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volcanoes
| Question | Answer |
|---|---|
| volcano | a weak spot in the crust where molten material, or magma, come to the surface |
| lava | when mag,ma reaches the surface |
| magma | molten mixture of rock-forming substance, gases, and water from the mantle |
| ring of fire | formed by the many volcanoes that rim the Pacific ocean |
| hot spot | an area where material form deep within the mantle rises and then melts, forming magma |
| shield volcano | gently sloping mountains formed by repeated lava flows |
| composite volcano | formed by lava flows alternating with explosive eruptions |
| cinder cone volcano | cone shaped mountain formed from ash, cinder, and bombs |
| sill | when magma squeezes between horizontal layers of rock, forms sill |
| dike | magma that forces itself across rock layer hardens into dike |
| ;/batholith | a mass of rock formed when a large body of magma cools inside the crust |
| lava plateau | high, level area formed by repeated lava flows |
| extinct | unlikely to erupt again |
| dormant | might erupt anytime |
| active | erupting and showing signs of erupting in the near future |
| element | a substance that cannot be broken down into other substances |
| silica | a rock that forms light-colored lava |
| basalt | low-silica magma that forms rocks |
| phhoehoe | hot, fast-moving lava |
| aa | cool, slow-moving lava |
| viscosity | physical property of liquid |
| compound | substance made of two or more elements that have been chemically combined |
| volcanic ash | rocky particle as small as a speck of dust |
| magma chamber | magma collects in a pocket |
| crater | a bowl shaped area that may form at the top of a volcano around the central vent |
| vent | molten rock and gas leave the volcano through an opining |
| pipe | magma moves upward through the pipe |
| caldera | hole left by the collapse of a volcano mountain |
| geyser | fountain that erupts from the ground |