Download 3.2 Wind Erosion and Deposition

3.2 WIND EROSION
AND
DEPOSITION
Kavya, Olga, Ivy, and Grace
Questions For You!!!
• What are the three different processes of
erosion by wind?
• Why is loess found very far away from its
source?
FUN FACTS
Wind erosion causes more than half of the soil
loss in the U.S.A. per year.
 In the Great Plains, five million acres are
damaged by wind erosion annually.
 Landmarks such as Bryce Canyon, the Grand
Canyon, and others are formed partially by wind
erosion.

THE PROCESS OF
WIND EROSION

Saltation is the movement of sand or other sediments by short jumps and
bounces that is caused by wind or water.

Deflation is a form of wind erosion in fine, dry soil particles are blown away.

Abrasion is the grinding and wearing away of rock surfaces through the
mechanical action of other rock or sand particles.
SALTATION

When moving sand grains hit each other it
causes other grains of sand to bounce up or fall
forward.
DEFLATION


Wind removes the top layer of sediment and
leaves behind the larger, heavier pieces of rock.
In areas where there are few plants the wind
may scoop out depressions in the landscape.
These depressions are called deflation hollows.
ABRASION


Abrasion occurs most often in areas where there
are strong winds, loose sands, and soft rocks.
When the wind picks up millions of sharp sand
grains it creates a sandblasting effect. This effect
helps to erode and smooth rocks.
WIND DEPOSITED MATERIALS
•
Vocabulary
Loess- very fine sediments deposited by wind
•Dune- a mound of wind-deposited sand
that keeps its shape even though it moves
LOESS
Because wind carries fine-grained material much
higher and further than it carries sand, loess
deposits are sometimes found far away from their
source.
DUNES
1)
2)
3)
When the wind hits an obstacle, such as a
plant or rock, it slows and drops heavier
materials.
The material collects creating a new obstacle
which causes even more material to be
deposited, forming a mound. The original
obstacle is eventually buried.
These mounds are called dunes and are
commonly found in sandy deserts and along
the shores of lakes and oceans.
THE MOVEMENT OF DUNES
Dunes move in the direction of strong winds.
 The gently sloped side faces the wind, which
constantly transports material up this side.
 As sand moves over the crest, or peak, of the
dune, it slides down the slip face, creating a steep
slope.

ANSWERS FOR YOU
Q: What are the three different processes of erosion
by wind?
A: Saltation, Deflation, and Abrasion.
Q: Why is loess found very far away from its
source?
A: Because wind carries fine-grained material
(loess) much higher and further than it carries
sand.