| A | B |
|---|
| continental drift | the slow movement of continents on the earth's surface |
| deep-ocean trench | a narrow and elongated section of seafloor where oceanic lithosphere is pulled into the mantle |
| hot spot | a place in the mantle where hot rock continually rises and melts through a plate |
| hypothesis | an idea that can be tested by a scientific investigation |
| law | a description of something that always happens in nature |
| lithosphere | the rock layer comprised of the crust and the upper mantle |
| paleomagnetism | the study of the Earth's magnetic field throughout the history of the planet |
| Pangea | the single landmass that scientists believe separated to form today's arrangement of continents |
| seafloor spreading | the theory suggesting that new oceanic crust is formed at midocean ridges |
| theory | a well-supported, dominant explanation of many observed phenomena |
| theory of plate tectonics | the theory that the earth's crust is broken up into about a dozen large plates that float above the mantle; this theory is used to explain much of modern geology |
