WIND EROSION

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WIND EROSION
1. Most common places where wind erosion occurs: arid desert
regions, lake or ocean coastlines
2. Loose sediments must be available, picked up by wind; only
small sand, silt, and clay can be carried
3. Two main aspects of wind erosion:
a. Deflation – occurs in areas where small, loose sediments
are exposed to atmosphere, picked up by wind, and land
surface is continuously lowered until it reaches the
“desert pavement”
b. Sandblasting or abrasion – winds blow sand or silt grains
against rocks and other objects, which results in
weathering of rock surfaces; since wind can only lift sand
grains about 1 meter into the air, “mushroom rocks” tend
to form
4. When sand grains collide, abrasion occurs, resulting in a
frosted or pitted appearance to the grains and rock surfaces
5. Rock surfaces that face into the wind become flattened due to
abrasion, called ventifacts
DEPOSITION BY WIND
6. When wind slows down or stops, sediments are dropped
7. Sand is deposited by wind in layers or mounds called sand
dunes
a. Can be many different shapes, but usually there is a more
gentle slope facing into the wind and steeper slope facing
away from it
b. Dunes tend to migrate downwind as sand from the
windward side blows up and over and becomes deposited
on the other side of the mound
c. This creates layers of sloping, sorted sediments within
the dunes
d. If the wind shifts directions, beds of sand will cross one
another at various angles – called crossbedding
e. Most sand grains in dunes are very rounded and frosted
due to numerous collisions during erosion
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