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TitreCruise Report 86303 : Coastal Surveys in the Central Queen Elizabeth Islands (Dundas, Devon, Somerset, Cameron, and Lowther Islands, NWT)
TéléchargerTéléchargements
AuteurTaylor, R B
SourceCommission géologique du Canada, Dossier public 1595, 1987, 45 pages, https://doi.org/10.4095/130319 (Accès ouvert)
Image
Année1987
Documentdossier public
Lang.anglais
DOIhttps://doi.org/10.4095/130319
Mediapapier; en ligne; numérique
Formatspdf
ProvinceNunavut
SNRC48F; 48G; 49B; 58E; 58F; 58G; 58H; 59A; 59B; 68E; 68F; 68G; 68H; 69A; 69B; 78E; 78F; 78G; 78H; 79A; 79B
Lat/Long OENS-112.0000 -84.0000 77.0000 74.0000
Sujetsétudes côtières; plages; profils de plage; dépôts de tempête; plages soulevées; topographie; datations au radiocarbone; glace marine; photogéologie; érosion; géologie des dépôts meubles/géomorphologie; géochronologie
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12,00 $
Diffusé1987 11 01; 2011 12 22
Résumé(disponible en anglais seulement)
Twenty-five beach stations were examined during helicopter operations from CSS Hudson (cruise 86027) from August 25 to September 16, 1986. A 10-year comparison between 1976 and 1986 beach surveys indicated a net vertical degradation of less than 0.5 m at most of the 18 profiles resurveyed. Many of the profiles exhibited a partial rebuilding in the form of new swash ridges, but none of these new features exceeded the elevation of the 1976 storm ridges. The greatest changes were recorded at Cape Ricketts, Devon Island where as much as 11 m of recession occurred to the northwest of the Cape and a new 1.2 m high storm ridge formed at the end of the Cape. Survey evidence further suggests that the beaches were reworked by waves more since 1981 than during the first 5 years after 1976. At two locations on Lowther Island and one on Sheills Peninsula, northwest Devon Island, surveys were extended across the raised beach sequence to elevations of 17 to 25 m asl. Vertical spacing of the beach ridges was 0.9- 1.9 m and horizontal spacing varied from 14-29 m. The largest ridges of 1.8 m amplitude were formed across marine benches or at distinct breaks in topographic slope. The smallest and closest spaced ridges occurred on western Lowther Island which has a steeper inherent slope and experiences very limited wave activity.
Since 1969 when our beach surveys began, no new beach ridges, comparable in size to those on the emergent coast have been observed with the single exception of the new ridge at Cape Ricketts. Using radiocarbon dates of material from raised beach sequences near our survey sites, the average time span required to develop a primary beach ridge is estimated to be 275 years on northwest Devon Island and 225-300 years on Lowther Island. This is considerably longer than the 45 year cycle previously reported in the literature. Aerial video surveys of the southeast coast of Melville Island and western Byam Martin Island provided information on shore and nearshore morphology and sediment character, as well as the locations of severe sea ice ridging and shore ice override in 1986.
GEOSCAN ID130319