What Is a Mouth of a River?

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The mouth of a river is another name for its terminus, where it meets an ocean, sea or lake. Because rivers generally carry abundant sediment and deposit it at the mouth, they often form deltas, or broad, shallow areas. The opposite end of the river is called the headwaters or the source; however, the headwaters are often formed by several discreet sources that all occur in the same general area.