Wind Erosion
Take-Away Points
1. Wind erosion has little effect on solid rock
2. Wind mostly moves loose material
3. Sand dunes depend on strength and
steadiness of wind and abundance of sand
4. Windblown silt is called loess
5. Loess is the raw material for many
mollisols, the best agricultural soils
Abrasion
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Ventifacts or Dreikanters
Polishing,
Undercutting
Streamlining (Yardangs)
On Mars, with billions of years of only
wind erosion, wind has had much greater
effects
1. Wind erosion has little effect on solid rock
Ventifacts, Antarctica
Dreikanter, Wisconsin
Wind Abrasion, Independence Rock, Wyoming
Wind (Aeolian) Landforms
Little Power to Attack Solid Rock
Most Effective in Moving Loose Material
Mechanisms
• Suspension (Silt)
• Saltation (Sand)
• Rolling
2. Wind mostly moves loose material
Wind (Aeolian) Landforms
Deposition
• Dunes
• Loess
Erosion
• Deflation Basins (Blowouts)
• Lag Deposits, Desert Pavement
2. Wind mostly moves loose material
Sand Dunes
3. Sand dunes depend on strength and steadiness of wind and abundance of sand
Longitudinal Dunes, Colorado
Longitudinal Dunes, Colorado
Longitudinal and Transverse Dunes, Colorado
Transverse Dunes, Sand Hills, Nebraska
Beach Dunes, Michigan
Barchans, Sand Hills, Nebraska
Snow Barchans, Wisconsin
Snow Barchans, Wisconsin
Star Dune, Nevada
Great Sand Dunes, Colorado
Great Sand Dunes, Colorado
Great Sand Dunes, Colorado
Desert Pavement, California
Lag Deposit, Minnesota
Blowout, Wisconsin
Loess
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Silt-sized
Derived from Glacial Outwash in U.S.
Found in U.S., E. Europe, China
Parent material of world’s prime agricultural soils
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Available nutrients
Fine size – lots of surface area
Cohesive – good root support
Porous – retains water well
No Rocks!!!!
4. Windblown silt is called loess
Loess, Wisconsin
Loess in
the U.S.
Loess is the raw material for many mollisols, the best agricultural soils
Loess in Europe
5. Loess is the raw material for many mollisols, the best agricultural soils
Loess in China
5. Loess is the raw material for many mollisols, the best agricultural soils
Take-Away Points
• Wind has little effect on solid rock
• Wind mostly moves loose material
• Sand dunes depend on strength and
steadiness of wind and abundance of sand
• Windblown silt is called loess
• Loess is the raw material for many
mollisols, the best agricultural soils