Wind ErosionWind Erosion

How the wind transports and erodes material

• When the particles carried by the wind are dragged across a surface, they act like sandpaper, etching, polishing and pitting surfaces.

• Wind can erode by abrasion or deflation

Deflation ---the process of removing surface materials by wind erosion

• High elevations are left due to vegetative stabilization

Natural arch

• Typically formed by a combination of wind and water

• Narrow ridges are formed and the softer substrata is weathered first, forming a bridge/arch overhead

http://upload.wikimedia.org/wikipedia/en/1/13/Delicate_Arch_LaSalle.jpg

Ventifact

• Stones that have been sculpted by the wind

• Wind carries fine particles that work like a sand blaster (i.e. sand, silt, clay, and ice particles)

• The windward face of the rock is flattened and smoothed

• Usually pebble to cobble sized

• A type of ventifact that has three ridges

• Multiple faces have been formed by either a changing prevailing wind or movement of the actual rock being weathered

Dreikanter

Desert pavement

• Formed in arid environments when wind carries finer, more lightweight particles such as sand away

• Large particles are left behind and protect from further erosion

http://upload.wikimedia.org/wikipedia/en/c/c7/Desert_Pavement_Mojave_2000.jpg

Loess

• Yellowish, fine grained silt and clay sized particles

• Formed by glaciers

• Carried and deposited by wind

Sand Dunes

• Piles of sand

• Deposited by wind

• Leeward side (slipface) has a steeper slope

• Windward side is more gradual

leeward leewardwindward

Barchan Dune• Crescent shaped dunes

• Concave side is the leeward side

• Formed from a unidirectional wind

http://rds.yahoo.com/_ylt=A0PDoTEjNVhNaxsAx5ejzbkF/SIG=126dmsrp2/EXP=1297655203/**http:/www.ux1.eiu.edu/~jpstimac/1300/barchan2.gif

Transverse dunes

• A dune that elongates perpendicular to the prevailing wind (rippled appearance)

• Caused by a combination of wind directions

http://rds.yahoo.com/_ylt=A0PDoS.ENVhNJAUAwL2jzbkF/SIG=12204p5jf/EXP=1297655300/**http:/www.geomorph.org/gal/mslattery/IAG6.jpg

Parabolic dunes

• Crescent shaped dunes, U-shaped

• Concave side is the windward side

• Found in coastal deserts

• Arms of the crescent lag behind because they are held in place by vegetation

Linear dunes

• Form in areas with limited sand supplies and winds that converge from different directions

Star dunes

• Form in areas of abundant sands and variable wind directions

Ergs

• Huge dune fields

Ripple marks

• Miniature dunes within a dune (not more than 2 inches tall)

• Formed by wind

• May form from cross winds and appear to be traveling in a different direction than the large dune

Pedestal rock

• Base of a rock is weathered and eroded more quickly due to sand blasting

Yardang

• Streamlined, bedrock hills

• extensively grooved, fluted, and pitted by wind erosion.

• alternating ridges parallel to the dominant wind direction

• occur in various deserts of the world including the Turkistan and the Mojave deserts