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

2. Something to warm us up…
Watch Ice Age: Continental Drift – Scrat’s Continental Crack Up (

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

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:

13. Continental Drift Theory

14. 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
Complete questions on handout