Earth's Layers | Middle school Earth and space science | Khan Academy

Earth is composed of three main layers: the thin crust (less than 1% of Earth's volume) made of igneous rocks rich in oxygen, the thick mantle (84% of Earth's volume) of hot, slowly flowing rocks that drive tectonic plate movement, and the core (15% of Earth's volume) consisting of a liquid outer core of molten iron and nickel that generates Earth's protective magnetic field, and a solid inner core of iron and nickel kept solid by immense pressure despite being hotter than the outer core.