It creates the Earth's magnetic field and is about 1,400 miles (2,300 kilometers) thick. The next layer is the mantle. Many people think of this as lava, but it's actually rock. The rock is so hot ...

A volcano is an opening in the Earth's crust that allows magma ... They can have violent eruptions and can grow bigger as layers of thick lava and ash harden on top of each other.

A giant patch of black, fossilized lava that was spewed across the Sahara desert over millions of years looks like an eerie, ...