1. Plate tectonics (pp 339-343) Plate boundaries (pp 343-348) Earthquakes (pp 375-384) Wednesday July 11

4. Free floating magnetite particles align following a well defined pattern around a magnet. If support is frozen, and magnet is moved, magnetite particles keep trace of the old position of the magnet

5. Magnetic poles drift? Yes, but not possible to have two north poles!!!

6. Plate tectonics is the explanation!!

9. Evidences of plate tectonics 1)Shape of continents 2)Magnetic pole drift 3)Hot spots 4)Magnetic striping and age of seabed 5)Similarities in fauna and flora

12. Evidences of plate tectonics 1)Shape of continents 2)Magnetic pole drift 3)Hot spots 4)Magnetic striping and age of seabed 5)Similarities in fauna and flora

15. Evidences of plate tectonics 1)Shape of continents 2)Magnetic pole drift 3)Hot spots 4)Magnetic striping and age of seabed 5)Similarities in fauna and flora

17. Plate motion and boundaries

18. Why do plates move??

19. PLATE MOTION Three types of plate boundary

20. Divergent boundary

21. Animation 1

23. Example: Mid-Atlantic Ridge a topographically high area near the middle of the Atlantic Ocean splits nearly the entire Atlantic Ocean north to south,

24. Divergent: Atlantic Ridge LAVA FOUNTAINS KRAFLA VOLCANO ICELAND

25. Rio Grande Rift

28. Animation 2 Convergent boundary I: oceanic -continental plate involved -> Subduction

29. OCEANIC-CONTINENTAL COLLISONS SUSTAIN MOST VOLCANIC ACTIVITY AROUND THE PACIFIC OCEAN

30. Convergent boundary II: oceanic -oceanic plates involved -> Subduction Subduction processes in oceanic- oceanic plate convergence result in the formation of volcanic arc islands

31. Animation 3 Convergent boundary III: NO oceanic plate(s) involved -> Mountain chains

33. Example: Andes Mtns West margin of the South American continent oceanic Nazca Plate is pushed toward and beneath the continental portion of the South American Plate typical example of a convergent plate boundary

34. Nazca - S.America plate collision

35. Transform boundary

36. Animation 4 Transform boundary

37. Example: San Andreas fault in California Pacific Plate slides past the North American Plate.

38. Transform boundary

39. Plate Motion Summary

40. Earthquakes

42. Are due to the release of strain in the lithosphere They propagate as waves of two types: Compression (or longitudinal or P- mode) waves Deformation (or transversal or S-mode) waves