The Core: At the center of the Earth is the core. Its upper boundary is approximately 1,800 miles (2,900 km) below the surface. The core is predominately formed of iron (85 %) and nickel (5 %) with a number of siderophile (iron liking elements forming the remainder). It is divided into two layers based on the cores state of matter, the inner core and the outer core. The inner core which is at the very center of the Earth is a solid layer approximately 780 miles (1,250 km) thick. The core is at a very high temperature and so the outer core is always molten, however as the depth within the core increase the pressure drives the melting temperature up above the in-situ temperatures even though they reach 6700ºF (3700ºC). The outer core is approximately 1370 miles (2,200 km) thick. It is thought that the movement of the liquid outer core is responsible for the creation of earth's magnetic field.

The Mantle: The mantle lies directly above the core (this boundary is known as the core-mantle-boundary or Gutenberg discontinuity and is named after the geophysicist who discovered it (trivia - Beano Gutenberg, the geophysicist in question also worked with Charles Richter in the development of the Richter magnitude scale). Its upper boundary lies approximately 6 miles (10 km) below the surface of the oceanic crust and about 19 miles (30 km) below the surface of the continental crust. The mantle is broadly divided into two main sections. The upper and the lower mantle based on changes in the crystalline structure of the mantle material caused by pressure changes at increasing depths. The mantle is approximately 1,800 miles (2,900 km) thick and makes up nearly 80 percent of the Earth's