1. CHAPTER 2 Plate Tectonics and the Ocean Floor (B)
Dr. Dong, El Camino College

2. Review Chap 2 (A) Evidences to support continental drift
Evidences to support plate tectonics theory

3. Plate Tectonics Theory
Lithospheric plates “float” on the asthenosphere
Large scale geologic features occur at plate boundaries
Driving force of plate motion:
Friction: slab suction
Gravity: slab pull

4. Figure 2.13b: Plates

5. Types of Plate Boundaries
Divergent
Convergent
Transform
Fig. 2.14

6. Exe 03-01 List three types of plate boundaries
Describe the main content of plate tectonics

7. Divergent Boundary Features
Fig. 2.15
Plates move apart
Mid-ocean ridge
Rift valley
New ocean floor created
Shallow earthquakes
Iceland is the only country which is located along a mid-ocean ridge

8. A new ocean is formed
Fig. 2.17

9. Iceland is located along the mid-ocean ridge
Fig. 2.16

10. Red Sea is expanding
Fig 2.16

11. Exe. 03-02 Describe how a new ocean is formed
Which country is located over the mid-ocean ridge?

12. Three Types of Convergent Plate Boundaries
Fig. 2.20

13. Convergent Boundary Features
Plates move toward each other
Oceanic crust destroyed
Ocean trench
Volcanic arc
Deep earthquakes

14. Types of Convergent Boundaries
Oceanic-continental convergence
Ocean plate subducted
Continental arc
Oceanic trench
Deep earthquakes

15. Fig. 2.21a,b

16. Fig. 2.22

17. Exe. 03-03 List types of convergent plate boundaries.
How was the Himalayas mountain formed?
Explain how St. Helens volcano was formed?

18. Transform boundary features
Offsets oriented perpendicular to mid- ocean ridge
Segments of plates slide past each other
Offsets permit mid-ocean ridge to move apart at different rates
Shallow but strong earthquakes

19. transform faults
Fig. 2-23

20. San Andreas Fault
Fig. 2.23

21. Exe
Explain why earthquakes frequently take place in the California?

22. Fig. 2.24

23. Applications of plate tectonics model to intraplate features
Fig. 2.25

24. Fig. 2.26

25. Measuring plate motion by satellites
Fig. 2.30

26. Exe
Explain how Hawaii chain islands were formed ?

27. Paleoceanography Reconstructing paleogeography Continental accretion
Continental material added to edges of continents through plate motion
Continental separation or rifting
Continents move apart

28. Paleo-reconstructions
Fig. 2.31

29. Future predictions Future positions of continents and oceans
Assume same direction and rate of plate motions as now

30. World map 50 million years from now
Fig. 2.32

31. Wilson cycle John Tuzo Wilson Life cycle of ocean basins Formation
Growth
Destruction

32. Wilson cycle
Fig. 2.33

33. Exe
Describe Ocean floor cycle