GEO 13

  1. Spatial Distribution of deserts is related to three climatological factors
    • Subtropical High-pressure cells
    • Rain shadows on the lee sides of mountain ranges
    • long distance from moisture-bearing air masses
  2. alternating basins (valleys) and
    north-south aligned mountains
    (ranges) cover almost 800,000
    km2 of the American West
  3. tectonic forces created parallel
    series of horsts (upward-
    faulted ranges) and grabens
    (downward-faulted basins)
  4. Bolson
    Slope and basin area between the crests of two adjacent ridges in a dry region
  5. Desertification
    • Expansion of deserts along the margins of existing arid and semi-arid lands
    • caused by poor farming practices, over-grazing, deforestation, climate change
  6. what is an active agent of geomorphic change
  7. aeolian describes the work of wind and refers to the greek god aeolus
  8. Deflation and abrasion
    two principal wind erosion
  9. Deflation
    removal and lifting of individual loose or non-cohesive particles of sediment by wind
  10. Desert pavement
    Deflation results in a concentrated layer of pebbles and gravel
  11. blowout depressions
    basins that can be hundreds of meters wide and very deep
  12. Chinese word for desert pavement
  13. Abrasion
    Grinding of rock surfaces in a sandblasting action driven by particles carried on the wind
  14. Rock hardness, wind velocity and wind constancy effect abrasion
  15. yardangs
    wind sculpted features
  16. Pinnacles
    small landform created by differential weathering and erosion
  17. Buttes
    Medium-sized landform created by differential weathering and erosion
  18. Mesas
    Large landform created by differential weathering and erosion
  19. steady wind of 50 kph can move roughly about 0.5 ton of sand per day
  20. suspension
    less than 0.1 mm
  21. 80% saltation
    skipping and bouncing particles .1-.3 mm
  22. rolling and surface creep
  23. Dune
    • wind sculpted accumulated sand
    • steep leeward slope
  24. sand sea
    a lot of dunes
  25. Loess
    thick deposits of fine-grained class and silts created as a result of glacial retreat 15000years ago
  26. Playa
    • dry lake
    • alkali salts and fine grained sediments
  27. alluvial fan
    water flow out of steep canyon onto flat desert sediment
  28. bajada
    alluvial fans coalesce into sloping surface
Card Set
GEO 13