| A | B |
|---|
| crust | the thin and solid outermost layer of the Earth above the mantle |
| mantle | the layer of rock between the Earth's crust and core |
| core | the central part of the Earth below the mantle |
| lithosphere | the solid, outer layer of the Earth that consists of the crist and the rigid upper part of the mantle |
| asthenosphere | the soft layer of the mantle on which the tectonic plates move |
| mesosphere | the strong, lower part of the mantle between the asthenosphere and the outer core |
| tectonic plate | a block of lithosphere that consists of the crust and the rigid, outermost part of the mantle |
| continental drift | the hypothesis that states the continents once formed a single landmass, broke up, and drifted to their present locations |
| sea-floor spreading | the process by which new oceanic lithosphere forms as magma rises torward the surface and solidifies |
| plate tectonics | the theory that explains how large pieces of the Earth's outermost layer, called tectonic plates, move and change shape |
| convergent boundary | the boundary formed by the collision of two lithospheric plates |
| divergent boundary | the boundary between two tectonic plates that are moving away from each other |
| transform boundary | the boundary between the tectonic plates that are sliding past each other horizontally |
| compression | stress that occurs when forces act to squeeze an object |
| tension | stress that occurs when forces act to stretch an object |
| folding | the bending of rock layers due to stress |
| fault | a break in a body of rock along which one block slides relative to another |
| uplift | the rising of regions of the Earth's crust to higher elevations |
| subsidence | the sinking of regions of the Earth's crust to lower elevations |
