Desert LandscapesDominated by Wind
“We don’t survive the desert,  we live here”   - Pima Indian
Deserts: where & why Earth’s dry regions: 30% of all land 2 climate types of dry regions:    ◦ desert (arid)    ◦ steppe...
Climate Graphs – Semi-arid and AridWhat do you notice about the minimum and maximum temperatures?What do you notice about ...
Deserts: where & why What causes deserts? Global distribution of    ◦ air pressure    ◦ wind   Relationship between    ...
Deserts: where & why   Low-latitude deserts    ◦ Tropic of Cancer    ◦ Tropic of Capricorn   In contrast….    ◦ Equator:...
Deserts: where & why
Deserts: where & why
Deserts: where & why
Deserts: where & why
Deserts: where & why   Middle-latitude deserts (ie. 45°N)    ◦ exist in rain shadows.
Deserts: where & whyMiddle-latitude deserts
The Great Basin   Basin (valley) and    Range (mountains)    topography    ◦ mountainous desert      landscape    ◦ Nevad...
Great Salt Lake, Utah
Evaporation > Precipitation   Playa: ephemeral (not existing all year    long) lake beds that consist of salt and    mud ...
Wind erosion + deposition Wind erosion: Important in arid  environments Example…Sand dune shape depends  on:    ◦   Flat...
Wind erosion   Desert pavement
Wind erosion   Deflation: the process of wind    removing silt and sand-sized particles
Wind erosion + deposition   Ergs: seas of dunes
Wind erosion + deposition   Sand dune formation
Wind erosion   Ventifacts: rocks abraded, pitted,    polished by windblown sand
Wind Deposition   Loess from Aeolian    (or Eolian)    transportation:    ◦ Deposit of wind-      blown silt and clay in ...
Water Erosion   Wadi: a dried up river bed that only    has water during rainy season                               Town ...
Water Erosion                                    Hoodoos (or fairy                                     chimneys): column ...
Water ErosionFairy chimneys that people still live inside in Cappadocia,Turkey
Water Erosion                 Antelope Slot                  Canyons, Page,                  AZ                 Flash fl...
Water ErosionMesa: a flat-topped “table” formed bydifferential erosion of softer rockunderneath a layer of “cap” rock
Water Erosion  Butte: a smaller version of a mesa
Water Erosion                   Pedestal rock:                    softer rock erodes                    quicker than     ...
Water DepositionAlluvial Fan: deposition of sediments as rivers or flashfloods leave mountain ranges and spread into theva...
Water Deposition   Bajada: several adjacent alluvial fans    that have merged together
Desert landscapes dominated by wind
Desert landscapes dominated by wind
Desert landscapes dominated by wind
Desert landscapes dominated by wind
Desert landscapes dominated by wind
Desert landscapes dominated by wind
Desert landscapes dominated by wind
Desert landscapes dominated by wind
Desert landscapes dominated by wind
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Desert landscapes dominated by wind

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Desert landscapes dominated by wind

  1. 1. Desert LandscapesDominated by Wind
  2. 2. “We don’t survive the desert, we live here” - Pima Indian
  3. 3. Deserts: where & why Earth’s dry regions: 30% of all land 2 climate types of dry regions: ◦ desert (arid) ◦ steppe (semi-arid, surrounds deserts) Question:How much rain do deserts get every year? ◦ Sahara Desert receives as little as 2mm and as much as 100mm of precipitation per year
  4. 4. Climate Graphs – Semi-arid and AridWhat do you notice about the minimum and maximum temperatures?What do you notice about the amount of precipitation?
  5. 5. Deserts: where & why What causes deserts? Global distribution of ◦ air pressure ◦ wind Relationship between ◦ rainfall ◦ evaporation
  6. 6. Deserts: where & why Low-latitude deserts ◦ Tropic of Cancer ◦ Tropic of Capricorn In contrast…. ◦ Equator:  hot air  rises to 15-20 km  low pressure belt
  7. 7. Deserts: where & why
  8. 8. Deserts: where & why
  9. 9. Deserts: where & why
  10. 10. Deserts: where & why
  11. 11. Deserts: where & why Middle-latitude deserts (ie. 45°N) ◦ exist in rain shadows.
  12. 12. Deserts: where & whyMiddle-latitude deserts
  13. 13. The Great Basin Basin (valley) and Range (mountains) topography ◦ mountainous desert landscape ◦ Nevada, Arizona, California, Utah ◦ Death Valley, Mojave Desert, Great Salt Lake
  14. 14. Great Salt Lake, Utah
  15. 15. Evaporation > Precipitation Playa: ephemeral (not existing all year long) lake beds that consist of salt and mud flats Spotted Lake, just outside of Osoyoos, BC
  16. 16. Wind erosion + deposition Wind erosion: Important in arid environments Example…Sand dune shape depends on: ◦ Flat or hilly? ◦ How much sand? ◦ Winds steady or intermittent? ◦ Wind direction constant? ◦ Vegetation present?
  17. 17. Wind erosion Desert pavement
  18. 18. Wind erosion Deflation: the process of wind removing silt and sand-sized particles
  19. 19. Wind erosion + deposition Ergs: seas of dunes
  20. 20. Wind erosion + deposition Sand dune formation
  21. 21. Wind erosion Ventifacts: rocks abraded, pitted, polished by windblown sand
  22. 22. Wind Deposition Loess from Aeolian (or Eolian) transportation: ◦ Deposit of wind- blown silt and clay in angular grains and weakly cemented by calcite ◦ Develop rich, fertile soils
  23. 23. Water Erosion Wadi: a dried up river bed that only has water during rainy season Town of WadiTiwi, Oman
  24. 24. Water Erosion  Hoodoos (or fairy chimneys): column of soft sedimentary rock often with resistant layer of “cap” rock on top  Water flows through badlands causing further erosion to theBryce Canyon National Park, Utah spires
  25. 25. Water ErosionFairy chimneys that people still live inside in Cappadocia,Turkey
  26. 26. Water Erosion  Antelope Slot Canyons, Page, AZ  Flash floods from localized thunderstorms carry sediments that abrade and polish the sandstone
  27. 27. Water ErosionMesa: a flat-topped “table” formed bydifferential erosion of softer rockunderneath a layer of “cap” rock
  28. 28. Water Erosion Butte: a smaller version of a mesa
  29. 29. Water Erosion  Pedestal rock: softer rock erodes quicker than resistant “cap” rock
  30. 30. Water DepositionAlluvial Fan: deposition of sediments as rivers or flashfloods leave mountain ranges and spread into thevalley
  31. 31. Water Deposition Bajada: several adjacent alluvial fans that have merged together
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