Chap. 17 Plate Tectonics

3. two tectonic plates are moving toward each other
10. a region where two plates slide horizontally past each other
11. the weight of the relatively cool, dense subducting plate pulls the trailing slab into the subduction zone
12. process where two plates collide, the denser plate eventually descends below the other less dense plate
14. a device that can detect small changes in magnetic fields
15. huge pieces of crust and rigid upper mantle that fit together at their edges to cover Earth's surface

1. a process where older portion of the sea-floor sinks, the weight of the uplifted ridge is thought to push the oceanic plate toward the trench formed at the subduction zone
2. a hypothesis developed by Alfred Wegener that proposed that Earth's continents had once been joined as a single landmass that broke apart and sent the continents adrift
4. regions where two tectonic plates are moving apart
5. is an imaginary line on a map that shows points that have the same age, that is they formed at the same time
6. happens when the flow in the outer core changes, and Earth's magnetic field changes direction
7. the theory that explains how new oceanic crust is formed at ocean ridges, slowly moved away from ocean ridges and destroyed at deep ocean trenches
8. a single landmass that broke apart 200 mya
9. is the study of history of Earth's magnetic field
13. a long narrow depression formed when continental crust begins to separate