| A | B |
|---|
| asthenosphere | softer weaker layer of mantle that flows slowly |
| continental drift | sections of the earths crust moving slowly across surface |
| sedimentary rock | rock formed from the deposition of materials in layers |
| divergent boundary | plate boundary where plates move away from each other |
| lithosphere | upper mantle and the crust |
| depression of crust at a convergent boundary | trench |
| igneous rock | rock formed from magma or lava |
| crust | rocky outer layer of the Earth |
| silicates | light weight rocks containing silica and oxygen |
| sea floor spreading | the forming of new oceanic crust at a divergent boundary |
| transform boundary | where two plates slide past each other |
| plate tectonics | the crust is made up of sections that move |
| convergent boundary | boundary where the plates move towards each other |
| pangaea | supercontinent of 260 million years ago |
| mid oceanic ridge | structure that forms at a divergent boundary |
| subduction | old oceanic plate sinking under continental crust |
| mantle | Earth's layer under the crust |
| core | centermost layer of the Earth |
| metamorphic rock | rock formed by high temperature and/or pressure on other rock types |
| geologist | scientist who studies the Earth |
| mesosphere | strong, rigid innermost layer of the mantle |
| lava | igneous rock that forms on the earth's surface |
| trench | a depression of the earth at a subduction zone |
| magma | molten rock under the earth's surface |
