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from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. A zone of the earth's mantle that lies beneath the lithosphere and consists of several hundred kilometers of deformable rock.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. The zone of the Earth's upper mantle, below the lithosphere.

from the GNU version of the Collaborative International Dictionary of English

  • n. the lower layer of the earth's crust, below the lithosphere. It is estimated as from fifty to several hundred miles thick. It is less rigid than the lithosphere, but still rigid enough to transmit some transverse seismic waves.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. the lower layer of the crust


Greek asthenēs, weak; see asthenia + sphere.
(American Heritage® Dictionary of the English Language, Fourth Edition)
From Ancient Greek ἀσθενής ("weak") + sphere. (Wiktionary)


  • This was cool becuase we looked at how upper crust interaction ie mountain building events are affected by the underlaying interaction of the crust and upper mantle - he actually mentioned the word asthenosphere which I haven't heard since like A'level geology I swear!

    Snell-Pym » East Asian Monsoon

  • They travel at a speed of about 5 to 7 kilometers per second through the lithosphere and about 8 kilometers per second in the asthenosphere.


  • In any one region, the asthenosphere is slowly moving in a consistent direction, and then circling back in the opposite direction down in its deeper layers.


  • The asthenosphere is weak in the sense that it is not rigid and brittle like the rocky plates of the lithosphere but behaves somewhat like a liquid: yielding, like putty or toffee, if not necessarily molten.


  • The asthenosphere, in its capacity as a quasi-liquid, has convection currents that extend throughout its whole surface, under the entire area of the plates.


  • The upper layer of asthenosphere under the South American plate, for example, is moving inexorably westward.


  • The plates constitute the hard lithosphere – literally, ‘sphere of rock’ – which floats atop the hot, semi-molten asthenosphere – ‘sphere of weakness’.


  • Near the top of the mantle is a region of partially melted rock called the asthenosphere.

    AP Environmental Science Chapter 3- The Solid Earth

  • The lithosphere, and therefore, the earth's crust, is not a continuous shell, but is broken into a series of plates that independently "float" upon the asthenosphere, much like a raft on the ocean.

    AP Environmental Science Chapter 3- The Solid Earth

  • The layer of the mantle above the asthenosphere plus the entire crust make up a region called the lithosphere.

    AP Environmental Science Chapter 3- The Solid Earth


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  • JM steps lightly so as to leave the asthenosphere undisturbed.

    May 20, 2011

  • JM ponders the asthenosphere but thinks he may not be on firm ground.

    January 18, 2011

  • Lithosphere link.

    April 23, 2009

  • The asthenosphere and mantle are not the same thing. The asthenosphere is the majority of the mantle but not the uppermost section which is part of the lithosphere. The distinction between the lithospheric mantle and the asthenosphere is not one of composition but to do with the way it is able to deform. The asthenosphere can flow by diffusion creep whereas the lithospheric mantle can only move by dislocation creep. The result is that the asthenosphere can (and does) undergo convection which keeps it's temperature more or less constant and the lithosphere has a sharp temperature gradient.

    December 9, 2006