What is typically found at the mouth of a river where it meets another body of water?

At the mouth of a river where it meets another body of water, a delta forms when the river deposits sediment as it slows down. This sediment, consisting of sand, silt, and clay, builds up over time, creating land that extends out into the water. Deltas are characterized by their triangular or fan-like shape and are often rich in biodiversity and nutrients, making them essential ecosystems.

While an estuary (often found at river mouths) includes a mix of fresh and saltwater and is important for various ecological processes, the term “delta” specifically refers to the landform created by sediment deposition. Mouth bars and alluvium are related concepts, but they do not encompass the broader landform created at the river mouth like a delta does. Therefore, the term "delta" directly addresses the specific landform that is commonly recognized at the meeting point of rivers and larger bodies of water.