Download Study Guide: Volcano Test

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Study Guide: Volcano Test
Volcanoes and Plate Tectonics (p. 82-85)
volcano - a mountain formed when magma comes to the surface and builds up
lava - when magma reaches the surface and cools
magma - a molten mixture of rock-forming substances, gases, and water from the mantle
Ring of Fire - a major volcanic belt formed by the many volcanoes that surround the Pacific Ocean
island arc - a string of volcanic islands
3 Places Volcanoes Can Form:
A
A. divergent boundary - two plates moving apart; allows
magma to rise to the surface and causes a volcano to form
B. convergent boundary - two plates moving together; one
plate subducts causing a volcano to form
hot spot - an area where material deep within the mantle rises
and then melts forming magma; a volcano forms above a hot
spot when magma erupts through the crust and reaches the
surface
B
Properties of Magma (p. 87-90)
element- a substance that cannot be broken down into other substances
compound- a substance made of two or more elements that have been chemically combined
physical property- any characteristic of a substance that can be observed or measured without changing the
composition of the substance (ex. density, hardness, melting point, boiling point)
chemical property- any property that produces a change in the composition of matter (ex. ability to burn, ability
to combine, or react, with other substances)
viscosity- the resistance of a liquid to flowing; low viscosity flows freely, high viscosity resist flowing
silica- a compound made up of oxygen and silicon particles
pahoehoe- fast-moving, hot lava with low viscosity; forms wrinkles, billows, and ropelike coils
a’a- slower-moving, cooler lava with high viscosity; hardens into a rough surface with jagged chunks
Viscosity
of Magma
Thickness
Ability to
Flow
Temperature
Silica
Content
Color
Rock
Formed
High
Thick
difficult, like
cold honey
lower (cooler)
High
light
colored
Rhyolite
(like granite)
Low
Thin
easy, like
water
higher (hot)
Low
dark
colored
Basalt
Volcanic Eruptions (p. 91-98)
magma chamber- a pocket under a volcano where magma collects
pipe- a long tube in the ground that connects the magma chamber to the Earth’s surface
vent- an opening in a volcano where molten rock and gas escape
lava flow- the area covered by lava as it pours out of a vent
crater- a bowl-shaped area that may form at the top of a volcano around the central vent
pyroclastic flow- occurs when an explosive eruption hurls out a mixture of hot gases, ash, cinders, and bombs
dormant- a sleeping volcano; it may awaken and erupt again sometime, but hasn’t erupted in a long time
extinct- a dead volcano; it will never erupt again
stages of a volcano- active, dormant, extinct
Name________________________________________________________________Per_______Date________________
Type of
Volcano
Shape
Style of Eruption
Characteristics
of Magma
Diagram
Examples
shield
wide, gently
sloping
mountain
quiet
lava pours out
and hardens
building up layers
low viscosity
low silica
content
thin
fluid
Hawaiian Islands,
Hawaii
cinder
cone
steep, coneshaped hill or
small mountain
explosive
ash, cinders, and
bombs erupt
explosively
high viscosity
high silica
content
thick
sticky
Paricutin, Mexico
composite
tall, coneshaped
mountains with
sloping sides
alternating quiet
and explosive
eruptions with
lava and ash
alternating
between high
viscosity and
low viscosity
Mount St. Helens,
Washington State
Volcanic Landforms (p. 99-105)
shield volcano- a volcano with wide, gently sloping sides and quiet eruptions
cinder cone volcano- a volcano with steep sides and a flat top with explosive eruptions
composite volcano- a volcano with tall, cone-shaped mountains with alternating quiet and explosive eruptions
caldera- a huge hole left by the collapse of a volcanic mountain
volcanic neck- forms when magma hardens in a volcano’s pipe; softer rock wears away leaving behind the hard
rock of the volcanic neck
dike- magma that is squeezed vertically (up and down) into rock layers and hardens
sill- magma that is squeezed horizontally (sideways) into rock layers and hardens
batholith- a mass of rock formed when a large body of magma cools inside the crust
geothermal activity- magma in Earth’s surface heats underground water (ex. hot springs and geysers)
geyser- a fountain of water and steam that erupts from the ground
1
volcanic neck
2
1
3
1
Geyser
4
batholith
sill
1
5
1
dike
How a Caldera Forms