Deck 4: The Way the Earth Works: Plate Tectonics

Question 1

Tectonic plates might consist of ____________.

A)continental lithosphere only
B)oceanic lithosphere only
C)oceanic or continental lithosphere or a combination of both
D)either oceanic or continental lithosphere,but not both

Answer 1

C

Question 2

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

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

Answer 2

B

Question 3

In a hot-spot volcanic island chain,such as the Hawaiian Islands,all islands possess active volcanoes simultaneously and therefore the risks of volcanic hazards are about the same for all islands.

Answer 3

False

Question 4

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 5

Within the terminology of plate tectonics,an active margin is ____________.

A)synonymous with "subduction zone"
B)a 5-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 6

The theory of plate tectonics ____________.

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

Question 7

Consult the figure below.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 8

Earthquakes are most frequent near coastlines that are termed ____________.

A)active margins
B)passive margins
C)aseismic margins
D)geodesic margins

Question 9

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 10

The lithosphere of Earth can be bent and broken,but will not flow because it ____________.

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

Question 11

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 12

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

Question 13

The thickness of oceanic lithosphere is ____________.

A)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 14

According to the figure below,every plate boundary can be recognized by ____________.

A)the presence of active volcanoes
B)the presence of an earthquake belt
C)a deep chasm that can be seen from space
D)None of the above are correct.

Question 15

All lithospheric plates are approximately the same size and contain a combination of oceanic and continental crust.

Question 16

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

A)active margins
B)passive margins

Question 17

The average thickness of continental lithosphere is about ____________.

A)30 km
B)60 km
C)150 km
D)10,000 km

Question 18

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 19

The pulling forces that produce the most rapid plate velocities are concentrated at ____________.

A)mid-ocean ridges
B)ocean trenches
C)continental collision zones
D)stable continental interiors

Question 20

Consult the figure below.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 21

As lithosphere cools to the sides of a mid-ocean ridge,it begins to ____________.

A)rise with respect to material located closer to the ridge axis
B)sink with respect to material located closer to the ridge axis

Question 22

The number of lithospheric plates on the Earth has been variable through geologic time.Hundreds of millions of years ago,there were plates that no longer exist today.

Question 23

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 24

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 25

All rock produced at the mid-ocean ridges consists of basalt.

Question 26

As compared to a slowly spreading mid-ocean ridge,a rapidly spreading ridge is ____________.

A)wider
B)narrower
C)more silicic in lava composition

Question 27

The youngest sea floor occurs ____________.

A)along passive margins
B)along active margins
C)along mid-ocean ridges
D)randomly over the entire ocean basin

Question 28

The lithosphere of the Earth is generally thinnest at and near ____________ plate boundaries.

A)convergent
B)divergent
C)transform

Question 29

The primary difference between lithospheric and asthenospheric mantle that gives rise to numerous divergent 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 30

As compared to the density of the asthenosphere,the oceanic lithosphere is ____________.

A)always more dense
B)always less dense
C)initially more dense at the age of formation,but eventually becomes less dense
D)initially less dense at the age of formation,but eventually becomes more dense

Question 31

The rate of motion of a lithospheric plate with respect to a stationary hot spot is termed ____________.

A)relative plate velocity
B)absolute plate velocity

Question 32

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

Question 33

Mid-ocean ridges are ____________.

A)convergent plate boundaries
B)divergent plate boundaries
C)transform plate boundaries

Question 34

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 35

At a divergent plate boundary (shown below),two opposed plates ____________.

A)move toward one another
B)move away from one another
C)slide past one another

Question 36

Summed over the entire surface of Earth,____________.

A)the rate of lithospheric production at ridges is greater than the rate of lithospheric consumption at subduction zones
B)the rate of lithospheric consumption at subduction zones is greater than the rate of lithospheric production at ridges
C)rates of lithospheric production and consumption are equal

Question 37

At a convergent plate boundary (shown below),two opposed plates ____________.

A)move toward one another
B)move away from one another
C)slide past one another

Question 38

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 or either oceanic or continental lithosphere

Question 39

Virtually all of the sediment atop a downgoing plate becomes subducted into the mantle along with the plate.

Question 40

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

A)convergent
B)divergent
C)transform

Question 41

A volcanic island arc forms when _______________.

A)an oceanic plate subducts beneath continental lithosphere
B)an oceanic plate subducts beneath another oceanic plate
C)continental lithosphere subducts beneath an oceanic plate
D)two oceanic plates collide

Question 42

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 rises up through cooler,denser surrounding rock
D)factors that remain completely unknown at this time

Question 43

Segments of the mid-ocean ridge system 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)None of the above are correct.

Question 44

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

A)30 km
B)150 km
C)670 km
D)990 km

Question 45

Consult the figure below.The Wadati-Benioff zone is a belt of earthquakes found ____________.

A)within an otherwise stable continental interior
B)within an overriding plate at a subduction zone
C)within a downgoing plate at a subduction zone
D)along mid-ocean ridges

Question 46

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 47

All portions of the mid-ocean ridge system have a well-defined axial trough (central rift).

Question 48

At a transform plate boundary (shown below),two opposed plates ____________.

A)move toward one another
B)move away from one another
C)slide past one another

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)the boundaries of three lithospheric plates meet to form an elongate surface

Question 50

Large,thick,nonvolcanic mountain belts,like the Himalayas,have features associated with ____________ plate boundaries.

A)convergent
B)divergent
C)transform

Question 51

Deep oceanic trenches are features of ____________ plate boundaries.

A)convergent
B)divergent
C)transform

Question 52

The volcanoes of the Cascades Mountains are related to melting of rock associated with a ____________ plate boundary.

A)convergent
B)divergent
C)transform

Question 53

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

A)convergent
B)divergent
C)transform

Question 54

Consult the figure below.Hot-spot tracks result from moving _____________.

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

Question 55

Consult the figure below.Subduction zones are ____________.

A)convergent plate boundaries
B)divergent plate boundaries
C)transform plate boundaries

Question 56

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

A)convergent
B)divergent
C)transform

Question 57

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

Question 58

Sliding motion along transform faults caused the segments of the mid-ocean ridges to become dislocated with respect to one another.

Question 59

Consult the figure below.Hawaii is an example of ____________.

A)hot-spot volcanism
B)mid-ocean ridge volcanism
C)volcanic island arc
D)transform margin

Question 60

Subducted slabs have never been detected below the Wadati-Benioff zone.

Question 61

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

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

Question 62

When two bodies of continental lithosphere are pulled together at a convergent boundary,the result is ____________.

A)subduction
B)collision and mountain formation

Question 63

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

A)ridge rocks are hot and therefore of relatively low density
B)the lithospheric plates are thickest at the ridges so they stand up taller
C)rising ocean currents leave a vacuum above the ridge
D)ridge rocks are mafic,whereas the ocean basin crust consists of ultramafic rock

Question 64

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