| A | B |
|---|
| Moho | the boundary between the crust and the mantle |
| Pangaea | name of a 'supercontinent' that existed 200 million years ago with all the land |
| asthenosphere | the lower mantle that has plasticity, or the ability to flow |
| continental drift | the slow movement of the Earth's continental and oceanic plates |
| continental shelf | the shallow underwater plain that borders continents |
| convergent boundary | where two neighboring plates are moving towards each other |
| crust | the solid outer layer of the Earth, from 5 to 90 kilometers thick |
| divergent boundary | where two neighboring plates are moving away from each other |
| inner core | the center of the Earth, thought to be made of a solid core |
| lithosphere | the upper mantle of the Earth |
| mantle | the thick middle layer between the crust and the core |
| mid-ocean ridge | an undersea mountain range where molten rock rises and widens the ocean floor |
| ocean floor spreading | divergent plate movement on the ocean floor |
| outer core | the liquid part of the core that surround the solid inner core |
| plate tectonics | Earth's crust is made up of many plates that move slightly on top of the Earth's mantle |
| plates | rigid blocks of the Earth's crust and upper mantle |
| trench | a long narrow valley on the ocean floor at a subduction zone |
| convection current | large circular flows in the mantle that lets the tectonic plates move |
| core | solid center of the Earth made of iron |
| magma | molten rock under the Earth's surface |
| subduction zone | where two plates collide and one plate slides under the other plate |
