| A | B |
|---|
| Geologist | A scientist who studies the forces that make and shape planet Earth. |
| Rock | The material that forms Earth's hard surface. |
| 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. |
| Pressure | The amount of force pushing on a surface or area. |
| Crust | The layer of rock that forms Earth's outer surface. |
| Basalt | A dark, dense, igneous rock with a fine texture, found in oceanic crust. |
| Granite | A usually light-colored rock that is found in continental crust. |
| 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 | The layer of molten iron and nickel 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. |
| Radiation | The transfer of energy through empty space. |
| Conduction | The transfer of heat by direct contact of particles of matter. |
| Convection | The transfer of heat by movements of a heated fluid. |
| Pangaea | The name of the single landmass that broke apart 200 million years ago and gave rise to today's continents. |
| 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; a divergent plate boundary. |
| 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 towards 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. |
