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The dynamics of the north-western Laurentide Ice Sheet margin
Stoker, Benjamin James ; Margold, Martin (advisor) ; Darvill, Christopher (referee) ; Nývlt, Daniel (referee)
The Laurentide Ice Sheet (LIS) was the largest ephemeral ice sheet in the Northern Hemisphere, reaching its all-time maximum during the last glacial cycle (~115 ka to ~11.7 ka) as it coalesced with the Cordilleran and Innuitian ice sheets over northern North America and the Canadian Arctic Archipelago. At its maximum extent it was comparable in size to the modern-day Antarctic Ice Sheet and may provide a useful analogue for understanding the long-term dynamics of ice sheets. There are considerable regional variations in our understanding of the deglaciation of the LIS. In particular, the northwestern LIS remains one of the most poorly understood sectors, as the latest reconstruction of this sector dates to the early 1990s and empirical constraints on the timing of deglaciation are sparse. In this thesis, I reconstruct the deglaciation of the northwestern LIS from its local Last Glacial Maximum (LGM) position using numerical dating methods and glacial geomorphological mapping. I use a combination of high-resolution digital elevation models (DEMs) and satellite imagery to map the glacial geomorphology of much of the Northwest Territories, Canada, and reconstruct the ice margin retreat patterns, ice flow dynamics, and interaction of the northwestern LIS with other ice masses. This new information is...
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Reconstructing the central sector of the Cordilleran Ice Sheet
Dulfer, Helen Elizabeth ; Margold, Martin (advisor) ; Ely, Jeremy (referee) ; Nývlt, Daniel (referee)
The Quaternary Period (last 2.6 Ma) was a time of increased climate oscillation that resulted in the repeated growth and decay of Northern Hemispheric ice sheets. During this period the Cordilleran Ice Sheet (CIS) repeatedly covered mountainous western North America and attained a volume and area similar to the present-day Greenland Ice Sheet. At the Last Glacial Maximum (LGM) the CIS formed part of the North American Ice Sheet Complex (NAISC), coalescing with the Laurentide Ice Sheet east of the Rocky Mountains. However, the high relief bed and remote location mean there are few empirical constraints pertaining to the nature of ice sheet build-up and retreat in the central region of the CIS, in northern British Columbia, making it one of the least understood ephemeral Pleistocene ice sheets. In this thesis I use glacial geomorphology and quantitative dating techniques to reconstruct the advance of the CIS to its LGM position and subsequent retreat. I use high resolution remotely sensed data to create a detailed map of glacial landforms for the central sector of the CIS, beneath the local LGM ice divide (55řN to 60řN; paper I). Seven landform categories were mapped: ice flow parallel lineations, moraines (CIS outlet glacier moraines, Late Glacial moraines and moraines of unknown origin), meltwater...
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