1. Continental Drift and the Origin of Plate Tectonics

2. The Theory of Plate Tectonics
The Earth’s lithosphere is made of a number of solid pieces, called __________ which move in relation to each other.
Tectonic plates

3. Alfred Wegener Theory of Continental Drift
Proposed by __________ __________ in It stated that the earth’s continents separated and collided as they have moved over the surface of the Earth for millions of years.
Alfred
Wegener

4. Geographer and Polar Explorer
Alfred Wegener ( )
Geographer and Polar Explorer

5. Wegener’s Map showing the breakup of Pangea
(Pangea song)
See
Reference Table
Page 9

6. Future Super Continents

7. Africa S.America B. Wegener’s evidence for his his theory:
1. When you line up __________
and ___________________
they fit like a puzzle.
Africa
S.America

8. Fossil
2. __________ species have been found on widely separated parts of the earth.

9. 3. Permian fossils are very similar in widely separated continents

10. Cynognathus

11. Lystrosaurus

12. Mt. Sirus
Antarctica
Lystrosaurus beds

13. Mesosaurus

14. S. America Africa fault fold
3. _____________ and ______________ have a good match of ancient continental rocks and tectonic _________ and _________ structures.
fault
fold

15. continent
4. Some mountain chains appear to be continuous from ____________ to___________
continent
Ex: Appalachians &
Caledonian

16. 5. Evidence of _________ climates different from today
ancient
5. Evidence of _________ climates different from today
Finding coal beds which indicate tropical climates
Ex.

17. Technology developed during Seafloor spreading Video
Sonar - image the deep ocean using reflected sound.
Magnetometer - detect faint magnetic fields.
Developed to search for U-boats

20. Mid-ocean ridge

21. II. Sea Floor Spreading:
Further evidence of horizontal movement of earth’s crust:
A. The ocean floor has a system of submerged mountain ranges called
______________________
Mid-Ocean Ridges

22. Harry Hess Geologist at Princeton U. 1962 publishes “geopoetry.”
Sea floor spreading hypothesis.
Suggested that the ocean floor itself might be moving.
Harry Hess

23. Material from deep within the earth comes to the surface at the ___________________ where it spreads apart to make ________________.
Ocean ridges
New ocean crust

25. B. The two major pieces of evidence are:1.
Age of igneous
ocean material

26. Rocks of the ocean basins are _________ than continental rocks.
younger

27. 2. Reversal of magnetic polarity

28. When the rock hardened it kept the alignment forming a permanent record of the ___________________ of the earth at that time.
Magnetic field

30. N S

31. N S

33. S
Magnetic polarity reversal N

34. reversed magnetism reversals
Rocks found farther from the ridges have a _____________ magnetic polarity. Parallel stripes of ________________ on either side of these ridges preserve the record of many ____________ of the earth’s magnetic field.
reversals

35. Sea Floor Spreading Video

36. dark
dense
C. The _______ _________ (basaltic) igneous rocks of the crust near the ocean ridges are covered with a thin layer of ____________.
sediment

37. This is evidence that the earth’s crust is very ___________ near the ridges.
young

38. The oldest parts of the ocean crust are found far from the ___________ ridges and near the _______________
ocean
continents

39. Observation- as you increase distance from the ridge there is an increase in in the thickness of the layer. Inference: The thicker the layer of sediments on top the ocean floor the older the crust is because more time has passed

40. Magnetic Poles Shifting Video

41. Acceptance of Sea Floor Spreading (Plate Tectonics)
1970’s - rapid confirmation of remaining predictions and acceptance of the basic theory by most geologists.
1980’s - Plate Tectonics becomes the dominant paradigm in geology.
1990’s - Development of a detailed plate tectonic history of the last 700 million years.
Continental Drift Song
Plate Tectonic Whistle