1. Add to Table of Contents:
Boundaries Draw-Along Pg. 56
Plate Tectonics Pg. 57

2. Don’t write-Review
Prior to Alfred Wegener’s theory of continental drift geologists thought continents were fixed in their locations. In developing his theory which of the following evidence was NOT used by Wegener?
Fossil similarities between southern continents.
Evidence of polarity change in found along the Mid-Atlantic Ridge.
Similarities in the paleoclimates of South America and Africa.
The apparent fact the South America and Africa seemed to fit together. b

4. Plate Tectonics Pg. 57
Lithosphere - the rigid outer layer of the Earth.
Made of the crust and the solid outer layer of mantle.
Asthenosphere - the layer of “plastic” rock in the lower mantle.
Flows like a very thick liquid.

5. Lithospheric Plates
Lithospheric Plates-The rigid lithosphere is broken into plates
=tectonic plates
Float on the semi rigid, moving asthenosphere.

6. Theory of Plate Tectonics – explains how the lithospheric plates move and change shape.

7. Tectonic Plates

8. Earth’s lithosphere is broken into 7 major(large) plates and numerous minor (smaller) ones.
The plates glide over the asthenosphere and produce earthquakes, volcanoes and create mountains.

10. Convection Currents
- driving forces of plate tectonics - very hot material at the deepest part of the mantle rises, then cools and sinks again, then repeating. This cycle is repeated over and over. ***Remember…this heat is generated by the core!!
HOT!!!!

12. How Plate Tectonic Works
As magma heats up and rises, it exits through the rift in the middle of the mid-ocean ridge. It cools and pushes the plates apart.

13. What is the average rate of movement from lithospheric plates?
5cm/yr (2inches) and it is driven by unequal heating of the Earth.

14. Plate Boundaries
1. Convergent – moving together 2. Divergent – moving apart 3. Transform – moving side by side

15. Convergent Boundary – Oceanic & Oceanic
Note – plates are reversed
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16. Aleutian Islands, Alaska, May 23, 2006

17. Convergent Boundaries Continental - Continental
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18. Himalayan Mountains

19. Convergent Boundary – Oceanic & Continental
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20. Mt. St. Helen – Cascade Mtns. May 20, 1980

21. Divergent boundary – Continental - Continental

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

23. Divergent Boundary Oceanic - Oceanic

27. Transform Boundary – San Andreas Fault

28. San Andreas Fault

29. Train crossing San Andreas Fault – Cajon Pass, CA

30. Draw – Alongs!