| A | B |
|---|
| fossil | preserved remains or traces of an ancient organism |
| Pangaea | single giant landmass |
| theory of continental drift | continents were once joined together and have since drifted apart |
| midocean ridge | a constructive (divergent) plate boundary |
| ocean-floor spreading | process in which old ocean floor is pushed away from a midocean ridge |
| transform fault | fault that runs across a midocean ridge |
| trench | a V-shaped valley on the ocean floor |
| subduction | process in which crust plunges back into the interior of the Earth |
| theory of plate tectonics | links the ideas of continental drift and ocean-floor spreading |
| plate | a moving, irreularly shaped slab that makes up the Earth's lithosphere |
| tectonics | deals with the movements that shape the Earth's crust |
| lithosphere | topmost solid part of the Earth |
| divergent boundary | plates move apart |
| convergent boundary | plates come together |
| strike-slip boundary | two plates slip past each other horizontally |
| convection current | movement of materials caused by differences in temperature |
