1. Plate Tectonics

2. Tectonic Plates

3. Continental Drift

4. Continental Drift
Geologist Alfred Wegener-first to propose evidence that continents were once connected.
He called this “super” continent Pangaea, meaning “All Earth”

5. Pangaea

6. Political Pangaea

7. Support for Continental Drift
Shape of the continents
They fit together like jigsaw puzzle pieces.

8. Support for Continental Drift
2. Fossil Correlation
SAME FOSSILS : DIFFERENT CONTINENTS

9. Support for Continental Drift
3. Rock and Mountain Correlation
SAME ROCK : DIFFERENT RANGE
Existing mountain ranges separated by vast oceans contain rocks of identical mineral content.
Ex: Appalachian Mtns in the eastern US and Caledonian Mtns in the British Isles

11. Support for Continental Drift
4. Past Climate Data (Paleoclimates)
Glacial Scars show past cold climate
SAME SCARS : DIFFERENT CONTINENTS
Coal Deposits show past warm climate

12. Glacial Scars

13. Coal Deposits

14. Continental Drift in Doubt
Why didn’t people believe in continental drift?
People couldn’t imagine how the Earth could be millions of years ago.
People couldn’t imagine a force great enough to move the continents.
BUT…by the 1960s, evidence would prove continental drift is TRUE!

15. How Plates Move

16. The Lithosphere & The Asthenosphere
The lithosphere floats on top of the asthenosphere. Convection currents that occur in the asthenosphere, cause the lithosphere to move. This creates/destroys landforms on Earth’s crust.

17. Sea Floor Spreading

18. Sea Floor Spreading Harry Hess-1960s
Discovered the Mid-Atlantic Ridge while mapping the ocean floor.
Mid-Ocean Ridges-underwater mountain chains
Magma rises to the surface and solidifies to form new oceanic crust.
Older crust is pushed farther away from the ridge

19. Sea Floor Spreading

20. Plate Tectonics
The theory that Earth’s crust and upper mantle (lithosphere) are broken into sections, called plates, that slowly move around on the rest of the mantle (asthenosphere) due to convection currents.

21. Types of Crust
The type of crust present and the direction of the convection current determines how Earth’s surface will be effected.
Oceanic: made primarily of basalt; more dense
Continental: made primarily of granite; less dense

22. Different Types of Boundaries

23. Divergent Boundary – Arabian and African Plates
Arabian Plate
Red Sea
African Plate

24. Divergent Boundary – Iceland

25. Divergent Boundary - Oceanic

26. Divergent Boundary - Continental

27. Convergent Boundary – Indian and Eurasian Plates
Indian Plate

28. Convergent Boundary – Oceanic & Continental
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29. Convergent Boundary – Oceanic & Oceanic
NOTE – PLATES ARE REVERSED
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30. Convergent Boundaries - Continental
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31. Transform Boundary – San Andreas Fault

32. Review Name the 3 main layers of the Earth What is a tectonic plate?
What was Pangea?
What is Sea-Floor spreading?
Name the three different types of plate boundaries and one location on Earth for each one