Corrasion is a geographical term for the process of mechanical erosion of a rock surface caused when materials are transported across it by running water, glaciers, wind, waves or gravitational movement downslope, for example, the wearing away of fine particles of rock on a river or seabed by a sandpapering action, causing it to collapse and form a dip in the bed. The resultant effect on the rock is called abrasion

Abrasion (geology)

Abrasion is the mechanical scraping of a rock surface by friction between rocks and moving particles during their transport by wind, glacier, waves, gravity, running water or erosion. After friction, the moving particles dislodge loose and weak debris from the side of the rock...

. This sometimes happens at the bottom of cliff

Cliff

In geography and geology, a cliff is a significant vertical, or near vertical, rock exposure. Cliffs are formed as erosion landforms due to the processes of erosion and weathering that produce them. Cliffs are common on coasts, in mountainous areas, escarpments and along rivers. Cliffs are usually...

s to a slanted edge. Other forms of sea erosion include hydraulic action

Hydraulic action

Hydraulic action is strong enough to loosen sediment along the river bed and banks this will take rocks from the side of the banks and add it to the rivers loads. The water compresses the air in the crack, pushing it right to the back. As the wave retreats, the highly pressurized air is suddenly...

 and attrition

Wear

In materials science, wear is erosion or sideways displacement of material from its "derivative" and original position on a solid surface performed by the action of another surface....

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Corrasion can refer to stream erosion and transport. Corrasion involves wearing away surfaces that the water flows over through the impact or grinding action of particles moving with the water.