**CRUST** : The crust ranges from 5–70 km (3–44 miles) in depth and is the outermost layer. The thin parts are the oceanic crust, which underlie the ocean basins (5–10 km) and are composed of dense (mafic) iron magnesium silicate igneous rocks, like basalt.
**CORE**: The average density of Earth is 5,515 kg/m3. Because the average density of surface material is only around 3,000 kg/m3, we must conclude that denser materials exist within Earth's core. Seismic measurements show that the core is divided into two parts, a "solid" inner core with a radius of 1,220 km and a liquid outer core extending beyond it to a radius of 3,400 km.