A mature river is somewhere inbetween a youthful river and an old river. The bottom of youthful rivers tends to be a sharper V-shape, while mature rivers form more of a U-shape, though not as wide a U as old rivers. Mature rivers do not have as steep a gradient as youthful rivers, and so they flow more slowly, though not as slowly as old rivers. The edges of mature rivers have a floodplain area and wider banks than a youthful river. Mature rivers are more likely to have meanders than youthful rivers, but the meanders will be smaller than in old rivers. Finally, mature rivers tend to be wider and have a larger amount of water than youthful rivers, partly because they have more tributaries that flow into them, which means they also carry more sediment in them.
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