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100
A ___________ forms a mountain when layers of lava and volcanic ash erupt and build up.
What is volcano
100
Dikes are formed when____________. A. magma heats water B. the top of a volcano collapses down C. magma enters a vertical crack between rock layers and hardens D. magma enters a horizontal crack between rock layers and hardens.
What is magma enters a vertical crack between rock layers and hardens.
100
Magma that squeezes into a horizontal crack between rock layers and hardens is called a ___________. A. Dike B. batholith C. sill D. volcanic neck
What is sill
100
The steep-walled depression around a volcano's vent is a _____. A. caldera B. crater C. volcanic rock D. dike
What is crater
100
Crater Lake in Oregon- the top of a volcano collapsed down. A. caldera B. batholith C. volcanic neck D. composite volcano
What is caldera.
200
More than ________ of Earth's volcanoes are currently active. A. 1600 B. 1500 C. 100 D. 600
What is 600
200
A batholith is created when______________ A. magma heats water B. lava fills a vent C. magma cools underground before reaching the surface D. magma in a sill pushes up to form a rock dome.
What is magma cools underground before reaching the surface.
200
Some volcanoes form islands as ________ flows from rifts in the seafloor and builds up high enough to break the ocean's surface. A. tephra B. lava C. water D. gas
What is lava
200
Paricutin, in Mexico, is a ___________ volcano. A. composite B. shield C. cinder cone D. hot spot
What is cinder cone
200
Yosemite National Park granite domes in California-expose at Earth's surface by erosion. A. caldera B. batholith C. volcanic neck D. shield volcano
What is batholith
300
Magma forms deep inside Earth because of _________. A. a rise in temperature B. a drop in pressure C. an increase in pressure D. both a and b
What is both a and b
300
The Soufriere Hills volcano is an example of a _________ volcano. A. composite B. cinder cone C. shield D. Hawaiian
What is composite
300
Magma that is squeezed into a vertical crack that cuts across rock layers and hardens is called a ____________. A. dike B. batholith C. sill D. volcanic neck
What is dike.
300
Soufriere Hills volcano, in Montserrat, is a _________ volcano. A. shield B. cinder cone C. hot spot D. composite
What is composite
300
Ash, lava, and ____________ erupt from the crater of a volcano.
What is gases.
400
Devil's tower in Wyoming is an example of a A. caldera B. volcanic neck C. dike D. batholith
What is volcanic neck
400
Kilauea in Hawaii is the world's most _______ volcano. A. dormant B. active C. explosive D. all of the above
What is active
400
Differences in ____________ cause a volcanic neck to form. A. eruptive forces B. water content C. resistance to erosion D. silica content
What is resistance to erosion.
400
Silica-rich magma__________. A. sometimes forms where Earth's plates are coming together and one plate is forced under another. B. produces explosive eruptions C. is thick and gas gets trapped, causing pressure to build up D. all of the above.
What is all of the above
400
Magma is _________ dense than the rock around it, so it is forced _________ Earth's surface.
What is less and toward
500
One factor that determines whether a volcanic eruption will be quiet or explosive is ____________. A. the number of cinder cones B. the height of the volcano's vent C. the amount of water vapor and other gases trapped in magma D. the amount of tephra in the magma.
What is the amount of water vapor and other gases trapped in magma.
500
If, after an eruption, the top of a volcano collapses down, a _______ forms. A. caldera B. vent C. crater D. volcanic neck
What is caldera
500
Sills are formed when _____________ A. magma is squeezed into a horizontal crack between rock layers and hardens B. the top of a volcano collapses down C. mama flows onto the surface D. magma enters a vertical crack between rock layers and hardens
What is magma is squeezed into a horizontal crack between rock layers and hardens.
500
Two important factors that control whether an eruption will be explosive or quiet are the amount of ____________ and other gases and the amount of _____________ in the magma.
What is water vapor and silica
500
How are a soft-drink container and magma alike?
What is that both contain gases under pressure. If the pressure is reduced gradually, the gases escape easily and there is a quiet eruption. But if the pressure stays high, the gases escape in an explosive eruption.