Unit 47
Longitudinal dune
Long, ridge-like sand dune that migrates in a direction parallel to the ridge crest, often formed as a result of strong winds from two directions
Surface creep
Movement of fairly large rock fragments by the wind actually pushing them along the ground,
Eolian
Pertaining to the action of the wind
Saltation
Process in which sediment is moved by stream flow or wind; sand and gravel can saltate in a stream, while the wind generally moves only sand-sized particles in saltation
Deflation
Process whereby wind erodes the land surface and carries away the eroded material; may produce basins and troughs
Transverse dune
Ridge-like sand dune in which the ridge crest is oriented at a right angle to the prevailing direction of strong winds; usually straight or slightly curved
Erg
Sand sea; large expanse of sandy desert landscape
Deflation hollow
Shallow desert basin created by the wind erosion process of deflation
Ripples
Small, regularly spaced ridges on the surface of a dune or streambed, usually less than 1 cm high on a dune, but sometimes larger on streambeds
Desert pavement
Smoothly weathered, varnish-like surface of closely packed pebbles that has developed on the upper part of an alluvial fan or bajada, no longer subject to stream deposition
Yardangs are formed when wind
cuts troughs into soft bedrock leaving a ridge of rock, desert structure
The following is an erosional landform produced by winds:
deflation hollows, desert pavement, yardang
The points or horns of a barchan dune point
downwind
Loess deposits are from
dust blown from glacial deposits
Dune
Accumulation of sand that is shaped by wind action
Barchan
Crescent-shaped sand dune with low arms or "horns" pointing downwind. Convex side is the windward side
Loess
Deposit of dust laid down after having been blown by the wind; mostly made up of silt grains, formed by productive soils, can stand in steep vertical walls.
Wind abrasion
Erosion of rock surfaces by windborne sand particles
Slip face
Leeward slope of a sand dune
Barchans form in areas with strong unidirectional winds and a limited sand supply
True
Generally, the highest part of the dune is the
crest
Crescent-shaped sand dunes that form along coastlines with some vegetation are called __ dunes
parabolic
Transverse dunes are aligned
perpendicular to wind direction
In a sandstorm, ___ is the dominant mode of particle movement
saltation
These particles are more easily moved by wind
sand with a diameter of about 0.1 mm
Sand grains are deposited on the ________ producing crossbeds as the sand dune migrates
slipface
Dunes covered by vegetation probably indicates that the dune is
unstable