| A | B |
|---|
| active volcano | currently erupting , erupted in the recent past or likely to erupt again |
| ash | fine articles of pulverized rock; can be liquid or solid initially |
| aquifer | body of rock that contains water that can be tapped by wells or springs |
| basalt | volcanic rock- dark in color;45-54% silica;rich in FE and MG |
| basic | magma with silica content of 44-52% |
| bomb | fragment of moten or semi-moten rock;>2.5" in diameter; |
| caldera | basin shaped depression formed by subsidene |
| composite or stratovolcano | explosive eruptions; lays down layers of lava and tephra |
| cinder cone | explosive liquid lava comes from small opeming; not very tall - 1000 ft max; not explosive |
| shield volcano | gentle bulge; low sloping sidesl not very tall, can be wide |
| volcanic dome | makes a bulge from lava after an explosiong; beginning of the volcano rebuilding itself |
| lahars | tremendous mudflows filled w volcanic debris and water from snow, ice or rain |
| tephra | lava thrown high in air by explosive eruption;when cool can be ash to size of "bombs"; with lava flow creates layered (composite) volcano |
| batholith | largest intrusive igneous rock body |
| crater | steep walled depression at top of volcano's vent |
| hot spot | hot area in Earth's mantle that melts rock into magma |
| dike | magma hardened in vertical crack |
| sill | magma hardened in horizontal crack |
| vent | magma flows out of this opening in a volcano |
| volcanic neck | solid core exposed when volcano cone erodes away |
