The Earth's interior is composed of four layers, three solid and one liquid—not magma but molten metal, nearly as hot as the surface of the sun. The deepest layer is a solid iron ball ...

Over time, Earth's interior—which is made mostly of silicate rocks and metals—differentiated into four layers. At the ... the seafloor is thinner—about three miles thick—and denser.

The rocks on Earth are constantly changing due to many different processes. There are three main types of rock ... Over time, the layers are compressed and glued together.Metamorphic rocks ...