| Earth's Crust | Earth's outermost layer of rock. |
| Fault | The boundary between two sections of rock that can move relative to one another. |
| Earthquake | Vibration of the earth that results either from volcanic activity or rock masses suddenly moving along a fault. |
| Epicenter | The point on the surface of the earth directly above an earthquake's focus. |
| Focus | The point where an earthquake begins. |
| Plastic Rock | Rock that behaves like something between a liquid and a solid. |
| Metamorphic Rock | Igneous or sedimentary rock that has been changed into a new kind of rock as a result of great pressure and temperature. |
| Igneous Rock | Rock that forms from molten rock. |
| Sedimentary Rock | Rock formed when chemical reactions cement sediments together, hardening them. |
| Sediment | Small, solid fragments of rock and other materials that are carried and deposited by wind, water, or ice. Examples would be sand, mud, or gravel. |
