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molten rock, suspended minerals and gases

magma is a mixture of


wet minerals and rocks melt at _______ temperatures than do dry minerals and rocks


As pressure increases, the temperature that dry things melts _______

pressure, temperature and water content

Three things that affect formation of magma

Because the pressure increases the melting temperature

why isn't Earth's mantle liquid?

it's present in the pore spaces of some rocks and can be bound in the crystal structure of some minerals

How is water present in rocks and minerals?


Magmas are named after _________rocks


Basaltic magma forms when rocks in the _______mantle melt

1 small.......2 low......3 quiet..

Basaltic magma contains__1___ amounts of silica and has __2___ viscosity and fuels relatively ____3__eruptions


Andesitic magma fuels volcanoes with_______ eruptions

1silica 2 intermediate

Andesitic magma contains about 60%___1___ and has ____2____viscosity

oceanic crust and sediments

Andesitic magma forms from __________ and _______


Rhyolitic magma forms beneath _______crust


Rhyolitic has the_____silica content of all


Rhyolitic magma has the same composition as_______

1 viscosity 2 slowly

Rhyolitic magma has high__1____ and flows ___2___


Rhyolitic magma produces very ________ volcanoes

viscosity increases with a decrease in temperature

How does the viscosity of magma change as magma cools?

It flows less quickly

Does cooler magma flow more or less quickly than hotter magma?

magma high in silica has a higher viscosity than magma low in silica

Is the viscosity of magma that is high in silica higher or lower than magma that is lower in silica?

basaltic lava flows faster because basaltic lava has less silica

Which type of lava-basaltic lava or rhyolitic lava-flows faster? Explain.

intrusive igneous rock body

what is a pluton?

pluton that is parallel to the rocks it intrudes

what is a sill?

a mushroom shaped pluton

what is a laccolith

irregular shaped pluton that is like a batholith but smaller

what is a stock?

pluton that cuts across preexisting rocks

what is a dike

mountain building

what is responsible for the formation of many plutons?


opening where lava erupts from


the depression around the vent


rock pieces thrown in air during eruption


smallest tephra is...


tephra that is larger than dust

fast moving clouds of ash, gas and other tephra

pyroclastic flows


forms when part of the volcano collapses into the magma chamber

volcanic blocks

large, angular volcanic fragments are called

volcanic bombs

large, rounded or streamlined tephra are called


most of the world's volcanoes form along_______plate boundaries

locations of most convergent boundary volcanoes

circum pacific belt marks...

western coasts of N and S America and down the eastern coast of Asia

circum pacific belt stretches along the

slabs of oceanic crust descend into mantle and melt; magma that forms is forced upwards and volcanoes form

how do volcanoes form?

Hawaiian Islands

___________ forming as a result of a hotspot

1 high temperature plumes melting the rock which causes magma to move upward and cause volcanoes
2 from the formation of flood basalts (outpourings of basalt lava) which erupt from fissures to form a flat plain or a plateau instead of volcanic mountains

hot spots can forms from_____1____and ______2_____

divergent plate

at______ _____ boundaries, magma squeezes through cracks and forms mountains

under water along ocean ridges

most volcanoes that are formed along divergent plate boundaries are___________


divergent plate boundary activity can be observed in _______

-composite volcano-in between cinder and shield, forms with layers of tephra and lava, has lots of silica, water and gases, most dangerous type of volcano

-cinder-cone volcano-small and steep, formed from tephra being thrown in air and then piling up around vent, lava has higher silica and water than shield volcanoes but still not a lot, contains a large volume of gases

-shield volcano-really big and sloped, lava has small amounts of gas and silica, forms when layers of basaltic lava accumulate during a non-explosive eruption

3 types of volcanoes

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