Landforms Shaped by Wind Chapter 6, LESSON 2

Water Erosion and Deposition Streams are active systems that erode land and transport sediment. Slower moving water erodes the sides of a stream channel more than its bottom, and the stream develops curves. A meander is a broad, c-shaped curve in a stream. An alluvial fan forms when river waters empty from a mountain valley out onto a flat open plain. It forms when water loses its energy of motion.

Water erosion and deposition Like streams, coastlines continually change. Waves crashing onto shore erode loose sand, gravel, and rock along coastlines. A longshore current is a current that flows parallel to the shoreline. This current moves sediment and continually changes the size and shape of beaches.

Groundwater Erosion Water that flows underground can also erode rock. An acidic groundwater seeps through rock and soil, it can pass through layers of limestone. The acidic water dissolves and washed away the limestone, forming a cave.

Water Deposition Deposition by a stream can occur anywhere along its path where the water’s speed decreases. A stream also slows and deposits sediment when it reaches flat land or a large body of water, such as a lake or ocean. A delta is a triangular or fan-shaped large deposit of sediment that forms where a stream enters a large body of water. A floodplain is the broad, flat area located next to a river.

Land Use Practices Damage caused by water erosion can be affected by the ways people use land. Reducing the amount od vegetation or removing it from the land increases surface erosion. Agricultural production, construction activities, and cutting trees for lumber and paper production are some reasons that people remove vegetation.

Wind Erosion and Deposition As wind carries sediment along, the sediment cuts and polishes exposed rock. Abrasion is the grinding away of rock or other surfaces as particles carried by the wind, water, or ice scrape against them. When you drive down an unpaved road on a dry day, and the dust blows up in a cloud behind you the billowing dust is undergoing erosion. When you get home you realize your car is covered in dust. The dust settling on your car has undergone deposition. Two common types of wind blown deposits are dunes and loess.

Wind Erosion and Deposition A dune is a pile of windblown sand. Over time, entire fields of dunes can travel across the land as wind continues to blow the sand. Loess is a crumbly, windblown deposit of silt and clay. One type of loess forms from rock that was ground up and deposited by glaciers. Wind picks up the fine grain sediment and redeposits it as thick layers of dust called loess.

Wind erosion and deposition People contribute to wind erosion. For example, plowed fields and dry, overgrazed pastures expose soil. Strong winds can remove topsoil that is not held in place by plants.