Wind Earth’s Changing Surface
Review • 5 Agents of Erosion • Gravity • Running Water • Glaciers • Wind Waves
Erosion by Wind • Wind by itself is the weakest agent of erosion. • Powerful force where there are few plants to hold the soil in place.
Wind Erosion • Deflation • The process by which wind removes surface material.
Abrasion • Abrasion • Sand carried by wind can polish rocks
Wind Deposition • Wind Erosion and Deposition form sand dunes and loess deposits. • Sand dunes – A deposit of wind-blown sand • Forms when the wind strikes an obstacle. The sand then begins to pile up. • Sand dunes move over time
Loess Deposits • Sediment that is finer than sand, such as particles of clay and silt, is sometimes deposited in layers far from its source.
Waves Earth’s Changing Surface
How are Waves formed? • The energy in waves comes from wind that blows across the water’s surface.
Waves • Waves shape the coast through erosion by breaking down rock and transporting sand and other sediment.
Erosion by Waves • Impact – large waves can hit rocks. The energy in waves can break apart rocks. • Abrasion – sediment picked up by waves wear away rock. • Waves changing direction – waves begin to drag on the bottom as they approach the shore.
Deposits by Waves • Waves shape a coast when they deposit sediment, forming coastal features such as beaches, spits, and barrier beaches.
Beaches • As waves reach the shore, they drop the sediment they carry, forming a beach • A Beach is an area of wave-washed sediment along a coast. • Usually sand • Some are made of small fragments of coral or sea shells, Florida