Glacial History and Landform Genesis in the Lac de Gras Area, Northwest Territories

Date created: 
Quaternary Geology
Laurentide Ice Sheet
Lac de Gras
Surficial mapping
Glacial landform genesis
Subglacial meltwater flow

The Quaternary geology of the Lac de Gras area was studied by 1:20 000 surficial geology mapping of 770 km2 and investigating the genesis of enigmatic landforms. Three distinct flow directions of the Laurentide Ice Sheet are recorded: flow to the southwest, then west, and finally to the west northwest. Digital mapping with high-resolution orthoimagery and a 30 cm lidar DEM provides insight into the deglacial history. ‘Subglacial meltwater corridors’ are prominent in the area. These are tracts that roughly parallel the final ice-flow direction, where basal till has been eroded, bedrock is exposed, and glaciofluvial sediments have been deposited; enigmatic, glaciofluvial mounds composed of sandy diamicton are common. These mounds have highly variable morphologies and occur in groups. They are typically 50 m wide and rise up to 15 m above the surrounding topography. Subglacial meltwater corridors and enigmatic mounds likely formed when supraglacial lakes drained catastrophically during deglaciation.

Document type: 
This thesis may be printed or downloaded for non-commercial research and scholarly purposes. Copyright remains with the author.
Senior supervisor: 
Brent Ward
Science: Department of Earth Sciences
Thesis type: 
(Thesis) M.Sc.