WindWind

SWBAT describe conditions that contribute to the SWBAT describe conditions that contribute to the likelihood that an area will experience wind erosion; likelihood that an area will experience wind erosion;

identify wind-formed landscape features; describe how identify wind-formed landscape features; describe how dunes form and migrate; explain the effects of wind dunes form and migrate; explain the effects of wind

erosion on human activities erosion on human activities

• What is unusual about the surface of these rocks?

• What do you think shaped these rocks?

Wind Erosion and TransportWind Erosion and Transport

• Two methods for wind to move sand– Suspension

• Wind lifts and keeps the particles airborne for a long distance

– Saltation• Particles bounce along the ground

Wind Erosion and TransportWind Erosion and Transport

• Where does wind erosion primarily occur?– Wind erosion is most common in areas with

little vegetative cover, semi-arid areas, as well as seashores or lakeshores

Wind Erosion and TransportWind Erosion and Transport

• Deflation– The lowering of the land surface as a result of

surface particles being removed by wind

• Abrasion– Occurs when particles such as sand rub

against the surface of rocks or other materials

Wind Erosion and TransportWind Erosion and Transport

• Why is sand such an effective agent of wind erosion?– Sand is generally made up of quartz, which is

a very hard mineral that can scratch away at surfaces

• Ventifacts– Rocks shaped by wind blown sediments

Wind DepositionWind Deposition

• How is wind deposition similar to water deposition?– They both erode sediments, and the

sediments are dropped when they slow down

• Dune– A pile of wind-blown sand that accumulates

on an object

Dune FormationDune Formation

• What conditions determine a sand dunes shape?– Sand availability– Wind velocity– Wind direction– Amount of vegetation

Dune FormationDune Formation

Barchan

Transverse

Parabolic

Longitudinal

Solitary, crescent-shaped dunes

Form in flat areas with little vegetation

Long series of ridges that are perpendicular to the wind

Form in areas with lots of sand and strong steady winds

U shaped Form in humid areas between clumps of plants

Long series of ridges that are parallel to the wind

Form in areas with limited sand and strong prevailing winds

Wind DepositionWind Deposition

• Loess– Thick wind blown deposits of silt and fine

sediment

Get Your Lab NotebooksGet Your Lab Notebooks

• In your groups complete the minilab on page 194

• Title: Where does wind erosion occur• Using the map on page 192, answer the 3

analyze and conclude questions in complete sentences.

• When you finish you may start the assessment questions 1-6 on page 197, you may work in your groups