The Wonders of Nature: We’re still drifting …

1. The Wonders of Nature:We’restilldrifting… Canadian War Museum Gr. 9 Geography (Applied) CGC1P

2. Something to warm us up… Watch Ice Age: Continental Drift – Scrat’sContinental Crack Up (http://www.youtube.com/watch?v=q_IYQdKkWsU)

3. Structure of the Earth The Earth is made up of 4 main layers: • Inner Core • A mass of sold iron over 7000 degrees hot! • Approx. 5000km below the crust of the earth, 2500km in diameter Mantle Outer core • Outer Core • Super-heated liquid molten lava • Approx. 3000km thick • Electrical currents found here produce earth’s magnetic field Inner core • Mantle • Parts are hot enough to form slow moving molten rock or magma • About 85% of the earth’s weight Crust

4. The Crust • Continental Crust • thick (10-70km), buoyant, mostly old • Oceanic Crust • thin (~7 km), dense (sinks under continental crust), young Mantle Outer core Inner core Crust This is where we live!

5. Structure of the Earth • Geophysical surveys: gravity, magnetics, electrical etc. • Acquisition: land, air, sea and satellite • Geological surveys: fieldwork, boreholes, mines

6. Plate Tectonics From Scrat’s video, what do you think “plate tectonics” refers to?

7. Plate Tectonics If you look at a map of the world, you may notice that some of the continents fit together like pieces of a puzzle… What do you think happened?

8. Continental Drift Theory

9. Continental Drift Theory • Continental drift: movement of the Earth's continents relative to each other by appearing to drift across the ocean • Theory developed by Alfred Wegener in 1912 • developed concept of Pangaea “one-earth”

10. Continental Drift Theory

11. Continental Drift Theory Continents Today

12. Continental Drift Theory • 3 pieces of evidence for Wegener’s theory (idea) were: • Rocks that were the same age and type across continents • The shape of the continents (look like puzzle pieces that fit together) • Fossils that were the same • Watch National Geographic – Continental Drift short video: • http://www.natgeoeducationvideo.com/film/1042/continental-drift

13. Continental Drift Theory

14. Theory of Plate Tectonics • Theory of Plate Tectonics: • Developed by J. Tuzo Wilson in 1968. • Earth’s crust broke into 12 pieces called plates • Earth’s crust is made up of many plates that move on top of the mantle. • The movement of the plates causes changes to the Earth’s surface(mountains, volcanoes form…) • The plates float on the interior of the Earth—like crackers in a hot bowl of soup!

15. Theory of Plate Tectonics • Theory of Plate Tectonics (con’t): • Heat from deep inside the earth causes plates to move • Earth’s continents sit on plates, so when the plates move, the continents move with them • The movement of these plates is called PLATE TECTONICS

16. Theory of Plate Tectonics On average, the plates move about as fast as fingernails grow…an inch or so every year

17. Theory of Plate Tectonics

18. Theory of Plate Tectonics • Why do plates move? • Because of Convection currents: • The mantle is made of much denser, thicker material, because of this the plates "float" on it like oil floats on water. • Movement of plates is caused by very hot material at the deepest part of the mantle rising, then cooling, sinking again and then heating, rising and repeating the cycle over and over • Example:The next time you heat soup in a pot, you can watch the convection currents move in the liquid. When the convection currents flow in the mantle they also move the crust. The crust gets a free ride with these currents.

19. Theory of Plate Tectonics

20. Theory of Plate Tectonics Copy this diagram on your handout:

21. Theory of Plate Tectonics • Watch National Geographic – Plate Tectonics • http://www.natgeoeducationvideo.com/film/1041/tectonic-plates • Complete questions on handout