| A | B |
|---|
| continental drift | theory that continents move over plates |
| Pangaea | idea that continents were once a single large land mass |
| plates | huge slabs of the crust and mantle that are divided |
| seafloor spreading | the process of the ocean floor extending out when two plates move apart |
| convection current | heated water rises to top and then cools sinking to bottom |
| subduction | the process of plates moving and one goes underneath another |
| Alfred Wegener | German scientist who developed the idea of continental drift |
| Mid Atlantic Ridge | magma that has cooled and formed a ridge that stretches for 50,000 miles |
| lithosphere | solid outer portion of earth which is composed of crust and mantle |
| asthenosphere | soft layer of mantle, below the lithosphere |
