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Erosion Erosion goes on continuously and it should be the concern of all of us. There is evidence of this process of erosion all about us. Both the small gullies in the side of a nearly hill and the immense Grand Canyon of the Colorado River and other gorges represent results of erosion. A muddied river after a heavy rain and a dust storm in a parched area of farmland both are carrying particles of soils from one place to another. Likewise, a creeping glacier in a mountain valley, the pounding waves of the ocean, and an underground river in a limestone cavern are all agents of erosion. Erosion levels the earths surface. Essentially, erosion is the natural process that ceaselessly tries to level the earths surface. If it were not for other forces also constantly at work, the mountains and hills would eventually disappear and all of the land would be under water. Fortunately, however, many areas of the earths surface are being raised by volcanic action and by balancing movements of the earths crust. For example, great pressures exerted by the water and sediments on the ocean floor along many shorelines result in forces that cause the land area to be uplifted. Thus erosion never completely succeeds in leveling the earths surface. Gravity is influential. The force of gravity is responsible for both the falling of rain from the clouds and for the water running off the land as it always seeks a lower level. Likewise, the great moving currents of air that we call winds are the result of unequal heating of the earths surface and the convection currents that are set up in the atmosphere. Here again the force of gravity is responsible for the downward movement of the cooler, denser air toward the earth which starts the air moving. | 
