1. Wind Erosion Glencoe Earth Science

2. Wind Erosion & Transport • Current of rapidly moving air can carry sediment • Move sand on the ground in a rolling motion • Suspension • Strong winds can cause small particles to stay airborne • Saltation • Bouncing motion of larger particles • Occur in areas of little vegetative cover • Deserts • Semiarid areas • Seashores • lakeshores

3. Deflation • Lowering of land surface • Results from winds removal of surface particles • Desert pavement • Coarse surface left behind by removal of finer surface by wind erosion

4. Deflation • Dust Bowl • Great Plains 1930’s • Severe drought • Poor agricultural practices • Removal of natural vegetation • Strong winds led to severe dust storms • Present time- thousands shallow depressions • Deflation blowouts

5. Abrasion • Particles such as sand rub against the surface of rocks or other materials • Due to erosion by wind, water, and glaciers • Wears away rocks • Pitted & grooved to smooth surfaces • Ventifacts • Rocks shaped by windblown sediments • Arches & pillars

6. Wind Deposition • Occurs when wind velocity decreases • Windblown sand deposits on the ground • Forms a dune • Dunes • Windward side – side from which the wind blows • Gentler slope • Leeward side – side protects from wind • Steeper slope

7. Dunes • Factors in dune Formations that determines its shape • Availability of sand • Wind velocity • Wind direction • Amount of vegetation present

8. Dune Migration • Prevailing wind continues to move sand from the windward side to the leeward side • Dune moves slowly over time

9. Types of Dunes • Barchan Dunes • Form solitary, crescent shapes • Form from small amount of sand • Minimal or no vegetation • Form in flat areas of constant wind direction • Crests point downwind • Reach max size of 30m

10. Types of Dunes • Transverse Dunes • Form series of ridge shapes • Form from large amount of sand • Minimal or no vegetation • Form in ridges that are perpendicular to the direction of the strong wind • Reach max size of 25m

11. Types of Dunes • Parabolic Dunes • Form u-shapes • Form from large amount of sand • Minimal vegetation • Form in humid areas with moderate winds • Crests point upwind • Reach max size of 30m

12. Types of Dunes • Longitudinal Dunes • Form series of ridge shapes • Form from small or large amount of sand • Minimal or no vegetation • Form parallel to variable wind direction • Reach max height of 300m

13. Types of Dunes

14. Loess • Thick, windblown silt deposits • Accumulated as a result of thousands of years of dust storms