which attain a thickness of 2,000 feet and more.

“The voleanic rocks comprise by far the greater bulk of the group
and underlie fully nine-tenths of the area under discussion. Andesites
are the prevailing types, but dacites and basalts are also found, and con-

siderable quantities of tuffs, breccias, and agglomerates. . . . The
andesites . . . . are seldom found in a fresh condition. They

usually contain high proportions of chlorite, actinolite, and epidote, giving
the rocks a dull greenish colour, or else they contain considerable hematite
which gives them a decidedly reddish to brownish tint.

“Puffs are plentifully distributed throughout the group. They are
usually well bedded and clearly indicate the attitude of the beds of the
formation. They present a great variety of colour, from dark purple
through shades of brown and red to light grey, but very commonly also
assume various shades of dull green. They vary likewise in texture from
coarse agglomerates through many gradations down to material so fine
that its components can be resolved only by the use of a microscope. at ve

“The tuffaceous argillities, the least abundant rocks of the group,
are always associated more or less closely with the limestones, and are con-
fined to relatively thin beds occurring north of Kyuquot sound. . . . In
the hand specimen they are fine-grained to dense, finely banded, usually
black, but often grey, brown, or dark green and have a distinct cleavage
parallel to the bedding. ‘

“Beds of limestone varying from a few feet to 2,000 feet or more in
thickness were found at many places, interbedded conformably with the
andesites and tuffs of the Vancouver group. . . . These limestones
for the most part are very pure, light grey to bluish-grey in colour, and
have been metamorphosed into a medium coarse, even-grained marble. . .

“The limestones, where cut by plutonic rocks of the Coast Range
batholith, are intensely metamorphosed into rocks containing garnet,
epidote, pyroxene, quartz. . ‘

“The Vancouver group is folded into steep anticlines and synclines
whose axes strike north 60 to 65 degrees west.

COAST RANGE BATHOLITH

“A great many intrusions of diorite and granodiorite, some of con-
siderable extent, occur in this district cutting the rocks of the Vancouver
group, and are believed to be related to the Coast Range batholith. They
are distributed throughout the district in the form of small batholiths,
stocks, dykes, and occasionally in the form of sills. In the southern part
these intrusions consist of two types distinctly different in composition
and age; a diorite consisting of oligoclase to an desine plagioclase, little or