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Why can glaciers erode basins that streams cannot create?

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esker: Nunavut — glacial landform Eskers, or narrow ridges of gravel and sand left by a retreating glacier, wind through western Nunavut, Canada, near the Thelon River.

Glaciers are capable of eroding deep basins that streams cannot create primarily because of the fundamental differences in how they move and interact with the landscape.

A key limitation of streams is that water cannot flow uphill; therefore, they are restricted by the existing topography and cannot carve out enclosed depressions or basins. In contrast, glaciers are not constrained by the same hydraulic limitations. As long as there is sufficient slope on the upper ice surface to drive the flow, a glacier can move uphill over obstacles at its base. This allows glaciers to scour out enclosed basins and depressions that remain as lakes once the ice retreats.12

Furthermore, glaciers possess a much larger cross-section and greater viscosity than rivers, allowing them to exert significant pressure across a wider area of the valley floor and sidewalls. While streams erode an extremely narrow line along the lowest part of a valley, glaciers act as massive abrasive systems, using embedded rock debris to scour, abrade, and pluck bedrock, effectively reshaping the landscape into deep, U-shaped troughs and basins.3415