continental drift and plate tectonics

Geography of Canada

Continental Drift and

Plate Tectonicshttp://www.youtube.com/watch?v=_5q8hzF9VVE 11:56mins

Earth’s Interior

Crust- 8-64 km thick- cold- Granite and Basalt

Mantle- 1800 km thick- hot, liquid rock- Magnesium and Silicon

Outer Core- 2000 km thick- 3 - 4000°C- liquid Nickel and Iron

Inner Core- 1400 km thick- 5 - 6000°C- solid Nickel and Iron

Air

Land

Water

LITHOSPHERE

HYDROSPHERE ATMOSPHERE

Theory of Continental Drift

• Alfred Wegener, in 1915, came up with the idea of Continental Drift.

• He said that the continents of the Earth slowly moved. He said they used to be one big continent (pangaea) a long time ago, but split apart and moved to where they are today.

Plate Tectonics - Continental Drift

Continental Drift

http://eesc.ldeo.columbia.edu/courses/w4947/images/plate_motions.gif

Plate Tectonics - Continental Drift

Antarctica

THE CONTINENTS TODAY

Wegener’s Proof

3 pieces of evidence for his theory (idea) were:

1. Rocks that were the same age and type

2. The shape of the continents (look like puzzle pieces that fit together)

3. Fossils that were the same

Plate Tectonics - Continental Drift

PROOF!

Theory of Plate Tectonics

• This theory (idea) was made by J. Tuzo Wilson in 1968.

• He said that the Earth’s crust is made up of many plates and that these plates move on top of the mantle. The movement of the plates causes changes to the Earth’s surface.

• Crust eventually broke apart into pieces called PLATES

• The plates float on the interior of the earth, like crackers on a bowl of hot soup

Plate Tectonics cntd.

• The Earth’s crust is divided into 12 major plates.• 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

• On average, the plates move about as fast as fingernails grow…an inch or so every year

The Plates

Plates are pieces of the Earth’s crust.

• The plates that move are both continental and ocean plates.

Plate Tectonics Cntd.

• Plates move constantly, and when they move different things happen…

• They can collide, pull apart, or scrape against each other.

• Each type of movement causes changes on Earth’s surface… structures or “tectonic” features (ex. Mountains, volcanoes).

• The word, tectonic, refers to the distorting of the crust as result of plate interaction.

Plate Tectonics Map

Convection Currents

• 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

Convection Currents