That is its volume.
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Answer: "cluster" .
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Explanation:
waterfalls are temporary features of rivers because stream erosion is greatest at waterfalls and rapids. The water that falls at the base of the waterfall erodes rock there, leaving the rock at the tops of the waterfalls to overhang. Overall, undermining causes waterfalls to recede farther upstream.
The Ural and Caucasus mountain Ranges