The Composition of the Interior of the Earth

Abstract

As is well known, the density of the earth's crust is about 2.7, while the density of the whole earth is 5.52 gms./cc. This difference is usually explained by the hypothesis that the interior of the earth is composed of heavy metals, chiefly of iron.' It is assumed that the heavy elements have fallen to the interior during the formative stages of the earth and stayed there.2 This theory is, however, open to very serious objections. The iron core theory would require that about 46% of the mass of the