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Erosion and Landscape Evolution

Erosion and Landscape Evolution. Anatomy of a Drainage System. The Continental Divide, Colorado. The Ideal Stream Cycle (W.M. Davis, 1880). Not a Literal Time Sequence Youth Maturity Old Age Rejuvenation  . The Ideal Stream Cycle. Youthful Landscape, Utah.

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Erosion and Landscape Evolution

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  1. Erosion and Landscape Evolution

  2. Anatomy of a Drainage System

  3. The Continental Divide, Colorado

  4. The Ideal Stream Cycle (W.M. Davis, 1880) Not a Literal Time Sequence • Youth • Maturity • Old Age • Rejuvenation  

  5. The Ideal Stream Cycle

  6. Youthful Landscape, Utah

  7. Young-Mature Landscape, California

  8. Mature Landscape, Pennsylvania

  9. Monadnock, Colorado

  10. Monadnocks, Maine

  11. Old Age Landscape, South America

  12. Rejuvenation • Some change causes stream to speed up and cut deeper. • Uplift of Land • Lowering of Sea Level • Greater stream flow • Stream valley takes on youthful characteristics but retains features of older stages as well. • Can happen at any point in the cycle.

  13. Rejuvenation

  14. Rejuvenation, San Juan River, Utah

  15. Machu Picchu, Peru

  16. Machu Picchu, Peru

  17. The Onset of Old Age? Indiana

  18. Why the Stream Cycle Doesn't Explain Everything • Changes in sea level during the ice ages • Most landscapes have been repeatedly rejuvenated • Seems to work best in stable interiors of Africa, Australia and South America.

  19. Superposed (Antecedent) Drainage Streams Cut Right Through High Topography • Crustal Uplift Across River • Rejuvenation • Buried Ridge

  20. The Ultimate Antecedent Drainage, India-Nepal-Tibet

  21.  Rejuvenated Peneplain

  22. Devil’s Gap, Wyoming

  23. The Huang He: “China’s Sorrow” • 1887: 2,000,000 dead • 1931: 3,700,000 dead • 1938: The Chinese dynamite levees to slow the Japanese; half a million Chinese died.

  24. River Diversions in the Caspian Region

  25. Why is the Danube Blue?

  26. Arid and Humid Weathering Compared • Rain: Rare, May Be Seasonal, Often Violent • Soil: Thin or Absent • Vegetation: Sparse-no Continuous Cover • Chemical Weathering: Weak • Episodic Processes Dominate

  27. Arid Erosion Cycle • Alluvial Fans • Playa Lakes • Pediments

  28. Alluvial Fans, Utah

  29. Old Arid Landscape

  30. Deltas

  31. Deltas, Greece

  32. Yosemite Falls, California

  33. Niagara Falls

  34. Evolution of Niagara Falls

  35. Limited Lifetime Thousands - Millions of Yr. How They Form: Grabens (Faulting) Tahoe 1600' Baikal 5600' Tanganyika 4000' Scour Great Lakes to 1300' Great Slave L. 2000' Lake Winnipeg Damming: Crustal movement, Landslide, etc. Volcanic Collapse - Crater Lake Sinkholes Kettle Ponds Lakes

  36. How Lakes Die • Eutrophication • Infilling - Only Way to Destroy Very Deep Lakes • Drainage at Outlet • Climate Change

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