What is "outwash plain"

An outwash plain, also called a sandur (plural: sandurs), sandr or sandar, is a plain formed of glacial sediments deposited by meltwater outwash at the terminus of a glacier. As it flows, the glacier grinds the underlying rock surface and carries the debris along. The meltwater at the snout of the glacier deposits its load of sediment over the outwash plain, with larger boulders being deposited near the terminal morraine, and smaller particles travelling further before being deposited. Sandurs are common in Iceland where geothermal activity accelerates the melting of ice flows and the deposition of sediment by meltwater. Sandurs derive their name from Skeiðarársandur in Iceland, the largest outwash plain in the world with an area of .