 Erg !
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| ERG LANDFORM
an erg is also known as duna sea is a large relatively flat area of desert covered with wind-swept san with little of to no vegetation cover. the term takes its name from the Arabic word erg mean "dune field". an ergis defined as to be a desert area that contains more than 125 square kilometers of eolian sand & where sand covers more than 20% of the surface approximately 85% of the earth's mobile sand is found in ergs that are larger than 32,000 km2. ergs are als found on other celestial bodies, such as venus & saturn's moon titan. erg are concentrated in 2 broad belts between 20 degree-40 degree S latitutdes, which includes regions crossed by the dry, subsiding air of the trade winds. averaged erg are limited to regions which receive not more than 150 mm of annual precipitation. sand sea & dune fields generally occur in regions downwind of copious sources of dry, loose sand, such as dry riverbeds , deltas, flood plains, glacial out wash plains, dry lakes & dry beaches. at least 1 million years are required to build ergs with very large dunes sand sea that have accumulated in subsiding structural & topographic basins, attain great thickness more than 1000m. by nature ergs are very active. individual dunes forming ergs typically have width, length / both dimensions greater than 500m.
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Linear Mode
