1. Plate Tectonics

2. Overview: The Lithosphere and the Crust Basic Concepts of Plate Tectonics Plate Movements and Boundaries

3. Inside the Earth:

4. The Lithosphere:

5. The Basic Concepts: - the earth is covered by several large lithospheric plates

6. These plates move slowly (about a few cm./yr) Due to convection cells in the asthenosphere

7. Convection movement driven by heat from the core:

8. Mantle convection produces lateral forces at the boundary between the mantle and the crust

9. Theory of Plate Tectonics:

11. Plate Movement and Boundaries Divergent Boundaries oPlates move apart oVolcanic activity oEarthquakes shallow oTwo types of boundaries  Oceanic  Continental

12. Oceanic divergent boundary Sea-floor spreading of ocean plates Mid-Atlantic Ridge

14. Page 43, Worrall

15. Continental Divergent Boundary Continental Rifting, eventually oceanic crust is formed Modern example ; East African Rift

16. Convergent Boundaries Plates move towards each other Volcanic activity common Deep, medium and shallow earthquakes Three types;  Ocean to ocean  Ocean to continent  Continent to continent

17. Ocean to Ocean- convergence Subduction - process which one plate slides under the other (subducts) Volcanic arc islands are formed

18. Ocean to Continent Convergence subductsOcean lithophere subducts under continent

19. Most tectonic activity occurs at or near these boundaries

20. Continent to Continent - Convergence Subduction does not occur Mountain building occurs without volcanic activity

21. Collision of India with Eurasia Height is still increasing

22. Transform Boundaries Plates slide past each other Little or no volcanic activity Shallow but strong earthquakes Example: San Andreas Fault

23. West Coast: unstable -subduction zone and transform fault zone

24. A Divergent B Convergent C Transform plates are moving apart new crust is created Magma is coming to the surface plates are coming together crust is returning to the mantle plates are slipping past each other crust is not created or destroyed

25. A Divergent B Convergent C Transform Continental crust  rift valley Oceanic crust  mid- ocean ridge 2 continental plates  mountain range Plates move against each other Stress builds up Stress is released  earthquake 2 oceanic plates or oceanic + continental  subduction

26. The Big Picture