Question 1

What weight percentage of silica (SiO?) typifies granites and rhyolites?

Accepted Answer

A)  30%
B)  90%
C)  70%
D)  50%

Question 2

What type of igneous rock is both glassy and highly vesicular?

Accepted Answer

The answer of What type of igneous rock is both...

Question 3

What is the role of water and other volatiles that are driven from the descending plate in the diagram below?

Accepted Answer

These volatiles lowe...

Question 4

Intermediate rocks like andesite and diorite ________.

Accepted Answer

A)  are major constituents of the oceanic crust
B)  rarely contain plagioclase feldspar, pyroxenes or amphiboles
C)  form mainly in convergent continental margins
D)  contain the semiprecious gems beryl, topaz, and tourmaline

Question 5

Exceptionally coarse grained felsic plutonic rocks that are rich in rare minerals and trace elements are probably ________.

Accepted Answer

A)  pegmatites
B)  obsidians
C)  porphyrys
D)  welded tuffs

Question 6

Which magma is most likely to quench (congeal) to a natural glass?

Accepted Answer

A)  highly viscous; cools quickly
B)  highly viscous; cools slowly
C)  highly fluid; cools slowly
D)  highly fluid; cools quickly

Question 7

In general, what happens in terms of composition as crystallization proceeds down the Bowen's reaction series?

Accepted Answer

The early-formed silicates are enriched ...

Question 8

The process of ________ is driven by ________ and transforms a magma into an igneous rock.

Accepted Answer

A)  crystallization, cooling (heat loss) 
B)  intrusion, overlying rock weight
C)  partial melting, pressure increase
D)  volcanism, internal heating

Question 9

Magmas rise to shallower depths and intrude the crust or extrude on the surface because ________.

Accepted Answer

A)  of buoyancy, the magmas are hotter and less dense than the surrounding rocks where they form
B)  of centrifugal and tidal forces as the Earth spins
C)  the pressure at depth is so great that the magmas are forced upwards
D)  earthquakes shake the crust and allow the magma to escape upwards

Question 10

What do pumice and obsidian have in common?

Accepted Answer

A)  basaltic composition
B)  glassy texture
C)  ultramafic composition
D)  phaneritic texture

Question 11

Intrusive rocks are named for the old God "Trudere".

Accepted Answer

A) True 
 B)False

Question 12

Briefly explain how magma compositions can change through magma mixing.

Accepted Answer

Renewed injection of a primiti...

Question 13

Name the texture that requires a magnifying glass or microscope to see individual mineral grains.

Accepted Answer

A)  aphanitic
B)  porphyritic
C)  phaneritic
D)  pegmatitic

Question 14

What tabular, nearly horizontal, igneous rock body is intruded concordantly between layers of older sedimentary rock?

Accepted Answer

The answer of What tabular, nearly horizontal, igneous rock body...

Question 15

Which texture would be most unlikely to occur in an extrusive igneous rock?

Accepted Answer

A)  pyroclastic
B)  glassy
C)  aphanitic
D)  phaneritic

Question 16

________ is a pyroclastic igneous rock with fragments smaller than 2 mm.

Accepted Answer

The answer of ________ is a pyroclastic igneous rock with...

Question 17

Yellowstone National Park is most famous for what?

Accepted Answer

A)  rich copper ore deposits
B)  komatiites; ultramafic lavas
C)  diamonds in rhyolite veins
D)  rhyolitic volcanism

Question 18

Compared to volcanic rocks, plutonic ones have many more crystals in the same volume.

Accepted Answer

A) True 
 B)False

Question 19

What is the average temperature rise below Earth's surface due to the geothermal gradient?

Accepted Answer

25 degrees...

Question 20

Which of the following best describes an aphanitic texture?

Accepted Answer

A)  The rock is crystalline; mineral grains are too small to be visible without a magnifying lens or microscope.
B)  The mineral grains have glassy textures.
C)  The rock consists of broken, volcanic-rock and mineral fragments.
D)  The rock is crystalline; mineral grains are of distinctly different sizes.

Exam 3: Igneous Rocks

What type of igneous rock is both glassy and highly vesicular?

Correct AnswerverifiedShow Answer

Compared to volcanic rocks, plutonic ones have many more crystals in the same volume.

Correct AnswerverifiedShow Answer

What is the average temperature rise below Earth's surface due to the geothermal gradient?

Correct Answerverified25 degrees...View AnswerShow Answer

What tabular, nearly horizontal, igneous rock body is intruded concordantly between layers of older sedimentary rock?

Correct AnswerverifiedShow Answer

In general, what happens in terms of composition as crystallization proceeds down the Bowen's reaction series?

Correct AnswerverifiedThe early-formed silicates are enriched ...View AnswerShow Answer

What do pumice and obsidian have in common?

Correct AnswerverifiedShow Answer

Which of the following best describes an aphanitic texture?

Correct AnswerverifiedShow Answer

Exceptionally coarse grained felsic plutonic rocks that are rich in rare minerals and trace elements are probably ________.

Correct AnswerverifiedShow Answer

Which texture would be most unlikely to occur in an extrusive igneous rock?

Correct AnswerverifiedShow Answer

Name the texture that requires a magnifying glass or microscope to see individual mineral grains.

Correct AnswerverifiedShow Answer

What weight percentage of silica (SiO?) typifies granites and rhyolites?

Correct AnswerverifiedShow Answer

What is the role of water and other volatiles that are driven from the descending plate in the diagram below?

Correct AnswerverifiedThese volatiles lowe...View AnswerShow Answer

Which magma is most likely to quench (congeal) to a natural glass?

Correct AnswerverifiedShow Answer

Yellowstone National Park is most famous for what?

Correct AnswerverifiedShow Answer

Magmas rise to shallower depths and intrude the crust or extrude on the surface because ________.

Correct AnswerverifiedShow Answer

Intermediate rocks like andesite and diorite ________.

Correct AnswerverifiedShow Answer

Intrusive rocks are named for the old God "Trudere".

Correct AnswerverifiedShow Answer

The process of ________ is driven by ________ and transforms a magma into an igneous rock.

Correct AnswerverifiedShow Answer

Briefly explain how magma compositions can change through magma mixing.

Correct AnswerverifiedRenewed injection of a primiti...View AnswerShow Answer

________ is a pyroclastic igneous rock with fragments smaller than 2 mm.

Correct AnswerverifiedShow Answer

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25 degrees...
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The early-formed silicates are enriched ...
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These volatiles lowe...
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The process of is driven by and transforms a magma into an igneous rock.

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Renewed injection of a primiti...
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