pothole, in geology, cylindrical pit formed in the rocky channel of a turbulent stream. It is formed and enlarged by the abrading action of pebbles and cobbles that are carried by eddies, or circular water currents that move against the main current of a stream. Potholes are most commonly found at the bottoms of eddies in rivers and in plunge pools below cataracts; sometimes potholes in a rock outcrop indicate the former site of a rapid or cataract. Potholes are often found in formerly glaciated regions where whirling columns of glacial meltwater sank well-like holes, or moulins, through the ice. Notable potholes are found in Ausable Chasm, N.Y., and Shelburne Falls, Mass. Potholes also refer to holes formed in human-made materials found in roads that are effected by natural freeze-thaw cycles or moisture (see weathering).