| A | B |
|---|
| plate tectonics | the study of the formation and movement of these plates |
| plates | a number of rigid, moving,pieces of the Earth's surface |
| lithosphere | the crust and the uppermost portion of the mantle |
| asthenosphere | the layer upon which the lithospheric plates rest (within the mantle) |
| convection currents | driving force behind lithospheric plate movement |
| continental drift | a theory that continents had once been part of a larger continent |
| plate boundaries | belts where earthquakes and volcanoes are located |
| spreading centers | where lava wells up from deep within Earth and continuously forms new rocks there |
| heat flow | a measure of the amount of heat leaving the rocks of the lithosphere |
| Alfred Wegener | a German scientist who proposed the theory of continental drift |
