2. Theory of Continental Drift

3. James Hutton 1785 Uniformitarianism

4. Uniformitarianism The present is the key to the past The present is the key to the past The geological forces and processes of today are the same as those from the past. The geological forces and processes of today are the same as those from the past. These forces are very slow and methodical. These forces are very slow and methodical.

5. Alfred Wegener 1915 Continental Drift

6. Recurring patterns on continents

7. Evidence for continental drift Matching Coastlines (jigsaw puzzle)

8. Evidence for continental drift Matching folded mountain Ranges (Atlas, Appalachians, and Scandinavian Highlands)

9. Evidence for continental drift Matching glacier deposits

10. Evidence for continental drift Matching Fossils (Lystrosaurus)

11. Evidence for continental drift Matching coastlines Matching coastlines Matching folded mountains Matching folded mountains Matching glacier deposits Matching glacier deposits Matching fossils Matching fossils

12. Pangaea A Greek word meaning “All-lands” A Greek word meaning “All-lands” Split apart approximately 200 MYBP Split apart approximately 200 MYBP

13. 1915 maps by Wegener of Pangaea

14. Continental drift Theory that continents drift on the surface of the Earth Theory that continents drift on the surface of the Earth No mechanism proposed No mechanism proposed No one believed this was possible No one believed this was possible Do you think continents can float ? Do you think continents can float ?

15. Glomar Challenger 1960’s this ship took core samples of ocean floor rocks as it crossed the Atlantic Ocean 1960’s this ship took core samples of ocean floor rocks as it crossed the Atlantic Ocean A map was produced from this data showing the rock types and ages A map was produced from this data showing the rock types and ages From this map a new theory was developed to explain Wegener’s evidence From this map a new theory was developed to explain Wegener’s evidence

16. Ocean floor rock ages Get older symmetrically away from ridges, the oldest rocks have to be 200,000,000 years old Get older symmetrically away from ridges, the oldest rocks have to be 200,000,000 years old Theory: sea floor splits apart and rocks move away from each other Theory: sea floor splits apart and rocks move away from each other Process: Seafloor spreading Process: Seafloor spreading Seafloor spreading provides clues to mechanism driving continental drift Seafloor spreading provides clues to mechanism driving continental drift

17. Topography of ocean floor

18. Does sea floor spreading explain everything ? Does sea floor spreading explain everything ? If the Atlantic Ocean is spreading, doesn’t that mean some place is being squeezed together If the Atlantic Ocean is spreading, doesn’t that mean some place is being squeezed together

19. Recurring patterns in oceans

20. Plate Tectonics Combining Wegener’s evidence, Glomar Challenger’s data, and the following world map the present theory of Plate Tectonics came into being Combining Wegener’s evidence, Glomar Challenger’s data, and the following world map the present theory of Plate Tectonics came into being

21. Earthquake and Volcano Distribution