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When the rainwater falls over an uplifted land, it erodes softer rocks faster than the harder rocks. Depressions are formed in the soft rocks. Gradually, these depressions take the form of streams. The consequent streams formed in the initial stage cut deep valley whose walls rise vertically from its channel. The stream flows roaring while striking against its banks. These valleys are known as gorges and have a V-shape.

The stream erodes its sides and undercuts them. As a consequence, the walls of the banks being undercut appear to be hanging over the stream. The hanging walls collapse in the stream when they are no longer able to withstand its weight. This process is known as Bank Caving. In the youth-full stage a stream can erode much more than it gets. In fact a stream is deficient of sediment because it has the capacity to carry tremendous amount of load. Whenever a soft rock obstructs the course of a stream, it is eroded and cut down and the sediment scattered all around. Eddies are formed and the water whirls around and produces depressions by plucking the sediment up. This makes the depressions deep and cylindrical. Sometimes these depressions look like discs and are known as Pot Holes. Stone pieces also enter the potholes along with the water and help water in boring and cutting the holes. These stone pieces are called Grinder. When these potholes grow in size they are called Plunge Pools.

Some people call these potholes and plunge pools as Devils Punch Bowl or Witches Cauldron because they think that such formations are due to the work of supernatural power.