A | B |
seismic waves | Vibrations that travel through Earth carrying the energy released during an earthquake |
pressure | The force exerted on a surface divided by the area over which the force is exerted |
crust | The layer of rock that forms the Earth's outer surface |
basalt | A dark, dense, igneous rock with a fine texture, found in oceanic crust |
granite | A usually light-colored igneous rock that is found in continental crust |
mantle | The layer of hot, solid material between Earth's crust & 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 & nickel the surrounds the inner core of Earth |
inner core | A dense sphere of solid iron & nickel at the center of Earth |
radiation | The transfer of energy through space |
conduction | The transfer of heat within a meterial or between materials that are touching |
convection | The transfer of heat by movement of a fluid |
density | The amount of mass in a given space; mass per unit volume |
convection current | The movement of a fluid, caused by differences in temperature, that transfers heat from one part of the fluid to another |
continental drift | The hypothesis that the continents slowly move across Earth's surface |
Pangaea | The name of the single landmass that broke apart 200 million years ago and gave rise to today's continents |
fossil | A trace of an ancient organism that has been preserved in rock |
mid-ocean ridge | An 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 beneath 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 masses of rock slip past each other |
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 |
transform boundary | A plate boundary where two plates move past each other in opposite directions |