Demo above requires Macromedia's Shockwave plugin.
The diagram above shows two columns of rock, a crust of density 2.75 g/cc over mantle lithosphere of density 3.25 g/cc over asthensophere of density 3.20 g/cc. If you grab the solid black lines at the base of the crust and mantle lithosphere, you can see how changing the thicknesses of these two parts of the lithosphere changes the isostatic elevation of the crust. [There is a bug at the moment so that the first time you grab the handles, the crust will jump, but after that things work fine]. Note that the topography is shown with an exaggeration of 3 relative to the rest of the plot.
The condition of isostasy is that the pressure in the asthenosphere is everywhere the same for a given depth. The pressure is calculated to be the weight of all the overlying material.
C. H. Jones | CIRES | Dept. of Geological Sciences | Univ. of Colorado at Boulder
Last modified at Thursday, September 30, 1999 3:51 PM
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