1. Theory of Plate Tectonics Oceans 11

2. But first…a little about the internal structure of the Earth A Brief look Earth’s 2 major layers

3. Earth’s Internal Structure Earth can be divided into 3 main layers: Crust (outside of Earth) Mantle Core (very inside)

4. Earth’s Crust Crust is the outermost layer. Two Parts of Crust: –Continental crust Mainly granite Up to 75km thick Density 2.6g/cm 3 –Oceanic crust Made up of basalt rock (type of volcanic rock) Up to 8 km thick Density 3.0g/cm 3

5. The Mantle The mantle is the next layer. This zone is about 2900km thick and makes up great 82% of Earth’s volume. Fragments of the mantle have been brought to the surface by volcanic eruptions.

6. Earth’s Core Earth’s core is extremely hot – hot as the sun! Divided into two parts. –Outer Core Liquid iron and nickel –Inner Core Solid iron

7. Now let’s look at the Theory of Plate Tectonics…

8. Plate Tectonics – brief history 1912 –Alfred Wegener, German geophysicist and meteorologist –Wegener thought that all landmasses formed one supercontinent approximately 225 mya “Pangaea” meaning all earth.

9. Wegener’s research: Geologic record (rock strata) Fossil record Climatic record of continents A KEY FINDINGS: –Southern America & Africa have many similarities Large coal deposits

10. Resistance… Wegener was met with a lot of skepticism from other scientists and the church. 1950 to 1960’s –Geologic Discoveries: Similar fossils on each continent Same age rock on coast lines It wasn’t until the 1960’s that Wegener’s theory was accepted and coined Theory Plate Tectonics

11. Animation of Continental Drift http://education.sdsc.edu/optiputer/flash/p angea_4.htmhttp://education.sdsc.edu/optiputer/flash/p angea_4.htm

12. PANGEA

15. Definition of Plate Tectonics Tectonic – Greek meaning “building” or “construction” Refers to the configuration of Earth’s crust as a result of internal forces.

16. Plate Tectonic Processes Include: –Upwelling of magma –Crustal plate movements –Sea-floor spreading –Subduction of crust –Earthquakes –Volcanic activity –Warping, folding and faulting of crust.

17. Earth’s Plates Plates are made up of: –Continental crust –Oceanic crust These plates float upon the moving asthenosphere. Plates move 1 to 19 cm per year –Movement of plates are a result of convection currents in the asthenosphere –http://education.sdsc.edu/optiputer/flash/convection.htmhttp://education.sdsc.edu/optiputer/flash/convection.htm

18. Earth’s Plates

19. What do you notice about the relationship between volcanoes(red), earthquakes (yellow) and location of plate boundaries?

20. 3 Main types of Plate Boundaries 1.Divergent plate boundary 2.Convergent plate boundary 3.Transform plate boundary

21. Divergent Plate Boundaries Plates separate (move away from each other) Almost always occurs between two ocean plates. When ocean plates separate, new crust is formed through the upwelling of magma. This is called sea-floor spreading. –http://education.sdsc.edu/optiputer/flash/seafloorspread.htmhttp://education.sdsc.edu/optiputer/flash/seafloorspread.htm –Mid-oceanic ridges –http://www.planetseed.com/files/flash/science/features/earth/livingplanet /plate_boundaries/en/index2.html?width=570&height=475&popup=truehttp://www.planetseed.com/files/flash/science/features/earth/livingplanet /plate_boundaries/en/index2.html?width=570&height=475&popup=true

22. Iceland, "the land of fire and ice", is being split by an oceanic ridge that surfaces to create an oceanic island (left and below) in the North Atlantic Ocean. Red triangles show Iceland's active volcanoes, including Krafla. Reykjavik is Iceland's capital.

23. Divergent Plate Boundaries Something interesting!!! Great Rift Valley in Africa A continental plate is breaking up! Convection currents under the crust are pulling this area apart! http://www.youtube.com/watch?v= w7Y2R4KBwvohttp://www.youtube.com/watch?v= w7Y2R4KBwvo

24. Convergent Plate Boundaries These plate boundaries can occur between: –Oceanic and Continental plates “Subduction Zones” http://www.planetseed.com/files/flash/science/features/earth/livingplanet/plate_boundaries/en/index2.html?wi dth=570&height=475&popup=truehttp://www.planetseed.com/files/flash/science/features/earth/livingplanet/plate_boundaries/en/index2.html?wi dth=570&height=475&popup=true –Continental and Continental plates Mountain building http://www.planetseed.com/files/flash/science/features/earth/livingplanet/plate_boundaries/en/index2.html?wi dth=570&height=475&popup=truehttp://www.planetseed.com/files/flash/science/features/earth/livingplanet/plate_boundaries/en/index2.html?wi dth=570&height=475&popup=true

25. Transform Plate Boundaries These are where plates move side-to-side. Trigger earthquakes http://www.planetseed.com/files/flash/science/features/earth/livingplanet/plate_bound aries/en/index2.html?width=570&height=475&popup=truehttp://www.planetseed.com/files/flash/science/features/earth/livingplanet/plate_bound aries/en/index2.html?width=570&height=475&popup=true

26. Your Task Complete the “checking your understanding” questions and hand in. Complete the Plate Tectonic Map Activity