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Geomorphological Methods

Geomorphological Methods

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Geomorphological Methods

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  1. Geomorphological Methods

  2. Systems Terminology • Steady State • A time-invariant condition • Equilibrium • A balance between form and process • Dynamic Equilibrium • State changes around a central point

  3. Systems Terminology • Threshold • A condition that must be exceeded in order for state to change within the system • Feedback • Positive – self-reinforcing; accelerating • Negative – self-regulating; damping • Equifinality • Similar final states achieved through different mechanisms

  4. Scale matters…

  5. GTOPO30

  6. USGS 30m: Mount St. Helens

  7. Time and Space in Geomorphology CLIMATE GEOLOGY Geology GEOMORPHOLOGY

  8. Rates of Processes

  9. Magnitude vs. Frequency

  10. How do geomorphic processes work? Process studies…

  11. Force balances

  12. Force balances

  13. Force balances

  14. How fast does this happen? Process studies and field measurements…

  15. USGS suspended sediment sampling apparatus, Cowlitz River, Washington (1982)

  16. Stream gauge on bridge support, Chippewa River, Wisconsin

  17. GPS Surveying in the Mojave Desert, CaliforniaRepeated high-resolution surveys can document landscape change and characterize landform.

  18. What is this landform made of? Field studies…

  19. Trench in floodplain sediments, Richmond, Virginia

  20. Drilling into floodplain sediments, Williamstown, Massachusetts

  21. Logging the wall of a trench across the San Andreas Fault, California

  22. How old is this rock, surface, or landform? Geomorphological dating techniques…

  23. Scarp degradation

  24. Thermochronometry

  25. Thermochronometry Different minerals have different cooling temperatures and thus reveal erosion rates over different time scales

  26. Radio carbon dating

  27. Radio carbon dating

  28. Dendrochronometry, tree-ring dating

  29. Lichenometry

  30. Cesium 137 dating

  31. Thermoluminescence dating (TL)

  32. Cosmogenic dating