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Earth in Motion

Earth in Motion. Principle of Uniformitarianism: Processes observable and measurable today have created all the geological features, over long periods of time. How are mountains made and why do they occur where they do?. Why are continents high and oceans deep?.

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Earth in Motion

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  1. Earth in Motion

  2. Principle of Uniformitarianism: • Processes observable and measurable today have created all the geological features, over long periods of time.

  3. How are mountains made and why do they occur where they do? Why are continents high and oceans deep? Why do continents across the Atlantic fit together like a jigsaw puzzle? Why were fossils similar in the past on continents that are now separated?

  4. Alfred Wegener

  5. Geographic Fit of the Continents One of the first pieces of evidence used to argue for continental drift Suggested that all continents were once together in a single supercontinent called Pangea Fig. 2.1

  6. Geology and Paleontology Matches on Opposite Sides of the Atlantic Fig. 2.2

  7. Wegener’s Pangaea

  8. Wegener’s Dilemma

  9. What is missing from this picture?

  10. Challenger Expedition

  11. Challenger Expedition • What’s down there? • The dredge

  12. Early Oceanographers

  13. Challenger Expedition • Determining Ocean Depth

  14. Wyville-Thompson’s Frontspiece

  15. Research Vessel Vema

  16. Coring on the Vema, 1960’s

  17. Vema Depth Record

  18. Earth’s Magnetic Field

  19. The Seafloor as a MagneticTape Recorder • During and after WWII, it was noticed that the magnetic field near the ocean floor exhibited significant variation. • Subsequent analysis shows that the changes in the rocks reflect changes in the Earth’s magnetic field over time.

  20. Fig. 2.11

  21. Magnetic Reversals in a Single Volcano Fig. 2.11

  22. The Magnetic Record Fig. 2.11

  23. Magnetic Reversals at Mid-ocean Ridges Fig. 2.11

  24. Figure 10-08

  25. Plate Tectonics

  26. Theory of Plate Tectonics • Surface of the Earth is covered by a series of plates • Creation of seafloor occurs at mid-ocean ridges, where volcanism creates the seafloor. • Consumption of the seafloor occurs at convergent margins, where plates are subducted back into the mantle. • Continents never subduct; they are passengers riding on the plates

  27. Plates of the Earth’s crust

  28. How ocean basins formed

  29. Plates • Group of rocks all moving in the same direction • Can have both oceanic and continental crust or just one kind.

  30. Three Types of Plate Boundaries Divergent Convergent Transform Fig. 2.5

  31. Transform Boundaries The San Andreas Fault

  32. Transform Plate Boundary Fig. 2.10

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