Question 1

What is one possible explanation for the crustal subsidence that created extensive areas of downwarping such as in Michigan and Illinois?

Accepted Answer

A) Cessation of compression along a convergent plate boundary 
B) Cessation of upwelling from a mantle plume 
C) Cessation of subduction, with detachment of the descending slab, creates a downward pull in the mantle 
D) The crust is extended to maintain a convergent plate boundary where the descending plate is sinking 
A) Cessation of compression along a convergent plate boundary 
B) Cessation of upwelling from a mantle plume 
C) Cessation of subduction, with detachment of the descending slab, creates a downward pull in the mantle 
D) The crust is extended to maintain a convergent plate boundary where the descending plate is sinking

Question 2

Volcanic island arc activity is short-lived and as a result will only produce tiny islands.

Accepted Answer

A) True 
 B)False

Question 3

What are the four regions of a subduction zone?

Accepted Answer

A) Tensional, compressional, shear, convection 
B) Oceanic, volcanic, continental, island 
C) Volcanic arc, deep-ocean trench, forearc, and back-arc 
D) Accretionary wedge, terrane, accumulation zone, submarine canyon 
A) Tensional, compressional, shear, convection 
B) Oceanic, volcanic, continental, island 
C) Volcanic arc, deep-ocean trench, forearc, and back-arc 
D) Accretionary wedge, terrane, accumulation zone, submarine canyon

Question 4

Which style of convergent boundary will characterize an Andean-type mountain building event?

Accepted Answer

A) Where oceanic lithosphere subducts beneath oceanic lithosphere 
B) Where continental lithosphere subducts beneath continental lithosphere 
C) Where oceanic lithosphere subducts beneath continental lithosphere 
D) Where continental lithosphere subducts beneath oceanic lithosphere 
A) Where oceanic lithosphere subducts beneath oceanic lithosphere 
B) Where continental lithosphere subducts beneath continental lithosphere 
C) Where oceanic lithosphere subducts beneath continental lithosphere 
D) Where continental lithosphere subducts beneath oceanic lithosphere

Question 5

If a back-arc basin is associated with a volcanic island arc, what tends to develop there?

Accepted Answer

A) Submarine trench 
B) Wide continental shelf 
C) Long, linear sea 
D) Rift valley 
A) Submarine trench 
B) Wide continental shelf 
C) Long, linear sea 
D) Rift valley

Question 6

Which of the following regions of a subduction zone are characterized by thick sequences of relatively undeformed sedimentary rocks?

Accepted Answer

A) Volcanic island arc 
B) Forearc region 
C) Suture 
D) Transform fault 
A) Volcanic island arc 
B) Forearc region 
C) Suture 
D) Transform fault

Question 7

Passive continental margins will have a well-developed forearc and back-arc basin system.

Accepted Answer

A) True 
 B)False

Question 8

Which of the following statements best characterizes the geology of western North America, starting in California and extending through British Columbia and up into Alaska?

Accepted Answer

A) Divergent rifting creating deep, wide valleys with grabens 
B) Collision of a massive subcontinent of old igneous and metamorphic rocks, resulting in fold-and-thrust mountains that are still growing 
C) Geologically distinct, microcontinent-sized fragments and terraces accreted to the continent 
D) Metamorphosed accretionary wedges 
A) Divergent rifting creating deep, wide valleys with grabens 
B) Collision of a massive subcontinent of old igneous and metamorphic rocks, resulting in fold-and-thrust mountains that are still growing 
C) Geologically distinct, microcontinent-sized fragments and terraces accreted to the continent 
D) Metamorphosed accretionary wedges

Question 9

If a back-arc basin is a region related to a subduction zone, how can such an extensional basin form near a boundary defined by compression?

Accepted Answer

A) Trench rolls back as the old, dense subducting plate sinks. 
B) Compression ceases before extension takes over. 
C) Rising magma is softening the crust, allowing it to stretch. 
D) A plate subducting at an extremely shallow angle is pushing against the back-arc region. 
A) Trench rolls back as the old, dense subducting plate sinks. 
B) Compression ceases before extension takes over. 
C) Rising magma is softening the crust, allowing it to stretch. 
D) A plate subducting at an extremely shallow angle is pushing against the back-arc region.

Question 10

Because the Indian subcontinent is still colliding with the Eurasian Plate, the Himalayas are still actively forming.

Accepted Answer

A) True 
 B)False

Question 11

Accreted terranes that are adjacent to each other will generally have similar geologic histories until the point where they accrete.After that, their geologic histories will differ.

Accepted Answer

A) True 
 B)False

Question 12

Instead of subduction down into the mantle, the Indian subcontinent was thrust beneath Tibet, helping to significantly raise the landscape.

Accepted Answer

A) True 
 B)False

Question 13

Notice the part of this image labeled "continued trench rollback." What is happening in "trench rollback"?

Accepted Answer

A) Old, dense lithosphere sinks, creating slab suction that pulls the upper plate toward the trench. 
B) Continued tension on the plate results in rifting, dropping blocks of continental crust. 
C) The trench gets deeper as the descending plate locks against the overriding plate and pulls it down. 
D) Rising magma plutons melt the base of the lithosphere to create a depression. 
A) Old, dense lithosphere sinks, creating slab suction that pulls the upper plate toward the trench. 
B) Continued tension on the plate results in rifting, dropping blocks of continental crust. 
C) The trench gets deeper as the descending plate locks against the overriding plate and pulls it down. 
D) Rising magma plutons melt the base of the lithosphere to create a depression.

Question 14

The subduction and melting of an accretionary wedge will result in a secondary magma.

Accepted Answer

A) True 
 B)False

Question 15

What is an accretionary wedge?

Accepted Answer

A) Deformed and thrust-faulted continental lithosphere 
B) A fan of sediments at the bottom of a deep-ocean trench 
C) Sediments and ocean crust fragments being scraped off of a subducting plate 
D) Fault blocks that are slipping down due to extension in a back-arc basin 
A) Deformed and thrust-faulted continental lithosphere 
B) A fan of sediments at the bottom of a deep-ocean trench 
C) Sediments and ocean crust fragments being scraped off of a subducting plate 
D) Fault blocks that are slipping down due to extension in a back-arc basin

Question 16

In which location on a continent would one be likely to find young mountain belts (less than 100 million years old)?

Accepted Answer

A) In the center of the continent 
B) On the continental shield 
C) On the stable platform 
D) Along the margins of the continent 
A) In the center of the continent 
B) On the continental shield 
C) On the stable platform 
D) Along the margins of the continent

Question 17

Which of the following best describes the formation of the Ural Mountains of Russia?

Accepted Answer

A) Marine sediments that had collected in a basin were compressed and uplifted as the former Asian and European plates merged 
B) Marine sediments were sheared along a transform boundary between the Eurasian and African plates 
C) A continental volcanic arc formed as two microcontinents collided and subducted 
D) The landscape was pulled apart by rifting and flood basalts piled up on the landscape 
A) Marine sediments that had collected in a basin were compressed and uplifted as the former Asian and European plates merged 
B) Marine sediments were sheared along a transform boundary between the Eurasian and African plates 
C) A continental volcanic arc formed as two microcontinents collided and subducted 
D) The landscape was pulled apart by rifting and flood basalts piled up on the landscape

Question 18

Which of the following terms describes the increasing downward force on basal rocks as a mountain continues to grow?

Accepted Answer

A) Isostacy 
B) Delamination 
C) Accretion 
D) Gravitational collapse 
A) Isostacy 
B) Delamination 
C) Accretion 
D) Gravitational collapse

Question 19

Which of the following locations is a remnant of a forearc basin?

Accepted Answer

A) Death Valley, CA 
B) Lake Baikal, Siberia 
C) Snake River Plain, ID 
D) Great Valley, CA 
A) Death Valley, CA 
B) Lake Baikal, Siberia 
C) Snake River Plain, ID 
D) Great Valley, CA

Question 20

________ is the driving force in orogenesis.

Accepted Answer

A) Extension 
B) Convection 
C) Temperature 
D) Subduction 
A) Extension 
B) Convection 
C) Temperature 
D) Subduction

Exam 14: Convergent Boundaries

What is one possible explanation for the crustal subsidence that created extensive areas of downwarping such as in Michigan and Illinois?

Volcanic island arc activity is short-lived and as a result will only produce tiny islands.

What are the four regions of a subduction zone?

Which style of convergent boundary will characterize an Andean-type mountain building event?

If a back-arc basin is associated with a volcanic island arc, what tends to develop there?

Which of the following regions of a subduction zone are characterized by thick sequences of relatively undeformed sedimentary rocks?

Passive continental margins will have a well-developed forearc and back-arc basin system.

Which of the following statements best characterizes the geology of western North America, starting in California and extending through British Columbia and up into Alaska?

If a back-arc basin is a region related to a subduction zone, how can such an extensional basin form near a boundary defined by compression?

Because the Indian subcontinent is still colliding with the Eurasian Plate, the Himalayas are still actively forming.

Accreted terranes that are adjacent to each other will generally have similar geologic histories until the point where they accrete.After that, their geologic histories will differ.

Instead of subduction down into the mantle, the Indian subcontinent was thrust beneath Tibet, helping to significantly raise the landscape.

Notice the part of this image labeled "continued trench rollback." What is happening in "trench rollback"?

The subduction and melting of an accretionary wedge will result in a secondary magma.

What is an accretionary wedge?

In which location on a continent would one be likely to find young mountain belts (less than 100 million years old)?

Which of the following best describes the formation of the Ural Mountains of Russia?

Which of the following terms describes the increasing downward force on basal rocks as a mountain continues to grow?

Which of the following locations is a remnant of a forearc basin?

________ is the driving force in orogenesis.

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

Divergent 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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