| A | B |
|---|
| aa | A slow-moving type of lava that hardens to form rough chunks; cooler than pahoehoe. |
| active | Said of a volcano that is erupting or has shown sighns of erupting in the near future. |
| caldera | The large hole at the top of a volcano formed when the roof of a volcan's magma chamber collapses. |
| cinder cone | A steep, cone-shaped hill or mountain made of volcanic ash, cinders, and bombs piled up around a volcano's opening. |
| composite volcano | A tall cone-shaped mountain in which layers of lava alternate with layers of ash and other volcanic materials. |
| crater | A bowl-shaped area that forms around a volcano'scentral opening. |
| dormant | Said of a volcano that does not show signs of erupting in the near future. |
| extinct | Said of a volcano that is unlikely to erupt again. |
| geothermal energy | Heat energy in Earth's interior from water or steam that has been heated by magma. |
| geyser | A type of hot spring that builds up pressure underground and erupts at regular intervals as a fountain of water and steam. |
| hotspring | A pool formed by groundwater has has risen to the surface after being heated by a nearby body of magma. |
| pahoehoe | A hot, fast-moving, type of lava that hardens to form smooth, ropelike coils. |
| pyroclastic flow | The explusion of ash, cinders, bombs, and gases during an explosive volcanic eruption. |
| shield volcano | A wide, gently sloping mountain mad eof layers of lava and formed by quiet eruptions. |
| silica | A material that is formed from the elements oxygen and silicon; silica is found in magma. |
