| A | B |
|---|
| convection | the movement of heat through a LIQUID or GAS; depends on density, heating, cooling, and gravity |
| continental drift | Wegener's theory that the present-day continents were once a super-continent (Pangaea) and have since drifted apart |
| Pangaea | The supercontinent that formed in the Paleozoic Era and broke apart throughout the Mesozoic Era |
| sea-floor spreading | Hess's theory that new sea floor emerges at mid-ocean ridges and hardens, pushing the older floor outwards |
| subduction | the process in which crust becomes dense enough to sink back down into the mantle |
| mid-ocean ridges | under-water mountain chains; where sea floor spreading occurs |
| sonar | process of using sound waves to map out the ocean floor |
| deep-sea trenches | under-water valleys where subduction occurs |
| plate tectonics | J. Tuzo Wilson's theory that the Earth's lithosphere is divided into plates that move over the Earth's surface because of convection currents in the mantle |
| convergent boundary | a tectonic plate boundary where plates collide, or come together |
| divergent boundary | a tectonic plate boundary where plates divide, or move apart |
| transform boundary | a tectonic plate boundary where plates slide past each other |
| fossil evidence | evidence for continental drift: same fossils found oceans apart |
| mountain ranges | evidence for continental drift: same type mountain chains found oceans apart |
| mismatched climates | evidence for continental drift: fossils or glacial deposits found in climates where they couldn't exist today |
| molten material | evidence for SFS: the only way to get these shapes rocks is if new material is coming up from the mantle |
| drilling samples | evidence for SFS: revealed that the rock gets older, the further you get from an MOR, meaning it wasn't all formed at once |
| magnetic stripes | evidence for SFS: the metal in the sea floor lines up in alternating directions, meaning the sea floor wasn't all formed at once |
