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CHAPTER 2 Plate Tectonics and the Ocean Floor (B)

CHAPTER 2 Plate Tectonics and the Ocean Floor (B). Dr. Dong, El Camino College. Review Chap 2 (A). Evidences to support continental drift Evidences to support plate tectonics theory. Plate Tectonics Theory. Lithospheric plates “float” on the asthenosphere

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CHAPTER 2 Plate Tectonics and the Ocean Floor (B)

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  1. CHAPTER 2Plate Tectonics and the Ocean Floor (B) Dr. Dong, El Camino College

  2. Review Chap 2 (A) • Evidences to support continental drift • Evidences to support plate tectonics theory

  3. Plate Tectonics Theory • Lithospheric plates “float” on the asthenosphere • Large scale geologic features occur at plate boundaries • Driving force of plate motion: Friction: slab suction Gravity: slab pull

  4. Figure 2.13b: Plates

  5. Types of Plate Boundaries Divergent Convergent Transform Fig. 2.14

  6. Exe 03-01 • List three types of plate boundaries • Describe the main content of plate tectonics

  7. Divergent Boundary Features Fig. 2.15 • Plates move apart • Mid-ocean ridge • Rift valley • New ocean floor created • Shallow earthquakes • Iceland is the only country which is located along a mid-ocean ridge

  8. A new ocean is formed Fig. 2.17

  9. Iceland is located along the mid-ocean ridge Fig. 2.16

  10. Red Sea is expanding Fig 2.16

  11. Exe. 03-02 • Describe how a new ocean is formed • Which country is located over the mid-ocean ridge?

  12. Three Types of Convergent Plate Boundaries Fig. 2.20

  13. Convergent Boundary Features • Plates move toward each other • Oceanic crust destroyed • Ocean trench • Volcanic arc • Deep earthquakes

  14. Types of Convergent Boundaries • Oceanic-continental convergence • Ocean plate subducted • Continental arc • Oceanic trench • Deep earthquakes

  15. Fig. 2.21a,b

  16. Fig. 2.22

  17. Exe. 03-03 • List types of convergent plate boundaries. • How was the Himalayas mountain formed? • Explain how St. Helens volcano was formed?

  18. Transform boundary features • Offsets oriented perpendicular to mid-ocean ridge • Segments of plates slide past each other • Offsets permit mid-ocean ridge to move apart at different rates • Shallow but strong earthquakes

  19. transform faults Fig. 2-23

  20. San Andreas Fault Fig. 2.23

  21. Exe. 03-04 • Explain why earthquakes frequently take place in the California?

  22. Fig. 2.24

  23. Applications of plate tectonics model to intraplate features Fig. 2.25

  24. Fig. 2.26

  25. Measuring plate motion by satellites Fig. 2.30

  26. Exe. 03-05 • Explain how Hawaii chain islands were formed ?

  27. Paleoceanography • Reconstructing paleogeography • Continental accretion • Continental material added to edges of continents through plate motion • Continental separation or rifting • Continents move apart

  28. Paleo-reconstructions Fig. 2.31

  29. Future predictions • Future positions of continents and oceans • Assume same direction and rate of plate motions as now

  30. World map 50 million years from now Fig. 2.32

  31. Wilson cycle • John Tuzo Wilson • Life cycle of ocean basins • Formation • Growth • Destruction

  32. Wilson cycle Fig. 2.33

  33. Exe. 03-06 • Describe Ocean floor cycle

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