Deck 4: The Way the Earth Works: Plate Tectonics

Question 1

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

Answer 1

A

Question 2

The lithosphere of Earth will not flow because it ________.

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

Answer 2

C

Question 3

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

Answer 3

D

Question 4

Broad,sediment-covered continental shelves are found along ________.

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

Question 5

Continental lithosphere ________.

A)is thicker than oceanic lithosphere
B)contains more mafic rocks than oceanic lithosphere
C)is denser than oceanic lithosphere
D)contains no crustal material,consisting solely of lithified upper mantle

Question 6

Deformed (bent,stretched,or cracked)lithosphere occurs ________.

A)randomly over the surface of Earth
B)primarily within the interiors of tectonic plates
C)primarily on the margins of tectonic plates
D)primarily at hot spots

Question 7

In the scope of plate tectonics,an active margin is defined as ________.

A)synonymous with "subduction zone"
B)a five-mile radius surrounding an active volcano
C)a continental coastline that coincides with a plate boundary
D)anywhere on Earth where earthquakes are especially frequent

Question 8

According to Archimedes' principle of buoyancy,an iceberg sinks until ________.

A)the total mass of the water displaced equals the total mass of the whole iceberg
B)the total mass of the iceberg is underwater
C)about 60% of the iceberg is underwater
D)the total mass of the water displaced equals 80% of the mass of the iceberg

Question 9

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 10

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 11

Earthquakes occur most frequently near ________ margins.

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

Question 12

The theory of plate tectonics ________.

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

Question 13

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

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

Question 14

Under the theory of plate tectonics,the plates themselves are ________.

A)discrete pieces of lithosphere at the surface of the solid Earth that move with respect to one another
B)discrete 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 15

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

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

Question 16

Which of the following is NOT true about Earth's tectonic plates?

A)Tectonic plates vary greatly in size.
B)Some tectonic plates contain only oceanic lithosphere.
C)Some tectonic plates contain only continental lithosphere.
D)Some tectonic plates contain both oceanic and continental lithosphere.

Question 17

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

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

Question 18

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

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

Question 19

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

Question 20

The primary difference between lithospheric and asthenospheric mantle that gives rise to numerous different patterns of physical behavior is ________.

A)physical state: the lithosphere is solid;the asthenosphere is liquid
B)chemical composition: the lithosphere is mafic;the asthenosphere is felsic
C)temperature: the lithosphere is cooler than the asthenosphere
D)chemical composition: the lithosphere is felsic;the asthenosphere is mafic

Question 21

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

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

Question 22

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 23

Iceland is one of the few places in the world that is both above sea level and situated atop a ________ plate boundary.

A)divergent
B)convergent
C)transform
D)Iceland is not located at a plate boundary.

Question 24

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

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

Question 25

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 26

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 27

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 28

The volcanoes of the Cascades Mountains in the northwest United States are related to melting of rock associated with a ________.

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

Question 29

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 30

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 31

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 faults
D)hot spots

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

Deep-oceanic trenches are features of ________ plate boundaries.

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

Question 34

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

A)faster than
B)slower than
C)equal to
D)This cannot yet be measured by geologists.

Question 35

The oceanic lithosphere is typically coated in a layer of sediment.Which of the following is NOT true about this sediment?

A)Some of the sediment may be scraped off at subduction zones by the overriding plate forming an accretionary prism.
B)All of the sediment is eventually subducted along with the lithosphere into the mantle.
C)The layer of sediment is generally thicker on older oceanic lithosphere.
D)The layer of sediment is generally very thin or nonexistent at mid-ocean ridges.

Question 36

The lithosphere of the Earth is generally thickest at and near ________ plate boundaries.

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

Question 37

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)conformal and transvergent

Question 38

Subduction zones are found at which basic plate boundary type?

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

Question 39

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

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

Question 40

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 41

________ is an example of a continental rift and the ________ is/are the result of collision.

A)The Basin and Range Province;Mid-Atlantic ridge
B)The Mid-Atlantic ridge;Himalayan Mountains
C)The Basin and Range Province;Himalayan Mountains
D)The San Andreas Fault;Himalayan Mountains

Question 42

A guyot is ________.

A)any portion of the ocean floor that is topographically higher than surrounding sea floor
B)an extinct oceanic hot-spot volcano that has not yet subsided below sea level
C)an extinct oceanic hot-spot volcano that has subsided below sea level
D)synonymous with the term hot spot

Question 43

The mid-ocean ridges are elevated above the surrounding sea floor because ________.

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

Question 44

Slab pull occurs because subducting slabs are ________.

A)less mafic,and therefore less dense,than surrounding asthenosphere
B)cooler,and therefore more dense,than surrounding asthenosphere
C)hotter,and therefore more dense,than surrounding asthenosphere
D)cooler,and therefore less dense,than surrounding asthenosphere

Question 45

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 ________.

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

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

The rate of motion of a lithospheric plate with respect to a stationary location inside the Earth is termed ________,while the motion of a plate with respect to another is termed ________.

A)absolute plate velocity;relative plate velocity
B)relative plate velocity;absolute plate velocity
C)Both are measures of absolute velocity.
D)Both are measures of relative velocity.

Question 48

In a hot-spot volcanic island chain,such as the Hawaiian Islands,which of the following is NOT 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 not related to a plate boundary.
D)The magma source stays approximately fixed,but motion of the overriding plate forms a hot-spot track.

Question 49

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 50

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 51

Hot spots can occur ________.

A)only within continental plates
B)only within oceanic plates
C)within either continental or oceanic plates
D)only when the thickness of the crust is less than 10 km

Question 52

Hot-spot tracks result from moving ________.

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

Question 53

When two plates composed of continental lithosphere are pulled together at a convergent boundary,the result is ________.

A)subduction
B)transform faulting
C)collision and mountain formation
D)a hot spot is formed

Question 54

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 55

Tectonic plates move at rates that are approximately ________.

A)1 to 5 cm every 1,000 years
B)1 to 15 cm/year
C)1 to 15 m/year
D)10 to 100 m/year

Question 56

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 57

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)transform margin