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)  are highly flammable. 
D)  evaporate easily and exist as gases. 
A)  crystallize most rapidly out of a melt. 
B)  melt immediately upon contact with a hot body of magma. 
C)  are highly flammable. 
D)  evaporate easily and exist as gases. D

Question 2

Important volatiles in magmas include

Accepted Answer

A)  mafic minerals,such as olivine. 
B)  potassium and aluminum. 
C)  water and carbon dioxide. 
D)  silicon and iron. 
A)  mafic minerals,such as olivine. 
B)  potassium and aluminum. 
C)  water and carbon dioxide. 
D)  silicon and iron. C

Question 3

The figure below shows mafic magma as it meets the seafloor,which cools to form an igneous rock called

Accepted Answer

A)  pegmatite. 
B)  pillow basalt. 
C)  laccolith. 
D)  pluton. 
A)  pegmatite. 
B)  pillow basalt. 
C)  laccolith. 
D)  pluton. B

Question 4

What is obsidian? How does it form?

Accepted Answer

Obsidian is a vesicle-free,fel

Question 5

A fragmental,extrusive igneous rock is referred to as which of the following?

Accepted Answer

A)  crystalline 
B)  vitric 
C)  pyroclastic 
D)  vesicular 
A)  crystalline 
B)  vitric 
C)  pyroclastic 
D)  vesicular

Question 6

Bombs,ash,and cinders are all examples of

Accepted Answer

A)  intrusive igneous rocks. 
B)  lava flows. 
C)  volatiles. 
D)  pyroclastic debris. 
A)  intrusive igneous rocks. 
B)  lava flows. 
C)  volatiles. 
D)  pyroclastic debris.

Question 7

If you find a tuff in the field,what type of geologic activity could you reasonably assume has occurred?

Accepted Answer

A)  an igneous intrusion 
B)  sea-level rise 
C)  a volcanic eruption 
D)  tectonic uplift 
A)  an igneous intrusion 
B)  sea-level rise 
C)  a volcanic eruption 
D)  tectonic uplift

Question 8

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

Accepted Answer

A)  porphyritic. 
B)  phaneritic. 
C)  aphanitic. 
D)  vitric. 
A)  porphyritic. 
B)  phaneritic. 
C)  aphanitic. 
D)  vitric.

Question 9

Viscosity does NOT depend on

Accepted Answer

A)  temperature. 
B)  volatile content. 
C)  silica content. 
D)  the total volume of the magma body. 
A)  temperature. 
B)  volatile content. 
C)  silica content. 
D)  the total volume of the magma body.

Question 10

Rhyolite and granite are both felsic igneous rocks,although they have different cooling histories,and consequently different textures.Explain the difference between the two rock types from a cooling perspective and be specific about which igneous texture can be applied to which rock.

Accepted Answer

Rhyolite is extrusive and consequently c

Question 11

A body of rock starts at location A in the graph below.The rock,over a period of time,moves to location B and begins to melt.This is an example of melting due to

Accepted Answer

A)  fractional crystallization. 
B)  heat transfer. 
C)  addition of volatiles. 
D)  decompression. 
A)  fractional crystallization. 
B)  heat transfer. 
C)  addition of volatiles. 
D)  decompression.

Question 12

A vast,composite intrusive igneous body that covers hundreds of square kilometers (in a map view)is called a

Accepted Answer

A)  pluton. 
B)  dike. 
C)  batholith. 
D)  sill. 
A)  pluton. 
B)  dike. 
C)  batholith. 
D)  sill.

Question 13

Briefly explain why and how magmas rise within the Earth.

Accepted Answer

Magmas are less dense than their solid s

Question 14

Which type of magma has the greatest silica content?

Accepted Answer

A)  felsic 
B)  intermediate 
C)  mafic 
D)  ultramafic 
A)  felsic 
B)  intermediate 
C)  mafic 
D)  ultramafic

Question 15

The difference between magma and lava is

Accepted Answer

A)  magma cools more rapidly than lava. 
B)  magma is found at the surface,whereas lava is found below the surface. 
C)  magma is melt underground,whereas lava is melt that has emerged from the surface. 
D)  There is no difference; the two terms mean the same thing. 
A)  magma cools more rapidly than lava. 
B)  magma is found at the surface,whereas lava is found below the surface. 
C)  magma is melt underground,whereas lava is melt that has emerged from the surface. 
D)  There is no difference; the two terms mean the same thing.

Question 16

List the four major magma compositions in order of silica content.
 $\begin{array}{c}
\begin{array}{|l|}
 \hline \text { Silica Content}\
 \hline \
\text { Highest}\
\
\
\text { Lowest}\
 \hline 
\end{array}
\begin{array}{l|}
 \hline \text { Magma Compositions }\
 \hline \
 \hline \
 \hline \
 \hline \
 \hline \
 \hline 
\end{array}
\end{array}$

Accepted Answer

The answer of List the four major magma compositions in...

Question 17

What is fractional crystallization? Briefly explain how it works and why different types of magmas result.

Accepted Answer

Fractional crystallization is a process

Question 18

In general,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). 
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).

Question 19

When magma solidifies below the surface of the Earth,________ are formed.

Accepted Answer

A)  intrusive igneous rocks 
B)  extrusive igneous rocks 
C)  volatiles 
D)  pyroclastic rocks 
A)  intrusive igneous rocks 
B)  extrusive igneous rocks 
C)  volatiles 
D)  pyroclastic rocks

Question 20

Which of the following processes is not responsible for the formation of magma within the Earth?

Accepted Answer

A)  decompression (due to a drop in pressure) 
B)  addition of volatiles 
C)  transfer of heat from adjacent magma or very hot rocks 
D)  loss of volatiles to the atmosphere 
A)  decompression (due to a drop in pressure) 
B)  addition of volatiles 
C)  transfer of heat from adjacent magma or very hot rocks 
D)  loss of volatiles to the atmosphere

Exam 6: Up From the Inferno: Magma and Igneous Rocks

Volatiles refer to substances that

Important volatiles in magmas include

The figure below shows mafic magma as it meets the seafloor,which cools to form an igneous rock called

What is obsidian? How does it form?

A fragmental,extrusive igneous rock is referred to as which of the following?

Bombs,ash,and cinders are all examples of

If you find a tuff in the field,what type of geologic activity could you reasonably assume has occurred?

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

Viscosity does NOT depend on

Rhyolite and granite are both felsic igneous rocks,although they have different cooling histories,and consequently different textures.Explain the difference between the two rock types from a cooling perspective and be specific about which igneous texture can be applied to which rock.

A body of rock starts at location A in the graph below.The rock,over a period of time,moves to location B and begins to melt.This is an example of melting due to

A vast,composite intrusive igneous body that covers hundreds of square kilometers (in a map view)is called a

Briefly explain why and how magmas rise within the Earth.

Which type of magma has the greatest silica content?

The difference between magma and lava is

List the four major magma compositions in order of silica content. Silica Content Highest Lowest Magma Compositions

What is fractional crystallization? Briefly explain how it works and why different types of magmas result.

In general,when rock is partially melted,the chemistry of the melt is

When magma solidifies below the surface of the Earth,________ are formed.

Which of the following processes is not responsible for the formation of magma within the Earth?

Cosmology and the Birth of the Earth

Journey to the Center of the Earth

Drifting Continents and Spreading Seas

The Way the Earth Works: Plate Tectonics

Patterns in Nature: Minerals

Pages of Earths Past: Sedimentary Rocks

Metamorphism: a Process of Change

The Wrath of Vulcan: Volcanic Eruptions

A Violent Pulse: Earthquakes

Crags,cracks,and Crumples: Crustal Deformation and Mountain Building

Deep Time: How Old Is Old

A Biography of the Earth

Squeezing Power From a Stone: Energy Resources

Riches in Rock: Mineral Resources

Unsafe Ground: Landslides and Other Mass Movements

Streams and Floods: the Geology of Running Water

Restless Realm: Oceans and Coasts

A Hidden Reserve: Groundwater

An Envelope of Gas: the Earths Atmosphere and Climate

Dry Regions: the Geology of Deserts

Amazing Ice: Glaciers and Ice Ages

Global Change in the Earth System

Introducing Rocks

a Surface Veneer: Sediments and Soils

the Rock Cycle in the Earth System

the Earths Interior, Revisited: Seismic Layering, Gravity, and the Magnetic Field

Memories of Past Life: Fossils and Evolution

Ever-Changing Landscapes and the Hydrologic Cycle

Prelude: and Just What Is Geology

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