outwash

**Definition:** Sediment — sand, gravel, silt — carried away from the front of a melting glacier by meltwater streams and deposited in broad, flat plains. Outwash is drift that has been sorted by water: the heaviest material drops first, near the ice; the finest is carried farthest. Outwash plains are the aprons of debris spread before a retreating glacier, often remarkably flat and fertile.