| Desert Landforms |
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Landforms shaped by Wind
Areas
where there is little or no vegetation are usually the most effected
places that experience shaping due to wind. This happens when the wind
picks up weathered rock materials and uses them to sand-blast larger
rock structures on the zone closet to the ground. The formation of
rock-strewn reg surfaces has resulted in the removal of finer material
by wind. The wind also plays an important role in moving and reshaping
dunes. Examples of landforms that are obvious in deserts are rock
pedestals, Yardangs, Desert pavements, Deflation hollows, Oasis and Sand
dunes.
Rock Pedestals
Rock
pedestals are landforms created by abrasion in which grains cut away
the base of rock structures but leaves their tips intact. This is due to
wind-borne sand grains following bouncing trajectories that carry sand
as high as 1m above the ground.
Deflation Hollows
When
the sand is carried away over long distances by the wind, depressions
are formed in the area from which is lands in. These depressions are
called deflation hollows and are commonly found in non-mountainous arid
regions. Deflation hollows are an example of wind erosion causing
deflation yet these depressions also tend to collect rainwater and hold
this water for a time depending on evaporation rates through the
stones.
Oasis
Oasis'
are found in the middle of deserts as fertile spots containing one or
more springs surrounded by vegetation. This is caused by a variety of
different temperature extremes causing islands of life. This outcome is
due to oasis usually been located in parts of the desert where the
elevation is low enough meaning the water table is underneath the
surface, allowing life to grow through their roots extending into the
moist land. Water is able to run right through the sand as it is holey
hence why the water can stay underneath the surface especially when
large quantities of sand is moved due to wind erosion.
Sand Dunes
There
are two different types of sand dunes which are the barchan dunes and
seif dunes. These are differentiated as barchan dunes are produced by
the action of wind predominately convex facing from one direction
forming crescent-shaped dunes , whereas the seif dunes are long and
narrow or can be a chain of dunes. These dunes are generally orientated
in a direction parallel to the wind or in a direction in which have been
the result of two or more winds blowing at acute angles to each other.
Wind directions can also alter the series of peaks, gaps, steepness and
the face of the sides. These sand dunes are mostly found in open deserts
and rest on a base of a sand sheet. Sand dunes are a result of
deposition processes.
Yardangs
Similarly
Yardangs are also the result of sand grains pushed by persistent winds
to form low ridges of sand carved in soft rock. This is commonly found
in flat deserts where steady winds blow away dust and silt. Higher front
faces of Yardangs are undercut as erosion is concentrated in the lower
areas because wind driven sand stays near the ground. These are an
example of erosional landforms
Desert Pavements
Pavements
are commonly covered with stones rather than sand. This may be due to
the wind blowing away the finest material leaving the stones behind as
they are the bigger particles and remain as a lag deposit or may be
through various physical processes including the soil in the ground as
the fine materials are moved down beneath the pebbles. This results in
the stones remaining on top. Desert pavements can be used as mulch for
plants or as a shelter for ants and rodents
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