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TitleRaised gravel beaches as proxy indicators of past sea-ice and wave conditions, Lowther Island, Canadian Arctic Archipelago
AuthorSt-Hilaire-Gravel, D; Bell, T J; Forbes, D L
SourceArctic vol. 63, no. 2, 2010 p. 213-226,
Alt SeriesEarth Sciences Sector, Contribution Series 20090112
Mediapaper; on-line; digital
File formatpdf
NTS68E/10; 68E/07NW
AreaLowther Island
Lat/Long WENS-97.6667 -97.0000 74.7500 74.4167
Subjectsraised beaches; coastal environment; coastal studies; shorelines; shoreline changes; depositional history; glacial history; climate; climate, arctic; sea ice; gravels
Illustrationsphotographs; location maps; graphs; plots; tables
ProgramBuilding Resilience to Climate Change in Canadian Communities, Climate Change Geoscience
AbstractThis study investigates whether raised beach sequences preserved on emergent coasts of the central Canadian Arctic Archipelago contain a proxy record of past sea-ice conditions and wave intensity. We hypothesize that periods of reduced sea ice (increased open water) expose shorelines to more prolonged and higher wave energy, leading to better-developed beach ridges. Surveys of raised beach sequences on Lowther Island revealed the following patterns: a) high, wide, single- to multi-crested barriers backed by deep swales or lagoons characterize both the active and lowest relict shorelines; b) small, narrow, discontinuous ridges of poorly sorted gravel extend from 1.0 to 7.5 m asl, except from 4.5 to 5.0 m asl; c) ridge morphology is similar to the active and first relict ridges between 7.5 and 11 m asl; d) a near-featureless zone with minor terraces and ridges above 11 m extends to above 30 m asl. These distinct morphological and sedimentary units are interpreted as a function of wave climate and thus of summer sea-ice conditions. This model suggests periods of greater wave activity from the present day back about 500 14C years (530 cal BP; Unit A), during a short interval from 1750 to 1600 14C years BP (1750-1450 cal BP; Unit B?), and earlier from 2900 to 2300 14C years BP (3030-2340 cal BP; Unit C). Units B and D are interpreted as the result of more severe ice conditions with lower wave energy from 2300 to 500 14C years BP (2340-530 cal BP) and earlier from more than 5750 to 2900 14C years BP (6540-3030 cal BP). Discrepancies with previously published interpretations of regional sea-ice history may reflect the local nature of the beach proxy record, which implies occurrences of extensive open-water fetch east and west of Lowther Island but cannot be extrapolated to a regional scale. The beach record shows distinct variation through time and provides an alternative window on past summer ice extent in central Barrow Strait.