| A | B |
|---|
| seismic waves | vibrations that travel through Earth carrying the energy released during an earthqake |
| crust | thelayer of rock that forms Earth's outer surface |
| mantle | the layer of hot,solid material between Earth's crust and core |
| asthenosphere | the soft layer of the mantle on which the lithosphere floats |
| inner core | a dense sphere of solid iron and nickel at the center of Earth |
| pressure | the force exerted on a surface divided by the area over which the force is exerted |
| granite | a usually light colored igneous rock that is found in continental crust |
| lithosphere | a rigid layer made up of the uppermost part of the mantle and the crust |
| outer core | a layer of molten iron and nickel that surrounds the inner core of earth |
| basalt | a dark,dens, igneous rock with a fine texture, found in the oceanic crust |
| radiation | the transfer of energy through space |
| convection | the transfer of hea tby movement of a fluid |
| convection current | the movement of a fluid, caused by differences in temperature,that transfers heat from one part of the fluid to another |
| conduction | the transfer of heat within a material or between materials that are touching |
| density | the amount of mass in a given space: mass per unit volume |
| 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 underseamountain 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 tranch and back into themantle 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 platesmove 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 |
