Below the crust is a layer called the mantle. Magma is in the mantle. This melted rock is like a thick, hot paste, and it moves about. Next come the outer core and inner core of the earth. Within the core, it is very, very hot.
Scientists think the outer core is liquid and the inner core is solid.
When a volcano erupts, the magma in the earth's mantle pushes its way through a hole in the crust. This hole is called a vent. Sometimes the magma erupts with great force, sending a red-hot fountain of lava high into the air. Other times, the lava slowly but steadily oozes out of the vent. Bits and pieces of rock also erupt from a volcano.