ABSTRACT
The predominance of quartz sand and silicic silt in aeolian sediments denotes a final sorting of the residual fractionates of other denudation processes. Aeolian bed forms can develop on a massive scale if the sediment source is sufficient. The prime ingredients of aeolian landsystems are effective wind velocities and turbulence, with a large supply of incohesive particles of sand, silt and clay size. Aeolian environments cover 20 per cent of global land surfaces, closely associated with hot and cold desert environments in zones of atmospheric subsidence and surface divergence of generally light winds. Aeolian denudation occurs through mechanical weathering and rock slopes are cut back, leaving residual buttes or inselbergs above low-angled pediments. Coalescence of aeolian sand into a sand sea or erg creates a large-scale depositional landsystem whose surface is ornamented by the wind. Plant communities tolerant of the harsh aeolian environment form distinctive biogeomorphic dune systems in suitable locations. Aeolian deposits are also common in the geological record.
