| A | B |
|---|
| volcanoes | a vent or fissure in the earth's surface throgh which magma and gases are expelled |
| magma | molten rock |
| lava | magma that flows onto earth's surface |
| ash | tiny dust particles that harden in the air |
| magma chamber | the body of molten rock that feeds a volcanoes |
| vent | an ppening at the surface of the earth through which volcaic materials pass |
| pumice | soild lava that can float |
| pyroclasic material | forms when magma is blasted into the air and hardens |
| aa | jagged rock with a brittle surface |
| pahoehoe | lava that flows slowly, glassy surface has rounded wrinkles |
| pillow lava | forms when lava erupts under underwater |
| blocky lava | cool, stiff lava that does NOT travel far from the erupting vent |
| lapilli | type of pyroclastic material |
| pyroclastic flow | dangerous type of volcanic flow |
| crater | a funnel-shaped pit near the top of the central vent of a volcano |
| caldera | large, semicircular depression that forms when the magma chamber below a volcano partically empties and causes the ground above to sink |
| rifts | surface erupted from long crakes |
| lava plateau | wide, flat landform that results from repeated nonexplosive eruptions of lava that spread over a large area |
| rift zone | an areaof deep crakes that form between two tectonic plates that are pulling away from each other |
| Surtsey | lava that poured ot at the MId- Atlantic Ridge near Iceland |
| subduction | the movement of one tectonic plate underneath another |
| hot spots | a volcanically active area of eath's surface far from a tectonic plate boundary |
| mantle plum | colums of rising magma |
| extinct volcanoes | volcanoes that have not erupted in recored history and probably never erupt again |
| dormant volcanoes | are currently no erupting, but the record of the past eruptiions sugest that the volcano may erupt again |
| actve volcanoes | are currently erupting or show signs of erupting in the near future |
| tiltmeter | helps scientist detect small changes in the angle of a volcano's slope |
