Figure 22 Wind erosion moves particles of different sizes. Small dust particles suspended in the air are blown about by the wind. Heavier sand grains move by saltation. Large particles slide or roll along the surface.
dWind Erosion and Deposition
Wind can also cause erosion and deposition. As with running water, the speed of the wind determines the size of the materials it carries. Slower winds carry only small particles, like dust. Faster winds have more energy and can lift larger particles, such as sand grains. A constant, strong wind can produce a large cloud of dust or sand.
Most wind erosion occurs in the dry areas of the world, such as deserts. Wind erosion also occurs in areas where drought has caused the ground to dry out and the soil is not held in place by plants.
How Wind Causes Erosion
As you can see in Figure 22, the wind moves small particles such as sand grains in a series of leaps called saltation. In saltation, wind lifts sand grains a short distance into the air. Gravity pulls the grains back down to the ground, where they collide with and loosen other grains. The result is that the sand grains leap-frog along.
Wind erodes the land by deflation and abrasion. The process of deflation occurs when wind picks up and carries away loose surface material. In dry regions where winds are strong, sand and dust are lifted from the surface and carried away. Over time, the surface of the ground is lowered. Larger rocks are left behind, forming a rocky surface that covers much of the land in dry regions.
Recall that abrasion is a type of mechanical weathering. Abrasion by wind occurs in much the same way as abrasion by flowing water. Wind blows sand against other rocks, slowly sandblasting them away and removing the weathered particles.
What is deflation?
Figure 23 Wind deposits sand in the form of dunes. These large sand dunes are found in the Namib Desert in Africa.
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