Formation of Pothole¡@
Pothole is a kind of fluvial feature found on the river bed in upper course. They can be seen in dry season.
Large boulders are commonly found on the river beds of the upper courses of rivers. Therefore, the ruggedness of the river bed is high over there. The flow of water is affected and eddies are commonly found. Eddies with gravels put strong abrasion on river bed. Circular grinding will eventually create round holes on river bed.
The mouth of a pothole is usually smaller than the inner part because gravels entering the pothole can hardly coming out again. The abrasion inside the pothole is therefore greater.