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Eolian Environments

Eolian Environments. Texture : super mature, very well sorted, clast sizes of medium sand to silt, clasts typically rounded and etched. Composion: siliciclastic (abundant quartz grains), carbonates (e.g., Bahamas), evaporites (e.g., gypsum in arid regions). SEM image (etched grain).

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Eolian Environments

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  1. Eolian Environments

  2. Texture:super mature, very well sorted, clast sizes of medium sand to silt, clasts typically rounded and etched Composion:siliciclastic (abundant quartz grains), carbonates (e.g., Bahamas), evaporites (e.g., gypsum in arid regions) SEM image (etched grain) Quartz clasts

  3. Structures:large-scale cross bedding (3–600 m in length; 10 cm–100 m in height), some plane beds, wind ripples

  4. Geometry of deposit: tabular and extensive (in deserts), linear (en coasts) Extensive dunes in the southern California desert (road for scale) Dunes along the Oregon coast

  5. Dunes Barchan Longitudinal Transverse Parabolic Transverse/Barchan Star

  6. Desert Pavement: the wind has removed all of the fine-grained clasts

  7. Lateral variations: alluvial fans, ephemeral rivers, lakes, oceans Dunes and fans in Death Valley Dune in Namibia Desert with braided river

  8. Vertical sequence: deserts—thick sequences of sand with cross bedding; coasts—associated with coastal sediments (e.g., beach) Sequence of alluvial sediments, coal (marsh sediment), dunes: Montara Beach sequence Desert sequence in Utah

  9. Biology: plant roots, bioturbation by both plants and animals

  10. Chemical processes: sediments often have red or orange colors because of iron oxidation in a subaerial environment; soil development

  11. Jurassic eolian sediment sequence in Nevado (near Las Vegas)

  12. Processes of deposition Great Sand Dunes National Park, Colorado

  13. Processes of deposition: traction flows (wind—air has low viscosity), primarily saltation and grain flow ripples Dune avalanche slope

  14. Processes of deposition: planar beds (deflaction areas between dunes); soil formation

  15. Processes of deposition: silt in suspension—e.g., loess (associated with glaciers)

  16. Depositional setting: dry regions (subtropical, yellow and orange colors on map) where there are large quantities of loose sediments; and along coasts in many locations

  17. Depositional setting: MARS (other planets)

  18. The most distintive characteristics: very well sorted and large-scale cross bedding A modern dune at Pescadero, California

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