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317; Lecture 20
Term | Definition |
---|---|
Lag deposits | a residual accumulation of coarse rock fragments on a surface after the finer material has been blown away by the wind |
Desert pavement | forms in desert environments |
Stone pavement | forms in alpine and periglacial environments with sparse vegetation |
Deflation hollows | depressions that form unconsolidated material as fine grained sediment is carried away by deflation |
Yardangs | streamlined, sharp, and sinuous ridges that extend parallel to the wind and are separated by parallel depressions |
Ventifacts | stones shaped by the erosive action of windblown sand |
Dunes | collections of loose sand deposited by the wind |
Stoss | upwind side of dune, gentle slope |
Lee | downwind side of dune, steep slope |
Free dunes | deposited in flat, expansive areas with little obstructions Deposited by sedimentation and accretion |
Anchored dunes | deposition controlled by vegetation and topography |
Dunefields | sand covers area <30,000 kilometers squared |
Sand sea | sand covers area >30,000 kilometers squared |
Crescentic/Barchan dunes | crescent-shaped mounds that bend away from wind direction, unidirectional wind |
Linear/Transverse dunes | straight or slightly sinuous ridges longer than they are wide, bidirectional wind but one direction is dominant over the other |
Star dunes | radially symmetrical, arms radiate from a central mound, multidirectional wind |
Dome dunes | oval, circular mounds lacking a slipface, rare and not well understood |
Parabolic dunes | u-shaped, similar form to crescentic, but the dune bends upwind instead of downwind |
Loess | a loosely compacted yellowish-brown deposits of windblown silt particles |