Delta

Delta, alluvial plain at the mouth of a river, often projecting into a sea or lake and crossed by many water channels. Deltas are generally formed of fertile mud dumped by a slow-flowing river. Often the river divides into two or more streams that thread their way through the delta to reach the sea or lake in different places, producing a tree-shaped pattern when seen from the air. The best-known deltas include the Mississippi Delta, the Nile Delta, and the Ganges-Brahmaputra Delta.