plain sandur ENVO ENVO:00000312 The plain formed by the large amounts of silt and sediment, picked up as a glacier erodes the underlying rocks as it moves slowly downhill, and at the snout of the glacier, meltwater can carry this sediment away from the glacier and deposit it on a broad plain. The material in the outwash plain is often size-sorted by the water runoff of the melting glacier with the finest materials, like silt, being the most distantly re-deposited, whereas larger boulders are the closest to the original terminus of the glacier. Wikipedia:Sandur outwash plain