Wind ErosionWind ErosionExplain how wind causes deflation and abrasion. Distinguish how loess and dunes form.
Wind Erosion• Different types of erosion.
Wind Erosion• Question: How would wind and other
types of erosion be different?– Air usually cannot pick up heavy
sediments. – Wind carries sediments over large
areas.– Wind can place dust high into the
atmosphere and thousands of miles away.
Wind Erosion• Deflation erosion: Wind erodes loose
sediment, such as silt and sand.
Wind Erosion• Abrasion Erosion: When
windblown sediment strikes rock, the surface of the rock gets scraped and worn away.
Wind Erosion• Question: What process do we
use that is similar to wind abrasion?
• Sandblasting: Machines that use sand and water under high pressure to clean dirt from stone, concrete, or brick.
Sandblasting
Wind Erosion• Sand storms: Most sand storms occur
in deserts.
• Wind blown sand grains form a low cloud.
Reducing Wind Erosion• Question: What is the best way to
slow or stop wind erosion?
• Plant vegetation.
Reducing Wind Erosion• Reduce wind erosion by planting
wind breaks.
Reducing Wind Erosion• Windbreaks: As the wind hits the
trees, its energy of motion is reduced. It is no longer able to lift particles.
Reducing Wind Erosion• Roots: Especially along sea coast
and deserts. Plants with fibrous root systems help stop wind erosion.
Deposition by Wind
• Question: What happens to sediments that are blown away by wind?
• These sediments are eventually deposited.
Deposition by Wind
Deposition by Wind
• Loess: Fine-grained sediments deposited by wind.– Many farmlands in the midwest have
fertile soil that developed from loess.
Deposition by Wind
• Dune: A mound of sediment drifted by the wind.– Air drops sediment when its energy
decreases. Sediment starts to build up behind the object.
Deposition by Wind
• Moving dunes: A sand dune has two sides.– The side facing the wind has a gentler slope.
The side away from the wind is steeper.
Deposition by Wind
• Moving dunes: Unless dunes are planted with grasses, most dunes will move away from the direction of the wind.
• Some dunes are known as traveling dunes because they move rapidly across desert areas.
