Which ice sheet helped carve the basins of North America’s Great Lakes?

The Laurentide Ice Sheet helped carve the basins of North America’s Great Lakes.

During the Pleistocene, this enormous ice sheet covered much of Canada and parts of the northern United States. Moving ice eroded existing valleys and bedrock depressions, deepening and reshaping the basins that later filled with glacial meltwater.

The Great Lakes were not made by a single event. Their modern form reflects repeated glacial advances, retreats, shifting drainage routes, and changes in land elevation caused by the weight and later removal of the ice. The final lake outlines developed after the last major glaciation.

The Laurentide Ice Sheet is distinct from the Cordilleran Ice Sheet, which covered parts of western North America. Together, those ice masses influenced the continent’s glacial landscape, but the Laurentide sheet was the principal one associated with the Great Lakes basins.