The rocky outer layer of the Earth. CRUST The rocky outer layer of the Earth.

Thick layer of hot but solid rock beneath Earth’s crust. MANTLE Thick layer of hot but solid rock beneath Earth’s crust.

Large sphere of metal at Earth’s center. CORE Large sphere of metal at Earth’s center.

A solid combination of minerals or other materials. ROCK A solid combination of minerals or other materials.

Rock that forms from magma or lava that cools and hardens. IGNEOUS ROCK Rock that forms from magma or lava that cools and hardens.

MAGMA Molten rock, or a mixture of molten rock and gases, including water vapor, that is underground.

Magma that flows over Earth’s surface. LAVA Magma that flows over Earth’s surface.

Igneous rock that cools underground from hardened magma. INTRUSIVE ROCK Igneous rock that cools underground from hardened magma.

Igneous rock that forms at Earth’s surface from lava. EXTRUSIVE ROCK Igneous rock that forms at Earth’s surface from lava.

SEDIMENTARY ROCK Rock that forms over time as sediment is squeezed and cemented together.

METAMORPHIC ROCK Rock that has been changed by temperature, pressure or reactions with water and chemicals.