Question 1

Describe how the thickness and age of sediments on the seafloor change with distance from a mid-ocean ridge.What can be learned from this?

Accepted Answer

Seafloor sediments everywhere are too thin to have been accumulating for the entirety of the Earth's history.They are thickest at the margins of continents and thinnest near the mid-ocean ridge axes,and become thicker with increasing distance from the ridge.The deepest sediments are older at locations further from ridges.These observations support seafloor spreading.As new oceanic crust moves away from the ridge,sediments begin to accumulate.The older the oceanic crust becomes,the more sediment accumulates.

Question 2

A ________ is a linear feature in continental lithosphere where a plate is pulled apart,resulting in a deep valley,extensive faulting and volcanism,and if sustained,division into two plates separated by new oceanic lithosphere.

Accepted Answer

A)  forearc basin 
B)  volcanic island arc 
C)  continental rift 
D)  mid-ocean ridge 
A)  forearc basin 
B)  volcanic island arc 
C)  continental rift 
D)  mid-ocean ridge C

Question 3

On either side of a mid-ocean ridge,oceanic lithosphere slowly _________

Accepted Answer

A)  rises because it becomes thicker away from the ridge. 
B)  rises because it becomes buoyant. 
C)  sinks into the asthenosphere because it cools and thickens,increasing in density. 
D)  sinks into the asthenosphere because convection pulls it downward. 
A)  rises because it becomes thicker away from the ridge. 
B)  rises because it becomes buoyant. 
C)  sinks into the asthenosphere because it cools and thickens,increasing in density. 
D)  sinks into the asthenosphere because convection pulls it downward. C

Question 4

At the subduction zone where the Pacific Plate is subducting under the islands of Japan,the Wadati-Benioff zone of deep earthquakes

Accepted Answer

A)  extends from the trench westward underneath Japan. 
B)  extends from the trench eastward underneath the Pacific Plate. 
C)  is confined to the trench. 
D)  is absent because there are no earthquakes at subduction zones. 
A)  extends from the trench westward underneath Japan. 
B)  extends from the trench eastward underneath the Pacific Plate. 
C)  is confined to the trench. 
D)  is absent because there are no earthquakes at subduction zones.

Question 5

In plate tectonics,a triple junction is a place on the Earth's surface where

Accepted Answer

A)  three volcanoes form a tight,triangular cluster. 
B)  glacial ice,continental rocks,and the ocean can be found together. 
C)  the boundaries of three lithospheric plates meet at a single point. 
D)  all three of the basic rock types are found in the same location. 
A)  three volcanoes form a tight,triangular cluster. 
B)  glacial ice,continental rocks,and the ocean can be found together. 
C)  the boundaries of three lithospheric plates meet at a single point. 
D)  all three of the basic rock types are found in the same location.

Question 6

During the past 5 million years,approximately how long have chrons lasted before the next major magnetic polarity reversal?

Accepted Answer

A)  10 to 20 years. 
B)  500 to 1000 years. 
C)  700,000 to 1.5 million years 
D)  There has not been a magnetic polarity reversal during the past five million years. 
A)  10 to 20 years. 
B)  500 to 1000 years. 
C)  700,000 to 1.5 million years 
D)  There has not been a magnetic polarity reversal during the past five million years.

Question 7

Limestone reefs and salt deposits are important in the reconstruction of the Earth's history because they

Accepted Answer

A)  can be used to infer the ancient climate of the Earth; they are deposited in environments that are restricted to warm climates. 
B)  automatically provide age information; all such deposits occurred between 200 and
400 million years ago. 
C)  are deposited in warm climates today,but there is good reason to think that they were deposited in cold climates millions of years ago. 
D)  pinpoint the locations of old subduction zones. 
A)  can be used to infer the ancient climate of the Earth; they are deposited in environments that are restricted to warm climates. 
B)  automatically provide age information; all such deposits occurred between 200 and
400 million years ago. 
C)  are deposited in warm climates today,but there is good reason to think that they were deposited in cold climates millions of years ago. 
D)  pinpoint the locations of old subduction zones.

Question 8

Much of the ocean floor in all major oceans consists of broad,flat regions called

Accepted Answer

A)  abyssal plains. 
B)  continental rises. 
C)  fracture zones. 
D)  seamounts. 
A)  abyssal plains. 
B)  continental rises. 
C)  fracture zones. 
D)  seamounts.

Question 9

Which of the following is true of the lithosphere?

Accepted Answer

A)  It is the same thing as the crust. 
B)  It is composed of the crust and the uppermost rigid part of the mantle. 
C)  It is a very ductile layer in the upper part of the mantle. 
D)  It is the layer of the mantle directly below the asthenosphere. 
A)  It is the same thing as the crust. 
B)  It is composed of the crust and the uppermost rigid part of the mantle. 
C)  It is a very ductile layer in the upper part of the mantle. 
D)  It is the layer of the mantle directly below the asthenosphere.

Question 10

What does the distribution of earthquakes around the globe tell us about plate tectonics? How do earthquakes differ among the three types of plate boundaries?

Accepted Answer

Earthquakes do not occur randomly and ar

Question 11

According to the theory of plate tectonics,plates are

Accepted Answer

A)  pieces of lithosphere that move over the surface of the Earth with respect to one another. 
B)  layers of lithosphere that are stacked one atop the other from the surface to the outer core. 
C)  pieces of continental rocks that move through the weaker oceanic rocks. 
D)  very thick (approximately one-quarter of the Earth's radius). 
A)  pieces of lithosphere that move over the surface of the Earth with respect to one another. 
B)  layers of lithosphere that are stacked one atop the other from the surface to the outer core. 
C)  pieces of continental rocks that move through the weaker oceanic rocks. 
D)  very thick (approximately one-quarter of the Earth's radius).

Question 12

Which of the following best describes the distribution of earthquakes around the globe?

Accepted Answer

A)  They tend to occur randomly on the continents. 
B)  They tend to occur randomly in the ocean basins. 
C)  They tend to occur randomly both on the continents and in the ocean basins. 
D)  They occur in distinct zones. 
A)  They tend to occur randomly on the continents. 
B)  They tend to occur randomly in the ocean basins. 
C)  They tend to occur randomly both on the continents and in the ocean basins. 
D)  They occur in distinct zones.

Question 13

How can hot-spot volcanoes be used to measure past plate velocities?

Accepted Answer

Hot-spot volcanic islands form on the su

Question 14

The distribution of _________ around the globe provides the primary indicator of the boundaries between lithospheric plates.

Accepted Answer

A)  basalt 
B)  earthquakes 
C)  mountains 
D)  ocean basins 
A)  basalt 
B)  earthquakes 
C)  mountains 
D)  ocean basins

Question 15

Most of the pulling force driving plate motion is produced

Accepted Answer

A)  at mid-ocean ridges. 
B)  at collision zones. 
C)  at subduction zones. 
D)  in the interiors of continental plates. 
A)  at mid-ocean ridges. 
B)  at collision zones. 
C)  at subduction zones. 
D)  in the interiors of continental plates.

Question 16

Describe the process of seafloor spreading,making sure to address why the diameter of the Earth is not growing.

Accepted Answer

Magma rises and erupts onto the surface

Question 17

How does continental rifting lead to the formation of a new plate boundary and new ocean basin?

Accepted Answer

During rifting,continental lithosphere i

Question 18

Wegener's evidence for a united Pangaea comes from the fossil record of which type of organisms?

Accepted Answer

A)  plant pollen 
B)  plankton 
C)  marine animals 
D)  land animals 
A)  plant pollen 
B)  plankton 
C)  marine animals 
D)  land animals

Question 19

The idea that the continents had once fit together as a single supercontinent called Pangaea was rejected when first proposed because

Accepted Answer

A)  geologists did not know of a force great enough to move continents. 
B)  the continents did not fit together tightly enough. 
C)  the fossil evidence was inconclusive. 
D)  the distribution of climatic belts did not make sense in that configuration. 
A)  geologists did not know of a force great enough to move continents. 
B)  the continents did not fit together tightly enough. 
C)  the fossil evidence was inconclusive. 
D)  the distribution of climatic belts did not make sense in that configuration.

Question 20

Paleomagnetic evidence for seafloor spreading is found in:

Accepted Answer

A)  basaltic rocks. 
B)  ocean floor sediments. 
C)  continental sediments. 
D)  all rocks and minerals. 
A)  basaltic rocks. 
B)  ocean floor sediments. 
C)  continental sediments. 
D)  all rocks and minerals.

Exam 2: The Way the Earth Works: Plate Tectonics

Describe how the thickness and age of sediments on the seafloor change with distance from a mid-ocean ridge.What can be learned from this?

A ________ is a linear feature in continental lithosphere where a plate is pulled apart,resulting in a deep valley,extensive faulting and volcanism,and if sustained,division into two plates separated by new oceanic lithosphere.

On either side of a mid-ocean ridge,oceanic lithosphere slowly _________

At the subduction zone where the Pacific Plate is subducting under the islands of Japan,the Wadati-Benioff zone of deep earthquakes

In plate tectonics,a triple junction is a place on the Earth's surface where

During the past 5 million years,approximately how long have chrons lasted before the next major magnetic polarity reversal?

Limestone reefs and salt deposits are important in the reconstruction of the Earth's history because they

Much of the ocean floor in all major oceans consists of broad,flat regions called

Which of the following is true of the lithosphere?

What does the distribution of earthquakes around the globe tell us about plate tectonics? How do earthquakes differ among the three types of plate boundaries?

According to the theory of plate tectonics,plates are

Which of the following best describes the distribution of earthquakes around the globe?

How can hot-spot volcanoes be used to measure past plate velocities?

The distribution of _________ around the globe provides the primary indicator of the boundaries between lithospheric plates.

Most of the pulling force driving plate motion is produced

Describe the process of seafloor spreading,making sure to address why the diameter of the Earth is not growing.

How does continental rifting lead to the formation of a new plate boundary and new ocean basin?

Wegener's evidence for a united Pangaea comes from the fossil record of which type of organisms?

The idea that the continents had once fit together as a single supercontinent called Pangaea was rejected when first proposed because

Paleomagnetic evidence for seafloor spreading is found in:

The Earth in Context

Patterns in Nature: Minerals

Up From the Inferno: Magma and Igneous Rocks

The Wrath of Vulcan: Volcanic Eruptions

Pages of the 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 the 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

Introducing Rocks

A Surface Veneer: Sediments and Soils

The Rock Cycle

The Earth’s Interior Revisited: Insights from Geophysics

Memories of Past Life: Fossils and Evolution

Ever-Changing Landscapes and the Hydrologic Cycle

Prelude: And Just What is Geology?

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