Where rivers flow over rock, the combined action of water and sediment can create intricate and beautiful natural sculptures. Some of the most striking forms are potholes: roughly circular depressions carved into the rocky beds of turbulent, upland rivers.

Where rivers flow over rock, the combined action of water and sediment can create intricate and beautiful natural sculptures. Some of the most striking forms are potholes: roughly circular depressions carved into the rocky beds of turbulent, upland rivers.