Why can geologists look inside Earth?
Despite attempts, getting through the crust has proven impossible with current economic and technological constraints. Temperatures vary from 900 to 1600 degrees F at the Mohorovicic discontinuity, the boundary between the crust and the upper mantle. And the lithostatic pressure at the line dividing the crust and the mantle is estimated to be up to 116,000 pounds per square inch. It is not surprising that drill bits and shafts would be under tremendously high stresses. Geologists look into the interior by indirect means; examination of deep sourced volcanic material, meteorite and moon material, and behaviors of seismic waves. Much can also be inferred by computer modeling of Earth’s gravitational influence and magnetic field.
