1. The Structure of the Earth and Plate Tectonics

2. One small addition to yesterday’s notes… Crust = 5 – 100 km thick Mantle = 2,900 km thick Core = radius of 3,430 km

3. Let’s watch a short video!Click Me!

4. Continental Drift: Pangaea
Continental Drift: the hypothesis that states that the continents once formed a single landmass, broke up, and drifted to their present locations.
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5. Evidence of Continental Drift
The continents fit together like puzzle pieces
Fossils of plants and animals were found in multiple continents; even some across oceans
Similar rocks and climate evidence were found on several continents
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6. Mid-Ocean Ridges
Mid-ocean ridges are underwater mountain chains that run through Earth’s ocean basins.
They are places where sea-floor spreading takes place
Sea-floor spreading is the process by which new oceanic lithosphere forms as magma rises toward the surface and solidifies
As tectonic plates move away from each other, the sea floor spreads apart, and magma fills in the gap.
New crust fills in the ridge as older crust gets pushed away.

7. Sea floor spreading video

8. Mid-Ocean Ridge