Landforms of British Columbia 1976 - Department of Geography

(1,500 to 2,000 feet) which truncated flat or gently dipping Tertiary sediments
and lavas (Princeton and Kamloops Groups) of Eocene* age. Erosion continued
until late Tertiary, and the land surface was locally modified by the accumulation
of basaltic lavas and associated volcanic products of shield volcanoes, and by
flows of olivine basalt that are Miocene and younger.
Throughout the Province the land surface of erosional and depositional origin
that had evolved by late Miocene time was differentially uplifted during the Pliocene.
The surface, which had some initial relief, was incised by the streams, whose erosion
was r.ejuvenated, and considerable additional relief was ‘produced. The differential
uplift and erosion of the late Tertiary established the present arrangement of
mountains, plateaus, plains, etc. It was this late Tertiary topography that during the
Pleistocene was covered by glacial ice and was modified by it to produce the
landscape of today,
[References: Guidebook for Geological Field Trips in Southwestern British
Columbia, prepared by Geological Discussion CZub, Vancouver, March, 1960;
Geol. SLUT., Canada, EC, Geol. Series No. 1, “ Geology and Economic Minerals of
Canada,” 1957.1
SYSTEM GF SUBDIVISION
British Columbia possesses a great diversity of landforms, ranging from
unmodified Recent lava plains to intensely glaciated mountains. Any description
of landforms, in terms of their origin, to be of value to geographers, teachers,
tourists, or others, requires the application of some unifying system of classification.
The physiographic subdivisions of the Province, as outlined on the map of the
Province, Figure 1, and described in detail in the following text are natural regions
in which there are similarities in the landforms resulting from (1) similar processes
of erosion and deposition, (2) similarities of bedrock response to erosion, and
(3) similarities of erogenic history. These factors provide the basis for outlining
the major physiographic subdivisions of the Province in which common denom-
inators of topography exist. Further subdivision of these major units is possible,
and undoubtedly will be made when specific detailed studies of the areas provide
the necessary information.
PREVIOUS WORK
The earliest important contributions to the physiography of British Columbia
are in the writings of G. M. Dawson, who for many years worked in the Province
whilst a member of the Geological Survey of Canada. Most of his ideas are
brought together in “ The Later Physiographic Geology of the Rocky Mountain
Region in Canada,” published by the Royal Society of Canada in Transactions,
Volume 8, Section IV, 1890, pages 3 to 74.
One of the first attempts at physiographic classification and systematization
of the nomenclature of the Canadian Cordillera along the 49th parallel was made
by R. A. Daly in Geological Survey of Canada Memoir 38, Part 1, 1912.
Although some details of nomenclature are changed, much of Daly’s scheme is
retained in the present bulletin.
An important contribution was the publication by Leopold Reinecke of
“ Physiography of the Beaverdell Map-area and the Southern Part of the Interior
Plateaus of B.C.,” Geological Survey of Canada, Museum Bulletin No. 11, 1915.
* Mathews, W. H., and Rouse, G. FL, Sckwce, Vol. 133, April, 1961, p. 1079.
23