2. Plate Tectonics

3. How can continents move? l In the 1960’s, scientists aboard the research ship Glomar Challenger drilled into the seafloor of the Atlantic Ocean and removed crust samples. l None of the rock samples were over 200 million years old. (Samples of continents are over 3 billion years old) l Rocks at the mid-ocean ridges were younger; rocks became older in both directions closer to the continents.

4. Glomar Challenger

5. l After analyzing the rock samples, scientists came up with a theory that molten material from Earth’s mantle is forced upward to the surface at mid- ocean ridges and cools to form new sea floor. l Movement in Earth’s mantle forces sections of crust apart, allowing magma to flow onto Earth’s surface and form new crust. l Therefore, the Atlantic Ocean is wider today than it was when Christopher Columbus crossed it!!!

7. Plate Tectonics- theory that Earth’s crust and upper mantle (lithoshphere) are broken into sections called plates that move on top of the asthenosphere.

9. Types of Plate Boundaries Convergent-plates collide Divergent-plates separate Transform-plates slide past each other

10. Plate Map

11. Converging Plates

12. Divergent Plates

13. Transform Plates

14. Convection Currents l Scientists believe plate movement is caused by convection currents. l When material in the mantle reaches an extreme high temperature, it rises. When it cools, it begins to sink back down. This motion creates a current, like when soup boils.

15. Convection currents

17. Convergent Boundaries Oceanic/Continental l Andes Mts (S. America) South American & Nazca Plates l Cascade Mts, Mt.St. Helens (N. America) North American & Juan de Fuca Plates

18. Effects of oceanic/continental convergence l Volcanic mountain chains l Faults l Earthquakes l Click picture for short video

19. Ocean/Continent Convergence

20. Andes Mountains

21. Mount St. Helens

22. Convergent Boundaries Con’t Oceanic/Oceanic l Japan Island chain Eurasian & Pacific Plates l Philippine Islands Eurasian & Pacific Plates

23. Effects of oceanic/oceanic convergence l Volcanic island arc l Faults l Earthquakes l Tsunamis

24. Ocean/Ocean Convergence

25. Mt. Pinatubo, Philiippines

26. Mt. Fugi, Japan

27. Convergent Plates Continued Continental/Continental l Appalachian & Atlas Mts. African & N. American Plates l Himalayas Indian & Eurasian Plates

28. Effects of continental/continental convergence l Folded mountain ranges l Faults l Earthquakes l Click pic for short video

29. Continent/continent convergence

31. Himalayas

32. Divergent Plate Boundaries Oceanic Crust l Mid Atlantic Ridge (MAR) and Iceland N. American & Eurasian plates Effects: l Mid ocean ridges l Faults l Earthquakes l volcanos

33. Computer generation of MAR

34. Mid Atlantic Ridge

35. Iceland

36. Continental crust divergence l East Africa, Red Sea & Rift Valley l Effects: l Rift valleys l Faults l Earthquakes l Inland seas l Rare volcanos

37. Red Sea

38. Transform Plate Boundaries Continental & Oceanic Plates San Andreas Fault (California) Pacific & N. American Plates Effects: l Faults l Volcanos Click for short video

39. Transform Boundary

40. San Andreas Lake

41. San Andreas trench

42. Hot Spots l Areas of volcanic activity formed by areas of intense heat in the mantle at places other than plate boundaries Ex: Hawaiian Islands, Yellowstone Natl. Park Click for short video

43. Hawaiian Islands

44. Cross section of hot spot