38

Triassic age and the latter is middle Jurassic. The lower members
of the Maude formation are very fine-grained, calcareous and
carbonaceous mud rocks, associated with bands of limestone.
Higher in the formation are pale green, hard sandstones, gradually
becoming tufaceous and passing into the conformably overlying
Yakoun formation. This formation is largely pyroclastic in
its origin, but probably consists in part of flows and sills.

The rocks of the Vancouver group were dynamically
metamorphosed and intruded by batholithic rocks. The
complex was then eroded, and a thick series of sediments of
Upper Cretaceous age, the Queen Charlotte series, was uncon-
formably laid down on the eroded surface. These rocks are
composed of the detritus of the older formations, and the lower
member contains coal-bearing horizons.

After the formation of the Queen Charlotte series and to
some extent during the period of its formation it was extensively
injected with numerous dykes and some sills of dacite and
andesite, up to 50 feet thick. This volcanic activity extended
into the Tertiary period, and the eroded surface of the Cretaceous
rocks was deeply buried under the accumulated flows of Tertiary
volcanics, with which occur some sediments.

Since the late Tertiary, erosion has been active in shaping
the present diversified topography, and deposits of Pleistocene
age, stratified and unstratified glacial drift, are widespread.

TABLE OF FORMATIONS.

Pleistocene and Recent | Superficial deposits. Gravels, sands, and
clays. Till.

Unconformity.

PHOCHHE CPs Soe es i Masset formation........ Basalt flows and agglom-

erates.

Unconformity ?

|
Pliocene-Miocene .. .(?)} Skonun formation........| Conglomerates, sand-

stones, and shales.