1. Plate Tectonics A Giant Jigsaw Puzzle and Continental Drift

2. Tectonic plates review
Tectonic Plates: a block of lithosphere that consists of the crust and the rigid, outermost part of the mantle
What type of crust…
Continental Crust
Oceanic Crust
Both

3. Major Tectonic Plates Review
Pacific plate
North American plate
Cocos plate
Nazca plate
South American plate
African plate
Eurasian plate
Indian plate
Australian plate
Antarctic plate

4. Tectonic Plate Close-up review
Consist of upper part of mantle
Oceanic Crust (thinnest)
Continental crust (thickest)

5. Wegener’s Continental drift Hypothesis
Alfred Wegener
1900s
Hypothesis about continental drift

6. Continental drift
Continental Drift: the hypothesis that states that the continents once formed a single landmass, broke up, and drifted to their present locations
Explains why fossils of the same plant and animal species are found on continents across oceans

7. The drifting continents
Pangaea
Wegener hypothesis that all of the present continents were once joined in a single, huge continent
Greek for “all earth”
Existed 245 million years ago
Split into 2 continents
Laurasia and Gondwana
180 million years ago
Split again into the continents of today
North America
South America
Asia
Europe
Australia
Antarctica
Africa
Wegener's hypothesis was not accepted by many scientist.
It wasn’t until many years later that evidence provided some clues to the forces that moved the continents.

8. More Evidence: Sea floor spreading
Sea Floor Spreading: the process by which new oceanic lithosphere forms as magma rises toward the surface and solidifies.
Chains of submerged mountains run through the center of the Atlantic Ocean.
Mid-ocean ridge system
As the tectonic plates move away from each other, the sea floor spreads apart and magma fills in the gap. As this new crust forms, the older crust gets pushed away from the mid-ocean ridge.
Magnetic reversals recorded in the ocean floor, throughout history, the north and south magnetic poles have changed places many times.

9. More Evidence: Magnetic reversals
Magnetic reversal: when the Earth’s magnetic poles changes
The molten rock at the mid-ocean ridges contains tiny grains of magnetic minerals such as iron.
These minerals act like compasses and align with the magnetic field of the Earth.
When the molten rock cools, the record of these tiny compasses remains in the rock.
As the sea-floor spreads the record is slowly carried away from the center.

10. Student task Elbow Partners: Create a puzzle piece for each continent.
See how many ways the continents can fit together