What feature indicates where a fast-moving ancient river slowed down upon entering a standing body of water on Mars?

Answer

Deltas—sedimentary fans

Deltas are sedimentary fans that characteristically build up where a river’s velocity decreases rapidly upon entering a larger, standing body of water, such as a lake or sea.

What feature indicates where a fast-moving ancient river slowed down upon entering a standing body of water on Mars?

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