| A | B |
|---|
| seafloor spreading | There is a split in the crust and magma is forced through the split onto the earth's surface as lava. Then the lava hardens and turns into volcanic rock |
| continental drift | The continents were one super continent (Pangea) and they slowly moved apart over 200 million years ago |
| plate tectonics | Earth's crust and upper mantle are broken into pieces called plates |
| lithosphere | Rigid layer of earth about 100 kilometers thick, made up of the crust and part of the upper mantle |
| divergent boundaries | plates that are moving apart |
| convergent boundaries | plates that are moving towards one another |
| magnetic field | Area around a magnet in which magnetic force exists |
| magnetism | A force that causes certain materials to attract each other |
| Convection | Forms as warm material rises and cold material sinks |
| Mid Ocean Ridge | Underwater mountain ranges along the center of the ocean floor. Ex: Mid-Atlantic Ridge |
| Subduction Zone | Area of convergent boundaries, in which one tectonic plate moves under another tectonic plate |
| Convergent Boundary | This boundary formed the Andes Mountains |
| How a mid ocean ridge is formed | When the sea floor spreads apart, magma moves upward and flows from the crack. The magma cools and it becomes solid sea floor. It becomes thick and dense and sinks. |
