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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 |