Section 1 – Wind Erosion Wind contains energy. It an turn a wind turbine or move a sailboat. It can also erode the land. Sand vs. Dust Sand is loose fragments of weathered rocks and minerals. Most grains of sand are made of quartz. Dust is particles that are smaller than the smallest sand grain. Most dust is microscopic fragments of rocks and minerals. How wind moves sand and dust Wind cannot keep sand up in the air. Most sand moves by a series of jumps and bounces called saltation. When the wind speed is fast enough to move sand grains along the ground, they move in the direction of the wind. The sand moves ahead a short distance, falls and strikes other sand grains that then bounce up. Most grains rarely rise above 1 meter in height.

Effects of wind erosion Dust particles are very small and light. Even gentle air currents can keep dust particles suspended in the air. Dust from volcanoes can stay in the upper atmosphere for several years. Strong winds can lift large amounts of dust and create dust storms. Effects of wind erosion Wind erosion happens everywhere there is wind. The most dramatic erosion occurs in deserts and coastlines. Deflation is the process by which wind removes the top layer of fine, dry soil and leaving behind large rock particles. This forms the desert pavement. Deflation blows away the best top soil used for growing crops. It may form shallow depressions in areas where the natural plant cover has been removed. The shallow depression is called a deflation hollow.

When pebbles and small stones in deserts and on beaches are exposed to wind abrasion, the surfaces of the rocks become flattened and polished on two or three sides. Rocks that have been pitted and smoothed by wind abrasion are called ventifacts. The direction of the prevailing wind can be determined in an area by the appearance of the ventifacts. Scientists once thought that many large rock structures were formed by wind erosion, but now they believe those large rock structures are due to surface water and weathering.

Wind deposition The wind drops particles when it slows down and can no longer carry them. These deposited particles and covered with other deposits. The best known wind deposits are dunes. Dunes form where the soil is dry and unprotected, and where the wind is strong. The dune begins to form where a barrier slows the wind speed, the sand falls from the air, and is dropped on both sides of the barrier. As more sand accumulates, the barrier is covered and the dune becomes the barrier. Shapes of dunes Loess – formed from fine dust that is deposited in thin layers that are not noticeable. Thick layers can form by an accumulation of the windblown dust. Loess is soft and easily eroded. It can form steep bluffs.

Section 2 – Wave Erosion Wave erosion changes the shape of the shorelines. Storms produce large waves that causes much of the erosion along the coastline. The waves break up the rocks into smaller fragments that continue the abrasive action or mechanical weathering. The waves force salt water and air into the cracks in the rocks causing the cracks to enlarge and cause chemical weathering.

Shoreline formations- Sea cliffs Sea caves Arches Stacks Terraces