| A | B |
|---|
| magma | molten rock beneath the Earth's surface |
| lava | molten rock at the Earth's surface |
| volcano | a place in the Earth's surface through which molten rock and other materials reach the surface |
| vent | an opening through which lava erupts |
| volcanic dust | the smallest rock particles blown into the air by a volcanic eruption |
| volcanic bomb | rock particles larger than 5 mm in diameter that are blown into the air by a volcanic eruption |
| cinder | a small, rough volcanic bomb no more than several centimeters |
| cinder cone | a volcano made mostly of cinders and other rock particles that have been blown in the air |
| shield volcano | a volcano composed of quiet lava |
| composite volcano | a volcano built of alternating layers of rock particles that have been blown in the wind |
| crater | a funnel-shaped pit at the top of a volcanic cone whose diameter is less than three times its depth |
| caldera | a roughly circular, steep-sided pit at the top of a volcanic cone whose diameter is at least three times its depth |
| Ring of Fire | the earthquake and volcano zone that encircles the Pacific Ocean |
