Geology Chapter 2

Identify the FALSE statement. A. 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. B. All polarity chrons are the same length of time; they differ only in the magnetic strengths they represent. C. 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. D. The width of each rock stripe is a measure of how long the polar direction remained constant.

B. All polarity chrons are the same length of time; they differ only in the magnetic strengths they represent.

Identify the FALSE statement. A. As the seafloor spreads, the asthenosphere rises, melts to become magma, and fills the space between plates. B. Some magma generated during seafloor spreading spills out to produce a new layer of seafloor called gabbro. C. Some magma generated during seafloor spreading erupts from submarine volcanoes. D. Observers in research submersibles have seen submarine volcanoes.

B. Some magma generated during seafloor spreading spills out to produce a new layer of seafloor called gabbro.

The Himalayas are growing because A. two plates are moving past each other there. B. a continental plate is colliding with another continental plate there. C. an oceanic plate is converging with a continental plate and subducting there. D. two plates are diverging there.

B. a continental plate is colliding with another continental plate there.

The constant motion of tectonic plates leads to convergent, divergent, and transform-plate boundaries. Which type of structure is shown in the figure below? A. a subduction zone B. a mid-ocean ridge C. a passive margin D. a strike-slip fault

B. a mid-ocean ridge

The center of a mid-ocean ridge is where A. molten basalt subducts back into Earth. B. new oceanic lithosphere is being created. C. you find the oldest, densest, hottest oceanic crust. D. two continental plates converge.

B. new oceanic lithosphere is being created.

Which of the following statements about lithosphere and asthenosphere is TRUE? A. Lithosphere and asthenosphere have the same physical properties; they are both rigid. B. Lithosphere is more mafic than asthenosphere. C. Lithosphere consists of the crust and the upper mantle, and behaves like a hard layer that breaks and bends. D. Asthenosphere consists of the lower, middle, and upper mantle, and is defined as mantle material that is cooler than 1280°C.

C. Lithosphere consists of the crust and the upper mantle, and behaves like a hard layer that breaks and bends.

The lithosphere is the rigid part of the mantle, while the asthenosphere is the relatively more fluid portion. The following figure shows the spatial relationship between the Earth's crust, lithosphere, and asthenosphere. Which of the following statements regarding the figure is FALSE? A. Continental lithosphere is thinner than oceanic lithosphere. B. The asthenosphere is denser than the lithosphere. C. Oceanic crust is thinner than continental crust. D. Oceanic lithosphere sinks deeper into the asthenosphere than continental lithosphere

A. Continental lithosphere is thinner than oceanic lithosphere.

Paleoenvironmental reconstructions of Pangea indicate that regional climates during the Paleozoic were significantly different than they are today. Looking at the following figure, which statement about climate and associated rock deposits from the Paleozoic is FALSE? A. Desert sands were deposited in South America. B. Coal swamps were present along the east coast of the United States. C. India was partially glaciated. D. Coral reefs were found in North America, Europe, and Asia.

A. Desert sands were deposited in South America.

In the following figure, the magnetic anomaly pattern is mirrored on either side of the central ridge. What is responsible for this pattern? A. Seafloor spreading builds new crust equally on both sides of the ridge. B. The magnetic anomalies follow a repetitious pattern in mantle convection. C. The anomalies follow El Niño /La Niña cycles D. The anomalies follow Milenkovich cycles based on orbital dynamics.

A. Seafloor spreading builds new crust equally on both sides of the ridge.

Accretionary prisms form due to what process? A. subduction B. divergence C. rifting D. transform motion

A. Subduction

Identify the FALSE statement. A subducting (or downgoing) plate ________ A. can be either continental or oceanic lithosphere. B. has a trench along its seaward edge. C. can be charted by noting its Wadati-Benioff zone. D. has a volcanic arc associated with it.

A. can be either continental or oceanic lithosphere

Earth's magnetic field is created by A. flow of liquid iron in Earth's molten outer core. B. centrifugal force pushing on Earth's crust. C. convecting iron-rich silicates in Earth's mantle. D. the rotation of the planet on its axis.

A. flow of liquid iron in Earth's molten outer core

The diagram shows how the tilt of a magnetic needle changes with latitude. What part of the Earth's magnetic field does this illustrate? A. inclination B. declination C. anomaly D. polar wander

A. inclination

Asthenosphere_____? A.is warm enough to flow slowly. B. subducts when it collides with continental lithosphere. C. is the lower layer of both continental and oceanic lithosphere. D. is the uppermost layer of Earth's core.

A. is warm enough to flow slowly.

Radiometric dating of a magnetic anomaly stripe of rock that is 225 km away from the mid-ocean ridge axis gives an age of 4.5 million years. Assuming a constant rate, seafloor spreading in this area occurs at a rate of A. 50 km per year. B. 1,012.5 km per year. C. 5 cm per year. D. 20,000 cm per year.

C. 5 cm per year

Plate tectonics theory was widely accepted by scientists in what decade? A. 1920s B. 1960s C. 1980s D. 1930s

B. 1960s

Multiple types of plate boundaries can often be found in close proximity to one another. Below is an image of the Juan de Fuca plate subducting beneath Washington and Oregon in the American Northwest. Match the type of plate boundary with the correct letter on the image. A.) A - Convergent, B - Divergent, C - Transform B.) A - Divergent, B - Transform, C - Convergent C.) A - Transform, B - Divergent, C - Convergent D.) A - Transform, B - Convergent, C - Divergent

B. A - Divergent, B - Transform, C - Convergent

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. Plate tectonic theory explains this as A. A hot spot moves under the Pacific Plate toward the southeast. B. A hot spot is currently situated under Hawaii and the Pacific Plate is moving across it in a northwesterly direction. C. Microplates break loose from the Pacific Plate as it moves, leaving this chain of islands in its wake. D. The Pacific Plate is undergoing rifting, starting at the northwest end of the chain and extending southeast to Hawaii.

B. A hot spot is currently situated under Hawaii and the Pacific Plate is moving across it in a northwesterly direction.

The following figures show what happens when two continents collide. In the upper figure, oceanic crust is being subducted until the continents collide. The bottom figure shows the collision. What happens to the subducting plate when continents collide? A. The subducting plate is uplifted into a volcanic-island arc. B. The subducting plate becomes detached and the convergent boundary sutures become closed, leaving a single plate. C. The subducting plate creates a transform-plate boundary. D. The subducting plate creates a backarc basin.

B. The subducting plate becomes detached and the convergent boundary sutures become closed, leaving a single plate.

Which of the following was NOT a line of evidence used by Wegener to develop this theory that continents drift? A. the distribution of fossil species B. the presence of earthquakes in seismic belts along trenches, ridges, and fracture zones C. the location of ancient till deposits and striations that indicated glacial movement toward the interior of continents D. matching mountain chains on continents currently separated by oceans

B. the presence of earthquakes in seismic belts along trenches, ridges, and fracture zones

This figure shows the mid-Atlantic ridge, south of Iceland. The arrows show the orientation of Earth's magnetic field as it has reversed several times over the last 180 Million Years. What information can be determined based on the width of the different anomaly rock units? A. the severity of the magnetic anomaly B. the relative duration of the anomaly C. the rate of crustal uplift D. the depth of the ocean at the time the anomaly was created

B. the relative duration of the anomaly

The global occurrence of earthquakes reveals that A. their locations are randomly scattered. B. they usually occur on the boundaries of plates or at hot spots. C. they usually occur at the center of plates. D. 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.

Identify the TRUE statement associated with this diagram. A. The apparent polar-wander path of Africa is the same as that of Europe. B. Apparent polar-wander paths prove that Earth's magnetic poles wandered up to 90 degrees from their current position through geologic time. C. Apparent polar-wander paths were created by measuring the paleomagnetism in rocks of different ages from the same location. D. The apparent polar-wander paths of North America and Europe are similar enough to indicate that these continents did not move with respect to each other.

C. Apparent polar-wander paths were created by measuring the paleomagnetism in rocks of different ages from the same location.

Which of the following statements is NOT true about the ocean floor? A. It is covered by a layer of sediment composed of clay and plankton shells. B. The heat flow through it is greatest at the mid-ocean ridges. C. Oceanic crust contains granite and metamorphic rocks. D. Oceanic crust is quite different from continental crust.

C. Oceanic crust contains granite and metamorphic rocks.

Plate tectonics theory took decades to be accepted because A. most of Wegener's ideas turned out to be wrong. B. of pure stubbornness by the scientific community. C. Wegener couldn't explain how continents moved. D. climate, fossil distributions, and land shape offered conflicting evidence.

C. Wegener couldn't explain how continents moved.

The chain of volcanoes along the west coast of South America (the Andes Mountains) exists because A. an oceanic plate is sliding past the South American Plate and heading toward the northwest. B. an oceanic plate is rifting apart from the South American Plate. C. an oceanic plate is subducting under the western edge of the South American Plate. D. basalt is pushing up through the trench that parallels the west coast of South America.

C. an oceanic plate is subducting under the western edge of the South American Plate.

Identify the FALSE statement. Oceanic lithosphere________ A. gets older and thicker as it gets farther from the ridge axis. B. gets cooler as it gets farther from the ridge axis. C. attains its maximum thickness when it is about 800 million years old. D. effectively does not exist beneath the mid-ocean ridge axis.

C. attains its maximum thickness when it is about 800 million years old.

Identify the FALSE statement. The rate of plate motion A. can be determined to within millimeters by using the global positioning system (GPS). B. can be expressed as relative plate velocity, which describes movement of one plate in relation to another plate. C. can range from 100 to 150 cm per year. D. can be expressed as absolute plate velocity, which describes movement of a single plate relative to a fixed point.

C. can range from 100 to 150 cm per year.

Choose the FALSE statement. Magnetic anomalies are ___ A.places where the magnetic field strength is either greater or less than the expected strength. B. termed normal if the atomic dipoles match Earth's current magnetic field and point from north to south. C. found only on the seafloor. D. measured with an instrument called a magnetometer.

C. found only on the seafloor

Identify the FALSE statement. Plate movement is influenced by ________ A. mantle convection, which creates shear at the base of plates. B. slab pull, in which the downgoing oceanic plate exerts a pull on the rest of the plate. C. mantle plumes, which are created when hot rock rises up from the deep mantle and creates melting at the base of the lithosphere. D. ridge push, in which the elevated rocks at the ridge axis push on rocks farther from the ridge.

C. mantle plumes, which are created when hot rock rises up from the deep mantle and creates melting at the base of the lithosphere.

Through plate tectonics, plates move about the Earth, slamming into, pulling away from, and sliding past one another. Match the images from the figure below with the appropriate boundary name. A.) A - Convergent, B - Divergent, C - Transform B.) A - Transform, B - Convergent, C - Divergent C.) A - Divergent, B - Convergent, C - Transform D.) A - Divergent, B - Transform, C - Convergent

C.) A - Divergent, B - Convergent, C - Transform

Identify the FALSE statement A. Plate boundaries where subduction occurs are also called consuming boundaries. B.Seafloor spreading behind a volcanic island arc creates a small ocean basin called a back-arc basin or marginal sea. C.An accretionary prism is a wedge-shaped mass of sediment scraped off a subducting plate as it slides under the overriding plate. D. A spreading boundary must be in the middle of the ocean basin where it is located.

D. A spreading boundary must be in the middle of the ocean basin where it is located.

The distribution of various geological features can be used to recreate what the world looked like millions of years ago. This figure shows the location and direction of glacial striations, which are indicators of the direction of glacial movement. Based on this information, where was the pole located? A. Antarctica B. North America C. Australia D. Southern Africa

D. Southern Africa

Identify the FALSE statement. A. Plates shift the continents around as they move, so Earth's surface is constantly changing. B. Plates may consist of all ocean floor or both ocean floor and continental crust. C. There are 12 major plates, and several microplates. D. The contacts between plates are called passive margins.

D. The contacts between plates are called passive margins.

During subduction, one tectonic plate is forced beneath another. In this image, an oceanic plate is subducting under another oceanic plate. What geologic feature is being created in the image? A. a forearc basin B. a backarc basin C. a mid-ocean ridge D. a volcanic island arc

D. a volcanic island arc

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.

D. are thought to originate at the crust-mantle boundary.

Ocean crust __________ A. is the same composition as continental crust. B. is the same age as continental crust. C. has not been sampled directly because it is too deep beneath the ocean. D. is covered by a thin blanket of sediment that thickens away from the ridge axis.

D. is covered by a thin blanket of sediment that thickens away from the ridge axis.