ARID AND EOLIAN LECTURE NOTES


VOCABULARY: wind; saltation; deflation; desert pavement; blowout; abrasion; ventifact; dune; sand supply; wind effectiveness; vegetation cover; barchan; slip face; parabolic; transverse; longitudinal; crossbedding; loess; early; middle; late; block faulted mountain; alluvial fan; bajada; playa; interior drainage; canyon; pediment; inselberg; exotic stream; arroyo; knick point; badlands; caprock; mesa; butte

agent--wind; process--eolian

wind is the least effective of all erosional agents, does considerably shape the land
most effective in areas that are 1) arid, 2) along seashores, 3) flat areas, and 4) areas of glacial deposition

sand moves by saltation--short jumps, usually below 3"
sand 1/100", silt and clay 1/400"

wind erodes the land surface by Deposits
form on deserts, plains, floodplains, beaches
when wind slows down, it drops material; size of particle and amount depends on velocity

Dunes--hills of wind-blown sand--need strong wind, sufficient sand If mean wind direction is nearly constant, sand dunes form as a function of three variables: Dunes

types of dunes
Dune Illustration

crossbedding--internal structure of sand dunes, steeply inclined layers of sand from sand building upon slope, can change

loess--wind-blown deposit of silt-sized particles, may be several hundred feet thick blanket, unweathered angular fragment, almost 90° angle of repose, easily eroded, good soil
sources--desert regions or deposits left by glaciers

erosional processes in arid region differ from humid 3 stages of erosion exotic stream--flows through an arid region from elsewhere
streams erode--ARROYO--water only after a rain
valley widening, slope remains fairly constant
knick point--distinct angular break

horizontal sedimentary rocks
badlands--form from erosion of fine grained clastics into rough topography in an arid or semi-arid area

when alternating resistant and non-resistant rocks in arid region

CAPROCK--resistant top layer of bedrock which protects underlying rock
mesa--a large flat-topped plateau or upland formed by the slowed erosion of a caprock
butte--a small mesa; forms as a mesa becomes dissected


Arid, Eolian, and Coast Block


Go to the Arid and Eolian Review Questions

Go to the Glossary of Landform Terms



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