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Continental Drift and Plate Tectonics

Continental Drift and Plate Tectonics. Take-Away Points. How we know plate tectonics happens Most earthquakes and volcanoes occur along plate boundaries New ocean crust is created along mid-ocean ridges Old ocean crust is recycled at subduction zones

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Continental Drift and Plate Tectonics

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  1. Continental Drift and Plate Tectonics

  2. Take-Away Points • How we know plate tectonics happens • Most earthquakes and volcanoes occur along plate boundaries • New ocean crust is created along mid-ocean ridges • Old ocean crust is recycled at subduction zones • Subduction zones are where mountain-building (orogeny) occurs • Small pieces of crust (terranes) are important in building up continents • Hot spots are long lived stationary magma sources

  3. Global Problems in Geology Distribution of Continents Mid-ocean Ridges Trenches Orogenic Belts • Deformation • Metamorphism • Volcanism • Earthquakes

  4. Development of Continental Drift • Lots of people had noticed that the coastlines of Africa and South America are similar • Frank Taylor (1910) • Alfred Wegener (1912) Die Entstehung Der Kontinente Und Ozeane 1. How we know plate tectonics happens

  5. The Permian Ice Age Problem 1. How we know plate tectonics happens

  6. Wegener’s Theory 1. How we know plate tectonics happens

  7. Dating the Breakup 1. How we know plate tectonics happens

  8. Frank Taylor • In some respects, Taylor’s ideas were more modern than Wegener’s • Taylor always thought Wegener had stolen credit from him 1. How we know plate tectonics happens

  9. Frank Taylor • Recognized role of Mid-Atlantic Ridge • Never reconstructed the continents like Wegener did 1. How we know plate tectonics happens

  10. Confirmation of Continental Drift • World War II technology • International Geophysical Year (IGY) 1957-58 • Worldwide Standardized Seismic Network 1963- 1. How we know plate tectonics happens

  11. The Geomagnetic Reversal Time Scale 1. How we know plate tectonics happens

  12. Discovery of Sea-Floor Spreading 1. How we know plate tectonics happens

  13. Sea-Floor Spreading 1. How we know plate tectonics happens

  14. Where Does Ocean Crust Go? Hugo Benioff, 1954 1. How we know plate tectonics happens

  15. Benioff’s Interpretation 1. How we know plate tectonics happens

  16. Benioff’s Interpretation Updated 1. How we know plate tectonics happens

  17. Worldwide Standardized Seismic Network 2. Most earthquakes and volcanoes occur along plate boundaries

  18. The Plate Tectonics Model

  19. The Plate Tectonics Model

  20. The Earth’s Plates

  21. Global Plate Motions

  22. What Drives It: Convection

  23. How Plates Move

  24. Reconstructing Plate Movements

  25. Fit of Continents Across the Atlantic

  26. Present Day Atlantic

  27. Atlantic 65 m.y. ago

  28. Geology of Plate Margins

  29. Ophiolites: Oceanic Crust

  30. Anatomy of a Mid-Ocean Ridge

  31. FAMOUS: Close-Up of the Mid-Atlantic Ridge

  32. Magnetic Stripes in the FAMOUS Area

  33. A Subduction Zone

  34. Why Mountains are High

  35. Where the Plates Meet

  36. Terrane Accretion

  37. Terranes in Western North America

  38. Plate Boundaries and Earthquakes

  39. Hot Spots

  40. Hot Spots: Hawaii

  41. Pacific Hot Spot Tracks

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