Erosion: The process by which the surface of the earth is worn away by the action of wind or water in the form of rain drops, surface runoff and waves.
(the surface of the earth; is worn away; by the action of wind or water in the form of rain drops, surface runoff and waves; L:The process)
the surface of the earth
is worn away
by the action of wind or water in the form of rain drops, surface runoff and waves L:The process