Download Chapter 18 Volcanic ActivityStudent Copy

Vocabulary
 Magma Chamber:
 The pocket beneath a volcano where
magma collects.
 Pipe:
 A long tube through which magma moves
from the magma chamber to Earth’s surface.
 Vent:
 The opening through which molten rock and
gas leave a volcano.
Vocabulary
 Lava Flow:
 The area covered by lava as it pours out of a
volcano’s vent.
 Crater:
 A bowl-shaped area that forms around a
volcano’s central opening.
 Silica:
 A material that is formed from the elements
oxygen and silicon; silica is found in magma.
How Magma Reaches
Earth’s Surface
 True or False: Magma forms in the
lithosphere.
 What happens during a volcanic
eruption?
 During a volcanic eruption gasses that have
been dissolved in the magma rush out,
carrying the magma with them.
Inside a Volcano
 Circle the letter of each feature that all
volcanoes share.




A. pocket of magma beneath the surface.
B. crack to the surface.
C. side vents.
D. crater.
Inside a Volcano
 What is a lava flow?
 A lava flow is the area covered by lava as it pours
out of a vent.
 Where does a crater form?
 A crater forms at the top of a volcano around the
central vent.
 True or False: The pipe of a volcano is a
horizontal crack in the crust.
Characteristics of Magma
 What factors determine the force of a
volcanic eruption.
 Factors that determine the force of a
volcanic eruption include the amount of gas
dissolved in the magma, how thick or thin
the magma is, its temperature, and its silica
content.
Types of Volcanic
Eruptions
 Hot, fast-moving lava is called ________.
pahoehoe
 Cool, slow-moving lava is called _____.
aa
 What is a pyroclastic flow?
 A pyroclastic flow is an explosive eruption of
ash, cinders, bombs, and gases.
Vocabulary
 Shield Volcano:
 A wide, gently sloping mountain made of
layers of lava and formed by quiet eruptions.
 Cinder Cone Volcanoes:
 A steep, cone-shaped hill or mountain made
of volcanic ash, cinders, and bombs piled up
around a volcano’s opening.
Vocabulary
 Composite Volcano:
 A tall, cone-shaped mountain in which layers
of lava alternate with layers of ash and other
volcanic material.
 Caldera:
 The large hole at the top of a volcano
formed when the roof of a volcano’s magma
chamber collapses.
Shield Volcano
Belknap-Oregon
Cinder Cone Volcano
Composite Volcano
St. Augustine, Alaska