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26 terms

Earth's Structure: Volcanoes

Lesson 1 - Volcanoes and Plate Tectonics Lesson 2 - Volcanic Eruptions Lesson 3 - Volcanic Landforms
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crust
Earth's rocky outer layer
plate
one of the large pieces that Earth's crust is broken into
boundary
the line along which something ends
volcano
a mountain that forms in Earth's crust when magma reaches the surface
magma
a molten mixture of rock-forming substances, gases, and water from the mantle
lava
the term used for magma when it reaches Earth's surface
Ring of Fire
a major belt of volcanoes that rims the Pacific Ocean
island arc
a string of volcanic islands created along a converging boundary
hot spot
a concentration of heat in the mantle capable of producing magma, which rises to Earth's surface
magma chamber
the area beneath a volcano where magma accumulates
pipe
a long tube that extends from Earth's crust us through the top of the volcano, connecting the magma chamber to Earth's surface
vent
any place where molten rock and gas leave a volcano
lava flow
the spread of lava as it pours out of a vent
crater
a bowl-shaped area that may form at the top of a volcano around the central vent
silica
a material found in magma that forms from oxygen and silicon
pyroclastic flow
the mixture of hot gases, ash, cinders, and bombs that flow down the sides of a volcano when it erupts explosively
dormant
sleeping; expected to awaken in the future and become active
extinct
dead; unlikely to ever erupt again
caldera
the hole left when a volcano collapses
cinder cone
volcanic material that has built up around a vent into a steep, cone-shaped hill or small mountain
composite volcano
tall, cone-shaped mountains in which layers of lava alternate with layers of ash
shield volcano
thin layers of lava pour out of a vent and harden on top of previous layers slowly building a wide, gently sloping mountain
volcanic neck
formed when magma hardens in a volcano's pipe and the surrounding rock later wears away
dike
magma that forces itself across rock layers and then hardens
sill
magma that squeezes between horizontal rock layers and then hardens
batholith
a mass of rock formed when a large body of magma cools inside the crust