1. Divergent Boundaries Plates move away from each other Marine –Ocean basins open & seafloor created Continental –Rift zones & new ocean basins created

2. Rift Zone East African Rift Valley Kilimanjaro and Mount Kenya Graben

3. Divergent Boundaries

6. Transform Boundaries Plates slide past one another Neither created nor destroyed

8. Convergent Boundaries Plates move toward each other Marine –Trenches, destruction of sea floor & closing of ocean basins Continental –Creation of mountain ranges

9. Convergent Boundaries Three types: 1.Ocean-Continent Convergence 2.Ocean-Ocean Convergence 3.Continent-Continent Convergence

10. Ocean-Continent Convergence

11. Mount St. Helens

12. Ocean-Ocean Convergence

13. Continent-Continent Convergence

14. Himalayas

15. Continental Margins Two types: 1.Passive –Closest to the divergent plate boundary 2.Active –Closest to the convergent plate boundary

16. Mechanisms of Motion Convection cells?? Ridge push force Slab pull force

18. Rates of Motion 1 – 20 cm per year Average rate of 5 cm/yr Slow spreading rates –Steep slopes Fast spreading rates –Gentle slopes

19. Iceland

21. Hawaiian Islands

23. Hydrothermal Vents