Deck 18: Plate Tectonics

Question 1

Evidence that Earth's magnetic field has undergone numerous reversals can be found

A)by noting the different behavior of the needles in ancient compasses.
B)in the orientation of iron minerals that cooled in once molten rock.
C)in samples of rock taken from Earth's core.
D)None of the above.

Answer 1

B

Question 2

The crust beneath the oceans is much younger than continental crust.

Answer 2

True

Question 3

Evidence for the theoretical formation of Earth and the structure of its interior comes largely from deep core samples.

Answer 3

False

Question 4

The interior of Earth is molten from the heat produced by the intense bombardment Earth experienced during its formation.

Question 5

From the study of ancient compasses, it has become apparent that Earth's magnetic polarity reverse every 2,000 years or so.

Question 6

Seismic evidence indicates that rocks of the crust "float" in a molten mantle.

Question 7

The spreading of the sea floor along the Mid-Atlantic ridge is supported by

A)changes in the orientation of magnetized rocks as one moved away from the ridge.
B)the increase in the thickness of the sediment layer as one moved toward the continents.
C)the large amount of heat escaping from the rift along the ridge.
D)all of these support the sea-floor spreading hypothesis.

Question 8

Hot, molten rock moves up from Earth's core, causing the continents to drift apart.

Question 9

Seismic waves show a sudden increase at the Mohorovicic discontinuity because the

A)mantle material is so much hotter than the crust.
B)composition of minerals on both sides of the layer is different.
C)mantle is so much thicker than the crustal layer.
D)mineral structure is different in this layer than in crustal rock.

Question 10

Which of the following statements about Earth's core is true?

A)Once molten, the core has gradually solidified as it cooled.
B)P-waves cannot travel through this layer of Earth.
C)The core makes up about 1/3 of Earth's volume.
D)The core is mostly made of iron.

Question 11

Earth's crustal layer is

A)thicker under the continents than beneath the oceans.
B)is composed largely of rocks rich in aluminum and silicon.
C)less dense than the mantle material.
D)All of the above.

Question 12

Which of the following statements about seismic waves is not true?

A)In a P-wave the material vibrates back and forth in the same direction as the direction of wave motion.
B)P-waves travel more rapidly than S-waves.
C)Both P-waves and S-waves travel readily through molten rock.
D)Seismic waves are reflected at boundaries between rock layers with different densities.

Question 13

The least dense rocks in Earth are found in

A)the continental crust.
B)oceanic crust.
C)mantle.
D)core.

Question 14

The asthenosphere is

A)the uppermost layer of the mantle.
B)the boundary between the mantle and the core.
C)a plastic layer in which the lithosphere is imbedded.
D)the solid, dense layer below the Moho.

Question 15

P-waves travel through both solid and liquid rock, but S-waves cannot travel through liquid.

Question 16

Long, high, and continuous mountain ranges run through the middle of the oceans.

Question 17

The crust is a thin layer of granite rock that makes up the continents and ocean basins.

Question 18

The mantle is largely composed of ferromagnesian minerals such as olivine.

Question 19

Geologists think that oceanic crust is different from continental crust because

A)seismic waves travel at different speeds through these layers.
B)oceanic crust is much thinner than continental crust.
C)S-waves don't travel through oceanic crust while they can through continental crust.
D)core samples reveal that oceanic crust is largely granite-like materials.

Question 20

Most of Earth's mass is contained in the

A)crust.
B)mantle.
C)outer core.
D)inner core.

Question 21

The Himalayan Mountains were formed as a result of

A)ocean-continent plate divergence.
B)ocean-continent plate convergence.
C)continent-continent plate convergence.
D)the deformation that occurred along a transform boundary.

Question 22

Japan is a group of arc islands associated with

A)the convergence of two oceanic plates.
B)the convergence of an oceanic and a continental plate.
C)the divergence of two oceanic plates.
D)None of the above.

Question 23

According to the plate tectonics theory, sea-floor spreading occurs at a

A)subduction zone.
B)convergent boundary.
C)divergent boundary.
D)transform boundary.

Question 24

The presence of an oceanic trench, a chain of volcanic mountains along the edge of a continent, and deep-seated earthquakes is characteristic of

A)ocean-ocean plate convergence.
B)ocean-continent plate convergence.
C)continent-continent plate convergence.
D)ocean-continent plate divergence.

Question 25

When an oceanic plate and continental plate converge

A)the continental plate is subducted beneath the oceanic plate.
B)the two plates buckle and uplift the crustal material.
C)the oceanic plate is subducted beneath the continental plate.
D)new crustal material is created at the boundary.

Question 26

The San Andreas Fault is the site of a

A)subduction zone.
B)transform boundary.
C)rift zone.
D)convergence boundary.

Question 27

Evidence shows that Earth's magnetic field is diminishing with time and may reverse orientations by the end of the next

A)200 years.
B)2,000 years.
C)25 million years.
D)4.5 million years.

Question 28

According to plate tectonics, new crustal material is created at

A)divergent plate boundaries.
B)ocean-continent plate convergence.
C)subduction zones.
D)ocean-ocean plate convergence.

Question 29

The Hawaiian Islands were formed as

A)new crust was created at an oceanic ridge.
B)the Pacific plate moved over a hot spot.
C)the Pacific Plate was subducted beneath part of the North American plate.
D)two oceanic plates in the Pacific converged.

Question 30

The driving force behind the movement of oceanic and continental plates may be

A)the rotation of Earth on its axis.
B)movements of Earth's liquid outer core.
C)adjustment of Earth's crust.
D)convection cells within the mantle.