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How does a sandur form in a low-relief area near a glacier?

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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.

A sandur, or outwash plain, forms in low-relief areas when meltwater streams issuing from a glacier deposit large quantities of sediment.1

As these streams emerge from the ice margin, they are no longer confined by tunnel walls, causing their velocity to decrease and forcing them to drop their heavy load of sand and gravel. Because the streams are typically laden to their transporting capacity with debris, the channels become choked with sediment. This forces the water to shift constantly, creating a network of braided, winding channels.1

In low-relief environments, the deposits from several of these ice-marginal streams merge to form a broad, gently sloping outwash plain. These deposits are often wedge-shaped in cross section, thinning as the distance from the glacier increases. While the term "sandur" refers to these plains, it is important to distinguish this geological feature from a "sandbur," which is a type of grass.12