09/09/2010 1 Wind Erosion Wind Erosion Wind does not have the same energy to Wind does not have the same energy to erode and transport larger fragments as erode and transport larger fragments as glaciers. glaciers. It is only usually strong enough to pick up and It is only usually strong enough to pick up and transport sand and fine sediments. transport sand and fine sediments. Beaches and deserts are especially Beaches and deserts are especially susceptible. susceptible.
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Wind ErosionWind Erosion
�� Wind does not have the same energy to Wind does not have the same energy to erode and transport larger fragments as erode and transport larger fragments as glaciers.glaciers.
�� It is only usually strong enough to pick up and It is only usually strong enough to pick up and transport sand and fine sediments.transport sand and fine sediments.
�� Beaches and deserts are especially Beaches and deserts are especially susceptible.susceptible.
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Wind ErosionWind Erosion
Occurs when sand and silt particles are Occurs when sand and silt particles are removed from one area and blown against removed from one area and blown against rock surfaces or other objects.rock surfaces or other objects.
When the particles are removed it leaves a When the particles are removed it leaves a slightly lowered or hollowed area. This slightly lowered or hollowed area. This process is known as process is known as deflationdeflation
HamadaHamada
Level, rocky desert Level, rocky desert that has been that has been smoothed by smoothed by abrasion. abrasion. Found in parts of Found in parts of Northern Africa.Northern Africa.
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AbrasionAbrasion
The surfaces of hamadas are smoothed The surfaces of hamadas are smoothed by the force of abrasion.by the force of abrasion.
WindWind--borne particles sand blast and wear borne particles sand blast and wear away the surface.away the surface.
This tends to occur close to ground.This tends to occur close to ground.
ErgErg
An Erg is a huge An Erg is a huge sandy area where sandy area where dunes are built by the dunes are built by the wind. Dunes are wind. Dunes are always moving : sand always moving : sand grains are pushed by grains are pushed by the wind and roll one the wind and roll one over the other. Some over the other. Some move slowly, other move slowly, other faster. faster.
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Erg ContinuedErg Continued
Sand Dunes Sand Dunes –– the most common the most common landscape feature in ergs. They are landscape feature in ergs. They are crescent or triangle shape pile of sand crescent or triangle shape pile of sand deposited when the wind stops blowing. deposited when the wind stops blowing. Size and shapes can vary.Size and shapes can vary.
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BarchanBarchan
A crescent shaped dune with horns or A crescent shaped dune with horns or arms streaming out at either side pointing arms streaming out at either side pointing the direction of the windthe direction of the wind
They have been known to exceed more They have been known to exceed more than 30m in height.than 30m in height.
Barchan DuneBarchan Dune
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LoessLoess
Refers to any unconsolidated, nonRefers to any unconsolidated, non--stratified, soil composed primarily of silt stratified, soil composed primarily of silt sized particles.sized particles.
It is very fertile agricultural soil.It is very fertile agricultural soil.
It occurs when wind transports and It occurs when wind transports and deposits dust, clay, and silt. These collect deposits dust, clay, and silt. These collect in a series of layers and become a loess.in a series of layers and become a loess.
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Winds moving across the outwash of the Winds moving across the outwash of the Matanuska River valley, Alaska, carry the Matanuska River valley, Alaska, carry the
silt fraction to produce loess. silt fraction to produce loess.
