UPPER MANTLE
- Lithosphere (Sial and Sima)
- Asthenosphere (Molten Rock River)
- Mesosphere
LOWER MANTLE
OUTER CORE (Liquid Iron and Nickel)
INNER CORE (Solid Iron Compounds)
When you learn the layers of the Earth there really isn't a lot to explain. It's one of those memorization things. You might be wondering how all the layers came to be. When the Earth was forming billions of years ago, the matter came together. The densest matter moved to the center of the planet. The lighter rocks remained on the surface. When everything was done, the mantle wound up being about 2/3 the mass of the planet.
