HTML University

Science Dept.

Geology and Soils GEO 100 Notes
Wind - Aeolian - Eolian [Aeolus: Greek God of the Wind]

1. Arid and Semi-Arid Areas
   1. About 1/3 Land Area

   2. Characteristics
      1. Running Water Important

      2. Deserts Have Less Than 10 inches of Rain a Year

      3. Some Have Internal Drainage

      4. Arroyos, Wadis, Dry Washes

   3. Geography
      1. Far from Oceans

      2. Rain Shadows

      3. Downward Air Movements, 10^o and 30^o North and South of the Equator

      4. Near Cold Ocean Currents

2. Wind Flow
   1. Turbulent

   2. Laminar

   3. Critical Size: the Minimum Wind Velocity to Move a Certain Size Particle

3. Transport
   1. Suspension: "Dust"

   2. Saltation: is Usually Containied 18" or Below

   3. Rolling

4. Sources
   1. Weathered Materials

   2. Unconsolidated Materials

   3. Volcanic Ash

   4. Man: "Accelerated Erosion"

5. Erosion by Wind
   1. Deflation: Removal of Dust and Sand Particles

   2. Abrasion or Impact
      1. Frosting of Sand Grains

   3. Ventifacts

   4. Wearing Away of Bedrock

6. Land Forms in Areas of Wind Erosion
   1. Blowouts in Sediments

   2. Hamnada: Rock Outcrop

   3. Mushroom, Table and Pedistal Rocks: Base Partially Cut by Sand Blasting

   4. Caves

   5. Desert Pavement: Wind Removes Fine Materials Leaving Behind Pebbles, etc Like a Cobble Stone Street

   6. Plateaus

   7. Mesas

   8. Buttes

   9. Parallel Retreat of Slope
      1. Mountain Front

      2. Pediment

      3. Bahada

7. Land Forms in Areas of Wind Deposition
   1. Water Deposition
      1. Alluvial Fans

      2. Playas

   2. Wind Sheet Deposits - Loess: Glacial Flour -> Flooplain Deposits -> Glacial Milk -> Wind

   3. Wind Dunes: Erg or "Sand Sea"
      1. Dune Formation

      2. Dune Composition: Sand 2 mm to 1/16 mm
         1. Quartz

         2. Gypsum

         3. Ice and Snow

      3. Dunes in Conflict With Vegetation
         1. Parabolic Dune

         2. Longitudinal Dune(occasionally)

      4. Dunes Not in Conflict With Vegetation
         1. Transverse

         2. Barchan

         3. Seif

         4. Longitudinal Dune

         5. Star Dunes

8. Stabilization of Dunes
   1. Wind Fences

   2. Oiled Surface

   3. Gravel Cover

   4. Vegetation Cover

9. Selected Desert Web Sites