GR. 9 GEOGRAPHY (APPLIED) CGC1P The Wonders of Nature: We’re still drifting… Canadian War...
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Transcript of GR. 9 GEOGRAPHY (APPLIED) CGC1P The Wonders of Nature: We’re still drifting… Canadian War...
GR. 9 GEOGRAPHY (APPLIED)CGC1P
The Wonders of Nature:We’re still drifting…
Canadian War Museum
Something to warm us up…
Watch Ice Age: Continental Drift – Scrat’s Continental Crack Up (http://www.youtube.com/watch?v=q_IYQdKkWsU)
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 diameterOuter 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
The Crust
Inner core
Outer core
Mantle
Crust
Continental Crust
• thick (10-70km), buoyant, mostly old
Oceanic Crust
• thin (~7 km), dense (sinks under continental crust), young
This is where we live!
Structure of the Earth
Geophysical surveys: gravity, magnetics, electrical etc.
Acquisition: land, air, sea and satellite Geological surveys: fieldwork, boreholes, mines
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?
Continental Drift Theory
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”
Continental Drift Theory
Continents Today
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
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!
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
Theory of Plate Tectonics
On average, the plates move about as fast as fingernails grow…an inch or so every year
Theory of Plate Tectonics
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.
Theory of Plate Tectonics
Copy this diagram on your handout:
Theory of Plate Tectonics
Watch National Geographic – Plate Tectonics http://
www.natgeoeducationvideo.com/film/1041/tectonic-plates
Complete questions on handout