Quaternary Geology of the Canadian Cordillera

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Abstract
The Canadian Cordillera, the westernmost of the major physiographic and geological regions of Canada, is an area of rugged mountains, plateaus, lowlands, valleys, and seaways. This region extends from the International Boundary on the south to Beaufort Sea on the north and from Pacific Ocean and Alaska on the west to the Interior Plains on the east, a land area in excess of 1 500 000 km2. The Canadian Cordillera is located at the edge of the America lithospheric plate and consists of the deformed western margin of the North American craton and a collage of crustal fragments, or terranes, that were accreted to the craton and subsequently fragmented and displaced northward along major strike-slip faults. These processes have given the Cordillera a strong northwest-southeast structural grain and are largely responsible for the present complex distribution of rocks, faults, and other structures in the region. The distribution of earthquakes, active and recently active faults, and young volcanoes in the Canadian Cordillera is controlled by the motions of the Pacific, America, Juan de Fuca, and Explorer plates and Winona Block which are in contact in the northeast Pacific Ocean west of British Columbia. Most large earthquakes and active faults are associated with offshore plate boundaries beyond the British Columbia continental margin; some, however, occur on the continental shelf and on land. Most Quaternary volcanoes are located in four narrow belts that constitute