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TitleBoulder-strewn flats in a high-latitude macrotidal embayment, Baffin Island: geomorphology, formation, and future stability
AuthorHatcher, S V; Forbes, D LORCID logo; Manson, G K
SourceCanadian Journal of Earth Sciences 2021 p. 1-18, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20190012
PublisherCanadian Science Publishing
Mediapaper; on-line; digital
File formatpdf
NTS25I; 25J; 25K; 25L; 16; 26; 36; 27; 37; 47E; 47F; 47G; 47H; 57E; 57H; 58A; 58D; 48A; 48B; 48C; 48D; 38A; 38B; 38C
AreaBaffin Island; Iqaluit; Koojesse Inlet
Lat/Long WENS -92.0000 -60.0000 74.0000 62.0000
Subjectssurficial geology/geomorphology; morphology; coastal studies; coastal environment; boulders; tidal flats; glacial landforms
Illustrationslocation maps; satellite images; photographs; composite sections; graphs; plots; models
ProgramClimate Change Geoscience Coastal Infrastructure
Released2021 07 27
AbstractTidal flats are widely distributed on high-latitude coasts, where sea ice processes have been invoked to explain the abundance and distribution of boulders. This study documents the surface morphology and sediment dynamics of a Low-Arctic macrotidal system, the boulder-rich tidal flats of Koojesse Inlet, fronting the Nunavut capital, Iqaluit, on Baffin Island. This is a region of postglacial isostatic uplift and forced regression, with raised littoral, deltaic, and glaciomarine deposits. The spring-tidal range is 11.1 m and sea ice cover lasts roughly 9 months of the year. The extensive intertidal flats are up to 1 km wide, with a veneer of sand and gravel (including large boulders) resting on an erosional unconformity truncating the underlying glaciomarine mud, forming a terrace within the present tidal range. Over a 3-year study, no consistent pattern of erosion or deposition was evident. Over a longer time scale, the concave hypsometry, low sediment supply, slight ebb dominance of weak tidal currents, abrasion by wave-entrained sand, ebb-oriented ripples formed under subaerial drainage, and slumps on the terrace flanks are consistent with seaward hydraulic and gravitational sediment transport. These processes may be of greater importance than shoreward ice transport. This study underlines the importance of relict glaciomarine deposits, postglacial uplift, and falling relative sea level in the erosional development of these high-latitude tidal flats. Relative sea-level projections for Iqaluit are ambiguous, but a switch to rising sea level, if it occurs, combined with more open water and wave energy, could alter the foreshore dynamics of the system.
Summary(Plain Language Summary, not published)
Our knowledge of tidal flats comes primarily from temperate regions. Arctic tidal flats are distinct because of the role of sea ice. This study examines the macrotidal flats fronting the Nunavut capital of Iqaluit, where the spring-tidal range is 11.1 m. The study has two main objectives: to describe the shape and structure of the flats and to assess the evidence for sediment reworking within the inlet. Based on our observations of sediment movement, we suggest this represents an eroding landform that is continually activating old glaciomarine sediments. No consistent pattern of erosion and deposition on the flats was evident over the three year study. The shape of the flats, and forms found on their surface and in the offshore, show us the ways that sediment is removed to deep water. This study builds off previous research in confirming the importance of land uplift in forming these high-latitude tidal flats.

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