Question 1

A ______ is an intrusive structure that formed from magma that solidified within the "throat" of a volcano.

Accepted Answer

A)  volcanic neck
B)  sill
C)  laccolith
D)  batholith
E)  diapir A

Question 2

The huge volume of mafic magma that erupted to form the Columbia plateau basalts of Washington and Oregon are attributed to ___.

Accepted Answer

A)  sea floor spreading
B)  a hot mantle plume
C)  subduction
D)  magma mixing
E)  meteorite impact B

Question 3

Ultramafic igneous rocks are composed almost entirely of __.

Accepted Answer

A)  feldspar
B)  quartz
C)  ferromagnesian minerals
D)  calcite
E)  diamonds C

Question 4

Lava is magma on the Earth's surface.

Accepted Answer

A) True 
 B)False

Question 5

The sequence in which minerals crystallize in a cooling igneous melt is called Bowen's Reaction Series.

Accepted Answer

A) True 
 B)False

Question 6

Mafic magma generated in the _______ rises to the base of the crust.

Accepted Answer

A)  continental crust
B)  outer core
C)  asthenosphere
D)  spreading ridges
E)  mantle plumes

Question 7

Hawaii and __________ eruptions are related to intraplate igneous activity.

Accepted Answer

A)  Japan
B)  Cascade
C)  Yellowstone
D)  Honduras
E)  California

Question 8

Igneous rocks may be either ____ if they form on or near Earth's surface,or ___ if they solidify under ground.

Accepted Answer

A)  intrusive; volcanic
B)  volcanic; extrusive
C)  extrusive; intrusive
D)  plutonic; intrusive
E)  intrusive; extrusive

Question 9

___ is a coarse-grained igneous rock (grains > 1 mm diameter)with visible grains of quartz.

Accepted Answer

A)  Gabbro
B)  Granite
C)  Basalt
D)  Peridotite
E)  Andesite

Question 10

Both andesite and ___ are composed of feldspars and 30% to 50% ferromagnesian minerals.

Accepted Answer

A)  granite
B)  diorite
C)  pegmatite
D)  gabbro
E)  rhyolite

Question 11

Imagine two magmas that are identical in all respects (for example,same chemistry,pressure,volume)except that one magma is hotter than the other.Which magma will have the higher viscosity?

Accepted Answer

A)  The hotter magma will be more viscous.
B)  The cooler magma will be more viscous.
C)  The magmas will have the same viscosity.
D)  There is not sufficient information to establish the relative viscosities of these magmas.
E)  Temperature does not affect magma viscosity.

Question 12

A dike is a discordant intrusive igneous structure.

Accepted Answer

A) True 
 B)False

Question 13

The geothermal gradient,on average,is about _____.

Accepted Answer

A)  0.004 ∘\circ∘ C/km
B)  2.5 ∘\circ∘ C/km
C)  25 ∘\circ∘ C/km
D)  30 ∘\circ∘ C/km
E)  2500 ∘\circ∘ C/km

Question 14

What is the process through which magma differentiation takes place?

Accepted Answer

A)  crystal settling
B)  partial melting
C)  viscosity of the magma
D)  heating of the country rock
E)  subduction

Question 15

A useful tool illustrating the relationships among igneous,sedimentary,and metamorphic rocks is called the ___.

Accepted Answer

A)  weathering and erosion of surface features
B)  plate tectonic cycle
C)  relationships between preexisting rock
D)  rock cycle
E)  Bowen's reaction series

Question 16

Although batholiths may contain mafic and intermediate rocks,they almost never composed of granite.

Accepted Answer

A) True 
 B)False

Question 17

What is the sequence of crystallization along the discontinuous branch of Bowen's reaction series?

Accepted Answer

A)  sodium-rich to calcium-rich plagioclase
B)  quartz,potassium feldspar,biotite
C)  silicic,felsic,mafic,intermediate
D)  olivine,pyroxene,amphibole,biotite
E)  framework,double chain,single chain,sheet,isolated

Question 18

Igneous rock names are based on grain shape and chemical composition.

Accepted Answer

A) True 
 B)False

Question 19

On its slow journey through the crust,mafic magma evolves into intermediate magma by differentiation and assimilation of ______.

Accepted Answer

A)  mantle rocks
B)  basalt
C)  gabbro
D)  silicic rocks

Question 20

The melting point of a rock decreases with increasing pressure.

Accepted Answer

A) True 
 B)False

Exam 11: Igneous Rocks, Intrusive Activity, and the Origin of Igneous Rocks

A ______ is an intrusive structure that formed from magma that solidified within the "throat" of a volcano.

The huge volume of mafic magma that erupted to form the Columbia plateau basalts of Washington and Oregon are attributed to ___.

Ultramafic igneous rocks are composed almost entirely of __.

Lava is magma on the Earth's surface.

The sequence in which minerals crystallize in a cooling igneous melt is called Bowen's Reaction Series.

Mafic magma generated in the _______ rises to the base of the crust.

Hawaii and __________ eruptions are related to intraplate igneous activity.

Igneous rocks may be either __ if they form on or near Earth's surface,or _ if they solidify under ground.

___ is a coarse-grained igneous rock (grains > 1 mm diameter) with visible grains of quartz.

Both andesite and ___ are composed of feldspars and 30% to 50% ferromagnesian minerals.

Imagine two magmas that are identical in all respects (for example,same chemistry,pressure,volume) except that one magma is hotter than the other.Which magma will have the higher viscosity?

A dike is a discordant intrusive igneous structure.

The geothermal gradient,on average,is about _____.

What is the process through which magma differentiation takes place?

A useful tool illustrating the relationships among igneous,sedimentary,and metamorphic rocks is called the ___.

Although batholiths may contain mafic and intermediate rocks,they almost never composed of granite.

What is the sequence of crystallization along the discontinuous branch of Bowen's reaction series?

Igneous rock names are based on grain shape and chemical composition.

On its slow journey through the crust,mafic magma evolves into intermediate magma by differentiation and assimilation of ______.

The melting point of a rock decreases with increasing pressure.