The Interior of the Earth

From GeoClasses

When the Earth coalesced from the solar nebula the pressure at the center of the Earth was (and still is) immense. The interior of the Earth was also heated by the decay of radioactive materials so much of the Earth melted.

There were many types of material in the dust of the solar nebula, just as there are many types of asteroids floating through space today.

• Stony meteorites: Some were stony made primarily of silicate rocks

Stony meteorite. Photo from NASA.

• Iron meteorites: Some were dense masses of iron

Surface of an iron meteorite after being melted during its passage through the atmosphere.

Both the silicate and iron rocks melted, but the iron was much denser than the silicates so it gradually drifted toward the center of the Earth. As a result, today, the core of the Earth consists mainly of iron and other heavy metals, while the rest of the Earth (mantle and crust) is primarily composed of silicates. The molten metal outer core of the Earth is the reason the planet has a magnetic field.

Image of the Earth showing its internal structure. Shown are the solid inner core, the liquid outer core, the mantle and the crust.