Evolution of a nearshore and coastal macrotidal sand transport system, Queen Charlotte Islands, Canada
Barrie, J.V.; Conway, K.W. (1996). Evolution of a nearshore and coastal macrotidal sand transport system, Queen Charlotte Islands, Canada, in: De Batist, M. et al. (Ed.) Geology of siliciclastic shelf seas. pp. 233-247 In: De Batist, M.; Jacobs, P. (Ed.) (1996). Geology of siliciclastic shelf seas. Geological Society Special Publication, 117. The Geological Society (London): London. ISBN 1-897799-67-5. 345 pp., more In: Hartley, A.J. et al. (Ed.) Geological Society Special Publication. Geological Society of London: Oxford; London; Edinburgh; Boston, Mass.; Carlton, Vic.. ISSN 0305-8719; e-ISSN 2041-4927, more |
| Abstract | An extensive (40 km) coastal plain is prograding on the north coast of the Queen Charlotte Islands off the Pacific margin of Canada while the entire 120 km eastern coast of Graham Island is actively eroding. At the junction of these two systems is Rose Spit, which extends northeastward at a point of sediment transport convergence. Historical bathymetrical data and aerial photographs indicate that a spit platform extends 10km to the northeast and at least four portions (up to 4km in length) of the platform bank have become emergent since 1911. The area is seismically active and subject to storm-related sediment transport events superimposed on strong semi-diurnal tidal flows. The rapid emergence of the offshore banks and the net coastal changes are primarily controlled by: (1) convergence of sediment transport between the waters of Hecate Strait to the south and Dixon Entrance to the north, particularly during winter storms; and (2) localized tectonic uplift. Sediment is transported north from the shallow waters of Recate Strait by southeasterly winter storms and east, by longshore transport, along the accreting northem coast of the Queen Charlotte Islands to converge at Rose Spit. A 'hydraulic fence' has formed resulting in the creation of the elongate spit platform with emergent sand bars, east of the spit. Transpressional folding has occurred in this area east of the Queen Charlotte Fault, which separates the North American and Pacific Plates. This has resulted in localized uplift since Pliocene time, complementing the accretion process. |
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