What is a river delta?

A river delta is a wetland that forms at the mouth of a river and flows into another body of water. Deltas are formed by sediment flowing downstream, creating a deltaic lobe. The silt, or finer sediment, continues to flow downstream and accumulates beyond the river's mouth, forming a delta.

A delta is divided into two parts: subaqueous, which is underwater, and subaerial, which is above water. Deltas are classified by the influence that creates the delta or the shape. Deltas only form where the flow of a river is slow enough to allow for silt accumulation and the river cannot be exposed to powerful waves or tides.