How are deltas formed?

Deltas are formed primarily through the process of sediment deposition when a river carrying sediments reaches a larger body of water, such as an ocean, sea, or lake. As the river flows, it picks up various sediments from the surrounding landscape, which can include soil, sand, and silt. Upon reaching the quieter waters of a larger body, the flow of the river slows down, leading to a decrease in the water's ability to hold sediment in suspension.

The reduction in flow velocity causes these sediments to settle and accumulate at the river's mouth, gradually building up landforms that are characteristic of deltas. Over time, as more and more sediments are deposited, the delta can grow in size and complexity, often exhibiting a branching or fan-like shape. This process is essential in creating fertile areas that support diverse ecosystems and is a critical aspect of coastal geography.