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TitleInfluence of ground ice and permafrost on coastal evolution, Richards Island, Beaufort Sea coast, N.W.T.
AuthorDallimore, S R; Solomon, S M; Wolfe, S A
SourceCanadian Journal of Earth Sciences vol. 33, no. 5, 1996 p. 664-675, (Open Access)
Alt SeriesGeological Survey of Canada, Contribution Series 25095
PublisherCanadian Science Publishing
Mediapaper; on-line; digital
File formatpdf
ProvinceNorthwest Territories
NTS107A/13; 107A/14; 107A/15; 107A/16; 107B/13; 107B/14; 107B/15; 107B/16; 107C; 107D
AreaRichards Island; Beaufort Sea Coast; North Head; Hooper Island; Kugmallit Bay
Lat/Long WENS-136.0000 -128.0000 70.0000 68.7500
Subjectsregional geology; surficial geology/geomorphology; stratigraphy; permafrost; ground ice; coastal environment; coastal studies; coastal erosion; ice wedges; coastal evolution; sediment budget; Quaternary
Illustrationstables; bathymetric profiles; stratigraphic sections; graphs
AbstractA long-term sediment budget (1947 1985) for northern Richards Island shows that, when ground ice and offshore erosion are accounted for, there is a near balance between headland erosion and coastal deposition. Excess ice constitutes about 20% of the total volume of eroded material from the headlands, with massive ground ice contributing nearly 9% and segregated ice lenses and ice wedges making up the remainder. Coastal response to major storms in 1987 and 1993 suggests that erosion is episodic, with short periods of intense disruption followed by readjustment of cliff profiles. Processes characteristic of this environment include mechanical erosion of ice-bonded sediments creating unstable erosional niches, mechanical failure of niches along ice-wedge planes, and longer term thermal erosion of ice-bonded sediments. Where ice contents are high, localized thaw slumps initiated by coastal erosion may retreat at rates substantially higher than those observed at other sections of the coast. Cliff-top retreat rates may be out of phase with storm-event chronology.

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