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CHAPTER II
THE COAST RANGE BELT: EASTERN SECTION
GENERAL GEOLOGY

Beyond Terrace on the eastern side of the great north-
south valley dividing the Coast range into two sections, the
western and eastern, Skeena valley again enters a mountainous area.
An unbroken succession of high and rugged peaks without systematic
arrangement border it until Dorreen is reached. Beyond this the
valley widens and the mountains do not tower directly above it,
but at Cedarvale the siowatbouran close in again and to the south
are higher and more impressive than at any other point on the
route. The eastern limit of the Coast range is marked by the
Kitwanga-Kitsequekla valley. The eastern section of the Coast
range adjacent to the railway is formed of sedimentary and

volcanic strata and large and small bodics of granitic rocks.
Sediments and Volcanic Rocks

Except for a few isolated masses of older, possibly
Permian, limestones, the sediments and volcanic rocks belong to
two groups. The older, of Triassic and (or) Jurassic age, is
made up of a thick series of extrusives (lava, tuff, etc.) and
of intrusives (dykes, stocks, and sills). These rocks are largely
dense and massive, mainly green but in places grey, red, purple,
or brown, and are andesitic in composition. They are generally
very irregularly fractured end, therefore, mineral deposits
formed in the fractures are commonly small and irregular. In
places, however, some strong fractures and well-developed shear
zones occur and within some of these larger orebodies have been

formed not only by fissure filling but by replacement.