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Transcript of Wind Erosion
Erosion Guiding Question: How does wind erosion help reshape the landscape?
Quick Write: Identify three things that you know about wind erosion from prior knowledge.
Mini Lesson: Present, Prezi, key terms and key information
Work Period: Students will work in their research teams, read and/or analyze photos to answer questions on the worksheet.
Closing: What are some locations in the world that wind erosion most drastically affects? All wind contains energy, this energy can erode the land. The wind can carry dust or sand as wind passes over the land One Way That Wind Moves Sand and Dust Saltation is one way that wind moves sand and dust. Saltation is the movement of sand or other sediments by short jumps and bounces that is caused by wind(or water). When rolling sand grains come together and some bounce up, saltation occurs. Once they are in the air, a sand grain goes ahead a short distance and later falls. How does wind move sand and dust? Wind moves sand and dust by saltation, the transportation of sediments through series of jumps and bounces. Saltation occurs when rolling sediments, surface creeps, collide and some bounce up. Smaller sediments, and particles and lifted and carried by the wind, suspension. Larger particles bounce and skip along the ground. http://croptechnology.unl.edu/pages/informationmodule.php?idinformationmodule=1086025423&topicorder=19&maxto=20&minto=1 Effects of wind erosion Desert Pavement:
Desert Pavement is a surface of tightly and closely packed small rocks, caused by deflation. Deflation is a type of wind erosion in which wind removes a top layer of fine, very dry soil or rock particles. Desert pavement protects underlying soil by forming a protective barrier. Ventifact Desert Pavement Deflation Hallow Deflation Hallows:
Deflation often forms shallow depressions in areas where natural plant covers have been removed . While the wind removes the topsoil a shallow depression, named Deflation Hallows form. Deflation is a serious problem for farmers because it removes away good soil for raising crops. Ventifacts:
Ventifacts are any rocks that are pitted grooved or polished by wind abrasion. Ventifacts most commonly occur when rocks on beaches and deserts are exposed to wind abrasion, and the surface of the rocks become flattened and polished on 2 or 3 sides. The direction of the wind can determine the appearance of the ventifact. Wind Erosion Deposits Dunes:
A dune is a mound of wind-deposited sand that moves as a result of the action of wind. Dunes are often found in places where the soil is dry and unprotected, also where wind is strong such as deserts and along the shore of oceans and large lakes. Types of dunes
There are many types of dunes, Barchan, Parabolic, Transverse and Longitudinal. The direction and strength of the wind shapes the dunes, the gentlest slope of the dune is most commonly the side that faces the wind. Sand blown over the crest of the dune tumbles down the opposite side, the slipface. The slipface has a steeper slope than the windward face does. Barchan Dunes: When sand is limited, strong winds form crescent shaped dunes. Two long, pointed extensions may form as wind sweeps around the ends of the dunes and gives the dune a crescent shape. Parabolic Dunes: Parabolic dunes form as sand collects around the rim of a deflation hallow. Parabolic dunes are crescent shaped dunes with the open side facing the wind. Transverse Dunes:
Transverse dunes are most commonly found in desert or coastal areas that have a great amount of sand. Transverse dunes are like ridges of sand in long wave-like patterns. Transverse dunes form at right angles to the wind direction. Longitudinal Dunes:
Longitudinal Dunes are similar to Transverse dunes except for the fact that longitudinal dunes lie parallel to the wind direction. Dune Migration:
Dune migration is the movement of dunes, if the wind moves the same direction the dune will move downwind. Dune migration occurs as sand is blown over the crest and builds up on the slip-face from the windward side. The dune migrates until it reaches a barrier. Longitudinal Dunes Transverse Dunes Parabolic Dunes Loess:
Loess is a fine grained sediments of quartz, feldspar, horneblende, mica, and clay deposited by the wind. Wind carries dust easier and more efficiently than it carries sand. Thick deposits of yellowish, fine grained sediments (loess) form by the collection of windblown dust. Extensive thick loess deposits commonly form in areas bordering, big continental glaciers Deflation and Abrasion are the two ways that wind erodes the land, deflation picks up loose particles and carries them away, and abrasion, exposed rock in worn away by wind-driven particles.
Wind does carry away particles, however wind carries and transports small particles, such as sand silt clay and dust easier, because their smaller particles.
The surface of the exposed rock and particles take on a frosted look due to the scratched caused on them.
The amount and type of erosion depends on three factors, speed of wind size of the particle and the length of the time it blows.
The faster wind blows,larger particles it move. Larger particles carried by wind, the greater the abrasion. The longer the wind blows, more deflation and abrasion occurs. Deflation & Abrasion