| A | B |
|---|
| fossils | preserved remains of dead animals or plants |
| Pangaea | The Earth once had a big landmass. |
| Wegener | theory of continental drift |
| plate tectonics | pieces of Earth's crust are moving slowly all the time |
| trench | V-shaped valleys along the ocean bottom |
| subduction | where the crust plunges back into the Earth |
| midocean ridges | mountains / rift vallley on the ocean floor |
| rift valley | under water mountains with a deep center crack; form at divergent boundary |
| ocearn-floor spreading | Lava from the rift valley forms a new ocean floor |
| transform fault | fault that runs across a mid-ocean ridge; 2 plates past each other, move in opposite directions |
| lithosphere | Earth's topmost solid part |
| convection currents | movement of things caused by temperature difference; cause plates' movement |
