Choose from: (I) clouds; (II) stars; (III) erosion; (IV) loose soil; (V) wind; (VI) ice wedging; (VII) rainwater; (VIII) calcite;

Fact 1: Most canyons are formed by flowing rivers through erosion over long periods of time. Fact 2: Rivers, rainwater, well water and most lakes contain fresh water. Given the two facts above, what are canyons formed by?
Answer:
(VII)