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VOLCANOES
VOLCANOES
• Up until now, we have discussed the earth and
its construction.
• We have discussed the ____________ and
____________ and _____________________.
• In a way, our discussion of ________________
will extend that old knowledge.
VOLCANOES
• A __________________ is a weak spot in the
crust where magma leaks to the surface.
• When magma escapes to the surface, it’s
called ______________.
VOLCANOES
• There are about ________________________
on land today.
• We know there are many more beneath the
sea, but because there are parts of the ocean
floor which are inaccessible, it is difficult to
__________ or even _____________ them.
VOLCANOES
• Volcanoes often occur in _______________.
• One of the most well known volcanic belts is
the _______________________around the
rim of the _______________________.
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• You may have noticed that he volcanic belts
occur near the ________________________
of the earth’s plates.
• This is because when __________________ or
__________________________ occurs cracks
form in the crust which make it easy for
volcanoes to occur.
VOLCANOES
• Underwater volcanoes spew magma
constantly and ______________ form
______________ or underwater mountains.
• This happens at __________________ plates.
• There may be a time in the future where our
map looks ______________ like it does today!
VOLCANOES
• When oceanic plates ___________________,
volcanos can be created.
• The plate that subducts gradually melts as it
gets closer to the warm material of the
_____________________.
• Since _____________________ is less dense
than the rock above it, it rises to the surface.
• Hence, a ___________________ is formed.
VOLCANOES
• Since volcanos often occur in _____________,
islands that spring from the ocean often do so,
likewise, in ____________________.
• These are called ______________________.
• These arcs echo the shape of the ocean
_________________.
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• This can occur when an _________________
plate subducts beneath a
_______________________ plate.
• This produced the _____________________
in South America and the ________________
____________________ in the United States!
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• Not all volcanoes form along a ridge.
• Some volcanoes form at what we call _______
_____________.
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• This happens when material from deep within
the mantle ____________, then ___________
forming ____________________.
• When this magma breaks through the crust,
we call it an ________________ and another
volcano is formed.
VOLCANOES
• _____________________ can form near a
fault or in the center of a plate.
• There is one very famous hot spot under
_____________________________________.
• What did that form?
VOLCANOES
• Volcanic ____________________ have been
explained in many ways over the years.
• In Hawaii, there are many myths about the
goddess of volcanoes, ___________________.
• When she is angry, volcanoes erupt.
• __________________________is formed
when lava sprays from the ground and
hardens in thin strands.
VOLCANOES
• Deep beneath the surface under volcanoes
there is always a pocket of _______________.
• This pocket is called a ___________________
________________________.
• The magma moves upward through a
_________________ or a long tube that runs
from the chamber to the surface.
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• ________________________ and _________
can leave a volcano through what’s called a
________________.
• Often there is a ___________________ on top
of a volcano, but it may have several more
____________________ along the sides.
VOLCANOES
• The area covered by lava as it pours from a
vent is called a _________________________.
• Oftentimes the central vent will have a bowlshaped crater around it.
• This is called a___________________.
VOLCANOES
• You guys know that trick I do with the pop
bottle?
• That happens because under pressure, the
_______________________in pop is very
compacted.
• When you open the pop and release the
pressure, the carbon dioxide can
_______________.
• This is also why pop bubbles when you open
it.
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• This is what happens in a volcanic
_________________ as well.
• Magma is under enormous pressure and when
that _________________is released, the
gasses in it _______________and an eruption
occurs.
VOLCANOES
• That pressure builds until the magma
____________ or ____________ out of the
vent.
• Once all the magma has escaped, the
remaining __________________ escape.
VOLCANOES
• In a geologist’s eyes there are two types of
eruptions…___________ or
________________.
• ________________ eruptions occur if the
magma is low in ________________.
• This magma has low ________________ and
flows easily.
• Because of this gasses bubble out
______________.
VOLCANOES
• As you could imagine, when the magma is
high in ___________________, oftentimes
eruptions are explosive.
• Because of its _____________________ the
magma often plugs the pipe.
• And the pressure builds…and builds until and
explosion happens.
VOLCANOES
• Explosive eruptions can actually ___________
lava.
• When it cools it can be as fine as __________
or as course as ____________________ on a
playground.
• When there is an explosive eruption, the
mixture of hot gasses, ash, and cinders is
called ___________________________.
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• While they are very different, both types of
eruptions cause significant damage.
• Quiet eruptions spew lava constantly
_______________________ to and
_______________ a large are around the
volcano.
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• An explosive eruption causes clouds of
_____________________________________
________________________.
• The _______________ alone can bury entire
towns.
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• A volcano’s activity can last from a
_________________ to ______________
_______________.
• Geologist work tirelessly to determine
__________________ or _____________a
volcano will erupt again.
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• A volcano has _________________ of activity.
• The first is _____________________.
• These are volcanoes that ________ erupting
or ________________ of erupting in the near
future.
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• The second type is _________________.
• These volcanoes are ones that scientist expect
to ______________________ in near future.
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• The final type is ___________________.
• This is one that is _______________ to ever
erupt again.
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• Geologists use what’s called a
___________________ to detect slight
changes in elevation near a volcano.
• This can let geologists know ___________ or
_______a volcano will erupt again.
VOLCANOES
• As destructive as volcanoes can be, they can
____________________ some of the world’s
most spectacular and awe-inspiring
landforms.
• ___________________in Japan is one of the
most beautiful and perfectly formed
mountains in the world.
VOLCANOES
• Volcanic eruptions can create landforms made
of ________________, _____________ and
_______________________________.
• These landforms include…
– ____________________________________
– ____________________________________
– ____________________________________
– ___________________________________
VOLCANOES
• ________________________are formed
when lava spews slowly and over time creates
layers of solidified magma that create a gently
sloping mountain.
• The ______________________are an example
of shield volcanoes.
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• _________________________ are when the
debris from volcanoes gathers and forms a
pile through which magma is still released.
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• ________________________ are when layers
of solidified lava ________________with
layers of ash.
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• __________________are when exceptionally
viscous lava spreads _____________ before
solidifying.
• This creates a wide area of hardened magma
that more resembles a ____________ than a
mountain.
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• Sometimes, volcanic mountains collapse.
• When this happens the resulting crater is
called a _____________________.
• It happens when the magma chamber is
_______________________ and the hill falls
in on itself.
• The crater fills with _____________ very
often.
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• Even with all the danger, people choose to live
near volcanoes.
• The reason for this is because they choose to
take advantage of the incredibly __________
______________________.
• Volcanic ash is rich in _________________,
____________________and many other
substances excellent for farming.
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• Many more landforms can be formed by
__________________ as well.
• The include…
– ______________________________
– __________________
– __________________
– _________________________
– _________________________________
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• A _________________________ is when the
water wears away the rock around a
_______________ where magma has
hardened inside.
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• ________________ and _________________
are basically rock ridges formed from magma
leaking from a ________________ crack in the
crust.
• Dikes form _____________________.
• Sills form _____________________.
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• A ___________________ is formed when a
large body of magma cools within the crust.
VOLCANOES
• __________________________form when a
batholith is pushed toward the surface by
tectonic forces.
VOLCANOES
• ____________________________ and
______________are two other creations of
____________________.
• ___________________are when groundwater
is heated and slowly rises to the surface,
collecting in a pool.
• _________________are more violent, and
shoot from the surface due to built up
pressure.
VOLCANOES
• Some people use the pressure built up from
the volcanic areas to produce _____________.
• This is called _________________________
and it can be used to produce ____________
and _______________________.