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Gravel would most likely exist in the bed load of a river.
Gravel is a term that refers to rocks with sizes in the range of 2-64 millimeters. They can be formed from artificial means or by natural ones. River Gravel is formed by a natural process in which rocks move in the bedside of a river and the movement gradually polishes and rounds them by weathering the edges of the rock. The resulting rock from this process is commonly called Creek Rock.
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