River delta

Nile River delta, as seen from Earth orbit. Photo courtesy of NASA

A river delta is a landform where the mouth of a river flows into an ocean, sea, desert, estuary, lake or another river. It is formed by sediment carried by the river being deposited in the wider mouth. The flow of water is often slower-moving there.

The word "delta" comes from the upper-case letter delta, Δ , in the Greek alphabet because many river deltas are triangular like this letter.

Other websites

• Louisiana State University Geology - World Deltas