What defines a delta?

A delta is defined as a landform that is created at the mouth of a river where it meets a body of water, such as an ocean, sea, or lake. This process occurs when sediment carried by the river is deposited as the water flow slows down upon entering the standing water. Over time, these deposits build up and form the characteristic triangular or fan-shaped landform associated with deltas.

The formation of a delta is a result of fluvial processes, which involve the erosion, transport, and deposition of sediments. The interaction between river water and the receiving body of water creates distinct ecological environments, supporting a diverse range of flora and fauna.

In contrast, the other options describe different coastal and geological features that do not pertain to the specific conditions under which a delta forms. For instance, glacial activity generates features like moraines and drumlins, while submerged coastal areas and rocky shorelines are entirely different landforms that arise from other geological processes.