Corrading (erosion by abrasion) caused by such as: wind-blown or water-borne sand, stream-borne or glacier-borne stones, or collisions between stones under the influence of seaside breakers.
The wearing away of surface material.
Mechanical or chemical breaking down of rocks in situ by weather or other causes.
The action of weather on objects exposed to it.
A slight inclination given to an approximately horizontal surface to enable it to throw off water.