Landforms of British Columbia 1976 - Department of Geography

are lithologic differences from place to place, but there is nevertheless an over-all
similarity of the landforms.
The erosion of a folded succession of volcanic and sedimentary rocks develops
landforms with some of the linear characteristics of folded sedimentary rocks, but
with other characteristics contributed by the diverse volcanic rocks, which are
hard and resistant to erosion and in which jointing is a more dominant property than
layering or bedding. As a consequence, volcanic rocks tend to produce landforms
more like those on granite and other intrusive rocks than those on sedimentary
rocks.
Figure 6. Diagram showing the main areas of folded and faulted
sedimentary and volcanic rocks.
Folded and faulted sedimentary and volcanic rocks of great variety occur on
Vancouver Island, Queen Charlotte Islands, as roof pendants and septa within
intrusive rocks of the Coast Mountains, and in belts and isoIated areas east of the
Coast Mountains and west of the Rocky Mountain Trench throughout the length
of the Province (,see Fig. 6). The largest single area extends northward from the
vicinity of WhitesaiI Lake into the drainage basins of the Skeena, Nass, and Stikine
Rivers.
(6) In British Columbia the group of foliated metamorphic rocks includes a
number of rock types which are mostly of sedimentary derivation. As a result of
various metamorphic processes, they may have been partly or completely recrystal-
lized, their original sedimentary characteristics may have been destroyed, and their
primary stratification replaced by a mineral layering which may transect earlier
bedding. Metamorphic rocks in this group contain a variable amount of igneous
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