Transcript Ch. 9 Study Guide Answers

Ch. 9
Study Guide Answers
2011
• A vent or fissure in the Earth’s surface through
which magma and gases are expelled is called
• A Volcano
• What would you expect to see during a nonexplosive eruption?
• Huge lava flows.
• Molten rock deep underground often gathers
in a
• Magma Chamber
• Which type of lava flows most like dripping
wax?
• Pahoehoe
• Lava that is very runny probably
• has a low silica content
• If the water content of magma is high,
• an explosive eruption is more likely
• When you talk about the viscosity of lava, you
are talking about
• how the lava flows (thickness).
• Most active volcanoes form
• (80%) where tectonic plates collide
• Cool, stiff lava that forms in jumbled heaps of
sharp chunks near the vent is called
• Blocky Lava
• Which type of pyroclastic material gets its
name from a word that means “little stones”?
• Lapilli.
• The pyroclastic material that can reach the
upper atmosphere and circle the Earth for
years is
• Volcanic Ash.
• Pyroclastic material forms when
• magma explodes from a volcano and hardens
in the air.
• Describe a possible climate change caused by
a volcanic eruption?
• Volcanic Ash high in the atmosphere could
block sunlight, causing (regions of earths)
temperatures to drop.
• Where are volcanoes most likely to form?
• Along plate boundaries
• Large blobs of magma that harden in the air
are called
• Volcanic Bombs.
• A large depression that forms when the
magma chamber partially empties is a
• Caldera.
• The three main types of volcanoes are
• Shield Volcano, Cinder Cone Volcano, and
Composite Volcano.
• The depression created when the roof of a
magma chamber collapses is called a
• Caldera
• Rock begins to melt when (what happens)
• temperature on the rock increases and
pressure decreases
• Most active volcanoes form
• where tectonic plates collide
• When an oceanic plate collides with a
continental plate, the oceanic plate is usually
sub-ducted because
• the oceanic plate is denser and thinner than
the continental crust.
• A cinder cone volcano
• has steep slopes
• The volcanoes of Hawaii and other places far
from tectonic plate boundaries are known as
• Hot Spots
• Which category of volcano is most likely to
erupt in the near future?
• An active volcano
• An active volcano
• is currently erupting or show signs of
erupting. In the near future.
• What would you expect to see during a nonexplosive eruption?
• Calm lava flows
• Pillow lava is
• formed when lava erupts under water
• Lava with a high viscosity
• is thick like pudding
• What would you expect after an explosive
eruption?
• Darkened Skies.
• A shield volcano
• has gently sloping sides
• A combination of explosive and non-explosive
eruptions will create a
• composite volcano