1. Plate Tectonics Alfred Wegener 1915Continental Drift

2. Matching Mtn Ranges

3. SA and Africa

5. Appalachains

6. Pangaea

7. Pang 1

8. Pang 2

9. Pang 3

10. Pang 4

11. Ship

12. Sonar

13. Atlantic Ocean

14. World Ocean Floor

15. Magnetic Field Magnetic north is several degrees off geographic north, and it also wanders around.

16. Rocks and magnetism Fe-rich minerals record the direction of ‘north’ as well as their latitude as they crystallize. Basalt, the kind of rock that makes up oceanic crust, has Fe-rich minerals.

17. Magnetic Reversals The Earth’s magnetic field reverses every so often. When this happens, magnetic north becomes located near the South Pole.

18. Magnetism across MOR Magnetometer readings show that basaltic rocks have the same readings on either side of the MOR (mid-oceanic ridge).

19. Magma generation at MOR

20. Rock Ages Basalts are youngest along the MOR, where they are generated, then get progressively older away from, and on either side of, the MOR.

21. Seafloor Spreading Generation of basalt at mid-oceanic ridge

23. Tectonic Plates 3 major types

24. MOR

25. MOR detail

26. Devils Tower

27. Submersible

28. Pillow Basalt Lava extruded in water takes the form of ‘pillows.’

30. Divergent Plate Boundaries MOR is 42,000 miles long

31. Triple Junction Initial formation of a divergent plate boundary takes the form of several triple junctions. As spreading continues, one of the rift valleys has to fail: Aulacogen

32. East African Rift Aulacogen

33. Upwarping

34. Rift Valley

35. Linear Sea

36. Oceanic Crust

38. Mature Divergent Boundary

39. 3 types of… 3 types of convergent plate boundaries: 1) Oceanic-Continental 2) Oceanic-Oceanic 3) Continental-Continental

40. Ocean-cont Oceanic-Continental Convergence Accretionary Wedge Volcanic arc appears approx. 200 miles inland from the trench. Magma pulses separated by about 400 years. Partial melting creates continental crust (we’ll discuss later).

41. Ocean-ocean Oceanic-Oceanic Convergence Older, and thus colder & denser, crust subducts. Similar to oceanic-continental convergence, but forms volcanic island arc.

42. Earthquake Distribution Map Distribution of earthquakes mirrors the tectonic boundaries.

43. Benioff Zone Deeper earthquakes are always found far inland of the trench.

44. Cont-Cont Continental-Continental Convergence Collision happens after oceanic crust is completely consumed during continental-oceanic subduction. Continental crust is not dense enough to be forced down into the mantle. Ocean-bottom sediments forced upward.

45. Collision

46. Himalaya

47. India-Asia Collision

49. Trenches Trenches: Where oceanic crust is subducting

50. Transform Plate Boundary

51. San Andreas Fault

52. Segments Each segment moves at a different rate, some not at all

53. Earthquake Hazards

54. Mantle Plumes Subducting oceanic crust melts at the core-mantle boundary, releasing lots of magma. Magma rises to the surface over a 600,000 year period.

55. Hawaii

56. Hawaiian hot spot Hot spot is fixed Plate moves over hot spot

58. Hawaiian Hot Spot

59. Hot Spots

60. Yellowstone

62. Fallout

63. Earth