Plate tectonics

8. the layer of Earth between the crust and the core
9. the amount of force per unit area that is put on a given material
10. the liquid layer of the Earth's core that lies beneath the mantle and surrounds the inner core
11. the type of stress that occurs when forces act to stretch an object
12. states that the Earth's solid outer crust, the lithosphere, is separated into plates that move over the asthenosphere
15. the process by which new oceanic lithosphere is created at mid-ocean ridges as older materials are pulled away from the ridge
16. the type of stress that occurs when an object is squeezed
17. the "middle sphere," the strong, lower part of the mantle between the asthenosphere and the outer core
18. is a seafloor mountain system formed by plate tectonics
19. the region where an oceanic plate sinks down into the asthenosphere

1. where crust is destroyed as one plate dives under another.
2. is the hypothesis that the Earth's continents have moved over geologic time relative to each other, thus appearing to have "drifted" across the ocean bed.
3. a geologist and Navy submarine commander during World War II. Part of his mission had been to study the deepest parts of the ocean floor.
4. the outermost, rigid layer of the Earth that consists of the crust and the rigid upper part of the mantle
5. where crust is neither produced nor destroyed as the plates slide horizontally past each other.
6. where new crust is generated as the plates pull away from each other.
7. the solid, dense center of the Earth
13. the thin, outermost layer of the Earth
14. a German meteorologist, geophysicist and polar researcher. In 1915 he published 'The Origin of Continents and Oceans', which outlined his theory of Continental Drift.
20. the central, spherical part of the Earth below the mantle