DESERTS AND WIND ACTION

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DESERTS AND WIND ACTION
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DESERTS AND WIND ACTION

• Desert regions and wind erosion
• Desert and adjacent region
• desert
• region which has an arid climate
• steppe
• region adjacent to a desert with semiarid climate

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DESERTS AND WIND ACTION
Desert (arid climate) and steppe
(semiarid climate) areas on Earth
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DESERTS AND WIND ACTION

• Wind erosion processes
• deflation is the removal of rock waste from the
  land by the wind
• blowout or deflation hollow is a depression
  excavated by the wind in materials as sand and
  silt deposits easily eroded because of a lack of
  the presence of adequate vegetation which impedes
  deflation

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DESERTS AND WIND ACTION
Blowout or deflation hollow
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DESERTS AND WIND ACTION
Deflation Hollow---Blowout
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DESERTS AND WIND ACTION
abrasion is the sandblastingeffect on materials
caused by the impact with particles carried by
the windfrosted windows in houses and ventifacts
form
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DESERTS AND WIND ACTION

• Wind erosion loads
• suspended load
• suspended wind blown particles
• consists primarily of silt or clay size particles
  and if highly concentrated can result in dust
  storms
• deposition of the suspended load can result in
  large deposits of loess lacking layering or
  stratification

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DESERTS AND WIND ACTION
Dust Storms
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DESERTS AND WIND ACTION
Loess Deposits
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DESERTS AND WIND ACTION

• bed load
• particles bounced along the ground
• usually consists of sand size particles
• accumulation of the bed load forms desert sand
  dunes which can migrate easily(active dunes)
• Active sand dunes
• Nature of active (unstable) dunes
• dune profile
• consists of a more gentle windward slope and
  steeper leeward slope or slipface

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DESERTS AND WIND ACTION
Dune profile
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DESERTS AND WIND ACTION

• shifting dunes
• shift downwind and can bury roads, airport
  runways, homes, etc.
• Categories of active dunes
• based on shape of dune in plan view
• barchan
• crescent shaped with convex portion facing the
  wind direction
• formed with a constant wind direction and limited
  sand supply

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DESERTS AND WIND ACTION
Barchan dunes
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DESERTS AND WIND ACTION

• transverse
• elongated perpendicular to direction of wind
• formed with a constant direction of wind and
  large supply of sand

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DESERTS AND WIND ACTION

• longitudinal or seif
• elongated in general direction of wind
• formed with slightly different wind directions
  and limited sand supply

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DESERTS AND WIND ACTION

• star or complex
• formed with variable wind direction

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DESERTS AND WIND ACTION

• Desert landscape and evolution
• Alluvial fan
• fan shaped deposit formed at the foot of
  mountains in the desert valley or basin

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DESERTS AND WIND ACTION
a bajada is an apron of sediment resulting from a
coalescence of alluvial fans
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DESERTS AND WIND ACTION
Playa lake and playa a temporary shallow lake
formed in the central basin of a desert during a
rare abundant rainfall--a playa is the dry flat
lake bed that remains
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DESERTS AND WIND ACTION

• Inselberg
• an isolated erosional remnant present after long
  term erosion of mountain areas which are reduced
  to these bedrock knobs elevated above the
  surrounding sediment filled basin

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DESERTS AND WIND ACTION

• Pediment
• a carved gently sloping erosional surface on the
  bedrock in a desert mountainous area

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DESERTS AND WIND ACTION
Stages of landscape in mountainous desert
regions
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DESERTS AND WIND ACTION

• Inactive or stable dune---mostly non-desert
• Parabolic dune(foredune)
• formed along coastlines of oceans or large lakes
• winds cause blowouts in sand resulting in a
  crescent shape with the concave side facing the
  prevailing wind direction

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THATS ALL THE CYBER GEOLOGY COURSE
FOLKS