nt sand, perpendicular to wind-linear dune- limited sand, parallel to variable wind direction-star dune- wind blows from all directions-parabolic dune- stabilized by vegetation, U/V shaped* dune migration- movement or migration of whole dune slowly downwind due to the transfer of sand from the windward to the lee side of an active dune* sand seas- deserts of vast tracks of shifting sand (4/5 dune types)-Africa, Arabian Peninsula, W. Chinaeolian deposits-dust:* loess- thick and uniform deposit of wind-laid dust* characteristics that identify loess from water deposits-uniform blanket, mantling hills and valleys (disregards Prin. of Horizontality)-fossils of land plants and mammals-homogenous: lacks stratification-forms vertical cliffs (molecular attraction)* origin of loess particles-deserts (China)-floodplains of glacial meltwater streams (Mississippi River valley)* dust in ocean sediments* dust in glacier iceeolian deposits-volcanic ash:* tephra ejected into the atmosphere during explosive volcanic eruptions is a significant source of wind-transported sediment* ash-tuff- layers of tephra similar to loess except particles are volcanic minerals and glass* course and dense particles fall out quickly* small particles may be carried great distances* fine ash that reaches stratosphere may circle the earthDeserts: Region of annual rainfall less than 250mm; evaporation rate exceeds precipitation rate.desert types:* subtropical- global circulation, dry descending air* continental- far from moisture sources* rainshadow- lee of mountain barriers* coastal- cold ocean cools air flowing onshore (fog)* polar- global circulation, cold dry descending air (ice and moisture) (mars)desert climates:* arid climate of hot desert* high T, low rain, high evaporation, windy* arid climate of polar desert* low T (all ice), low precipitation, extremely dry airSurface Processes in Deserts: None restricted to deserts.weathering:* mechanical weathering dominatesmass-w...
