(a) Name three processes of wind transportation in an arid region.
(b) With the aid of a diagram, describe the characteristics and mode of formation of a deflation hollow.
(a) Processes of wind Transportation in an Arid Region:- -Suspension -Traction/surface creep-Saltation.
(b) Characteristics and Mode of Formation of a Deflation Hollow: - Characteristics:--A wind erosional feature
-Found in desert areas -Depression in the desert-Has gentle slides-It is deep -Floor at times reaches the water table -Water sometimes collects in it to form oasis-May have luxuriant vegetation along its sides - Surface is of fine debris (clay or silt) -Surface could be of evaporite (sodium chloride or sodium carbonate) -Ranges in size from few square metres to hundreds of square kilometres-Some are of Quaternary age -Called playas/pans/flats/dayas/ deflation basins/blow outs -Habitable when occupied by oasis-Examples are the Qattara depression in Egypt, Tovat, Toaodeni, El Golea, Jalo, Dakhla, Al-Kufrah, Fayum in Egypt.
Mode of Formation:- -Formed in desert areas -Vegetation cover should be absent- Surface soil should be soft and jointed -Wind deflation process sets in - the softer materials are blown out -Continuous wind action -Eddy action sets in -Depression is created -Floor may reach the water table -Water collects to form a lake or an oasis -At times faulting occurs in less resistant rocks-The area is then affected by deflation -Eddy action aids to create a hollow.
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