a mudslide flowing down a steep hill
wind blasting sand at rocks and carving out arches
water getting into cracks, freezing and breaking the rocks or pavement apart
flood waters pounding against a canyon wall and wearing it down
flood waters moving soil from one location to another
caves being formed by acid rain dissolving underground limestone
wind blowing sand from one location to another
glaciers scrapping rocks across the Earth's surface
rain washing away soil from a hillside
rocks being made smooth by tumbling across a streambed
muddy water being carried away by a fast moving river
