Deck 4: The Way the Earth Works: Plate Tectonics

Question 1

The distribution of ________ across the globe provides the primary indicator of boundaries between all tectonic plates.

A) mountain ranges
B) volcanoes
C) mid-ocean ridges
D) earthquakes

Answer 1

D

Question 2

Broad,sediment-covered continental shelves are found along

A) active margins.
B) deep-sea trenches.
C) passive margins.
D) mid-ocean ridges.

Answer 2

C

Question 3

Earthquakes occur most frequently near ________ margins.

A) seismic
B) aseismic
C) active
D) passive

Answer 3

C

Question 4

Continental coastlines that occur within the interior of a tectonic plate are called ________ margins.

A) internal
B) passive
C) active
D) inert

Question 5

The lithosphere of the Earth is generally thinnest at ________ plate boundaries.

A) convergent
B) divergent
C) transform
D) transvergent

Question 6

The lithosphere of the Earth will not flow because it

A) is too old.
B) is too dense.
C) is too cool.
D) contains radioactive elements.

Question 7

Unlike the lithosphere,the asthenosphere

A) is able to flow over long periods of time.
B) has a density similar to the core.
C) varies in thickness from place to place.
D) is relatively cool.

Question 8

How does the lithosphere respond to stress?

A) It flows.
B) It bends only.
C) It breaks only.
D) It bends or breaks.

Question 9

An earthquake would be LEAST likely at a(n)

A) active margin.
B) passive margin.
C) continent-continent convergent zone.
D) subduction zone.

Question 10

Which of the following is true about Earth's tectonic plates?

A) All tectonic plates are about the same size.
B) All tectonic plates contain both continental and oceanic lithosphere.
C) Some tectonic plates contain only continental lithosphere.
D) Some tectonic plates contain both oceanic and continental lithosphere.

Question 11

Seafloor spreading is most likely to occur at

A) divergent boundaries.
B) convergent boundaries.
C) transform boundaries.
D) hot spots.

Question 12

__________ proposed seafloor spreading.

A) Harry Hess
B) Charles Darwin
C) Charles Lyell
D) Alfred Wegener

Question 13

Under the theory of plate tectonics,the plates themselves are

A) pieces of lithosphere at the surface of the solid Earth that move with respect to one another.
B) layers of lithosphere that are vertically stacked one atop the other.
C) composed only of continental rocks that plow through the weaker oceanic rocks.
D) very thick (approximately one-quarter of Earth's radius).

Question 14

Compared to typical oceanic lithosphere,the thickness of continental lithosphere is

A) less.
B) greater.
C) approximately the same.
D) There is not a consistent pattern of lithospheric thickness.

Question 15

__________ proposed the continental drift hypothesis.

A) Harry Hess
B) Charles Darwin
C) Charles Lyell
D) Alfred Wegener

Question 16

The theory of plate tectonics

A) incorporates and explains continental drift but not seafloor spreading.
B) incorporates and explains seafloor spreading but not continental drift.
C) incorporates and explains both seafloor spreading and continental drift.
D) does not incorporate or explain seafloor spreading or continental drift.

Question 17

Which of the following is true of continental lithosphere compared to oceanic lithosphere?

A) Continental lithosphere is thicker than oceanic lithosphere.
B) Continental lithosphere contains more mafic rocks than oceanic lithosphere.
C) Continental lithosphere is denser than oceanic lithosphere.
D) Continental lithosphere and oceanic lithosphere have similar compositions,densities,and thicknesses.

Question 18

With increasing distance from a mid-ocean ridge,the age of oceanic crust

A) increases.
B) decreases.
C) stays constant.
D) varies randomly.

Question 19

Which of the following is true of the lithosphere?

A) It is the same thing as the crust.
B) It is composed of the crust and the uppermost 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 20

The thickness of oceanic lithosphere is

A) nearly uniformly 100 km.
B) greatest at the geographic poles and least near the equator.
C) greatest near the mid-ocean ridges and thins out away from the ridges.
D) least near the mid-ocean ridges and thickens away from the ridges.

Question 21

The image below shows a cross-sectional view of a typical subduction zone,with earthquake locations shown with small dots.The band of earthquakes that follows the shape of the downgoing plate is termed the ________ zone.

A) transform fault
B) collisional
C) Wegener
D) Wadati-Benioff

Question 22

Which basic type of plate boundary is shown in the image below?

A) Divergent
B) Convergent
C) Transvergent
D) Transform

Question 23

Mid-ocean ridges are elevated above the surrounding seafloor because

A) rising ocean currents create a vacuum that pulls ridges up.
B) the lithosphere is thickest at the ridges so they stand up taller.
C) ridge rocks are hot and therefore are relatively less dense than the surrounding seafloor.
D) ridge rocks are mafic,which are less dense than ultramafic ocean basin rock.

Question 24

Mid-ocean ridges are segmented and contain which two basic types of plate boundaries linked together?

A) divergent and convergent
B) convergent and transform
C) divergent and transform
D) divergent and hot spot

Question 25

Subduction zones are found at ________ plate boundaries.

A) divergent
B) convergent
C) transvergent
D) transform

Question 26

The Wadati-Benioff zone extends down within the mantle to a maximum depth of ________ km.

A) 30
B) 150
C) 660
D) 990

Question 27

A volcanic island arc forms when

A) oceanic lithosphere subducts beneath continental lithosphere.
B) oceanic lithosphere subducts beneath another oceanic lithospheric plate.
C) continental lithosphere subducts beneath oceanic lithosphere.
D) two plates of continental lithosphere collide.

Question 28

Deep-oceanic trenches are features of ________ plate boundaries.

A) divergent
B) convergent
C) transvergent
D) transform

Question 29

At transform plate boundaries,

A) earthquakes are common but volcanoes are absent.
B) volcanoes are common but earthquakes do not occur.
C) both earthquakes and volcanoes are common.
D) neither earthquakes nor volcanoes are common.

Question 30

Segments of mid-ocean ridge systems are offset.Between the offset segments we observe

A) a second series of ridges,perpendicular to the main set.
B) deep-ocean trenches.
C) transform boundaries.
D) hot spots.

Question 31

At a subduction zone,the downgoing (subducting)plate

A) is always composed of continental lithosphere.
B) is always composed of oceanic lithosphere.
C) may be composed of either oceanic or continental lithosphere.
D) is composed entirely of asthenosphere.

Question 32

On either side of a mid-ocean ridge,the lithosphere begins to

A) rise because it thickens away from the ridge.
B) rise because it becomes buoyant.
C) sink because it cools and contracts.
D) sink because convection pulls it downward.

Question 33

The San Andreas Fault zone in California is an example of a ________ plate boundary.

A) divergent
B) convergent
C) transform
D) hot spot

Question 34

Seafloor spreading

A) recycles old oceanic crust.
B) recycles old continental crust.
C) creates new oceanic crust.
D) creates new continental crust.

Question 35

At a subduction zone,the overriding plate

A) is always composed of continental lithosphere.
B) is always composed of oceanic lithosphere.
C) may be composed of either oceanic or continental lithosphere.
D) is composed entirely of asthenosphere.

Question 36

Oceanic lithosphere thickens away from the mid-ocean ridge primarily due to

A) the addition of new crust due to hot-spot volcanism.
B) the addition of new crust due to sedimentation.
C) the addition of new lithospheric mantle as a result of cooling.
D) reasons that geologists cannot determine at present.

Question 37

Which basic type of plate boundary is shown in the image below?

A) Divergent
B) Convergent
C) Transvergent
D) Transform

Question 38

Which of the following statements is true concerning rock produced at mid-ocean ridges?

A) All of the rock produced is basalt.
B) All of the rock produced is gabbro.
C) Basalt is produced at shallow depths and gabbro at deeper depths.
D) Gabbro is produced at shallow depths and basalt at deeper depths.

Question 39

Summed over the entire surface of the Earth,the rate of spreading at divergent boundaries is ________ lithospheric consumption at subduction zones.

A) faster than
B) slower than
C) equal to
D) unrelated to

Question 40

The youngest sea floor is typically found

A) along passive margins.
B) along active margins.
C) along mid-ocean ridges.
D) randomly within abyssal plains.

Question 41

When two continental plates come together at a convergent boundary,the result is

A) subduction.
B) transform faulting.
C) collision and mountain formation.
D) hot spot formation.

Question 42

Describe the global distribution of earthquakes and provide an explanation for this pattern.

Question 43

Contrast the east and west coast of North America with respect to plate tectonics.

Question 44

In a hot-spot volcanic island chain,such as the Hawaiian Islands,which of the following is true?

A) All volcanoes in the chain can be simultaneously active.
B) The ages and distance between volcanoes can be used to calculate plate velocities.
C) The presence of volcanism is related to a plate boundary.
D) The magma source moves to form a hot-spot track.

Question 45

Slab pull occurs because subducting slabs are ________,and therefore ________ dense,than surrounding asthenosphere.

A) less mafic; less
B) cooler; more
C) hotter; more
D) cooler; less

Question 46

Large,thick-crusted,nonvolcanic mountain belts,like the Himalayas,are associated with

A) mid-ocean ridges.
B) hot spots.
C) subduction zones.
D) continent-continent collisions.

Question 47

According to the model proposed by geophysicist J.Tuzo Wilson,hot spots are caused by

A) friction due to the lithosphere sliding atop the asthenosphere.
B) unusually dense concentrations of radioactive isotopes at various points in the crust.
C) hot plumes of mantle material that rise up through cooler,denser surrounding rock.
D) zones of localized subduction that produce melting of the mantle.

Question 48

Most of the pulling force driving plate motion is produced

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

Question 49

Hot spots can occur

A) only within continental plates.
B) only within oceanic plates.
C) within either continental or oceanic plates.
D) only on plate boundaries.

Question 50

The image below shows a view of a typical segmented mid-ocean ridge.Which letter below marks the location of the active transform fault?

A) A
B) B
C) C
D) D

Question 51

Most of the pushing force driving plate motion is produced

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

Question 52

Compare the oceanic crust to the continental crust with respect to age.Why is this so?

Question 53

Consult the figure below.Hawaii is an example of

A) hot-spot volcanism.
B) mid-ocean ridge volcanism.
C) volcanic island arc formed by subduction.
D) volcanic continental arc formed by subduction.

Question 54

What happens when a continental plate meets an oceanic plate at a convergent boundary?

Question 55

Discuss why transform boundaries are found in conjunction with divergent boundaries.

Question 56

Describe the process of seafloor spreading.In your answer,please be sure to address why the diameter of the Earth is not growing.

Question 57

Hot-spot tracks result from moving

A) mantle plumes.
B) plates.
C) hot spots.
D) asthenosphere.

Question 58

Compare and contrast the lithospheric mantle and the asthenosphere compositionally and behaviorally.

Question 59

A triple junction,like the one shown below,is a place on Earth's surface where

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 60

Which basic type of plate boundary is shown in the image below?

A) Divergent
B) Convergent
C) Transvergent
D) Transform

Question 61

Compare and contrast a convergent boundary involving two continental plates with a convergent boundary involving two oceanic plates.

Question 62

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

Question 63

A geologist measures the amount of seafloor produced along an MOR to be 45 km.The oldest crust produced is 4.5 Ma.What is the spreading rate of the MOR in centimeters per year? Show your work.