| A | B |
|---|
| continental drift theory | Wegener's theory that all the plates were once together |
| Pangea | the single large landmass that existed millions of years ago |
| plate tectonic theory | the current theory that the Earth's lithosphere is broken into large pieces that can move |
| plate boundary | the edge of a plate |
| asthenosphere | the part of the mantle that the plates "float" on |
| convection currents | the reason why plates move |
| converging | plates push together |
| diverging | plates pull apart |
| subduction | plates converge and the heavier plate goes under |
| transform | plates move side by side |
| sea floor spreading | process in which lava hardens and adds new crust to the ocean floor |
| magma | molten rock inside Earth |
| lava | molten rock outside Earth |
| mountains | this feature may be seen in places where plates converge |
| fault | a break in Earth's crust where rocks have slipped past each other |
| rift | a deep valley where plates diverge |
| trench | place where one tectonic plate subducts under another |
