Question

formed at the mouth of a river, where the river flows into an ocean, sea, estuary, lake, or reservoir, formed from the deposition of the sediment carried by the river

Answer 1

What you are describing is known as a **delta**. Deltas form at the mouth of a river where it meets a body of water, such as an ocean, sea, estuary, lake, or reservoir. The sediment that the river carries is deposited as the water slows down upon entering the standing water, leading to the creation of landforms that can be rich in nutrients and biodiversity. Deltas often have a characteristic triangular or fan shape and can be very dynamic environments. Examples of famous deltas include the Nile Delta in Egypt and the Mississippi River Delta in the United States.