wind erosion explain how wind causes deflation and abrasion. distinguish how loess and dunes form
TRANSCRIPT
Wind ErosionWind ErosionExplain how wind causes deflation and abrasion. Distinguish how loess and dunes form.
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• 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.
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• 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
• 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.