Oceanography Chapter 2: Plate Tectonics Quiz
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Questions and Answers

Which type of plate boundary is most closely associated with the formation of new ocean floor?

  • Convergent
  • Transform
  • Divergent (correct)
  • None of the above

    • Which of the following statements about Earth's magnetic field is most accurate?

  • It remains constant over time.
  • It cannot be measured.
  • It switches polarity at irregular time intervals. (correct)
  • It is not affected by tectonic activities.

    • How often does the Earth's magnetic field switch polarity?

    Every 100,000 to several million years.

    How are normal polarity and reverse polarity of Earth's magnetic field different?

    <p>A compass points toward the North Pole during normal polarity and to the South Pole during reverse polarity.</p> Signup and view all the answers

    In general, what is our best evidence that the orientation of Earth's magnetic field has changed over time?

    <p>A record of Earth's magnetic field is recorded in oceanic rocks, which show a clear pattern of changes in Earth's magnetic polarity.</p> Signup and view all the answers

    Where would you expect to see alternating bands of rock with different magnetic polarities?

    <p>On both sides of the mid-ocean ridge.</p> Signup and view all the answers

    Where do mantle plumes originate?

    <p>Deep in the mantle, near the core.</p> Signup and view all the answers

    Why do hotspots result in chains of volcanoes instead of a single volcanic peak?

    <p>Because the plate is moving over the hotspot.</p> Signup and view all the answers

    Which geographic example below was created by a hotspot?

    <p>Hawaii.</p> Signup and view all the answers

    What happens when an oceanic plate converges with a continental plate?

    <p>The oceanic plate is subducted.</p> Signup and view all the answers

    What happens when an oceanic plate meets another oceanic plate?

    <p>The older, colder oceanic plate is subducted.</p> Signup and view all the answers

    What happens when a continental plate meets another continental plate?

    <p>The two plates are forced upward, and a large mountain range is formed.</p> Signup and view all the answers

    Which of the following features are found at an oceanic-continental convergent plate boundary?

    <p>All of the above</p> Signup and view all the answers

    Which geographic examples result from ocean-ocean convergence?

    <p>All of the above</p> Signup and view all the answers

    Transform boundaries are classified under what type of fault?

    <p>Strike-slip.</p> Signup and view all the answers

    What role do transform boundaries play?

    <p>Transform boundaries connect other segments of plate boundaries.</p> Signup and view all the answers

    Do fracture zones near transform boundaries play a role in plate motion?

    <p>False</p> Signup and view all the answers

    What is the relationship between transform boundaries and mid-ocean ridges?

    <p>Transform boundaries connect segments of mid-ocean ridges.</p> Signup and view all the answers

    What is the relationship between the crust and the lithosphere?

    <p>The crust is part of the lithosphere.</p> Signup and view all the answers

    Complete this statement: Divergence is to moving away as convergence is to _______.

    <p>Moving toward.</p> Signup and view all the answers

    Plates move apart at __________ boundaries, move together at __________ boundaries, and move side by side at __________ boundaries.

    <p>Divergent/Convergent/Transform.</p> Signup and view all the answers

    Which geologic features are associated with divergent boundaries?

    <p>Mid-ocean ridges and continental rift valleys.</p> Signup and view all the answers

    Which geologic features are associated with convergent boundaries?

    <p>Ocean trenches and volcanoes.</p> Signup and view all the answers

    Where is the youngest ocean floor found?

    <p>Along the crest of mid-ocean ridges.</p> Signup and view all the answers

    What would happen to Earth if ocean floor were created at divergent boundaries at a faster rate than it is destroyed at convergent boundaries?

    <p>Earth would increase in volume.</p> Signup and view all the answers

    What is a volcanic arc?

    <p>A row of volcanoes that forms on the overriding plate near a subduction zone.</p> Signup and view all the answers

    Which of the following mountain ranges are examples of continental arcs?

    <p>Both A and B</p> Signup and view all the answers

    What did Pangaea (All Earth) split into 200 MYA?

    <p>Two major landmasses: Laurasia and Gondwana.</p> Signup and view all the answers

    What is evidence for continental drift?

    <ol> <li>Fit of coastlines of South America and Africa; 2. Similarities of fossils found across separated continents; 3. Mountains line up in Northern Hemisphere; 4. Ancient glacier.</li> </ol> Signup and view all the answers

    What are supporting evidences for plate tectonics?

    <ol> <li>Locations of earthquakes ('Ring of Fire'); 2. Age structure of the seafloor and continents; 3. Seafloor spreading; 4. Paleomagnetism; 5. Hotspot tracks.</li> </ol> Signup and view all the answers

    What are the components that liquid iron in the outer core conducts?

    <p>Electricity and convective flow.</p> Signup and view all the answers

    When flow reverses, polarity of magnetic field __________.

    <p>Reverses.</p> Signup and view all the answers

    What is paleomagnetism?

    <p>Earth's 'fossil' magnetic field.</p> Signup and view all the answers

    What are magnetic stripes?

    <p>Creation of new ocean crust over geologic time.</p> Signup and view all the answers

    What does plate movements tracked by hotspots indicate?

    <p>Mid-plate volcanoes ('hot spots') are produced as they move over continuous upwelling from the hot mantle.</p> Signup and view all the answers

    Where else are plumes found besides mid-ocean areas?

    <p>In continental areas too.</p> Signup and view all the answers

    Study Notes

    Plate Boundaries and Ocean Formation

    • Divergent Boundaries: Associated with the formation of new ocean floor as plates move apart.
    • Convergent Boundaries: Oceanic plates subduct beneath continental plates, forming trenches and volcanoes.
    • Transform Boundaries: Plates slide horizontally past one another, creating strike-slip faults.

    Earth's Magnetic Field

    • Polarity switches occur at irregular intervals, every 100,000 to several million years.
    • Normal polarity indicates a compass points to the North Pole; reverse polarity points to the South Pole.
    • Oceanic rocks record changes in magnetic polarity, revealing a history of Earth’s magnetic field.

    Geological Features

    • Mid-Ocean Ridge: Long, underwater mountain ranges with alternating bands of rock displaying different magnetic polarities.
    • Ocean Trenches: Formed at oceanic-continental and oceanic-oceanic convergent boundaries, indicating subduction zones.

    Volcano Formation

    • Hotspots: Chains of volcanoes form as tectonic plates move over stationary mantle plumes. Example: The Hawaiian Islands.
    • Volcanic Arcs: Rows of volcanoes develop on overriding plates in subduction zones, exemplified by the Andes and Cascades mountains.

    Continental Drift Evidence

    • Continental coastlines, such as South America and Africa, fit together like puzzle pieces.
    • Similar fossils across separated continents support the theory of continental drift.
    • Glacial deposits align in the Northern Hemisphere evidencing past connections.

    Plate Movements and Rates

    • Tectonic plates move at a rate of approximately 5 cm per year, driven by mantle convection.
    • Divergence creates new oceanic crust, while convergence leads to subduction and recycling of crust.

    Rock and Crust Characteristics

    • Youngest ocean floor is found along mid-ocean ridges, indicating ongoing formation.
    • Ocean crust formed at divergent margins is dense and subducts when colliding with continental crust.

    Supporting Evidence for Plate Tectonics

    • Earthquake locations primarily clustered along plate boundaries, known as the "Ring of Fire".
    • Age differences in seafloor and continental geology support tectonic activity.
    • Paleomagnetism reflects historical changes in Earth’s magnetic field recorded in rocks.

    Transform Faults

    • Transform faults connect segments of mid-ocean ridges and exhibit a discontinuous pattern due to perpendicular fracture zones.
    • The San Andreas Fault is a notable continental transform fault, exhibiting significant tectonic activity.

    Additional Notes

    • Liquid outer core is responsible for conducting electricity and convective flow, influencing Earth’s magnetic field.
    • Magnetic stripes in ocean crust provide evidence of seafloor spreading and historical plate movements.
    • Hotspot volcanism indicates the presence of stationary plumes of hot mantle material rising to create island chains.

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    Description

    Test your knowledge on plate tectonics and the ocean floor with this quiz based on Chapter 2 of Oceanography. Explore concepts such as divergent boundaries and the Earth's magnetic field behavior. Perfect for students looking to master oceanography fundamentals.

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