The three layers of the earth, in order from outside to inside, are the crust, the mantle and the core. The mantle is the thickest and most massive layer, while the core has the highest temperatures of anywhere in the planet.
The crust ranges between 37 and 50 kilometers in thickness, and makes up only one percent of the earth's total mass. It is made up of primarily aluminosilicates. The mantle is made up dense, semi-solid rock that is composed of magnesium silicates. It is about 2,900 kilometers thick. The core, which is part solid and part liquid, is mostly iron, and creates the magnetic field for the planet.