Deck 5: Igneous Environments

Question 1

The site on the accompanying figure that would most likely form a rock that has a nonwelded texture with many fine particles is:

A) A
B) B
C) C
D) D
E) E

Answer 1

E

Question 2

A vesicular igneous texture indicates that:

A) there was a lot of gas in the magma
B) the rock cooled quickly
C) the rock broke apart as it flowed
D) the rock cooled slowly
E) the ash and pumice were hot and became compacted

Answer 2

A

Question 3

The site on the accompanying figure that would most likely form a rock with large crystals is:

A) A
B) B
C) C
D) D
E) E

Answer 3

A

Question 4

The site on the accompanying figure that would most likely form a rock that is glassy with no volcanic ash is:

A) A
B) B
C) C
D) D
E) E

Question 5

A welded igneous texture indicates that:

A) there was a lot of gas in the magma
B) the rock cooled quickly
C) the rock broke apart as it flowed
D) the rock cooled slowly
E) the ash and pumice were hot and became compacted

Question 6

What does this texture indicate about the formation of this rock?

A) It formed from an explosive pyroclastic eruption.
B) The rock solidified at great depth.
C) The magma formed some crystals before rising closer to the surface and solidifying.
D) The magma had abundant dissolved gas.

Question 7

A porphyritic igneous texture indicates that:

A) there was water in the magma
B) the rock cooled slowly and then quickly
C) the rock broke apart as it flowed
D) the rock cooled slowly
E) the ash and pumice were hot and became compacted

Question 8

The site on the accompanying figure that would mostly likely form a rock that is fine grained has small crystals but is not glassy) is:

A) A
B) B
C) C
D) D
E) E

Question 9

What texture is displayed by the igneous rock in this photograph?

A) vesicles
B) breccia
C) porphyritic
D) glassy
E) none of these

Question 10

Coarsely crystalline igneous textures indicate that:

A) there was a lot of gas in the magma
B) the rock cooled quickly
C) the rock broke apart as it flowed
D) the rock cooled slowly
E) the ash and pumice were hot and became compacted

Question 11

What texture is displayed by the igneous rock in this photograph?

A) vesicles
B) breccia
C) porphyritic
D) glassy
E) none of these

Question 12

A finely crystalline or glassy igneous texture indicates that:

A) there was a lot of gas in the magma
B) the rock cooled quickly
C) the rock broke apart as it flowed
D) the rock cooled slowly
E) the ash and pumice were hot and became compacted

Question 13

Which numbered feature on this figure formed by an explosive pyroclastic eruption?

A) Location 1, the Valles Caldera
B) Location 2, dark basalt flows along the Rio Grande
C) Location 3, the dark, basaltic volcanoes
D) Location 4, pegmatite in the northeastern part of the area

Question 14

An igneous pegmatite indicates that:

A) there was water in the magma
B) the rock cooled slowly and then quickly
C) the rock broke apart as it flowed
D) the rock cooled quickly
E) the ash and pumice were hot and became compacted

Question 15

The site on the accompanying figure that would most likely form a rock that has a welded texture is:

A) A
B) B
C) C
D) D
E) E

Question 16

A volcanic breccia texture indicates that:

A) there was a lot of gas in the magma
B) the rock cooled quickly
C) the rock broke apart as it flowed
D) the rock cooled slowly
E) the ash and pumice were hot and became compacted

Question 17

What texture is displayed by the igneous rock in this photograph?

A) vesicles
B) breccia
C) porphyritic
D) glassy
E) none of these

Question 18

What does this welded texture indicate about the formation of this rock?

A) It formed from an explosive pyroclastic eruption.
B) The rock solidified at great depth.
C) The magma formed some crystals before rising closer to the surface and solidifying.
D) The magma had abundant dissolved gas.

Question 19

What texture is displayed by the igneous rock in this photograph?

A) vesicles
B) breccia
C) porphyritic
D) glassy
E) none of these

Question 20

What does this texture indicate about the formation of this rock?

A) It formed from an explosive pyroclastic eruption.
B) The rock solidified at great depth.
C) The magma formed some crystals before rising closer to the surface and solidifying.
D) The magma had abundant dissolved gas.

Question 21

Which letter in this classification table indicates the position of rhyolite?

A) A
B) B
C) C
D) D
E) E

Question 22

Which number of this figure indicates transfer of thermal energy by conduction?

A) 1, heating of adjacent rocks by a magma
B) 2, cooling of hot lithosphere by contact with cooler rocks and seawater
C) 3, heating of the subducted plate by contact with hotter overlying materials
D) all of these

Question 23

To study an igneous rock with a phaneritic texture, a geologist would need:

A) a hand lens
B) a microscope
C) no special equipment

Question 24

Which of the following rock photographs depicts an igneous rock that trapped gas?

A)
B)
C)
D)

Question 25

Which letter in this classification table indicates the position of andesite?

A) A
B) B
C) C
D) D
E) E

Question 26

Which of the following can occur within a magma chamber?

A) Sinking or floating crystals may change the composition of the remaining magma.
B) Wall rocks can melt and become incorporated into the magma.
C) If two magmas mix, the resulting magma would be between the compositions of the two magmas.
D) All of these.

Question 27

Which of the following rock photographs depicts a felsic igneous rock?

A)
B)
C)
D)

Question 28

Rock that has formed from cooling magma or lava is:

A) Igneous rock
B) Metamorphic rock
C) Sedimentary rock

Question 29

Which letter in this classification table indicates the position of gabbro?

A) A
B) B
C) C
D) D
E) E

Question 30

A coarse-grained intrusive igneous rock composed mostly of feldspar and quartz is called:

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

Question 31

Tuff and volcanic breccia are both composed of a variety of igneous fragments. Their classification as either felsic, intermediate, or mafic therefore depends on the particular:

A) mineral content of each individual unit.
B) average grain size of each individual unit.
C) thickness of each individual unit.

Question 32

Which number on this figure indicates heating by conduction?

A) 1, direct contact between the burner and the pan
B) 2, heating by thermal radiation through the air
C) 3, heated water expands and rises to the top of the pan and then cools and flows back down
D) 4, moving a pan of water away from the stove

Question 33

Which of the following processes has added heat to Earth's interior during or after its formation?

A) collision of asteroids and meteoroids with Earth
B) formation and sinking of masses of iron and nickel
C) radioactive decay
D) all of these

Question 34

Which letter in this classification table indicates the position of granite?

A) A
B) B
C) C
D) D
E) E

Question 35

Which of the following igneous rocks can be composed of fragments?

A) tuff
B) scoria
C) volcanic breccia
D) all of these

Question 36

Which letter in this classification table indicates the position of basalt?

A) A
B) B
C) C
D) D
E) E

Question 37

Which of the following photographs depicts an igneous rock where the magma cooled slowly at first and then had fast cooling?

A)
B)
C)
D)

Question 38

Which of the following rock types does NOT involve dissolved gas in the magma?

A) tuff
B) pumice
C) scoria
D) diorite
E) vesicular basalt

Question 39

Which of the following rock types requires dissolved gas in the magma?

A) granite
B) pumice
C) gabbro
D) diorite
E) andesite

Question 40

The main process that happens during the alpha type of radioactive decay is:

A) an electron is given off
B) an electron is absorbed and turned into a neutron
C) an atom splits into two pieces
D) an alpha particle combines with a small atom to make a larger one

Question 41

Which of the following acts to keep a rock solid instead of melting)?

A) an increase in temperature
B) an increase in the vibration within a lattice
C) an increase in confining pressure
D) none of these

Question 42

The liquid-solid boundary on this graph slopes down and to the right because:

A) temperature increases down in the earth
B) temperature decreases down in the earth
C) pressure increases down in the earth
D) none of these

Question 43

Use this graph that relates temperature and pressure to answer this question. What is required if a rock in position B moves to position A on the graph?

A) Temperature would have to decrease.
B) Temperature and pressure would have to increase.
C) Temperature would have to increase and pressure decrease.
D) Temperature would have to decrease and pressure increase.

Question 44

Which of the following changes in conditions could represent melting of continental crust from the introduction of a mafic magma?

A) from A to B
B) from A to C
C) from A to D
D) from C to B
E) from B to D

Question 45

What does the texture of this rock indicate about its cooling history? The magma cooled:

A) entirely at the surface
B) for a while at some depth and then rose to the surface where it finished solidifying
C) slowly under relatively deep conditions
D) slowly in the presence of water

Question 46

Which of the following changes in conditions represents the main cause of melting beneath mid-ocean ridges?

A) from A to B
B) from A to C
C) from A to D
D) from C to B
E) from D to B

Question 47

Which of the following changes in conditions indicates heating of the rock?

A) from A to B
B) from B to C
C) from C to D
D) from D to A
E) none of these

Question 48

Which of the following is an example of heat transfer by convection?

A) water within a pan is heated and flows in a circular path
B) seawater is drawn into a mid-ocean ridge, heated, and rises
C) the rise of material beneath mid-ocean ridges coupled with subduction
D) all of these

Question 49

Which of the following changes in conditions would represent heating during burial?

A) from A to B
B) from B to C
C) from C to D
D) from D to A
E) from A to C

Question 50

How does the addition of water cause melting?

A) it heats the rocks
B) it decreases the pressure on the rocks
C) it increases the temperature while decreasing the pressure
D) it changes the location of the liquid-solid boundary

Question 51

Which of the following is the best example of heat transfer by conduction?

A) a pan is placed directly on a burner
B) water within the pan flows in a circular path
C) a burner gives heat through the air without touching the object
D) seawater is drawn into a mid-ocean ridge

Question 52

The geothermal gradient is the:

A) increase of the Earth's temperature with increase in depth
B) increase of the Earth's temperature on the surface as the Sun rises
C) decrease of the Earth's temperature with increase of depth
D) decrease of the Earth's temperature on the surface as the Sun sets

Question 53

The main source of heat energy for the Earth's interior is a direct result of:

A) alpha decay, which is an unstable atom losing 2 protons and 2 neutrons
B) beta decay, which is an unstable atom losing an electron
C) gamma decay, which is an unstable atom losing a photon

Question 54

What does the texture of this rock indicate about its cooling history? The magma cooled:

A) entirely at the surface
B) for a while at some depth and then rose to the surface where it finished solidifying
C) slowly under relatively deep conditions
D) slowly and underwater

Question 55

As depth increases into the Earth,:

A) there is an increase in temperature and pressure
B) there is an increase in temperature only
C) there is an increase in pressure only
D) there is an increase in temperature and a decrease in pressure

Question 56

Which of the following is the best example of heat transfer by conduction?

A) newly created lithosphere loses heat to adjacent rocks
B) water flows in a circular path in a pan
C) a burner gives heat through the air without touching the object
D) seawater is drawn into a mid-ocean ridge

Question 57

Which of the following changes in conditions would cause melting of a solid rock?

A) from A to B
B) from B to C
C) from C to D
D) from A to D
E) from A to C

Question 58

How could a rock at point C be melted?

A) increase in temperature
B) decrease in pressure
C) increase in temperature accompanied by a decrease in pressure
D) all of these

Question 59

Which of the following changes in conditions represents decompression melting?

A) from A to B
B) from B to A
C) from B to C
D) from C to B
E) from D to A

Question 60

Which number on this figure indicates transfer of thermal energy by a convection cell?

A) 1, direct contact between the burner and the pan
B) 2, heating by thermal radiation through the air
C) 3, heated water expands and rises to the top of the pan and then cools and flows back down
D) 4, moving a pan of water away from the stove

Question 61

An igneous rock that solidifies on Earth's surface is called an):

A) intrusive rock
B) extrusive rock
C) magma rock
D) vesicular rock

Question 62

On this figure of Bowen's Reaction Series, which mineral would crystallize last from magma?

A) 1, olivine
B) 2, calcium-rich plagioclase
C) 3, sodium-rich plagioclase
D) 4, K-feldspar

Question 63

Which of the following is common during crystallization of a magma?

A) felsic minerals crystallize first
B) mafic minerals are light and float in most magma chambers
C) felsic crystals are heavy and sink in most magma chambers
D) all crystals form at about the same time
E) none of these

Question 64

Which of the following igneous rocks would be formed by the fastest cooling?

A) very coarse granite pegmatite
B) coarse granite
C) medium-grained granite
D) fine-grained granite
E) volcanic glass

Question 65

Which of the following igneous rocks has a texture consistent with a magma that cooled and solidified slowly at first, followed by more rapid cooling?

A) small felsic crystals enclosed in large mafic ones
B) small mafic crystals enclosed in large felsic ones
C) large crystals like those in pegmatite
D) large, early formed crystals surrounded by smaller, late formed crystals

Question 66

Which of the following is likely to be true about the magma that formed the left volcanic feature compared to the right one in this figure?

A) the magma has a higher viscosity
B) the magma has a higher silicate content
C) the magma is probably more felsic
D) all of these

Question 67

Which of the following is likely to be true about the left volcanic feature compared to the right one in this figure?

A) the magma has a higher viscosity
B) the magma has fewer silicate chains
C) the magma probably formed at a higher temperature
D) all of these

Question 68

Which of the following statements correctly states how early crystallization affects the composition of a magma? Use the graph.

A) Early crystallization causes the MgO mafic) content to decline in the magma.
B) Early crystallization causes the MgO content to increase in the magma.
C) Early crystallization causes the SiO content to decline in the magma.

Question 69

Which of the following minerals would likely crystallize early from magma?

A) mafic minerals
B) quartz
C) muscovite
D) potassium feldspar

Question 70

The place in the crust or mantle where igneous rocks begin to form is called the:

A) source area
B) magma chamber
C) intrusive area
D) extrusive area

Question 71

Which of the following is NOT a way that magma can lose heat to begin solidifying?

A) conduction to surrounding solid rocks
B) loss of thermal energy to the air and water
C) water that is heated and circulated near the magma
D) an increase in the rate of radioactive decay

Question 72

Which of the following processes could result in a felsic magma?

A) partial melting of an intermediate-composition source
B) partial melting of continental crust
C) formation and settling of mafic crystals in an intermediate magma
D) all of these

Question 73

Which of the following causes magma to be less viscous?

A) a lower temperature
B) fewer silicate chains in the magma
C) a more felsic composition
D) a higher percentage of crystals
E) none of these

Question 74

Which of the following factors helps magma rise toward Earth's surface?

A) pressure decreases with increasing depth
B) magma is more dense and therefore tougher than the surrounding solid rocks
C) gas bubbles generally form at great depth and drive magma upward
D) none of these

Question 75

What is a path for magma as it solidifies at great depth and then is uplifted slowly toward the surface?

A) from B to A
B) from C to A
C) from C to B to A
D) from D to C to B
E) from D to C to A

Question 76

Which of the following igneous rocks would be formed by the slowest cooling?

A) coarse granite
B) medium-grained granite
C) fine-grained granite
D) volcanic glass
E) there is not enough information to tell

Question 77

When melting forms magma:

A) rocks in the source region generally are completely melted
B) partial melting produces a magma that is more felsic than the source
C) melting of the mantle generally produces felsic magma
D) melting of continental crust generally produces mafic magma
E) none of these

Question 78

Which are important ways that magma can raise through the crust?

A) through fractures that can form dikes
B) pieces of the wall rocks that break off and provide space
C) tectonic forces can help open pathways
D) magma is hotter and less dense than its surrounding
E) all of these

Question 79

An igneous rock that solidifies below the surface is called an):

A) intrusive rock
B) extrusive rock
C) magma rock
D) lava rock

Question 80

Which of the following is NOT a factor that affects the viscosity of magma?

A) pressure
B) temperature
C) composition
D) crystal content
E) depth