The Theory of Plate Tectonics
Across
- 2. At a _________ boundary, two plates slide past each other, as at the San Andreas Fault in California.
- 6. At a _______ boundary, two plates are moving apart.
- 7. the name of the landmass when all of the Earth’s continents were a single giant continent
- 10. deep valleys running through the center of mid-ocean ridges
- 11. At a _________ zone, one plate sinks beneath another plate resulting in the formation of a chain of volcanic islands or a mountain range.
- 15. the uppermost, rigid part of the mantle + the crust; cool solid rock portion of the Earth’s surface
- 16. deep valleys in the seafloor
- 17. molten rock inside the Earth
- 18. At a colliding or _______ boundary, two plates push together.
Down
- 1. In the theory of ___________, new crust emerges from the rift valley in a mid-ocean ridge by magma pushing up and causing the seafloor to move away from the ridge on both sides.
- 3. The theory of _____________ states that the continents were once a single giant supercontinent that broke apart and drifted apart over time.
- 4. hot molten or semifluid rock erupted from a volcano or fissure, or the solid rock resulting from cooling of this
- 5. The theory of ________ states that the continents float on the Earth’s molten interior gradually moving over millions of years.
- 8. a break or fracture in the ground that occurs when the Earth's tectonic plates move
- 9. an elevated area caused by hot magma pushing up at a divergent boundary
- 12. massive, rigid slabs of solid rock composed of Earth’s lithosphere floating on the asthenosphere
- 13. the layer that includes the top part of the upper mantle; it’s between a solid and molten rock and flows slowly over time
- 14. small melting areas within the mantle where thermal plumes cause magma to push up through the crust; often are far from a plate edge