Post on 03-Jan-2016
description
transcript
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