How does erosion occur on the the river bed?

Erosion is the process of wearing away the rock and soil found along the river bed and banks.  Erorsion also occurs through the breaing down of the rock particles which are being carried away by the river.

There are four main forms of river erosion.  The first being hydraulic action which is the force of the river against the banks which can cause air to be trapped in cracks and crevices.   As the pressure increases betwen the cracks and crevices in the bank the pressure weakens the banks and gradually wears in away.  Abrasion is  the proccess of rocks being carried along the river bed and banks.  Attrition is the process of erosion where small rocks being carried by the river collide/ smash together and break into smaller, smoother and rounder pieces of rock and then into small particulates.   The final way river erosion occurs in rivers is solution.  This is where soluble particles in the water react with the chemicals in the rock and wear the rock away.