Erosion and Landscape Evolution from UWGB University of Wisconsin, Green Bay

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Erosion and Landscape Evolutionfrom
UWGBUniversity of Wisconsin, Green Bay
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Anatomy of a Drainage System
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The Continental Divide, Colorado
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The Ideal Stream Cycle (W.M. Davis, 1880)

• Not a Literal Time Sequence
• Youth
• Maturity
• Old Age
• Rejuvenation  

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The Ideal Stream Cycle
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Youthful Landscape, Utah
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Young-Mature Landscape, California
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Mature Landscape, Pennsylvania
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Monadnock, Colorado
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Monadnocks, Maine
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Old Age Landscape, South America
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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.

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Rejuvenation
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Rejuvenation, San Juan River, Utah
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Machu Picchu, Peru
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Machu Picchu, Peru
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The Onset of Old Age? Indiana
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Why the Stream Cycle Doesn't Explain Everything

• Changes in sea level during the ice ages
• Seems to work best in stable interiors of Africa,
  Australia and South America.

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Superposed (Antecedent) Drainage

• Streams Cut Right Through High Topography
• Crustal Uplift Across River
• Rejuvenation
• Buried Ridge

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The Ultimate Antecedent Drainage,
India-Nepal-Tibet
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 Rejuvenated Peneplain
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Devils Gap, Wyoming
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The Huang He Chinas 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.

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River Diversions in the Caspian Region
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Why is the Danube Blue?
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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

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Arid Erosion Cycle

• Alluvial Fans
• Playa Lakes
• Pediments

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Alluvial Fans, Utah
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Old Arid Landscape
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Deltas
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Deltas, Greece
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Yosemite Falls, California
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Niagara Falls
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Evolution of Niagara Falls
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Lakes

• 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

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How Lakes Die

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

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Power Point from

• www.uwgb.edu/DutchS/EarthSC102PowerPoint/
  102Erosion-Landscape20Evolution.ppt -
• UWGB
• University of Wisconsin,Green Bay