Wind Erosion Glencoe Earth Science

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

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

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

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

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

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

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

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

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

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

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

Types of Dunes

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