Plate Tectonics

Practice exam questions written by Timothy H. Heaton,
Professor of Earth Sciences, University of South Dakota

Click the circle by an answer with the mouse, then click on the Submit button to get a response. You will be told if your answer is correct or not and will be given some comments.

  1. What is the concept that adding or removing a weight from the earth's crust causes it to depress or rebound?
    Continental drift
    Isostasy
    Plate tectonics
    Rifting
    Seafloor spreading

  2. What name did Alfred Wegener give to his theory of horizontal crustal movements?
    Continental drift
    Isostasy
    Plate tectonics
    Rifting
    Seafloor spreading

  3. What name did Wegener give to his proposed single supercontinent?
    Eurasia
    Gondwanaland
    Laurasia
    Pangea
    Panthalassa

  4. What type(s) of evidence did Wegener use to support his theory?
    Distributions of fossil plants and animals
    Distributions of modern plants and animals
    Geographic fit of the continents and features thereon
    Paleoclimatic oddities such as glacial till, coral reefs, and coal
    All of the above

  5. Why was Wegener's theory rejected by geophysicists of the 1920's?
    Lack of a mechanism for continents to plough through oceanic crust
    The concentration of continents in the northern hemisphere
    The earth was then thought to be too young for such movements
    The presence of a continent directly over the south pole
    Wegener was not a geologist by training and couldn't get his ideas heard

  6. How did non-believers in Wegener's theory explain plant and animal distributions in the southern hemisphere?
    Dispersal by the will of God
    Dispersal by winds
    Dispersal via northern continents
    Dispersal via now-sunken land bridges
    Dispersal via rafting on logs

  7. What finally convinced geologists that the continents did move?
    Dinosaur distributions
    Lystrosaurus in Antarctica
    Mantle convection
    Paleomagnetism
    The mid-Atlantic ridge

  8. Iron-rich minerals loose their magnetism when heated above what temperature?
    Blocking point
    Boiling point
    Breaking point
    Curie point
    Melting point

  9. When a ship passes over seafloor that has a 'reverse' magnetic polarization, how does this effect the magnetic field reading?
    The magnetic field is directed east.
    The magnetic field is directed south.
    The magnetic field is directed west.
    The strength of the magnetic field is slightly stronger than usual.
    The strength of the magnetic field is slightly weaker than usual.

  10. What is the character of magnetic anomalies on the seafloor?
    They occur in stripes that parallel mid-ocean ridges and are offset along transform faults.
    They occur in stripes that run perpendicular to mid-ocean ridges and parallel transform faults.
    They occur in stripes that parallel continental margins and transform faults.
    They occur in stripes that run perpendicular to continental margins and parallel to transform faults.
    They occur in stripes that parallel transform faults and end at mid-oceanic ridges.

  11. What theory did magnetic anomalies on the seafloor give rise to?
    Continental drift
    Isostasy
    Plate tectonics
    Rifting
    Seafloor spreading

  12. What is the current comprehensive theory of horizontal crustal movements?
    Continental drift
    Isostasy
    Plate tectonics
    Rifting
    Seafloor spreading

  13. What is the age order of sea floor types (the crust underlying them) from oldest to youngest?
    Abyssal hills, abyssal plains, mid-ocean ridge, continental shelf
    Abyssal plains, abyssal hills, mid-ocean ridge, continental shelf
    Continental shelf, abyssal plains, abyssal hills, mid-ocean ridge
    Mid-ocean ridge, abyssal hills, abyssal plains, continental shelf
    Mid-ocean ridge, abyssal plains, abyssal hills, continental shelf

  14. Which sea is an example of rifting forming an incipient ocean?
    Baltic Sea
    Bering Sea
    Black Sea
    English Channel
    Red Sea

  15. Which sea is a remnant of a larger ocean that has closed up?
    Baltic Sea
    Bering Sea
    Black Sea
    English Channel
    Red Sea

  16. How does plate tectonic theory explain the Ural Mountains separating Europe and Asia?
    Ancient collision and suturing of Europe and Asia
    Eurasia is moving over a hot spot in the mantle
    Incipient rifting apart of Europe and Asia
    Intraplate orogenesis in Eurasia
    The Urals are the one mountain chain that was better explained by older theories.

  17. What does plate tectonic theory predict about the distribution of volcanoes and earthquakes?
    They should be evenly distributed throughout the earth.
    They should occur primarily along plate boundaries.
    They should occur primarily in deep ocean basins.
    They should occur primarily on continents.
    They should only occur along continental margins.

  18. Match the geologic features with the type of plate boundaries they are associated with.
    Geologic feature Plate boundary type
    Andesitic volcanoes
    Basaltic volcanoes
    Continental collisions
    Deep-focus earthquakes
    Deep-sea trenches
    Island arcs
    Long linear scarps
    Mid-ocean ridges
    Normal faults
    Reverse faults
    Rift valleys
    Strike-slip faults
    Subduction zones
    Convergent plate boundaries
    Divergent plate boundaries
    Transform plate boundaries

  19. Match each mountain/island system with the kind of convergent plate boundary that formed it (if any).
    Mountain/island system Plate boundary type
    Aleutian Islands
    Alps
    Andes Mountains
    Appalachian Mountains
    Cascade Mountains
    Hawaiian Islands
    Himalayan Mountains
    Mariana Islands
    Ural Mountains
    Continental crust colliding with continental crust
    Continental crust colliding with oceanic crust
    Not a case of plate convergence
    Oceanic crust colliding with oceanic crust

  20. What is the east coast of the United States an example of?
    Active continental margin
    Convergent plate boundary
    Divergent plate boundary
    Passive continental margin
    Transform plate boundary

  21. What is the San Andreas Fault in southern California an example of?
    Active continental margin
    Convergent plate boundary
    Divergent plate boundary
    Passive continental margin
    Transform plate boundary

  22. What happens when a piece of continent reaches an ocean-bound subduction zone?
    A decollement forms along a foredeep
    An island chain is quickly formed
    Subduction ceases
    Subduction switches to the other plate
    The continent is subducted

  23. What has become accepted as the primary mechanism for seafloor spreading?
    Density differences in the crust
    Gravitational and tidal forces
    Mantle convection cells
    The pole-fleeing force
    Weight of seafloor sediments

  24. How is oceanic crust forced back into the earth's mantle?
    It wants to float but is forced to curl as it cools.
    It wants to float but is forced under by colliding plates.
    It wants to sink because it is made of high density minerals.
    It wants to sink because it is cold and therefore dense.
    It wants to sink because of its high iron content.

  25. Which modern continents were derived from Gondwanaland?
    Africa, Antarctica, Australia, India, South America
    Africa, Antarctica, Australia, North America, South America
    Asia, Antarctica, Australia, Europe, South America
    Asia, Antarctica, Australia, North America, South America
    Asia, Europe, India, North America, South America

Please report any problems or errors to Dr. Heaton.