The Earth's Interior

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. For matching questions, select items one at a time in the left column, and for each one choose the matching item in the right column, then click on the Submit button to get a response.

  1. Match each layer of the earth's interior with its thickness.
    Layer Thickness
    Continental crust
    Inner core
    Mantle
    Oceanic crust
    Outer core
    1216 km
    2270 km
    2885 km
    40 km
    5 km

  2. Match each layer of the earth's interior with its composition.
    Layer Composition
    Continental crust
    Inner core
    Mantle
    Oceanic crust
    Outer core
    Felsic silicate minerals
    Iron and nickel
    Mafic silicate minerals
    Nitrogen and oxygen
    Ultramafic silicate minerals

  3. What has been the most useful method for determining the structure of the earth's interior?
    Core samples
    Density studies
    Magnetic field
    Meteorites
    Seismology

  4. Which layer of the earth's interior is liquid?
    Crust
    Inner core
    Mantle
    Outer core
    All of the above

  5. Which layer produces the earth's magnetic field?
    Crust
    Inner core
    Mantle
    Outer core
    All of the above

  6. Which layer of the earth's interior has the lowest density?
    Continental crust
    Inner core
    Mantle
    Oceanic crust
    Outer core

  7. Which layer of the earth's interior has the highest density?
    Continental crust
    Inner core
    Mantle
    Oceanic crust
    Outer core

  8. What portion of the earth's volume is occupied by the mantle?
    20%
    35%
    50%
    65%
    80%

  9. What is the lithosphere composed of?
    The continental and oceanic crust
    The crust and uppermost mantle
    The lower mantle
    The lower mantle and outer core
    The upper mantle

  10. What property distinguishes the earth's crust, mantle, and core?
    Composition
    Pressure
    State (solid vs. liquid)
    Temperature

  11. What property distinguishes the lithosphere, asthenosphere, and mesosphere within the earth's mantle?
    Composition
    Pressure
    State (solid vs. liquid)
    Temperature

  12. What keeps the lithosphere from melting (in contrast to the asthenosphere)?
    Cool temperatures
    Distance from the sun
    High pressures
    Low pressures
    Minerals with higher melting temperatures

  13. What keeps the mesosphere from melting (in contrast to the asthenosphere)?
    Cool temperatures
    Distance from the sun
    High pressures
    Low pressures
    Minerals with higher melting temperatures

  14. What keeps the outer core molten (in contrast to the mantle)?
    Cool temperatures
    Distance from the sun
    High pressures
    Low pressures
    Minerals with lower melting temperatures

  15. What keeps the inner core solid (in contrast to the outer core)?
    Cool temperatures
    Distance from the sun
    High pressures
    Low pressures
    Minerals with higher melting temperatures

  16. The Gutenberg discontinuity lies at the boundary of what two layers?
    Crust and mantle
    Crust and outer core
    Mantle and inner core
    Mantle and outer core
    Outer core and inner core

  17. The Mohorovicic discontinuity lies at the boundary of what two layers?
    Crust and mantle
    Crust and outer core
    Mantle and inner core
    Mantle and outer core
    Outer core and inner core

  18. As seismic waves penetrate deep into the earth, through which layers do they slow down rather than speed up?
    Asthenosphere and lithosphere
    Asthenosphere and outer core
    Lithosphere and mesosphere
    Lithosphere and outer core
    Outer core and inner core

  19. The P-wave shadow zone lies between what latitudes relative to an earthquake epicenter?
    100-120
    105-140
    105-180
    115-160
    115-180

  20. The S-wave shadow zone lies between what latitudes relative to an earthquake epicenter?
    100-120
    105-140
    105-180
    115-160
    115-180

  21. Through which layer of the earth do P-waves travel fastest?
    Crust
    Inner core
    Lower mantle
    Outer core
    Upper mantle

  22. Which of the following statements is false?
    Compression waves travel through solids as well as liquids
    In all materials S-waves travel faster than P-waves
    Seismic waves always slow down when reaching a liquid or partially liquid layer
    The speed of seismic waves generally increases with depth in a layer
    When seismic waves pass from one material to another, the path of the waves is refracted

Please report any problems or errors to Dr. Heaton.