Sample Problems for Earth’s Structure & Setting; Drift & Plate Tectonics

1)     All of the following were necessary factors for the Oracle of Delphi to function and exist, EXCEPT:

• Collision between Africa and Eurasia had to uplift and expose the older marine rock of the area.
• There had to be some volcanic activity and magma beneath the ground to act as the source for the gases.
• A system of faults (fractures) had to exist to allow gases to rise to the Earth’s surface.
• The gases had to vent into a small enclosed cavern that contained and concentrated them.
• People had to not only discover the cavern, but interpret the phenomena as a religious experience.

2)     Erastothenes conducted one of the first recorded scientific experiments, using the angle of shadows cast by the Sun to:

• prove that the Earth was round.                                    
• measure the distance from the Earth to the Sun.
• calculate the mass of the Earth.                                     
• measure the circumference (size) of the Earth.
• all of the above.

3)     If the Earth had not experienced a period of almost complete melting early in its history, which of the following would be true?

• The Earth would not have the Moon in orbit around it.
• The Earth would be more spherical than it currently is.
• The Earth would not have as great a mass as it now does, so it would have a cooler climate.
• The Earth would have a greater mass than it does now, so it would have a warmer climate.
• The Earth would not have internal layers with different compositions.

4)     If the Earth had not been hit by a Mars-sized body early in its history, all of the following would be true, EXCEPT:

• The Earth would probably not travel as quickly around the Sun as it does now.
• The Earth would probably not rotate as quickly around its axis as it does now.
• The Earth would probably not have its present Moon.
• The Earth would probably have a less tilted (more vertical) axis than it does now
• None of the above (Use this choice if all of the above are true statements.)

5)     The asthenosphere is a heat-softened solid because its temperature is close to the melting point of its minerals. The lower mantle is:

• More fluid than the asthenosphere because its pressure is higher.
• More fluid than the asthenosphere because its temperature is higher.
• More rigid than the asthenosphere because its pressure is higher.
• More rigid than the asthenosphere because its temperature is lower.
• More rigid than the asthenosphere because it is composed of denser minerals.
  

6)     Which of the following was the MOST important reason why most scientists dismissed Wegener’s Continental Drift hypothesis?

• Wegener’s fossil evidence might have been explained by land bridges or the incompleteness of the fossil record.
• At the time little was known of Antarctica’s geology, so Wegener’s hypothesis could not be fully tested.
• Wegener was a meteorologist rather than a geologist, so he had little credibility in the geological community.
• At the time nearly everyone, including Wegener, thought that the sea floor was the oldest part of the Earth’s surface.
• Although Wegener had an intriguing idea, he had little real evidence to show that the continents had shifted their position through time.

7)     Of the following, which was the crucial evidence that convinced nearly everyone that the continents had indeed moved through time?

• The past distribution of glacial deposits and tropical swamp coals.
• Fossils of land animals and plants that are only found on the southern continents and India.
• The trends of ancient mountain belts only match up if the continents are moved to fit together.
• The presence of tropical fossils in areas that are now high latitude.
• The rock sequences on each continental mass exhibit a different apparent polar wandering path.

8)     If the Earth’s lower mantle had the same physical state as its outer core then which of the following would occur?

• Plate tectonic activity would decrease as the plates could no longer move over a physically weaker layer.
• Plate tectonic activity would increase in response to faster heat flow from the Earth’s interior.
• The Earth would have a much stronger magnetic field.
• The Earth would have a much warmer climate then it does at present.
• The Earth would have a much weaker magnetic field.

9)     If continental crust was denser and thinner than oceanic crust all of the following would occur, EXCEPT:

• There would be no significant difference in how plate tectonics occurred, only in the rate at which they occurred.
• A plate segment topped by continental crust would be more likely to subduct than one topped by oceanic crust.
• Oceans would be located over areas of continental crust rather than over areas of oceanic crust.
• The Earth’s oceanic crust would tend to be older than its continental crust.
• None of the above (Use this choice if all of the above are true statements.)

10)   If rock had been as good a conductor of heat as metal, then by now (after 4.5 billion years) all of the following would be true, EXCEPT:

• The Earth would probably be a frozen world with no life on its surface.             
• The Earth would probably no longer have any active volcanic activity.
• The Earth would probably have very few, if any, earthquakes.
• The Earth would probably no longer have an active magnetic field.
• The Earth would probably no longer have any active plate tectonic processes.

Answer Key