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Physiographic Physiographic TraverseTraverse

Physiography of British Columbia

• Tectonic setting• Geology/Glacial history• Climate• Vegetation/biogeography• Soils• Hydrology • Human influence

Tectonic setting of BC

Tectonic setting of Vancouver

Geologic history of BCMuch of the rocks that underlie British Columbia formed elsewhere and were transported here in the distant geologic past. The margin of the North American continent has grown westward from the Alberta border by the addition of exotic fragments of the Earth's crust, which geologists call “terranes.”Wrangellia Terrane, which forms most of Vancouver Island, originated within what is now the Pacific Ocean and was transported northeasterly to collide with North America about 100 million years ago. The force of this collision crumpled North American rocks as far to the east as the Rocky Mountains.

Generalized stratigraphy of BC

Summary of tectonic history

• On boundary of North America and Juan de Fuca plates – very “active”

• Implications of prolonged subduction of oceanic lithosphere and compression of crust– Accretion of exotic “terranes” to western margin (complete by

~95 Ma)– Episodes of igneous intrusion and volcanism (e.g., Garibaldi

Volcanic Complex, flood basalts)– Episodes of crustal uplift and thinning in Cretaceous and late

Cenozoic (lead to the development of present major relief forms)

Maximum extent of the Cordilleran ice sheet

during the late Pleistocene

After Clague, GSC

Late Quaternary chronology of BC

Phases of a glacial cycleInterglacial – small glaciers in high cirques, most subearial erosion accomplished by rivers

Alpine glacier phase – cirque glaciers grow, flow downvalley, tributaries coalesce

Intense alpine phase – ice caps form over high topography

Mountain ice sheet phase – glaciers, ice caps, ice fields coalesce. Flow is driven by topography

Continental ice sheet phase – extensive ice cover, ice flows radially from high interior

Early deglaciation -- retreat along periphery

Late deglaciation - Ice stagnation and lakes form in valleys, uplands ice free

Surficial Geology of BC

http://webmap.em.gov.bc.ca/mapplace/minpot/bcgs.cfm

Glaciolacustrine

Alpine complex

Till blanket

Quaternary volcanics

Glaciofluvial

Colluvial blocks

Till veneer

Organics

Alluvial deposits

Climate

Relation between mean annual precipitation and topography (BC)

•↑With elevation• Rain shadow• Declines inland

↑

Source: Bruce and Clark, 1966

BIOGEOGRAPHY

SOILS

HYDROLOGY

Eaton and Moore, 2007

LAND USE

Canada Pacific Railway, Kamloops, 1937

Front Street, Yale, circa 1882

Revelstoke dam

Sun Peak Resort

Adams Lumber Company, Chase, 1920

Weyerhauser pulp mill, Kamloops

Hope

Fraser Canyon

Chase

Kamloops

Cache Creek

Fraser Canyon

Revelstoke

Salmon Arm

3 valley gap

FieldGoldenRMT

Rogers Pass

RevelstokeKAN