Presentation on theme: "Erosion and Landscape Evolution. Anatomy of a Drainage System."— Presentation transcript:
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
Young-Mature Landscape, California
Mature Landscape, Pennsylvania
Old Age Landscape, South America
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.
Rejuvenation, San Juan River, Utah
Machu Picchu, Peru
The Onset of Old Age? Indiana
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.
Superposed (Antecedent) Drainage Streams Cut Right Through High Topography Crustal Uplift Across River Rejuvenation Buried Ridge
The Ultimate Antecedent Drainage, India-Nepal- Tibet
Devil’s Gap, Wyoming
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.
River Diversions in the Caspian Region
Why is the Danube Blue?
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