1. Evidence for Movement of Continents

2. Biggest obstacles to acceptance You can not see the continent move You can not feel the motion of the continent Yet a lot of physical evidence supports the idea that the continents move across the earth over time

3. Goal for this section Review the evidence that supports continental drift Understand the process that allows continents to move (theory of plate tectonics) Predict what happens to continents and the life on them as they move

4. Question What kind of physical evidence could be used to show that continents move?

5. Alfred Wegener

6. First proposed that continents move over time (continental drift) in early 20 th century Meteorologist and German (what effect on acceptance of his ideas did his background have) Could not explain how continents move, led to rejection of theory

7. Evidence for continental drift 1)Physical shape of continents 2)Rock evidence of change in climate 3)Fossil evidence, including Mesosaurus 4)Location of volcanoes and earthquakes 5)Difference in ages of oceanic crust vs continental crust. Relate age to plate boundaries 6)Magnetic orientation of rock on either side of the Mid Atlantic ridge

8. Shape of the continents

10. Pangaea and Panthalassa

11. Pangea or Pangaea Pangaea- name of supercontinent the last time the continents were joined Panthalassa- name of the single ocean that existed at the same time as Pangaea

12. Evidence for movement of continents

13. Fossil evidence

14. Different animals and plants require certain climate conditions to live When the fossils found do not match current climate… How did the climate change so much?

15. Fossils of ferns found in Antarctica

16. Mesosauras Small aquatic reptile Less than 3 ft long Breathed air Freshwater hunter Fossils found only in eastern South America and western Africa

17. The mystery In the 1800s, scientists began finding fossils of these ancient reptiles, which had long since become extinct. These fossils were found in only two regions, southern Africa and the southern part of South America. The shaded areas on the map show where fossils of Mesosaurus have been discovered. This distribution is a curious one—only two regions far from each other and separated by the Atlantic Ocean. What could explain this distribution?

18. From experience with modern plants and land animal Migrate and expand primarily over land, not oceans. How can the exact same land animal or plant species have existed on a number of unconnected continents ?

19. Possible answers Either the animals evolved the same all over the world (not consistent with recent evolution) Or The places were connected and closer in the past

20. Paper Exercise Use the fossil evidence of shown to reassemble a supercontinent made from South America, Africa, Antarctica, India and Austraila 1.Remember, all regions of the same fossil must connect 2.It is ok to slightly overlap continents 3.Glue final answer in your comp book

23. point of exercise Areas where fossils of land animals/plants located must be connected This is possible only if Continents can move

24. Microfossils Very small life forms, organic matter Diatoms in ocean Algae, pollen on land Localized Quick evolution

25. Rock evidence Rock Type indicate climate Change in climate suggest requires change

26. Coal Made from organic remains of vast jungle swamps Indicates a tropical environment

29. Gypsum Created from what remains after ocean water has completely evaporated Indicates a hot, dry environment

30. Rock Evidence for glaciers Deposits made up of rocks with different size, composition, and roughness

31. Evidence of Glaciers Striations

33. Location of volcanoes and earthquakes around the world

34. World Volcanoes

35. World Earthquakes

36. Volcanoes (triangles) Earthquakes (circles)

39. Location of volcanoes and Earthquakes Volcanoes and earthquake line up, not randomly placed around the world Something must be happening on a global scale to account for this match

40. Difference in the maximum ages of ocean and continental rocks Max Oceanic Rock: 180 million Years old Max Continental Rock: over 4 Billion years old If continents did not move, both types should have similar ages

41. Age of the sea floor Red = young Blue = old Connect lines created by earthquakes to ages

43. Oldest Oceanic crust is farthest away from the ocean ridges Newest Oceanic rock is found at the oceanic ridges

44. Location of world’s Oldest rocks

45. Question We have fossil evidence that oceans have been around for longer than 180 million years It was destroyed by a continuing process- suggests motion of ocean crust

47. Paleomagnetism

48. Study of the Earth’s magnetic record over time Many rocks contain magnetic minerals When these rocks are hot, the magnetic orientation of the minerals are random As they cools, the magnetic orientation of the minerals is fixed in the direction of the magnetic field of earth

49. What is magnetic orientation? Means the direction the compass points when moving over the rock

50. Surprising Data Some rocks have a magnetic orientation different from the orientation of Earth In the 1960’s researchers mapping the orientation of rock across the Mid Atlantic ridge found a strangely symmetric result

51. Different colors represent rocks with different magnetic orientation

55. What has been discovered… Discovered bands of rock with different magnetic orientation as the ship moves away from ridge Evidence that the orientation reverses every 200,000 to several million years Matched bands with the same magnetic orientation are found on both sides of a ridge