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Aeolian processes are generally
associated with desert areas. Desert environments are characterized by very low
mean annual rainfall (less than 250 mm, average being 100 mm). Winds may erode,
transport and deposit materials and are effective agents in regions with sparse
vegetation, a lack of soil moisture and a large supply of unconsolidated
sediments. Aeolian processes are important in arid environments such as
deserts. Wind erodes the earth’s surface by deflation and by abrasion. Regions
which experience intense and sustained erosion are called deflation zones. Most
aeolian deflation zones are composed of desert pavement. The rock mantle in
desert pavements protects the underlying material from deflation.

                            In the desert, it
is true, there are some extraordinary components of what can loosely be called
dust, like the ‘manna lichen’ which fed the Isralites in Sinai and Alexander’s
armies in the desert of central Asia. Small particles may be held in the
atmosphere in suspension. Upward currents of air support the weight of
suspended particles and hold them indefinitely in the surrounding air. Typical
winds near earth’s surface suspend particles less than 0.2 millimeters in diameter
and scatter them aloft as Dust or
haze. Surface creep accounts
for as much as 25 percent of grain movement in a desert. The desert having
mobile sands are called Ergs.
The model size of erg is about 188,000 km2  whereas the largest erg of the world is Rub
Khali in Arabia( 560,000 km2). Aeolian turbidity currents are better
known as Dust storms. Air over deserts is cooled significantly when rain passes
through it. Crops, people, villages and possibly even climates are affected by
dust storms. Loess is a
material that originated as aeolian dust, and is thus composed mostly of
particles in the 10-15 mm range. In loess the dust has been transformed by
diagenesis, in which it is lightly cemented, usually by carbonate dissolved out
of the dust itself and by local reworking by sheetwash or slumping. It has been
claimed that loess covers 10 percent of the terrestrial globe. The thickest
known deposit of loess, 335 meters, is on the loess plateau in china. This very
same Asian dust is blown for thousands of miles, forming deep beds in places as
far away as Hawaii. Small whirlwinds, called Dust devils. The largest stretches
of true deserts are found in five great provinces, 1. Sahara-central Asia
Province, 2. Southern African Province, 3. South American Dry Zone, 4. Noth
American Desert Province, 5. Australian Desert Province. Heaps or mounds of
sands are generally called sand dunes or simply dunes. Sand dunes are
significant depositional features of desert areas but they are also formed in
all those areas where sands are available in profusion and wind is capable of
transporting and depositing them in suitable areas. They also vary in height
and length. On an average, their height ranges between a few meters and 20
meters but some times they are several hundred meters in height and 5-6 km in
length.  

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