The Ideal Stream Cycle (W.M. Davis, 1880) Not a Literal Time
Sequence Youth Maturity Old Age Rejuvenation
Slide 5
The Ideal Stream Cycle
Slide 6
Youthful Landscape, Utah
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Young-Mature Landscape, California
Slide 8
Mature Landscape, Pennsylvania
Slide 9
Monadnock, Colorado
Slide 10
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
Slide 14
Rejuvenation, San Juan River, Utah
Slide 15
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 Most landscapes have been repeatedly
rejuvenated Seems to work best in stable interiors of Africa,
Australia and South America.
Slide 19
Superposed (Antecedent) Drainage Streams Cut Right Through High
Topography Crustal Uplift Across River Rejuvenation Buried
Ridge
Slide 20
The Ultimate Antecedent Drainage, India-Nepal- Tibet
Slide 21
Rejuvenated Peneplain
Slide 22
Devils Gap, Wyoming
Slide 23
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.
Slide 24
River Diversions in the Caspian Region
Slide 25
Why is the Danube Blue?
Slide 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
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
Slide 36
How Lakes Die Eutrophication Infilling - Only Way to Destroy
Very Deep Lakes Drainage at Outlet Climate Change
