If you were to slice through it, you would see the Earth is divided into distinct layers. On top is the relatively thin crust where we live. Beneath that is the 2,900 km thick mantle layer.

Over time, the layers are compressed and glued together.Metamorphic rocks are formed from other rocks, igneous or sedimentary, which are heated and compressed underground.Igneous rocks are formed ...

molten rock rises and falls, driving the movement of tectonic plates on our planet's surface — and for some time, researchers have debated whether the moon also has a molten layer of rock ...