Question 1

The oceanic crust is composed almost entirely of ________ rocks that are underlain by ________ rocks, which makes up the lithospheric mantle.

Accepted Answer

A) felsic; sediments 
B) intermediate; felsic 
C) sedimentary; mafic 
D) mafic; ultramafic 
A) felsic; sediments 
B) intermediate; felsic 
C) sedimentary; mafic 
D) mafic; ultramafic

Question 2

How do researchers today routinely determine the depth of the water to the seafloor?

Accepted Answer

A) Ship-mounted gravimeters 
B) A weighted roped or cable 
C) High-resolution multibeam instruments 
D) Laser reflector systems linked to satellites 
A) Ship-mounted gravimeters 
B) A weighted roped or cable 
C) High-resolution multibeam instruments 
D) Laser reflector systems linked to satellites

Question 3

Thermal springs known as ________ are often associated with oceanic ridges, where hot water containing dissolved minerals gushes from the seafloor.

Accepted Answer

A) hot springs 
B) geysers 
C) black smokers 
D) ophiolites 
A) hot springs 
B) geysers 
C) black smokers 
D) ophiolites

Question 4

Oceanic ridges form as a result of compressional stress.

Accepted Answer

A) True 
 B)False

Question 5

A passive continental margin is located hundreds of miles away from the nearest tectonic boundary.

Accepted Answer

A) True 
 B)False

Question 6

A ________ forms when a rising mantle plume causes the overlying crust to dome and separate into three rifts.

Accepted Answer

A) triple junction 
B) complex rift 
C) submarine canyon system 
D) divergent boundary 
A) triple junction 
B) complex rift 
C) submarine canyon system 
D) divergent boundary

Question 7

Which of the following locations is an example of forced subduction?

Accepted Answer

A) Mariana Trench 
B) Peru-Chile Trench 
C) East African Rift 
D) Mid-Atlantic Rift 
A) Mariana Trench 
B) Peru-Chile Trench 
C) East African Rift 
D) Mid-Atlantic Rift

Question 8

What is the name of the supercontinent that preceded Pangaea?

Accepted Answer

A) Amasia 
B) Rodinia 
C) Challenger 
D) Africana 
A) Amasia 
B) Rodinia 
C) Challenger 
D) Africana

Question 9

What kind of subduction occurs when old, dense lithosphere sinks into the mantle by its own weight rather than by compressional force?

Accepted Answer

A) Forced subduction 
B) Mantle plume subduction 
C) Spontaneous subduction 
D) Overriding subduction 
A) Forced subduction 
B) Mantle plume subduction 
C) Spontaneous subduction 
D) Overriding subduction

Question 10

Why do mantle plumes tend to concentrate beneath supercontinents such as Pangaea?

Accepted Answer

A) Concentrations of radioactive materials build up as continents assemble. 
B) Partial melting from subduction concentrates large volumes of magma. 
C) A large landmass acts as an insulating blanket to trap heat in the mantle. 
D) Friction from converging landmasses heats up the mantle. 
A) Concentrations of radioactive materials build up as continents assemble. 
B) Partial melting from subduction concentrates large volumes of magma. 
C) A large landmass acts as an insulating blanket to trap heat in the mantle. 
D) Friction from converging landmasses heats up the mantle.

Question 11

Which of the following is not a method of obtaining samples and observations of the oceanic ridge system?

Accepted Answer

A) Finding segments of ocean floor that have been thrust up onto the continent 
B) Visual inspections using submersible equipment 
C) Deep sea core samples 
D) Side-scan sonar 
A) Finding segments of ocean floor that have been thrust up onto the continent 
B) Visual inspections using submersible equipment 
C) Deep sea core samples 
D) Side-scan sonar

Question 12

What feature in this image is indicated with arrow X? (Note: it is made of sediments.)

Accepted Answer

A) Deep-sea fan 
B) Accretionary wedge 
C) Turbidity current 
D) Deep-ocean trench 
A) Deep-sea fan 
B) Accretionary wedge 
C) Turbidity current 
D) Deep-ocean trench

Question 13

What is the name the physical feature in this diagram, marked with an arrow?

Accepted Answer

A) Submarine canyon 
B) Deep-ocean basins 
C) Abyssal plains 
D) Rift valley 
A) Submarine canyon 
B) Deep-ocean basins 
C) Abyssal plains 
D) Rift valley

Question 14

Which of the following is associated with a passive continental margin?

Accepted Answer

A) Divergent boundaries 
B) Convergent boundaries 
C) Transform boundaries 
D) No tectonic boundaries nearby 
A) Divergent boundaries 
B) Convergent boundaries 
C) Transform boundaries 
D) No tectonic boundaries nearby

Question 15

Along which tectonic boundary are deep-ocean trenches found?

Accepted Answer

A) Convergent 
B) Divergent 
C) Transform 
A) Convergent 
B) Divergent 
C) Transform

Question 16

Which location possesses the continental margin in this image?

Accepted Answer

A) Western margin of South America 
B) Eastern margin of North America 
C) East of Japan 
D) Around the Philippines 
A) Western margin of South America 
B) Eastern margin of North America 
C) East of Japan 
D) Around the Philippines

Question 17

Abyssal plains are flat areas of the ocean floor that are likely the most level places on Earth.

Accepted Answer

A) True 
 B)False

Question 18

Volcanic island arcs are found near which features on the seafloor?

Accepted Answer

A) Abyssal plains 
B) Coral atolls 
C) Deep-ocean trenches 
D) Rift zones 
A) Abyssal plains 
B) Coral atolls 
C) Deep-ocean trenches 
D) Rift zones

Question 19

Although many areas of the continental shelves are relatively featureless, there are some locations on the shelves that have received extensive glacial deposits and significant dissection by streams.How would this have been possible?

Accepted Answer

A) Glaciers and streams were powerful enough to shape the shelf underwater. 
B) The shelves were once above sea level but have since dropped below sea level due to tectonic activity. 
C) The sea level dropped during the last glacial episode because water was stored in large ice sheets, exposing the shelves. 
D) As the continents collided in the past, the shelves were lifted above sea level and became exposed to the elements. 
A) Glaciers and streams were powerful enough to shape the shelf underwater. 
B) The shelves were once above sea level but have since dropped below sea level due to tectonic activity. 
C) The sea level dropped during the last glacial episode because water was stored in large ice sheets, exposing the shelves. 
D) As the continents collided in the past, the shelves were lifted above sea level and became exposed to the elements.

Question 20

What is the source of flood basalts associated with oceanic plateaus?

Accepted Answer

A) Decompression melting associated with seafloor spreading 
B) Partial melting associated with subduction 
C) Impact heating from a meteorite strike 
D) The melting of the head of a mantle plume 
A) Decompression melting associated with seafloor spreading 
B) Partial melting associated with subduction 
C) Impact heating from a meteorite strike 
D) The melting of the head of a mantle plume

Exam 13: Divergent Boundaries

The oceanic crust is composed almost entirely of ________ rocks that are underlain by ________ rocks, which makes up the lithospheric mantle.

How do researchers today routinely determine the depth of the water to the seafloor?

Thermal springs known as ________ are often associated with oceanic ridges, where hot water containing dissolved minerals gushes from the seafloor.

Oceanic ridges form as a result of compressional stress.

A passive continental margin is located hundreds of miles away from the nearest tectonic boundary.

A ________ forms when a rising mantle plume causes the overlying crust to dome and separate into three rifts.

Which of the following locations is an example of forced subduction?

What is the name of the supercontinent that preceded Pangaea?

What kind of subduction occurs when old, dense lithosphere sinks into the mantle by its own weight rather than by compressional force?

Why do mantle plumes tend to concentrate beneath supercontinents such as Pangaea?

Which of the following is not a method of obtaining samples and observations of the oceanic ridge system?

What feature in this image is indicated with arrow X? (Note: it is made of sediments.)

What is the name the physical feature in this diagram, marked with an arrow?

Which of the following is associated with a passive continental margin?

Along which tectonic boundary are deep-ocean trenches found?

Which location possesses the continental margin in this image?

Abyssal plains are flat areas of the ocean floor that are likely the most level places on Earth.

Volcanic island arcs are found near which features on the seafloor?

Although many areas of the continental shelves are relatively featureless, there are some locations on the shelves that have received extensive glacial deposits and significant dissection by streams.How would this have been possible?

What is the source of flood basalts associated with oceanic plateaus?

An Introduction to Geology

Plate Tectonics: a Scientific Revolution Unfolds

Matter and Minerals

Magma, Igneous Rocks, and Intrusive Activity

Volcanoes and Volcanic Hazards

Weathering and Soil

Sedimentary Rocks

Metamorphism and Metamorphic Rocks

Geologic Time

Crustal Deformation

Earthquakes

Earths Interior

Convergent Boundaries

Mass Wasting

Running Water

Groundwater

Glaciers and Glaciation

Deserts and Winds

Shorelines

Global Climate Change

Earths Evolution Through Geologic Time

Energy and Mineral Resources

Touring Our Solar System

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The oceanic crust is composed almost entirely of rocks that are underlain by rocks, which makes up the lithospheric mantle.