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|Title:||Quaternary Stratigraphy and Glacial History of Bylot Island, n.w.t., Canada|
|Author(s):||Klassen, Rodney Alan|
|Department / Program:||Geology|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||The glacial history of Bylot Island concerns large ice sheets centred to the south and west (foreign glaciers), glaciers fed from highland areas on the island (native glaciers), and interaction between them. In this study, the determination of ice provenance and extent is based on lithology of erratic clasts, and their distributions. Relative age of glacial events and stratigraphic correlations are based on amino acid ratios of shells (ratio of D-alloisoleucine to L-isoleucine of naturally hydrolyzed amino acids (Free). At least three separate foreign glaciations are recognized. The oldest glaciation occurred prior to a period of interglacial climatic conditions (warmer than present) and is least known.
During a foreign glaciation, named informally Eclipse, foreign ice attained elevations of (TURN)600 m a.s.l. along the northern coast and > 800 m a.s.l. along the southern coast. The maximum extent of this ice is marked by major moraines, named Lancaster Moraine and Pond Moraine. Ice movement followed two main paths; (1) northward via Admiralty Inlet and then eastward via Lancaster Sound, and (2) northward across Baffin Island through Milne Inlet and then eastward via Pond Inlet. In Lancaster Sound ice surface gradients were low, and grounded ice extended to the head of Baffin Bay. Glacier reconstruction indicates that basal shear stresses within channels were low (25-60 kPa), implying wet-based ice, and against the island were high ((TURN)150 kPa) implying cold-based ice.
Native glaciers were not well nourished during Eclipse glaciation, and some were no more extensive than now. A major native advance is thought to have occurred as Eclipse foreign ice left the channels, and native ice held against the topographic divide moved outwards. Eclipse glaciation occurred > 39 000 B.P., and Eclipse sediments are bounded stratigraphically by shells with amino acid ratios of 0.30 (lower boundary) and 0.24 (upper boundary).
During post-Eclipse glaciation(s), foreign ice was much less extensive, and was not likely grounded in channels around the Island. Grounded ice occupied all of Milne Inlet until 9 500 B.P. A lower stratigraphic boundary for this (these) glaciation(s) is defined by shells with amino acid ratios of 0.15.
Native glaciers on Bylot Island have recently (< 120 B.P.) advanced, although most are now retreating. At this recent maximum, they are considered to have been as far advanced as at any time since Eclipse glaciation.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1982.
|Date Available in IDEALS:||2014-12-16|