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Plate tectonics theory was widely accepted by scientists in what decade?
A. 1980s
B. 1920s
C. 1930s
D. 1960s
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D
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Plate tectonics theory took decades to be accepted because
A. of pure stubbornness by the scientific community.
B. most of Wegener’s ideas turned out to be wrong.
C. Wegener couldn’t explain how continents moved.
D. climate, fossil distributions, and land shape offered conflicting evidence.
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C
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Which of the following was NOT a line of evidence used by Wegener to develop this theory that continents drift?
A. the presence of earthquakes in seismic belts along trenches, ridges, and fracture zones
B. the location of ancient till deposits and striations that indicated glacial movement toward the interior of continents
C. the distribution of fossil species
D. matching mountain chains on continents currently separated by oceans
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A
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Which of the following statements is NOT true about the ocean floor?
A. Oceanic crust is quite different from continental crust.
B. The heat flow through it is greatest at the mid-ocean ridges.
C. It is covered by a layer of sediment composed of clay and plankton shells.
D. Oceanic crust contains granite and metamorphic rocks.
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D
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Choose the FALSE statement. Magnetic anomalies are
A. measured with an instrument called a magnetometer.
B. found only on the seafloor.
C. termed normal if the atomic dipoles match Earth’s current magnetic field and point from north to south.
D. places where the magnetic field strength is either greater or less than the expected strength.
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B
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Identify the FALSE statement.
A. All polarity chrons are the same length of time; they differ only in the magnetic strengths they represent.
B. Positive magnetic anomalies occur over areas of seafloor when the poles of Earth’s magnetic field and the paleopoles preserved in the seafloor basalt agree; negative anomalies occur when they are opposite each other.
C. The width of each rock stripe is a measure of how long the polar direction remained constant.
D. The series of rock stripes parallel to and bilaterally symmetrical across the mid-ocean ridge record the sequence of Earth’s magnetic reversals over time.
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A
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Ocean crust
A. is the same age as continental crust.
B. is covered by a thin blanket of sediment that thickens away from the ridge axis.
C. is the same composition as continental crust.
D. has not been sampled directly because it is too deep beneath the ocean.
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B
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The global occurrence of earthquakes reveals that
A. they prove that Earth is splitting apart (rifting) at all plate boundaries.
B. they usually occur on the boundaries of plates or at hot spots.
C. they usually occur at the center of plates.
D. their locations are randomly scattered.
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B
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Asthenosphere
A. subducts when it collides with continental lithosphere.
B. is the lower layer of both continental and oceanic lithosphere.
C. is warm enough to flow slowly.
D. is the uppermost layer of Earth’s core.
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C
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Identify the FALSE statement.
A. There are 12 major plates, and several microplates.
B. The contacts between plates are called passive margins.
C. Plates shift the continents around as they move, so Earth’s surface is constantly changing.
D. Plates may consist of all ocean floor or both ocean floor and continental crust.
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D
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Identify the FALSE statement.
A. Observers in research submersibles have seen submarine volcanoes.
B. As the seafloor spreads, the asthenosphere rises, melts to become magma, and fills the space between plates.
C. Some magma generated during seafloor spreading erupts from submarine volcanoes.
D. Some magma generated during seafloor spreading spills out to produce a new layer of seafloor called gabbro.
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A
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The center of a mid-ocean ridge is where
A. new oceanic lithosphere is being created.
B. molten basalt subducts back into Earth.
C. you find the oldest, densest, hottest oceanic crust.
D. two continental plates converge.
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A
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Accretionary prisms form due to what process?
A. subduction
B. divergence
C. rifting
D. transform motion
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A
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Identify the FALSE statement.
A. Seafloor spreading behind a volcanic island arc creates a small ocean basin called a back-arc basin or marginal sea.
B. An accretionary prism is a wedge-shaped mass of sediment scraped off a subducting plate as it slides under the overriding plate.
C. Plate boundaries where subduction occurs are also called consuming boundaries.
D. A spreading boundary must be in the middle of the ocean basin where it is located.
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D
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The chain of volcanoes along the west coast of South America (the Andes Mountains) exists because
A. an oceanic plate is rifting apart from the South American Plate.
B. an oceanic plate is subducting under the western edge of the South American Plate.
C. an oceanic plate is sliding past the South American Plate and heading toward the northwest.
D. basalt is pushing up through the trench that parallels the west coast of South America.
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B
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Identify the FALSE statement. A subducting (or downgoing) plate
A. can be either continental or oceanic lithosphere.
B. has a volcanic arc associated with it.
C. can be charted by noting its Wadati-Benioff zone.
D. has a trench along its seaward edge.
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A
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Identify the FALSE statement. According to the mantle plume model, hot-spot plumes
A. stream upward slowly because their hot rock is less dense than the overlying rock.
B. can occur beneath ocean plates as well as continental plates.
C. produce volcanoes that do not always coincide with a plate boundary.
D. are thought to originate at the crust-mantle boundary.
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D
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The chain of Hawaiian Islands extends northwest across the Pacific as shown in the figure. The island of Hawaii is the youngest, and the islands get progressively older to the northwest. How does plate tectonic theory explain this?
A. The Pacific Plate is undergoing rifting, starting at the northwest end of the chain and extending southeast to Hawaii.
B. A hot spot moves under the Pacific Plate toward the southeast.
C. Microplates break loose from the Pacific Plate as it moves, leaving this chain of islands in its wake.
D. A hot spot is currently situated under Hawaii and the Pacific Plate is moving across it in a northwesterly direction.
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D
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The Himalayas are growing because
A. two plates are moving past each other there.
B. two plates are diverging there.
C. a continental plate is colliding with another continental plate there.
D. an oceanic plate is converging with a continental plate and subducting there.
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C
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Alfred Wegener proposed the idea of continental drift after he observed evidence from fossils, glacial deposits, and the fit of the continents that suggested all of the continents were once
A. aligned east to west along the equator during the late Mesozoic through the Cenozoic.
B. combined to form a supercontinent (which he termed Rodinia) in the Proterozoic.
C. combined to form a supercontinent (which he termed Pangaea) in the late Paleozoic through the Mesozoic.
D. aligned north to south along the prime meridian during the late Cenozoic.
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C
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Identify statements true of Pangaea.
A. Pangaea was one of several supercontinents that have formed and broken up during Earth’s history.
B. Pangaea consisted of all of the Earth’s continents pushed together with the exception of Antarctica.
C. Rates of seafloor spreading in the Atlantic Ocean are compatible with what is known about the breakup of Pangaea.
D. The regional-scale folds visible in the Appalachian Mountains are remnants of Pangaea’s formation.
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A,C,D
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The San Andreas fault is
A. categorized as a transform fault, one of four types of plate boundaries.
B. part of the boundary between the North and South American Plates.
C. one of the few transform faults that cut across continental lithosphere.
D. a vertical fault along which the slip direction is perpendicular to Earth’s surface.
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C
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