Lithosphere

lithosphere (lĭth`əsfēr '), brittle uppermost shell of the earth, broken into a number of tectonic plates. The lithosphere consists of the heavy oceanic and lighter continental crusts, and the uppermost portion of the mantle. The crust and mantle are separated by the Moho or Mohorovicic discontinuity (see earth and seismology). The thickness of the lithosphere varies from to around 1 mi (1.6 km) at the mid-ocean ridges to approximately 80 mi (130 km) beneath older oceanic crust. The thickness of the continental lithospheric plates is probably around 185 mi (300 km) but is uncertain due to the irregular presence of the Moho discontinuity. The lithosphere rests on a soft layer called the asthenosphere, over which the plates of the lithosphere glide. See plate tectonics.

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lithosphere

Rigid, rocky outer layer of the Earth, consisting of the crust and the solid outermost layer of the upper mantle. It extends to a depth of about 60 mi (100 km). It is broken into about a dozen separate, rigid blocks, or plates (see plate tectonics). Slow convection currents deep within the mantle, generated by radioactive heating of the interior, are believed to cause the lateral movements of the plates (and the continents that rest on top of them) at a rate of several inches per year.

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lithosphere [′lith·ə‚sfir]

(geology)

The rigid outer crust of rock on the earth about 50 miles (80 kilometers) thick, above the asthenosphere. Also known as oxysphere.

Since the development of plate tectonics theory, a term referring to the rigid, upper 60 miles (100 kilometers) of the crust and upper mantle, above the asthenosphere.

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Lithosphere 

the outer sphere of the “solid” earth, including the earth’s crust and the upper layer of the mantle (substratum). The lower boundary of the lithosphere runs above the asthenosphere. Until the 1960’s “lithosphere” was a synonym for the earth’s crust.