| A | B |
|---|
| inner core | A solid layer of iron and nickel |
| outer core | a liquid layer of iron and nickel |
| mantle | The layer below the Earth's crust. It is much thicker than other layers and its lower portion has a semi-molten, slowly flowing consistency |
| crust | The outside layer of the earth's surface. It is made of solid rock. |
| seismology | The study of the movements produced by earthquakes |
| tectonic plates | A large piece of the earth's fractured crust |
| continental drift | The idea that tectonic plates moved around in the distant past and are still moving today. |
| Pangaea | One landmass or supercontinent of the earth's plates that existed about 250 million years ago |
| convergent boundary | The boundary between two tectonic plates that are colliding and pushing directly into each other |
| divergent boundary | The boundary between two tectonic plates that are moving directly away from each other |
| mid-ocean ridge | An underwater volcanic mountain chain foremed as two plates move away from each other |
| transform boundary | the boundary between two tectonic plates that are sliding past each other |
| earthquakes | Shaking or trembling of the earth's crust due to volcanic forces or the shifting of tectonic plates deep underground |
| tsunami | A huge wave of ocean water that hits land and is caused by an earthquake, landslide, or volcanic eruption under the ocean |
| landslide | A mass of rocks, soil, and debris that suddenly slides down a steep slope |
