They’re found in the front of the glacier’s snout and are deposited by the meltwater streams issuing from the ice. They consist of material that was brought down by the glacier and then picked up, sorted and dropped by running water beyond the position of the ice front.
The coarsest material travels the shortest distance and is therefore found near the glacier, whereas the finest material like clay is carried some distance across the plain before being deposited.
Outwash plains have a shallow gradient. The deposited are also layered vertically, which reflects the seasonal flow of meltwater streams.