Landforms of British Columbia 1976 - Department of Geography

traveller. If he SO wishes, his enjoyment of scenery and of general travel,may be
considerably enhanced through an understanding of the origins and development of
landforms.
The development of landforms (geomorphology) is governed by factors that
can be grouped under three headings-(l) process, (2) character of bedrock,
and (3 ) erogenic or structural history.
The agents of erosion- streams, ice, wind, and chemical decomposition-are
constantly at work breaking down the rock which forms the land surface, allowing
it to be transported elsewhere and deposited. ‘Thus the surface in one place is being
lowered and elsewhere is being built up. At intervals there may be periods of
mountain-building or crustal movement which may elevate or depress the land
surface and in so doing may accelerate or diminish the rate of erosion. Volcanic
episodes are not uncommon, at which time the land surface may be built up by the
accumulation of large cones of lava and fragmental materials or by the outflowing
of large volumes of molten lava over the surface, filling in the low areas and creating
extensive lava plains. At all times the surface of the land is being modified, subject
to the complex interplay of several factors, and the resulting landforms are influ-
enced at all times by the nature and structure of the bedrock.
INFLUENCE OF PROCESS
Stream erosion under moist temperate climatic conditions has been the
dominant process in developing British Columbia landforms. The wearing-down
and sculpturing of the earth’s surface by the forces of stream erosion and the trans-
portation and disposal of the waste products are familiar to all. The details of the
process, the progression of events, and the characteristic Iandforms are described in
standard textbooks.*
The rate at which stream erosion takes place varies according to the regional
climate, especially the amount of rainfall, the gradients of the streams, and the
surface relief of the land. Twice in the recent past the relief has been greatly
increased through uplift of the land, once during the early Tertiary and again at the
end of that period, and, as a consequence, those were times of greatly accelerated
stream erosion. Throughout British Columbia, differences in climate and relief
have resulted in the production of greatly diverse landforms by stream erosion.
In British Columbia the second most important agent of erosion has been
glacial ice. Glaciers are a prominent feature in many parts of the Provincial land-
scape, and the work they do in sculpturing the higher regions and contributing
gravels and silts to the streams is apparent to anyone who has seen them at close
range. Almost all of our glaciers are now retreating, and it is obvious that their
erosiona activity has declined in very recent time. However, during the Pleistocene
the surface of the land was profoundly affected by a continental ice-cap that covered
all of British Columbia. The effects of Pleistocene glaciation are evident in every
landscape-landforms resulting from ice erosion are present in many places, and
much of the land is mantled with the products of erosion. An almost universal
veneer of ground moraine is concentrated locally into minor landforms, and the
deposits left by meltwater streams are to be seen on all sides. Reference is made
to glaciation in all descriptions that follow, and a section on glaciation appears on
pages 99 to 105.
* Cotton, C. A., ” Landscape,” Whitcombe and Tombs, Ltd., 1948
Davis, W. M., “ Geographical Essays,” Dover Press, 1954.
Dwy, G. FL, “ The Face of the Earth,” Penguin Emks, 1960.
Lobeck, A. K., “ Geot~~orphology,” McGraw Hill, 1939.
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