1. Lab 06 ONLINE LESSON

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5. Plate Tectonics

6. Plate Tectonics is a geologic idea that states the surface of the planet is covered by a series of rigid plates that move…

7. These plates move away each other

8. These plates move toward each other

9. These plates move past each other

10. Plate Tectonics is driven by heat within the interior of the planet…

11. A current theory suggests that radioactive materials are the source for the earth’s internal heat…

12. This heat melts the surrounding rock

13. Melted rock (magma) rises to the surface and pushes the plates…

14. There are three types of plate boundaries

15. Divergent, Convergent and Transform

16. Divergent boundary: the plates move away from each other

17. Convergent boundary: the plates move toward each other

18. Transform boundary: the plates move past each other

19. Atransform boundary: cuts across a divergent boundary…

20. A divergent boundary is also referred to as a spreading center, such as the Mid Atlantic Ridge…

21. A divergent boundary is a part of the earth’s surface where new crust is formed…

22. A convergent boundary is also known as a subduction zone…

23. Subduction is the process of pushing seafloor crust into the interior of the planet…

24. A convergent boundary is where crust is destroyed and massive earthquakes occur…

25. A transform boundary is also known as a fracture zone or fault…

26. The San Andreas Fault is a well known transform fault in this area…

28. Earthquakes occur at all of these boundaries because solid rock is moving against solid rock…

29. The bigger earthquakes occur at the convergent and transformboundaries…

30. But small and shallow earthquakes can occur at transform and divergentboundaries…

31. Shallow earthquakes occur at divergentboundaries because the crust is thin… 5 -10 km thick…

32. The following is a map of many divergent, convergent and transformboundaries…

34. Plate Tectonics can be thought of as a grand unifying theory in geology…

35. Meaning that many geologic phenomena are associated with Plate Tectonics

36. And can be explained by Plate Tectonics

37. At convergent boundaries …volcanoes, earthquakes and mountains and deep sea trenches can be formed…

38. Right click to play

39. Also at convergent boundaries …the deepest earthquakes occur

40. Subducted seafloor is pushed into the interior of the planet….

41. As much as 650 kilometers

42. At divergent boundaries …heat, volcanoes, earthquakes and new seafloor can be formed…

44. Since new seafloor is formed at the divergentboundaries…the notion of seafloor spreading can also be observed…

45. Seafloor crust is made primarily of iron rich (MAFIC) minerals

46. These MAFIC minerals are subject to the earth’s magnetic field…

47. Magma rises up from the interior of the planet…

48. And punches through the ocean crust to form new crust…

49. The newly formed MAFIC crust can record the prevailing magnetic field

50. The earth’s magnetic field has changed direction over the course of the life of the planet