Erosion is the wearing away of rock and soil. It is done by physical processes, such as the actions of wind, water, and ice. Bits of rock and soil are broken apart by wind, water, and ice; the pieces are then moved to a different location by these forces and eventually deposited in a new location. The effects of erosion can be as dramatic as the formation of the Grand Canyon. There, the water of the Colorado River cut into the rock over millions of years, washing the pieces downstream and eventually creating a canyon that is eighteen miles wide and up to a mile deep in some areas. Water erosion can also be seen in action in the force of the ocean waves, which change the shape of the shoreline. Erosion by wind moves sand, rock, and soil. The dust bowl of the 1930s was a result of wind erosion (aided by lack of rainfall), as are the landforms in such areas as Arches National Park. Ice, in the form of glaciers, has repeatedly cut into the Earth. When the glaciers retreat, moraines and fjords result.
Erosion is not always a negative process; in some cases, the sediment washed downstream in a river builds up into a fertile area for farming.
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