Landforms of British Columbia 1976 - Department of Geography

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Pleistocene probably has been between 400 and 500 feet in total amount. It, of
course, is related to the world-wide distribution of snow and glacial ice. Currently
it is believed that in stable regions in post-glacial time the sea has not risen appre-
ciably above its present level and that it has risen continuously, though perhaps
intermittently, up to modern time. This rising sea-level has affected the British
Columbia coast during the last 10,000 years.
The combination of these factors operating during and since the Pleistocene
has resulted in changes of sea-level, whose net effect, measured by beach deposits
and Recent marine fossils at various heights above sea-level, has been a post-
Pleistocene emergence of the land of 485 feet at Stewart, 500 feet at Campbell River,
465 feet at Qualicum, 470 feet at Nanaimo, 424 feet on Texada Island, 300 feet at
Victoria, about 300 feet in Alberni Basin, 575 feet at Vancouver, 50 feet along the
west coast of Vancouver Island, and 20 to 30 feet on Queen Charlotte Islands.
[References: Twenhofel, W. S., “ Recent Shoreline Changes along the Pacific
Coast of Alaska,” Am. Jour. Sci., Vol 250, 1952, pp. 523-548; Peacock, M. A.,
“ Fiord-land of British Columbia,” Geol. Six., Am., Bull. Vol. 46, 1935, pp. 633-
696; Guilcher, A., “ Coastal and Submarine Morphology,” Methuen & Co., Lon-
don, 1958; Flint, R. F., “ Glacial and Pleistocene Geology,” John Wiley & Sons,
New York, 1957; Fairbridge, R. W., ” Eustatic Changes in Sea Level,” in Physics
and Chemistry of the Earth, Vol. LV, Pergamon Press, 1961, pp. 99-185; Ban-
croft, J. A., “ Geology of the Coast and Islands, Strait of Georgia to Queen Char-
lotte Sound,” Geol. Surv., Canada, Mem. 23, 1913; Dohnage, V., “Coast and
Islands of British Columbia between Burke and Douglas Channels,” Geol. Surv.,
Conada, Sum. Rept., 1921, Pt. A, pp. 22-49; Fyles, J. G., “Surf&l Geology,
Oyster River,” Geol. Surv., Canada, Map 49-1959; Pickard, G, L., “Physical
Features of British Columbia Inlets,” Trans., Roy. Sm., Can., Vol. L, Ser. III, 1956,
pp. 47-58.1
[Photographs: Shoreline Features-B.C. 667: 107; B.C. 1499:46, 52; B.C.
1919:46, 57; B.C. 2248:2, 5; B.C. 2250:27, 98; Fiords-B.C. 501:111; B.C.
516:34; B.C. 663:95; B.C. 666:71; B.C. 674:15; B.C. 996:19; B.C. 1403:108.]
VOLCANIC LANDFORMS IN BRITISH COLUMBIA
British Columbia lies within a belt in which there has been volcanic activity
since mid-Tertiary time. In the same belt there are active volcanoes in Alaska today,
and there have been active volcanoes in the Cascade Mountains of Washington and
Oregon within historic time, There is no historic record of volcanic activity in
British Columbia, but there is evidence of some activity within the last few hundred
years, and much activity has been sufficiently recent that the characteristic volcanic
landforms, such as cones, shield volcanoes, explosive calderas, and lava plains, have
been little modified by erosion or glaciation. The locations of a great many volcanic
landforms are shown on Figure 1.
The late Miocene and early Pliocene* was a time of considerable volcanic
activity in the interior of British Columbia, when numerous lava flows of basaltic
composition spread over great areas of the Interior Plateau and Stikine Plateau.
Several centres of eruption in the western part of the Fraser Plateau are prominent
features of the landscape. These are the huge accumulations of lava 50~s and
fragmental materials in the large shield volcanoes which constitute the Rainbow
Range and the Itcha (see Plate XXVIA) and Ilgachuz Ranges. These are domes
10 to 15 miles across that stand 3,000 feet above the general level of the plateau.