Question 1

A blob-like igneous rock body that has cooled beneath the surface of Earth is ____________.

Accepted Answer

A)  guyot 
B)  pluton 
C)  lava flow 
D)  andesite 
A)  guyot 
B)  pluton 
C)  lava flow 
D)  andesite B

Question 2

Pegmatites,which occur in dikes,are unusual among shallow intrusive rocks in that they ____________.

Accepted Answer

A)  possess porphyritic texture 
B)  possess exceptionally coarse grains 
C)  are mineralogically identical to the extrusive rock basalt 
D)  are glassy, cooling so rapidly that crystals do not have time to form 
A)  possess porphyritic texture 
B)  possess exceptionally coarse grains 
C)  are mineralogically identical to the extrusive rock basalt 
D)  are glassy, cooling so rapidly that crystals do not have time to form B

Question 3

A volcano emits ash,which falls from the sky,settles in layers,and is eventually cemented.The resulting rock is termed ____________.

Accepted Answer

A)  pumice 
B)  granite 
C)  tuff 
D)  ignimbrite 
A)  pumice 
B)  granite 
C)  tuff 
D)  ignimbrite C

Question 4

The difference between magma and lava is ____________.

Accepted Answer

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

Question 5

In regard to the cooling of molten rock,a __________ volume and a __________ shape cools faster.

Accepted Answer

A)  larger; spherical 
B)  larger; pancake 
C)  smaller; spherical 
D)  smaller; pancake 
A)  larger; spherical 
B)  larger; pancake 
C)  smaller; spherical 
D)  smaller; pancake

Question 6

The silicate mineral that is found in the greatest variety of igneous rocks is ____________.

Accepted Answer

A)  olivine 
B)  plagioclase 
C)  pyroxene 
D)  quartz 
A)  olivine 
B)  plagioclase 
C)  pyroxene 
D)  quartz

Question 7

If the volatile content of magma is increased,its viscosity will ____________.

Accepted Answer

A)  increase 
B)  decrease 
C)  stay the same 
A)  increase 
B)  decrease 
C)  stay the same

Question 8

As compared to coarse-grained igneous rocks,all fine-grained 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 temperatures 
A)  cool and solidify more quickly 
B)  cool and solidify more slowly 
C)  solidify at higher temperatures 
D)  solidify at lower temperatures

Question 9

Why are igneous rocks important?

Accepted Answer

A)  They provide information about the mantle. 
B)  They can be used to reconstruct tectonic activity. 
C)  They host important mineral deposits. 
D)  All of the above are correct. 
A)  They provide information about the mantle. 
B)  They can be used to reconstruct tectonic activity. 
C)  They host important mineral deposits. 
D)  All of the above are correct.

Question 10

Igneous rocks ____________.

Accepted Answer

A)  are formed through the freezing of melt 
B)  can be produced at the surface of the Earth as well as deep below the surface 
C)  are the most common type of rocks within Earth 
D)  All of the above are correct. 
A)  are formed through the freezing of melt 
B)  can be produced at the surface of the Earth as well as deep below the surface 
C)  are the most common type of rocks within Earth 
D)  All of the above are correct.

Question 11

Not all magmas have the same initial composition.Which of the following is LEAST likely to cause variation in the composition?

Accepted Answer

A)  source of magma 
B)  amount of partial melting 
C)  amount of magma mixing 
D)  depth in the Earth 
A)  source of magma 
B)  amount of partial melting 
C)  amount of magma mixing 
D)  depth in the Earth

Question 12

The formation of magma within Earth is NOT caused by which of the following processes?

Accepted Answer

A)  decompression (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 (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

Question 13

If a body of igneous (source)rock is subjected to partial melting,the magma that is produced is expected to be ____________.

Accepted Answer

A)  identical in chemical composition to the source rock 
B)  more mafic than the source rock 
C)  more felsic than the source rock 
A)  identical in chemical composition to the source rock 
B)  more mafic than the source rock 
C)  more felsic than the source rock

Question 14

If magma did not move up from where it was formed,which of the following would be true?

Accepted Answer

A)  No new oceanic crust would be made. 
B)  Volcanoes would not erupt. 
C)  Plates would not move. 
D)  Both a and b are correct. 
E)  All of the above are correct. 
A)  No new oceanic crust would be made. 
B)  Volcanoes would not erupt. 
C)  Plates would not move. 
D)  Both a and b are correct. 
E)  All of the above are correct.

Question 15

Without igneous rocks,which of the following would not be significantly different on our planet?

Accepted Answer

A)  sea-floor spreading 
B)  volcanic eruptions 
C)  formation of deserts 
D)  mountain building 
E)  evolution of continents 
A)  sea-floor spreading 
B)  volcanic eruptions 
C)  formation of deserts 
D)  mountain building 
E)  evolution of continents

Question 16

Most commonly,felsic igneous rocks ____________.

Accepted Answer

A)  contain more iron and magnesium than intermediate rocks 
B)  are lighter in color than mafic rocks 
C)  are darker in color than mafic rocks 
D)  are found in oceanic crust 
A)  contain more iron and magnesium than intermediate rocks 
B)  are lighter in color than mafic rocks 
C)  are darker in color than mafic rocks 
D)  are found in oceanic crust

Question 17

Which of the following is NOT a factor controlling the cooling rate of magma?

Accepted Answer

A)  depth of intrusion 
B)  shape and size of magma body 
C)  presence of circulating groundwater 
D)  All of the above are factors. 
A)  depth of intrusion 
B)  shape and size of magma body 
C)  presence of circulating groundwater 
D)  All of the above are factors.

Question 18

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 19

If a body of magma is subjected to fractional crystallization,the rock that results is expected to be ____________.

Accepted Answer

A)  identical in chemical composition to the magma 
B)  more mafic than the magma 
C)  more felsic than the magma 
A)  identical in chemical composition to the magma 
B)  more mafic than the magma 
C)  more felsic than the magma

Question 20

Which of these is an example of a continental volcanic arc?

Accepted Answer

A)  the Aleutian Islands of Alaska 
B)  the Andes Mountains 
C)  Hawaii 
D)  Japan 
A)  the Aleutian Islands of Alaska 
B)  the Andes Mountains 
C)  Hawaii 
D)  Japan

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

A blob-like igneous rock body that has cooled beneath the surface of Earth is ____________.

Pegmatites,which occur in dikes,are unusual among shallow intrusive rocks in that they ____________.

A volcano emits ash,which falls from the sky,settles in layers,and is eventually cemented.The resulting rock is termed ____________.

The difference between magma and lava is ____________.

In regard to the cooling of molten rock,a __________ volume and a __________ shape cools faster.

The silicate mineral that is found in the greatest variety of igneous rocks is ____________.

If the volatile content of magma is increased,its viscosity will ____________.

As compared to coarse-grained igneous rocks,all fine-grained igneous rocks ____________.

Why are igneous rocks important?

Igneous rocks ____________.

Not all magmas have the same initial composition.Which of the following is LEAST likely to cause variation in the composition?

The formation of magma within Earth is NOT caused by which of the following processes?

If a body of igneous (source)rock is subjected to partial melting,the magma that is produced is expected to be ____________.

If magma did not move up from where it was formed,which of the following would be true?

Without igneous rocks,which of the following would not be significantly different on our planet?

Most commonly,felsic igneous rocks ____________.

Which of the following is NOT a factor controlling the cooling rate of magma?

Which type of magma has the greatest silica content?

If a body of magma is subjected to fractional crystallization,the rock that results is expected to be ____________.

Which of these is an example of a continental volcanic arc?

The Earth in Context

The Way the Earth Works: Plate Tectonics

Patterns in Nature: Minerals

The Wrath of Vulcan: Volcanic Eruptions

Pages of Earths Past: Sedimentary Rocks

Metamorphism: a Process of Change

A Violent Pulse: Earthquakes

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

Deep Time: How Old Is Old

A Biography of Earth

Riches in Rock: Energy and 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

Dry Regions: the Geology of Deserts

Amazing Ice: Glaciers and Ice Ages

Global Change in the Earth System

Rock Groups

A Surface Veneer: Sediments and Soils

The Rock Cycle

The Earths Interior Revisited: Insights From Geophysics

Memories of Past Life: Fossils and Evolution

An Introduction to Landscapes and the Hydrologic Cycle

Filters

In regard to the cooling of molten rock,a volume and a shape cools faster.