Plate Tectonics

5. innermost layer of Earth
8. When two plates come together
9. liquid layer made of iron and nickel
13. Thin shell on the outside of Earth.
14. Earth's layer of silicate rock between the crust and the outer core
16. when two tectonic plates move away from each other
17. On Earth, it is composed of the crust and the portion of the upper mantle
18. the outermost layer of Earth's lithosphere that makes up the planet's continents
19. proposed "Continental Drift" in 1912
20. quantity per unit volume

1. His theroy was that sedimentary layers are deposited in a time sequence with the oldest on the bottom and youngest on the top.
2. A supercontinent that existed around 310 million years ago
3. motion is predominantly horizontal
4. a revolutionary theory explaining that continents shift position on Earth's surface
6. His theory was that the states were once together, but they were spread apart by the earthquakes and floods
7. the outermost layer of Earth's lithosphere that is found under the oceans
10. a seafloor mountain system formed by plate tectonics
11. a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity
12. region of the upper mantle of Earth. It lies below the lithosphere
15. lowland region that forms where Earth's tectonic plates move apart, or rift