Deposits of sediment on the bottom of rivers, deposited either by rivers or by meltwaters which could have taken different flow forms, that helped to drain the melting glaciers. The drift that was released from the ice was carried away by the rivers. Lighter materials like sand, silt and clay remained suspended in the river water and were carried downstream, while the heavier materials like rock and gravel (sedimentary rocks) were deposited on the riverbed.
Material moved by glaciers and subsequently sorted and deposited by streams or rivers flowing from the melting ice. The deposits are stratified and may occur in the form of outwash plains, deltas, eskers and kames. [Fr. glace, ice + Lat. fluvius, river.