Starter: 10/9/13

1. Starter: 10/9/13 What do you think is occurring at these locations?

2. Starter 10-8-13 What, in your words, is plate tectonics? What is so important about this topic?

3. Plate Tectonics NOTES FOR YOUR JOURNAL!

4. Layers of Earth Core – most dense, 2 layers Mantle – 2 layers Crust – least dense

6. 2 Kinds of Crust Continental – less dense Oceanic – more dense

7. FYI…density of layers (gm/cm3) Inner core 11.5 Outer core 9.0 Mantle 4.5 Oceanic crust 2.9 Continental crust 2.8

8. Convection Currents • Movement of hot liquid or gas • Heated – rises • Cools – drops

9. Earth’s Crust Cracks… Convection currents in magma (in mantle) cause cracking in crust

10. Crustal Plates Huge sections of earth’s crust that move relative to each other

11. Alfred Wegener and Pangaea Pangaea is the name given to the single giant continent in a proposal by Wegener (1912). The theory of continental drift states that the continents were once a single landmass that drifted apart and are still doing so.

12. Evidence for Continental Drift • Wegener tried to support his theory with evidence: • Maps - continents apparently fit together like a jigsaw-puzzle • Plant and animal fossils - coal in Antarctica

13. Plate Map

14. Seafloor Spreading Seafloor constantly being created and destroyed New crust at rift valley Crust destroyed at trenches

15. Evidence for Seafloor Spreading Thin sediment in ridges Age of rock at ridges much younger than continents Patterns of magnetic polarity reversal

16. Plates Move in 4 Ways Subduction Transform faulting Divergent Convergent

17. Types of Movement Divergent – plates moving apart (rift valleys in MOR) Convergent – plates coming together Transform – plates slide past each other

18. Subduction Downward movement of an oceanic plate into the mantle

19. Subduction Zones Ocean plate into continent Trench, mountains, volcanoes formed

20. Subduction • Plate enters mantle • Rock broken • Friction heats • Magma develops • Magma pushed to surface • Volcanoes, deep earthquakes

21. Subduction causes… • Seafloor spreading • Magma rises – forms ridges, rises (large!) • Shallow earthquakes

22. Ocean Trenches • Form in subduction zones • Deep, narrow, long, steep

23. Convergent Continents Mountains form

24. Convergent Boundaries Here crust is destroyed and recycled back into the interior of the Earth as one plate dives under another. These are known as Subduction Zones - mountains and volcanoes are often found where plates converge. There are three different types: oceanic-continental, oceanic-oceanic and continental-continental

25. Divergent Boundaries At divergent boundaries new crust is created as twoor more plates pull away from each other. Oceans are born and grow wider where plates diverge or pull apart. As seen below, when a diverging boundary occurs on land a 'rift', or separation will arise and over time that mass of land will break apart into distinct land masses and the surrounding water will fill the space between them.

26. Transform Faults When two plates slide horizontally past one another Perpendicular breaks or fracture zones Defined by shallow earthquakes Ex. San Andreas fault in Ca.

27. WAYS TO REMEMBER THE THREE TYPES OF BOUNDARIES: Convergent: Collide Divergent: divide Transform: SLIIIIDE!

28. Hot Spots Magma chambers in mantle push through surface of crust Crust moves over mantle forming island chain

29. Continental Collision • 2 plates with continents collide • Continents don’t sink, subduction doesn’t occur • Crust moves up, folds, breaks, etc.

30. As plates move over hot spots… • New islands formed – island chains (archipelagoes)

31. Old islands sink… Atolls – submerged island group in ring-shape, coral reef grows on top Guyots – extinct submerged volcanoes