| Word | Definition |
| Geology | The study of planet Earth. |
| Constructive Force | A force that builds up mountains and landmasses on Earth's surface. |
| Destructive Force | A force that slowly wears away mountains and other features on the surface of Earth. |
| Continent | A great landmass surrounded by oceans. |
| Seismic Wave | A vibration that travels through Earth carrying the energy released during an earthquake. |
| Crust | The layer of rock that forms Earth's outer surface. |
| Mantle | The layer of hot, solid material between Earth's crust and core. |
| Lithosphere | A rigid layer made up of the uppermost part of the mantle and the crust. |
| Asthenosphere | The soft layer of the mantle on which the lithosphere floats. |
| Outer Core | A layer of molten iron and nickle that surrounds the inner core of Earth. |
| Inner Core | A dense sphere of solid iron and nickel in the center of Earth. |
| Heat Transfer | The movement of energy from a warmer object to a cooler object. |
| Conduction | The transfer of heat by direct contact of particles of matter. |
| Convection | The transfer of heat by movements of a heated fluid. |
| Radiation | The transfer of energy through empty space. |
| Density | The amount of mass in a given space. |
| Convection Current | The movement of a fluid caused by differences in temperature, that transfers heat from one part of the fluid to another. |
| Pangaea | The name of the single landmass that broke apart 200 million years ago. |
| Continental Drift | The hypothesis that the continents slowly move across Earth's surface. |
| Fossil | A trace of an ancient organism that has been preserved in rock. |
| Mid-Ocean Ridge | The undersea mountain chain where new ocean floor is produced. |
| Sonar | A device that determines the distance of an object under water by recording echoes of sound waves. |
| Sea-Floor Spreading | The process by which molten material adds new oceanic crust to the ocean floor. |
| Deep-Ocean Trench | A deep valley along the ocean floor through which oceanic crust slowly sinks toward the mantle. |
| Subduction | The process by which oceanic crust sinks beneath a deep-ocean trench and back into the mantle at a convergent plate boundary. |
| Plate | A section of the lithosphere that slowly moves over the asthenosphere, carrying pieces of continental and oceanic crust. |
| Scientific Theory | A well-tested concept that explains a wide range of observations. |
| Plate Tectonics | The theory that pieces of Earth's lithosphere are in constant motion, driven by convection currents in the mantle. |
| Fault | A break in Earth's crust where slabs of rock slip past each other. |
| Transform Boundary | A plate boundary where two plates move past each other in opposite directions. |
| Divergent Boundary | A plate boundary where two plates move away from each other. |
| Rift Valley | A deep valley that forms where two plates move apart. |
| Convergent Boundary | A plate boundary where two plates move toward each other. |
