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Class 11, Sand dunes

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  • 1. RELIC DUNE FIELDS IN NORTH AMERICA
  • 2. Photograph: kcspor our
  • 3. Sand and loess deposits in the United States Sun and Muhs 2007
  • 4. Global distribution of aeolian sand Sun and Muhs 2007
  • 5. Lt. G.K. Warren’s sketch of the Nebraska Sand Hills, 1855
  • 6. Source: Stephen Wolfe
  • 7. “...the men and horses were in great wantof water, and the heat was very great whiletravelling through miles of burning sand.” Captain John Palliser, 1863
  • 8. Source: Hughenholtz et al., Aeolian Research (2010)
  • 9. Were these dune fieldsmore active prior to the 20th century?
  • 10. Photograph: Stephen Wolfe
  • 11. Photograph: baba1627
  • 12. Impurities or defects in this structure can act as“traps” for free electrons.
  • 13. freeelectron
  • 14. The rate at which free electrons are produced,and traps are filled, is proportional to: • the amount of radioactive elements in the minerals being dated • the amount of radioactive elements in their surroundings.
  • 15. Photograph: Ben+Sam
  • 16. Photograph: Pandiyan
  • 17. Source: Wolfe et al., Geographie physique et Quaternaire, 2002
  • 18. Photograph: Stephen Wolfe
  • 19. Stephen Wolfe Geological Survey of Canada
  • 20. Source: Stephen Wolfe
  • 21. Source: Wolfe et al., Geographie physique et Quaternaire, 2002
  • 22. Source: Wolfe and Hughenholtz, Geology, 2010
  • 23. Source: Stephen Wolfe
  • 24. Light Detection and Ranging (LiDAR)
  • 25. barchan dune residual back ridge dune ridges parabolic duneSource: Wolfe and Hughenholtz, Geology, 2010
  • 26. Parabolic dunes Photograph: Shooting Chris
  • 27. Barchan dunes Photograph: Ron Scho
  • 28. S TA B L E I S O T O P E S I N PA L E O C L I M AT O L O GY
  • 29. “depleted” less O 18 more O18 “depleted” “enriched”less O 18 “enriched” more O 18
  • 30. Source: Jouzel et al., Journal of Geophysical Research, 1994
  • 31. “heavy” “light”Source: Jouzel et al., Journal of Geophysical Research, 1994
  • 32. “more positive” δO 18 = “heavy” = “enriched” for example, ocean water
  • 33. “more negative” δO18 = “light” = “depleted” for example, glacial ice
  • 34. δO18 in precipitationSource: Bowen and Wilkinson, Geology, 2002