Earth's Interior
Our model of the Earth’s interior is based on the study of seismic waves. The Earth has a layered structure because when it formed 4.6 billion years ago, it was mostly melted, allowing more dense materials to sink to the center and lighter materials to float to the surface. It is made of the following layers:
- Crust, the solid, rocky surface (Continental crust is thick, low density, and composed of granite, oceanic crust is thin, high density, and composed of basalt)
- Mantle, composed of the rigid mantle, plastic mantle, stiffer mantle (The Crust and the Rigid Mantle make up the lithosphere, the Moho is the boundary between the crust and the rigid mantle, and the Plastic Mantle is partially melted and known as the asthenosphere
- Outer Core (liquid iron)
- Inner Core (solid iron and nickel)
As depth within the Earth increases, density, pressure, and temperature increase.
