1. Aeolian (wind) Landscapes Mt Etna & the Aeolian Islands Aeolus, king of the Aeolian Islands, rules the winds in Greek Mythology

2. Wind Landscapes 1.Dust (Loess) 2.Dunes (sand) 3.Ventifacts (erosion)

3. 1. Dust (loess) Dust collects on margins of deserts and glaciers

4. Breck P. Kent Deflation Hollow Deflation The process of removing all of the small (easily moved) particles by wind.

5. Deflation lowering surface Old Palm surface Medium Palm surface Young Palm surface

6. Dust Deflation 1500 m dust storm, 300 km/hr winds San Joaquin Valley, California, 1977 drought Dust storm across Red Sea Dust storm Kaho’olawe Island, Hawai’i

8. The Dustbowl, America, 1930’s Period of severe droughts Wind erosion of soil Organic matter, clay, and silt removed –carried great distances by wind –darkened sky on Atlantic coast Abandoned farms worsened problem

9. Classroom Resource Movie of dust blow era deflation

10. Loess Source: Negev Desert

11. Loess Accumulation: Wetter Margin of the Negev Desert

12. Loess Source: Peru Desert Loess Source: Atacama Desert

13. Loess Accumulation: Wetter Margin of the Atacama Desert

14. Loess Plateau, China

15. 2. Dunes (sand) Tallest Dunes Found in Namibia (980 ft)

16. Dunes are less dominant than many think Deserts cover about 1/5 th of the land Only 10% of that is dune covered (1/50 th )

17. Transport of Wind-Borne Sediment

18. Classroom Resource Slowed down process of saltation (bouncing)

19. Ripples form on surface of Sand Dunes

20. Some dunes “anchored” Falling dunes, Sinai, Egypt (depend on mtn)

21. Coppice dunes, depending on vegetation

22. Beach Sand Dunes

23. Parabolic (blow-out) Dunes Horns pinned by plants

24. Parabolic (blow-out) Dune

26. True Dunes Migrate Stoss (backslope) Lee (slip) face Animation that will play in the powerpoint file, showing how older “slip faces” create the cross bedding

27. Ripples on Stoss Side Stoss (backslope)

28. Slip Face on Lee Side Steep side of dune Sand Surfing Dune Jumping

29. Cross Bedding characteristic of dunes Slip faces

30. Classroom Resources Crossbedding.swf – Animation of how crossbedding forms

31. Transverse Dunes

32. Slip face tells you the wind direction

33. Longitudinal (linear, seif) Dunes

34. Longitudinal (Linear or Seif) Dunes Elongate parallel to wind direction Slip faces change from one side to the other side, as wind changes directions

35. Longitudinal Dunes

36. Barchan Dunes

37. Barchan Dune Slip face tells you the wind direction

38. Transverse Dunes turn into Barchan when sand supply drops

39. Star Dunes

40. Erg (Sand Sea)

41. Largest Sand Seas Jurassic Today

42. Great Sand Dunes small erg

43. Great Sand Dunes Classroom Resource: Animation of how build up by wind reversing

44. Tremendous Variety Exists inside an Erg (Rub Al Khali, Arabia)

45. 3. Ventifacts (wind erosion)

46. Look at surfaces: Polished Smooth (with grooves) by sand and dust abrasion If boulders, grooved

47. Wind flow

48. If small enough (pebbles,cobbles), rock is rotated so that polishing occurs on several sides

49. Ventifacts very common on Mars

50. How do you know it’s a true ventifact? Rub with your hand. If wind-abraded the surface is smooth Iceland Mojave Desert (Greeley et al., ASU)

51. NOT FROM Wind Abrasion No evidence of sand blasting. Only evidence of water erosion (rainsplash and rill)

52. NOT FROM Wind Abrasion No evidence of sand blasting. Only evidence of weathering, splitting apart the individual mineral grains – roughening surface No! Salt weathering

53. Not from wind abrasion! Wind can help blow out weathered products (clays, silt) from tafoni. But form is made by weathering (salt, chemical)

54. Erosion by the wind: Abrasion smooths surfaces Ventifacts

55. Erosion by wind polishes rental cars

56. Claims of Yardangs in Iran See mostly evidence of water flow, not wind

57. I am very skeptical about claims of hills eroded by wind – when you look carefully, you don’t see evidence of wind abrasion, only evidence of water erosion

58. Notch where saltating sand grains erode Yardangs, White Desert, Egypt Right scale & Good Evidence

59. Wrong Correct Weathering only

60. Online Animations Dunes: Process and Form Visualizations http://serc.carleton.edu/NAGTWorkshops/visualization/collections/du nes.html http://serc.carleton.edu/NAGTWorkshops/visualization/collections/du nes.html Visualizations for Soil Erosion (wind) http://serc.carleton.edu/NAGTWorkshops/visualization/collections/soil_ erosion.html

61. Imagery seen in this presentation is courtesy of Ron Dorn and other ASU colleagues, students and colleagues in other academic departments, individual illustrations in scholarly journals such as Science and Nature, scholarly societies such as the Association of American Geographers, city,state governments, other countries government websites and U.S. government agencies such as NASA, USGS, NRCS, Library of Congress, U.S. Fish and Wildlife Service USAID and NOAA.c