Plate Tectonics

3. the name given to the area of the Pacific Ocean that is prone to earthquakes and volcanic activity is the Ring of _____
4. The crust is thinner under ____________.
6. undersea valleys formed through subduction
7. occur when molten material, or magma, reaches Earth's surface
10. plate boundary where plates move towards each other
12. the last name of the scientist who developed the theory of continental drift
14. __________ spreading--the process that caused South America and Africa to drift apart
16. The ___________ of an earthquake measures the energy released by the earthquake.
18. occur when the Earth's crust moves during an earthquake creating a wave or series of waves

1. mid-ocean _________ are zipper-like chains of undersea mountains
2. the hypothesis that all the continents were once fused together and over time they drifted apart is called continental _____
5. The ________________ crust is less dense than oceanic crust.
8. the name of the large landmass that scientists believed was a supercontinent
9. plate boundary where plates move past each other in opposite directions
11. plate boundary where plates move away from each other
13. occur when stress builds up causing the plates to lurch into motion releasing great amounts of energy
14. The tool scientists use to predict volcanic eruptions.
15. The tectonic plates are moved by _________ currents.
17. There is strong evidence that suggest ______ and South America were once connected to each other.
19. ocean trenches are where the oceanic crust sinks back into the mantle when it meets a continental crust