1. Earth in Motion

2. Principle of Uniformitarianism: Processes observable and measurable today have created all the geological features, over long periods of time.

3. Why are continents high and oceans deep? Why do continents across the Atlantic fit together like a jigsaw puzzle? Why were fossils similar in the past on continents that are now separated? How are mountains made and why do they occur where they do?

4. Alfred Wegener

7. Geographic Fit of the Continents One of the first pieces of evidence used to argue for continentaldrift Suggested that all continents were once together in a single supercontinent called Pangea Fig. 2.1

8. Geology and Paleontology Matches on Opposite Sides of the Atlantic Fig. 2.2

10. Wegener’s Pangaea

11. Wegener’s Dilemma

12. What is missing from this picture?

13. Challenger Expedition

14. What’s down there? –The dredge

15. Early Oceanographers

16. Challenger Expedition Determining Ocean Depth

17. Wyville- Thompson’s Frontspiece

18. Research Vessel Vema

19. Coring on the Vema, 1960’s

21. Vema Depth Record

25. Earth’s Magnetic Field

26. The Seafloor as a Magnetic Tape Recorder During and after WWII, it was noticed that the magnetic field near the ocean floor exhibited significant variation. Subsequent analysis shows that the changes in the rocks reflect changes in the Earth’s magnetic field over time.

27. Fig. 2.11

28. Magnetic Reversals in a Single Volcano Fig. 2.11

29. The Magnetic Record Fig. 2.11

30. Magnetic Reversals at Mid-ocean Ridges Fig. 2.11

33. Figure 10-08

35. Plate Tectonics

36. Theory of Plate Tectonics Surface of the Earth is covered by a series of plates Creation of seafloor occurs at mid-ocean ridges, where volcanism creates the seafloor. Consumption of the seafloor occurs at convergent margins, where plates are subducted back into the mantle. Continents never subduct; they are passengers riding on the plates

37. Plates of the Earth’s crust

38. How ocean basins formed

40. Plates Group of rocks all moving in the same direction Can have both oceanic and continental crust or just one kind.

41. Three Types of Plate Boundaries Fig. 2.5 Transform Divergent Convergent

42. Transform Boundaries The San Andreas Fault

43. Transform Plate Boundary Fig. 2.10