Deck 12: Global Tectonics: Plates and Plumes

Question 1

Figure 12.11
Refer to Figure 12.11 in your textbook. Which option correctly matches isotopic age and polarity of the seafloor.

A) 2.29 million years: reverse polarity; 1.37 million years: reverse polarity
B) 3.42 million years: reverse polarity; 1.74 million years: reverse polarity
C) 1.26 million years: normal polarity; 1.92 million years: reverse polarity
D) 2.12 million years: normal polarity; 3.01 million years: normal polarity

Answer 1

A

Question 2

Which statement is true about the lithosphere?

A) The lithosphere is thickest at the mid-ocean ridges because of the quantity of magma that flows up to the surface.
B) The lithosphere gets thicker as distance from the ridge increases, because it cools and the boundary between the lithosphere and asthenosphere occurs at greater depth.
C) The lithosphere maintains its thickness as distance from the ridge increases, because the boundary between the lithosphere and asthenosphere remains at a constant temperature and depth.
D) The lithosphere gets thinner as distance from the ridge increases, because decompression melting occurs with decreased pressure.

Answer 2

B

Question 3

Using Figure 12.11 in your textbook, which option correctly identifies a time that polarity changed from normal to reverse and back?

A) normal to reverse: 3.04 million years ago, reverse to normal: 2.60 million years ago
B) normal to reverse: 2.60 million years ago, reverse to normal: 1.79 million years ago
C) normal to reverse: 3.33 million years ago, reverse to normal: 3.04 million years ago
D) normal to reverse: 1.79 million years ago, reverse to normal: 0.99 million years ago

Answer 3

C

Question 4

Which of the following is true of divergent and convergent plate movement?

A) The direction of plate movement is the same.
B) Convergent plate movement is less symmetrical than divergent plate movement.
C) Material is destroyed with both plate movements.
D) Both plates have boundaries.

Question 5

The following statements relate to processes that occur because of plate subduction. Which of the following statements is not true?

A) Earthquake foci are deeper further from a deep-sea trench.
B) Mountains form further from a convergent boundary than from a divergent boundary.
C) Volcanoes of this kind tend to have a single type of magma.
D) Deep-sea trenches mark the plate boundary.

Question 6

How fast is North America moving away from Africa?

A) 3 cm/year
B) 3 m/year
C) 3 mm/year
D) 3 km/year

Question 7

Why are so few volcanoes mapped in the middle of the oceans?

A) The middle of the oceans corresponds with the middle of tectonic plates, so there are only hot-spot volcanoes there.
B) Geologists cannot pinpoint the locations of many recently active seafloor volcanoes.
C) There are only convergent plate boundaries under the ocean, which are less likely to have volcanoes than transform or divergent boundaries.
D) There are only divergent plate boundaries under the ocean, which are less likely to have volcanoes than transform or convergent boundaries.

Question 8

What do mountain belts such as the Caledonian and Appalachian Mountains suggest to scientists?

A) By uniformitarian principles, the tectonic plates may have been in different positions in the past.
B) The theory of tectonic plate action is not sufficient to explain all mountain building.
C) The continental lithosphere is more rigid than the oceanic lithosphere.
D) By evaluation of the deformations, the asthenosphere is more rigid than the lithosphere.

Question 9

Which of the following determines why subducting plates sink at a particular location?

A) the heat of the asthenosphere at the location
B) the density of the asthenosphere at the location
C) the pushing movement of the adjacent plate
D) the density of the lithosphere at the location

Question 10

After movement, the interior parts of ice slabs and continental plates

A) may be stretched.
B) may be rippled up to form hills, ridges, and mountains.
C) may be cracked to form crevices.
D) remain unchanged.

Question 11

Figure 12.25
Using Figure 12.25 in your textbook, which of the following is not a normal consequence of an oceanic-oceanic convergent plate boundary?

A) The denser crust subducts the less dense plate.
B) Thrust faults lift up above the subduction zone.
C) A volcanic island arc forms above where the subducting plate melts.
D) A trench forms at the location where subduction begins.

Question 12

At what point does the Wadati-Benioff zone have to end?

A) when it runs into the deep-sea trench
B) when it runs up against another plate
C) when it reaches a zone that is too hot
D) when it reaches Earth's surface

Question 13

Why does the heat flow dip east of the location where the Juan de Fuca Plate subducts beneath the North American Plate?

A) The ocean water cools the rock in the trench.
B) The cold subducted lithosphere dips there.
C) The rock is denser and cooler there.
D) The rock remained cold there after the most recent ice age.

Question 14

How do scientists measure the age of rocks at mid-ocean ridges?

A) radioactive dating methods
B) comparison of rock samples on mountain ranges
C) fossil stratification and the principle of horizontality
D) magnetic polarity measurements

Question 15

Which feature is not usually caused by convergent boundaries?

A) volcanoes
B) deep-sea trenches
C) rift valleys
D) mountains

Question 16

What evidence suggests to scientists that magma generation at convergent boundaries is different than magma generation at mid-ocean ridges?

A) crystal size
B) igneous action
C) partial melting caused by water
D) lava composition

Question 17

Approximately what percent of lithosphere deformation occurs at plate boundaries?

A) 60%
B) 70%
C) 80%
D) 90%

Question 18

What is true of Iceland?

A) Iceland is contracting at a rate of about 4 mm per year due to melting at the Mid-Atlantic Ridge.
B) Iceland is stretching at a rate of about 4 mm per year due to expansion at the Mid-Atlantic Ridge.
C) Iceland is contracting at a rate of about 4 m per year due to melting at the Mid-Atlantic Ridge.
D) Iceland is stretching at a rate of about 4 m per year due to expansion at the Mid-Atlantic Ridge.

Question 19

What is a typical depth of a deep-sea trench?

A) 5 m
B) 5 km
C) 50 m
D) 50 km

Question 20

Why did scientists reject Wegener's idea about how continents moved from Pangea to their present locations?

A) Scientists did not believe in a fluid mantle.
B) Scientists did not believe in uplift of continents from the ocean floor.
C) Scientists did not believe that the continental lithosphere could be stronger than the oceanic lithosphere.
D) Scientists were not convinced by his puzzle-like matching of continents into Pangea.

Question 21

What is a seamount?

A) an extinct underwater volcano
B) a wrinkle of crust formed by converging plates
C) an underwater sedimentary rock pile
D) an underwater volcano

Question 22

Which part of the plate theory from the 1960s was disproved by GPS technology?

A) plate velocity
B) relative plate motion
C) nature of the plates
D) tectonic action

Question 23

How far down do downwelling and upwelling reach in the Earth?

A) to the lithosphere
B) to the asthenosphere
C) to the transition zone
D) to the lower mantle

Question 24

When did Pangea begin to split apart?

A) 60 million years ago
B) 180 million years ago
C) 240 million years ago
D) 360 million years ago

Question 25

What is the primary force that drives plate motion?

A) slab pull
B) gravity
C) superplume push
D) mid-ocean ridge igneous push

Question 26

Which of the following is least likely to be mapped with data about ancient igneous rocks?

A) ancient hot spots
B) ancient convergent zones
C) ancient mountain ranges
D) ancient divergent zones

Question 27

What is the general direction of the movement of California compared to the center of the continent?

A) southeast
B) northeast
C) west
D) northwest

Question 28

Which of the following is not a normal consequence of the convergence of two continental crust plates?

A) subduction of the thicker plate
B) formation of thrust faults
C) increasing thickness of crust
D) formation of mountains

Question 29

Which process is most common at transform boundaries?

A) volcanic action
B) lithospheric formation
C) lithospheric destruction
D) lithospheric conservation

Question 30

What type of boundary is the San Andreas fault in California?

A) convergent
B) divergent
C) fault-block
D) transform

Question 31

The landmass that is now the eastern United States used to face

A) southwest.
B) north.
C) northeast.
D) south.

Question 32

What is the main frame of reference for GPS measurements?

A) rock compositions
B) satellite locations
C) Earth's magnetic pole
D) the absolute value of Earth's core

Question 33

When did the Himalayan Mountains form?

A) Cenozoic Era
B) Paleozoic Era
C) Mesozoic Era
D) Devonian Period

Question 34

A tectonically quiet zone results when

A) crust materials are soft.
B) the lithosphere is not too dense.
C) there are many small faults.
D) plates move in the same direction at the same velocity.

Question 35

Why is there a difference in the number of faults involved at transform boundaries in the ocean and those on continents?

A) Continental crust is weaker than oceanic crust.
B) The oceanic crust has a more crystalline rock composition.
C) The weight of the water equalizes the pressure on the oceanic crust.
D) Plates have more room to move in the ocean than on continents.

Question 36

When did the continents acquire outlines similar to the ones they have now?

A) Cenozoic Era
B) Paleozoic Era
C) Mesozoic Era
D) Devonian Period

Question 37

How many hot spots are there on Earth?

A) 4
B) 40
C) 400
D) 4000

Question 38

Which is not a piece of primary evidence in favor of the mantle-plume hypothesis?

A) basalt composition
B) volcanic locations
C) hot spot volcano types
D) plate velocity

Question 39

Why do hot spots form a trail of extinct volcanoes over time?

A) The mantle plume moves with Earth's rotation.
B) The tectonic plates that contain the volcanoes move over time.
C) The heat and debris from the eruptions are enough to form nearby islands.
D) The mantle-plume hypothesis assumes the hot plumes are wedge-shaped.

Question 40

What evidence shows that Yellowstone is a hot spot?

A) basalt flows
B) extinct volcanoes
C) a geyser
D) metamorphic rock banding

Question 41

All of the following processes aid the lithosphere in becoming denser than the asthenosphere except

A) cooling and contracting.
B) forming by decompression melting.
C) thickening by addition to the base.
D) metamorphosing into eclogite.

Question 42

Figure 12.43
According to Figure 12.43 when did the Appalachian Mountains form?

A) 540 million years ago
B) 430 million years ago
C) 300 million years ago
D) 170 million years ago
E) 90 million years ago

Question 43

Judge the following sentence according to the criteria given below. Seafloor elevations decrease away from mid-ocean ridges because cooling lithosphere contracts, becomes denser and sinks down into the weak asthenosphere.

A) The assertion is correct but the reason is incorrect.
B) The assertion is incorrect but the reason is correct.
C) The assertion and the reason are both correct, and the reason is valid.
D) The assertion and the reason are both correct, but the reason is invalid.
E) Both the assertion and the reason are incorrect.

Question 44

Which of the following is an example of a slow moving plate?

A) North American Plate
B) Nazca Plate
C) Cocos Plate
D) Pacific Plate
E) Philippine Plate

Question 45

The seafloor spreading hypothesis predicts that the mid-ocean ridges should be locations of rising asthenosphere. This prediction is supported by seismic data that indicates

A) faster seismic wave velocities at the trenches.
B) slower seismic wave velocities at the trenches.
C) faster seismic wave velocities at the ridges.
D) slower seismic wave velocities at the ridges.

Question 46

According to the Continental Drift hypothesis the continents and ocean basins on the same plate move together.

Question 47

All volcanic eruptions over the past 10,000 years occurred along or near plate boundaries.

Question 48

Judge the following sentence according to the criteria given below. Plate tectonic works because lithosphere is less dense than asthenosphere at divergent boundaries and more dense than asthenosphere at convergent boundaries.

A) The assertion is correct but the reason is incorrect.
B) The assertion is incorrect but the reason is correct.
C) The assertion and the reason are both correct, and the reason is valid.
D) The assertion and the reason are both correct, but the reason is invalid.
E) Both the assertion and the reason are incorrect.

Question 49

Figure 12.43
According to Figure 12.43 when did the Caledonian Mountains form?

A) 540 million years ago
B) 430 million years ago
C) 300 million years ago
D) 170 million years ago
E) 90 million years ago

Question 50

Most active mountain belts are located near plate boundaries.

Question 51

Judge the following sentence according to the criteria given below. Continental crust dominated by rocks older than 1 billion years but no ocean crust older than 180 million years exists because oceanic crust is created at mid-ocean ridges.

A) The assertion is correct but the reason is incorrect.
B) The assertion is incorrect but the reason is correct.
C) The assertion and the reason are both correct, and the reason is valid.
D) The assertion and the reason are both correct, but the reason is invalid.
E) Both the assertion and the reason are incorrect.

Question 52

The Wadati-Benioff zone outlines the ________ at a convergent boundary.

A) ocean trench
B) ocean ridge
C) subducting plate
D) transform fault

Question 53

300 million years ago Ancestral North America was

A) in its present day location.
B) part of Pangea.
C) at 60 degrees north latitude.
D) at the south pole.

Question 54

A present day example of an oceanic-oceanic convergent plate boundary is

A) Indonesia.
B) Andes Mountains.
C) Appalachian Mountains.
D) Hawaii.

Question 55

A present day example of a continental-oceanic convergent plate boundary is

A) Andes Mountains.
B) Himalayas and Tibetan Plateau.
C) Indonesia.
D) New Zealand.

Question 56

Which force may cause uplift, folding, and formation of reverse and thrust faults?

A) slab pull
B) gravity
C) compression
D) tension

Question 57

90 million years ago India was

A) in its present day location.
B) north of the equator.
C) at the south pole.
D) not part of Asia.

Question 58

All rift valleys extend sufficiently to form new continents and plate boundaries.

Question 59

Figure 12.43
According to Figure 12.43 when did the Rocky Mountains form?

A) 540 million years ago
B) 430 million years ago
C) 300 million years ago
D) 170 million years ago
E) 50 million years ago

Question 60

At convergent boundaries earthquake focal depths ________ with increasing distance from the trench.

A) decrease
B) erupt
C) increase
D) rotate

Question 61

Which type of convergent plate boundary raised the Tibetan Plateau?

A) oceanic-oceanic
B) continental-continental
C) continental-oceanic
D) ridge-hot spot

Question 62

Which of the following plates has the fastest average velocity?

A) North American Plate
B) Nazca Plate
C) Cocos Plate
D) Pacific Plate
E) Philippine Plate

Question 63

Why do we know that apparent polar wander didn't actually happen, and that the poles have remained more or less where they are now?

Question 64

What is the evidence that subduction occurs at convergent plate boundaries?

Question 65

What two types of locations are hot spots typically found in?

Question 66

Why do plate traces appear to have a curved path when plotted on a map?

Question 67

What does the Mantle-Plume hypothesis explain that plate tectonics cannot explain?

Question 68

"What is the evidence that plates slide past one another at transform plate boundaries?"

Question 69

Which part of the Atlantic Ocean is the youngest?

Question 70

How do convergent and divergent boundaries differ?"

Question 71

What observation supports the hypothesis that the slab-pull force is the primary cause of plate motion?

A) Divergent plate boundaries represent all of the upwelling expected by mantle convection.
B) Plumes are the deep upwelling component of convection with seismically slow velocities.
C) Earthquakes and volcanoes are concentrated at plate boundaries.
D) Plates with long subduction zones move faster than plates with short subduction-zones.

Question 72

What are the consequences of plate motion over geologic time?

Question 73

Which type of convergent plate boundary results in a chain of submarine volcanoes?

A) oceanic-oceanic
B) continental-continental
C) continental-oceanic
D) ridge-hot spot

Question 74

When were Africa and South America joined together?

Question 75

What is the evidence that plates move apart at divergent plate boundaries?

Question 76

What is the evidence that plates are rigid?

Question 77

How can we use sedimentary rocks to substantiate the moving of the continents through time?

Question 78

Which of the following is oldest?

A) Hawaiian Islands
B) Hawaiian Seamounts
C) Emperor Seamounts
D) East Pacific Rise

Question 79

How do we track the earth's magnetic field back through time?

Question 80

Which Hawaiian island is the youngest?

A) Hawaii
B) Kahoolawe
C) Oahu
D) Kauai