Potholes: Potholes are circular depressions formed because of stream erosion aided by the abrasion of rock fragments. Once a small and shallow depression forms, pebbles and boulders get collected in those depressions and get rotated by flowing water and consequently the depressions grow in dimensions.
Plunge pools: Plunge pools are large, deep potholes commonly found at the foot of a waterfall. They are formed because of the sheer impact of water and the rotation of boulders. These pools also help in the deepening of valleys.