| A | B |
|---|
| crust | Earth's outer layer; includes the rock of the ocean floor and large areas of land |
| mantle | the thickest layer of the earth; found just below the crust |
| core | the dense center of the Earth; a ball made mostly of two metals, iron and nickel |
| plates | continent sized slabs of Earth's crust and upper mantle |
| earthquake | a vibration, or shaking of Earth's crust |
| fault | a break in Earth's crust along which rocks move; where earthquakes occur |
| focus | the point underground where the movement of an earthquake first takes place |
| epicenter | the point on the surface of Earth that is right above the focus of an earthquake |
| seismograph | an instrument that records earthquake waves |
| volcano | a mountain that forms when red-hot melted rock flows through a crack onto Earth's surface |
| magma | melted rock inside the Earth |
| lava | melted rock that reaches the Earth's surface |
| vent | in a volcano, the rocky opening through which magma rises toward the surface |
| magma chamber | an underground pool that holds magma, below a volcano |
| crater | a large basin formed at the top of a volcano when the top falls in on itself, or blows its top |
