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River delta

A delta is the mouth of a river where it flows into an ocean, sea, or lake, building outwards (as a deltaic deposit) from sediment carried by the river and deposited as the water current is dissipated. Deltaic deposits of larger, heavily-ladden rivers are characterised by the river channel dividing into multiple streams (distributaries), these anastomizing (dividing and coming together again) to form a maze of active and inactive channels.

The most famous delta is that of the Nile River, and it is this delta from which the term is derived, because the Nile delta has a very characteristic triangular shape, like the (upper-case) letter delta (Δ). Other rivers with notable deltas include the Ganges/Brahmaputra combination (this delta spans most of Bangladesh), the Niger, the Amazon, the Mississippi, the Rhine, the Rhône, the Danube, the Mekong, and the Ebre.