Inside the earth

Term Definition
Crust The outermost layer of the earth
Mantel Much thicker than the crust
Core The central part of the earth below the mantel
Lithosphere The solid outer layer of the earth that consists of the crust and the rigid upper part of the mantel.
Asthenosphere The soft layer of the mantel on which the tectonic plates move.
Mesosphere The strong lower part of the mantel between the asthenosphere and the outer core.
Tectonic plates
A block of lithosphere that cosists of the crust and the rigid outermost part of the mantel.
Continental drift The hypothesis that states that 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 magma rises toward the surface and solidifies.
Plate tectonics The theory that explains how large pieces of the earths outermost layer called tectonic plates move and change shape
Convergent boundary The boundary formed by the collisions of two tectonic plates.
Divergent boundary
Tectonic plates move apart and divide mid ocean ridge and rift valleys form
Transform boundary Tectonic plates slide past past each other in opposite direction > earthquakes occur<
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 earths crust to higher elevations
Subsidence The sinking of regions of the earth crust to lower elevations

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