105_15-deserts_part_2 - Wind Deposits Loess Loess Dunes...

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Unformatted text preview: Wind Deposits Loess Loess Dunes Dunes Loess Wind Deposits – windblown silt and clay – from deserts, glacial outwash and arid river plains – accumulates in damp areas – soft but forms cliffs Loess deposits Dunes Dunes Wind Deposits – wind shadows around obstacles accumulate sand piles – sand piles may grow into dunes 1 Dune Migration Sand Sand blows up the windward side by saltation . . . . . . then slides down leeward side, then forming steep, large-scale cross-beds. largecross- Types Types of Dune barchan barchan dunes – crescent shaped – areas of limited sand supply 2 Types of Dune transverse transverse dunes – long ridges perpendicular to wind direction – areas with abundant sand – barchanoid dunes are intermediate towards barchan dunes Transverse dunes Novachott, capital of Mauritania, NW Africa Types of Dune parabolic parabolic dunes – some vegetation holds down dune sides – crescent shaped, tips upwind – mainly in coastal areas 3 Coastal parabolic dunes Types of Dune longitudinal (seif) dunes – long dunes parallel to wind – some variation in wind direction – may be very large Longitudinal Longitudinal dunes, Australia Types of Dune star star dunes – large dunes, abundant sand, highly variable wind directions Longitudinal dunes 4 Deserts and Wind Action Chapter Chapter 15 Star dunes 5 ...
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This note was uploaded on 05/18/2011 for the course GEOL 105 taught by Professor Jack during the Spring '08 term at University of Louisiana at Lafayette.

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