Question 1

Volatiles refer to substances that ____________.

Accepted Answer

A)   crystallize most rapidly out of a melt
B)   melt immediately upon contact with a hot body of magma
C)   have a tendency to evaporate and are stable as gasesD) None of the above
E) All of the above

Question 2

Why don't all igneous rocks contain all the minerals listed in Bowen's Reaction Series?

Accepted Answer

A)   Minerals degrade with time, leaving only some of the series behind in igneous rocks.
B)   Crystallization may be complete before all of the minerals in the series have had time to form.
C)   Not all of the minerals in the series have the ability to form in every rock.
D)   Bowen's Reaction Series only applies to some igneous rocks, not all.E) B) and C)
F) None of the above

Question 3

A volcanic island arc occurs at ____________.

Accepted Answer

A)   the Aleutian Islands of Alaska
B)   the Andes Mountains
C)   Hawaii
D)   Mt. St. Helens, WashingtonE) All of the above
F) A) and B)

Question 4

Vesicles is a term used mostly to describe a texture in __________ igneous rocks.

Accepted Answer

A)   crystalline
B)   glassy
C)   pyroclasticD) All of the above
E) B) and C)

Question 5

Geologically,melts are equivalent to both ____________ and ____________.

Accepted Answer

A)   felsic magma; mafic magma
B)   felsic lava; mafic lava
C)   lavas; magmas
D)   fine-grained igneous rocks; coarse-grained igneous rocksE) C) and D)
F) B) and D)

Question 6

Pillow basalts,shown below,attain their distinctive blob-like shapes because their parent lavas do not travel far prior to solidification.This is because the parent lavas ____________.

Accepted Answer

A)   are completely devoid of volatiles and thus travel slowly
B)   erupt underwater and thus cool very quickly
C)   are highly felsic and thus travel slowly
D)   are ultramafic and thus freeze at exceptionally high temperaturesE) A) and D)
F) None of the above

Question 7

A majority of the melts in the Earth form through the partial melting of ultramafic mantle rock.These newly formed magmas are ____________.

Accepted Answer

A)   ultramafic
B)   mafic
C)   felsic
D)   intermediateE) A) and D)
F) B) and C)

Question 8

Which of the following would help distinguish continental hot spots from oceanic hot spots?

Accepted Answer

A)   the presence of water
B)   the presence of both mafic and felsic magmas
C)   the presence of other, extinct or active, volcanoes nearby
D)   the presence of basaltE) All of the above
F) A) and B)

Question 9

The geotherm is the rate of change of ____________.

Accepted Answer

A)   pressure with depth in Earth's interior
B)   temperature with depth in Earth's interior
C)   temperature with altitude in Earth's atmosphere
D)   temperature with latitude on Earth's surfaceE) B) and C)
F) All of the above

Question 10

The difference between lava and magma is that magma ____________.

Accepted Answer

A)   is light in color, whereas lava is dark
B)   usually has mafic composition, whereas lava usually has felsic composition
C)   is found beneath Earth's surface, whereas lava has reached the surface
D)   flows more quickly than lavaE) B) and C)
F) A) and D)

Question 11

When rock is partially melted,the chemistry of the melt is ____________.

Accepted Answer

A)   more mafic than the original chemistry of the rock that was partially melted
B)   more felsic than the original chemistry of the rock that was partially melted
C)   identical to the original chemistry of the rock that was partially melted
D)   completely unpredictable (it could be more mafic or more felsic) E) A) and B)
F) A) and C)

Question 12

A famous example of hot-spot volcanism occurs at ____________.

Accepted Answer

A)   the Aleutian Islands of Alaska
B)   the Andes Mountains
C)   the island of Hawaii
D)   Mt. St. Helens, WashingtonE) All of the above
F) A) and D)

Question 13

Stoping by magmas occurs when ____________.

Accepted Answer

A)   pieces of surrounding country rock are broken off and assimilated
B)   the magma stops flowing and starts to solidify
C)   the magma becomes fully solidified to form intrusive rock
D)   the magma alters a thin rind of surrounding country rockE) A) and D)
F) None of the above

Question 14

Viscosity depends on ____________.

Accepted Answer

A)   temperature
B)   volatile content
C)   silica content
D)   All of the above are correct.E) A) and D)
F) B) and D)

Question 15

As compared to mafic igneous rocks,all felsic igneous rocks ____________.

Accepted Answer

A)   cool and solidify more quickly
B)   cool and solidify more slowly
C)   solidify at higher temperatures
D)   solidify at lower temperaturesE) C) and D)
F) A) and C)

Question 16

An igneous rock with a mixed texture of coarse grains (phenocrysts) surrounded by fine crystals (groundmass) is termed ____________.

Accepted Answer

A)   porphyritic
B)   phaneritic
C)   aphanitic
D)   necroticE) B) and D)
F) A) and B)

Question 17

A volcanic neck,such as that seen at Shiprock,New Mexico (below) ,is a(n) ____________.

Accepted Answer

A)   sheet-like intrusion that lies parallel to surrounding layers of sedimentary rock
B)   cooled layer of lava
C)   intrusion formed within a volcano
D)   sheet-like intrusion that cuts across preexisting layersE) C) and D)
F) None of the above

Question 18

Bowen's continuous reaction series describes the crystallization behavior of a single mineral (with variable chemical composition) ,____________.

Accepted Answer

A)   olivine
B)   plagioclase
C)   pyroxene
D)   quartzE) A) and D)
F) B) and C)

Question 19

If you determine the composition of an igneous rock,you can deduce a number of things about the rock's origin.Which one of these is NOT one of those things?

Accepted Answer

A)   the rate at which it cooled
B)   the environment in which it formed
C)   the original source of the magma
D)   the exact age of the rockE) A) and C)
F) None of the above

Question 20

Bombs,ash,and cinders are all examples of ____________.

Accepted Answer

A)   intrusive igneous rocks
B)   hot spots
C)   volatiles
D)   pyroclastic debrisE) B) and C)
F) None of the above

Exam 4: Up From the Inferno: Magma and Igneous Rocks

Pillow basalts,shown below,attain their distinctive blob-like shapes because their parent lavas do not travel far prior to solidification.This is because the parent lavas ____________.

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As compared to mafic igneous rocks,all felsic igneous rocks ____________.

Correct AnswerverifiedShow Answer

When rock is partially melted,the chemistry of the melt is ____________.

Correct AnswerverifiedShow Answer

Viscosity depends on ____________.

Correct AnswerverifiedShow Answer

Bowen's continuous reaction series describes the crystallization behavior of a single mineral (with variable chemical composition) ,____________.

Correct AnswerverifiedShow Answer

A majority of the melts in the Earth form through the partial melting of ultramafic mantle rock.These newly formed magmas are ____________.

Correct AnswerverifiedShow Answer

Volatiles refer to substances that ____________.

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Geologically,melts are equivalent to both ____________ and ____________.

Correct AnswerverifiedShow Answer

Bombs,ash,and cinders are all examples of ____________.

Correct AnswerverifiedShow Answer

A volcanic neck,such as that seen at Shiprock,New Mexico (below) ,is a(n) ____________.

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A volcanic island arc occurs at ____________.

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Vesicles is a term used mostly to describe a texture in __________ igneous rocks.

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If you determine the composition of an igneous rock,you can deduce a number of things about the rock's origin.Which one of these is NOT one of those things?

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The geotherm is the rate of change of ____________.

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Why don't all igneous rocks contain all the minerals listed in Bowen's Reaction Series?

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A famous example of hot-spot volcanism occurs at ____________.

Correct AnswerverifiedShow Answer

The difference between lava and magma is that magma ____________.

Correct AnswerverifiedShow Answer

An igneous rock with a mixed texture of coarse grains (phenocrysts) surrounded by fine crystals (groundmass) is termed ____________.

Correct AnswerverifiedShow Answer

Which of the following would help distinguish continental hot spots from oceanic hot spots?

Correct AnswerverifiedShow Answer

Stoping by magmas occurs when ____________.

Correct AnswerverifiedShow Answer

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Geologically,melts are equivalent to both and .

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