The solid interior part of the earth's core, presumed to be composed principally of iron with an alloy of about 10 percent oxygen, sulfur, or nickel, or perhaps some combination of these three elements. The inner core is about 1221 kilometers thick.
General Interest Publication on the structure of the planet Earth including the crust, the mantle, and the core with drawings to scale on the cover and a table listing the thickness of the parts.
U.S. Department of the Interior |
U.S. Geological Survey