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Transcript
Volcanoes
C20-25
Volcano
A
mountain formed when
red-hot melted rock
flows through a crack
onto the earth’s surface
Magma
 Melted
rock inside Earth
Lava
 Melted
rock that reaches
Earth’s surface
Vent
A
rocky opening that
magma flows through to
reach the surface of
Earth
Magma Chamber
An
underground pool
that holds hot magma
A
Crater
large basin formed at the
top of a volcano when the
top collapses after an
eruption
 Rain can collect in a crater
and form a lake. (Crater
Lake, in Oregon)
Ways Volcanoes Form
(#1)
 Plates
in the ocean move away
from each other. As they
move apart, magma rises
toward the surface. When it
reaches the surface, it hardens
to form new ocean floor.
Ways Volcanoes Form
(#2)
 When
ocean and continent
plates collide (hit), the ocean
plate falls into the mantle and
melts. Then it comes to the
surface as lava, through a
vent. This forms volcanic
How Volcanoes Form
#3
Plates
move over a hot
spot in the mantle and
hot lava comes through
the surface to form
volcanic islands.
Hawaiian Volcano
Hardened
Lava
Shield Volcanoes
Large,
gently sloping
mountains
Form from runny lava
Many are found in
Hawaii, rising from the
ocean floor
Cinder Cone Volcanoes
Have
steep sides
Made of hardened lava
chunks
Not very tall
Composite Volcanoes
 Medium-sized
volcanoes
 Made of lava and cinders
 Have steep peaks and sloping
sides
 Mt. Fuji (Japan), St. Helens (USA)
 Mount Vesuvius in Italy
 Explode when they erupt
Mt. St. Helens, Washington
Volcanoes Help Earth
 Minerals
deposited into the
soil around the volcano help
crops grow.
 Form new crust on
continents
 Form new ocean floor
Volcanoes Harm Earth
Erupting gasses and hot lava
destroy everything in their
paths.
Temperature at an eruption
point can reach 1470 degrees!
The powerful blasts may be felt
10-15 miles away!
Review
Volcanoes form when melted rock
called lava flows onto Earth’s surface.
 Most volcanoes form along plate
edges.
 They add crust and ocean floor.
 They add minerals to the soil.
 They can destroy anything in their
path.
