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Chapter 9 Test Review
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Iceland is one of the few places in the world where
a mid-ocean ridge is above sea level.
Active volcanoes near
convergent
boundaries, such as
those in the Andes
Mountains of South
America, would be
expected to erupt
explosively with
abundant pyroclastic
material.
Pyroclastic material is
made mostly of ash.
At a subduction boundary, a volcano is
most likely to form on the overriding
plate.
Crater lake is an example of a caldera type
volcano.
Io
Active volcanoes are known
to exist on the moon,
Mars, Earth, and even a
moon of Jupiter called Io.
Mount Olympus, Mars.
Pillow lava forms underwater.
Aa lava
Pahoehoe lava
Chains of volcanic islands often form when
one oceanic plate subducts beneath
another oceanic plate.
Mount St. Helens
and Crater Lake
are located in the
same mountain
chain.
Lava plateaus are likely to have formed
from magma that is basaltic with little
gas content.
Mt. Fuji is a composite cone volcano.
One advantage of monitoring volcanoes is
that scientists can predict volcanic
eruptions.
A shield cone has a broad base and
gently sloping sides.
The lava erupting from Mauna Loa, an
active volcano in Hawaii would most
likely be erupting quietly with little
pyroclastic material.
What would be a description of the type of magma found
erupting from Mount Pinatubo in the Philippines?
High gas content, with a high silica content.
Magma will not form on the Earth’s
surface. It can only form deep
below the surface. Lava is found
on the surface.
The formation of magma depends on
temperature, pressure, and water
content.
As silica content increases, magma tends
to have greater viscosity.
Magma tends to rise to the surface
because it is less dense than
surrounding materials.
Andesitic magma is associated with
relatively explosive eruptions, but basaltic
magma is associated with relatively
nonexplosive eruptions.
The diagram below represents a chain of volcanic
islands formed by the movement of a lithospheric
plate over a hot spot. Identify which island is most
likely to have an active volcano, which island is the
oldest, and where a new island is likely to form in
the future. (4 points)
Island D will have an active volcano.
Island A is the oldest.
A new island is likely
To form in
Future at
Point Y.
Essay 1: Cinder cone volcanoes are steepsided and relatively small. Shield volcanoes
are broad-based and very large. Explain
where each is likely to form, and give reasons
for the differences in shape and size.
Cinder cones are small, steep-sided volcanoes.
They form when molten lava ejected from a
vent breaks, then drops & hardens into
fragments. These fragments pile up in a cone
shape around the vent. Cinder cones tend to
form in groups or on the sides of larger
volcanoes. Compared to cinder cones, shield
volcanoes are very large. They form when
basaltic lava erupts and flows long distances
before hardening. Over time, layers of
hardened lava build up into a broad-based,
shield-shaped volcano.
Essay 2:
Describe how a volcanic eruption can
affect the lithosphere, the biosphere, the
hydrosphere, and the atmosphere.
A volcanic eruption affects the lithosphere
by ejecting lava and pyroclastic
materials that are part of the
lithosphere. An eruption affects the
atmosphere because it ejects gases into
the atmosphere. An eruption affects the
biosphere by altering the environment
around the volcano.
A: Composite cone, B:Shield volcano, C: Cinder cone,
D: Cinder cone, spatter cone.