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

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

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

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

Continental Drift Theory

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

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