| A | B |
|---|
| volcano | A depositional mountain built from solidified molten rock coming from deep in the earth. |
| igneous | A rock formed from solidified magma or lava. |
| vent | An opening in the earth's crust from which lava and gases can escape. |
| lava | Liquid magma that has escape from the earth's interior. |
| crater | Any distinct, roughly circular, walled depression in the earth's surface. |
| pyroclastic material | Sharp, fragmented, solidified lava including ash, cinders, tephra, and bombs. |
| tephra | Deposits of loose pyroclastic materials and ash covering the ground. |
| flood basalt | A thick layer of igneous rock that covers a large area of the earth's surface; also called a basalt trap. |
| shield volcano | A broad, flattened, dome-shaped volcano built up by successive quiet eruptions of runny lava. |
| cinder cone | A small, steep sided volcano made mainly of ciner like pyroclastic materials. |
| stratovolcano | A medium-sized volcano built up of deposits of lava from quiet eruptions alternating with layers of pyroclastic materials from explosive ones. Also called a composite volcano. |
| active volcano | A volcano that is currently erupting or has been observed to erupt in historical times |
| dormant volcano | A complete volcano that has not been observed to erupt within historical times. |
| extinct volcano | A volcano that has never erupted within historical times, shows no seismic activity, and is often heavily eroded. |
| Volcanic Explosive Index | An intensity scale that rates a volcano's destructiveness and explosive power on the amount of matter it ejects during an eruption. |
| intrusive volcanism | Any process or feature that involved the forcible entry of magma into a pre-existing rock formation. |
| pluton | An intrusive igneous feature that formed when a large volume of magma collected within a chamber in the earth's crust and then cooled and hardened. |
| geothermal gradient | the rate that temperature rises with increasing depth into the earth's interior. |
| geyser | A hot spring that forecefully effects hot water and steam from the ground at regular intervals. |
| geothermal energy | Steam from groundwater heated by magma intrusions that can be harnessed to generate electrical power and heat. |
