Which of the following types of seismic waves are the fastest?

1. Which of the following types of seismic waves are the fastest? • Love waves. • S-waves. • P-waves. • Rayleigh waves.

2. Which of the following types of seismic waves are the fastest? • Love waves. • S-waves. • P-waves. • Rayleigh waves. Explanation: Body waves are the fastest seismic waves, with P-waves faster than S-waves. Surface waves—Love waves and Rayleigh waves—are slower than body waves.

3. Which of the following seismic waves showed that Earth’s outer core is liquid? • Love waves. • S-waves. • P-waves. • Rayleigh waves.

4. Which of the following seismic waves showed that Earth’s outer core is liquid? • Love waves. • S-waves. • P-waves. • Rayleigh waves. Explanation: S-waves are transverse waves—they cannot travel through liquids.

5. What is the significance of the Mohorovicic discontinuity (also known as the Moho)? ´ ˇ • The Moho shows that the inner core is solid. • The Moho is the crust–mantle boundary. • The Moho is the core–mantle boundary. • The Moho is the boundary between oceanic and continental crust.

6. What is the significance of the Mohorovicic discontinuity (also known as the Moho)? ˇ ´ • The Moho shows that the inner core is solid. • The Moho is the crust–mantle boundary. • The Moho is the core–mantle boundary. • The Moho is the boundary between oceanic and continental crust. Explanation: The Moho marks the location where wave speed increases abruptly due to an increase of density. The denser rock is at the top of the mantle and the base of the crust.

7. How does erosion of a mountain affect the depth to which its root extends into the lithosphere? • Erosion has no effect on the depth of its root. • As erosion occurs, the mountains root is forced downward due to isostasy. • The eroding mountain is buoyed upward, which also raises the base of the mountain’s root. • Erosion forces the lateral shifting of the mountain’s root.

8. How does erosion of a mountain affect the depth to which its root extends into the lithosphere? • Erosion has no effect on the depth of its root. • As erosion occurs, the mountains root is forced downward due to isostasy. • The eroding mountain is buoyed upward, which also raises the base of the mountain’s root. • Erosion forces the lateral shifting of the mountain’s root. Explanation: Isostatic adjustment caused by a change in the buoyant force makes the mountain’s root extend to shallower depths.

9. How does temperature change with depth in Earth’s interior? • Deep in the mantle, temperature increases ~30°C per km. • Near Earth’s surface, temperature stays the same until the mantle is reached. • Earth is hottest in the plastically flowing asthenosphere. • Near Earth’s surface, temperature increases ~30°C per km.

10. How does temperature change with depth in Earth’s interior? • Deep in the mantle, temperature increases ~30°C per km. • Near Earth’s surface, temperature stays the same until the mantle is reached. • Earth is hottest in the plastically flowing asthenosphere. • Near Earth’s surface, temperature increases ~30°C per km. Explanation: ~30°C per km is the rate of temperature change near Earth’s surface, but the rate of change tapers off to as little as 1°C per km deeper within the mantle.

11. Plate tectonics differs from continental drift in which of the following ways? • Plate tectonics provides a credible driving force. • Plate tectonics does not explain the fit between South America and Africa. • Plate tectonics showed that ancient ice sheets did not exist. • Plate tectonics showed that Pangaea broke up much later than predicted by continental drift.

12. Plate tectonics differs from continental drift in which of the following ways? • Plate tectonics provides a credible driving force. • Plate tectonics does not explain the fit between South America and Africa. • Plate tectonics showed that ancient ice sheets did not exist. • Plate tectonics showed that Pangaea broke up much later than predicted by continental drift. Explanation: Alfred Wegener did not present a credible hypothesis for why the continents drifted, but plate tectonics recognizes the roles of mantle convection, slab-pull, and ridge-push in rearranging Earth’s surface.

13. Which of the following lines of evidence supported Wegener’s continental drift hypothesis? • Fit of continents, similar ocean basins, ancient ice sheets. • Fit of continents, ancient ice sheets, evolution of fish. • Fit of continents, similar fossils, matched-up rocks. • Fit of continents, matched-up rocks, east–west polarity.

14. Which of the following lines of evidence supported Wegener’s continental drift hypothesis? • Fit of continents, similar ocean basins, ancient ice sheets. • Fit of continents, ancient ice sheets, evolution of fish. • Fit of continents, similar fossils, matched-up rocks. • Fit of continents, matched-up rocks, east–west polarity. Explanation: The four lines of evidence are fit of continents, similar fossils, matched-up rocks, and ancient ice sheets.

15. How did seafloor spreading suggest a driving force for continental drift? • Youngest seafloor is found near continents. • Seafloor spreading pushes continents. • Mantle convection causes irreversible slippage. • Subduction creates the youngest seafloor.

16. How did seafloor spreading suggest a driving force for continental drift? • Youngest seafloor is found near continents. • Seafloor spreading pushes continents. • Mantle convection causes irreversible slippage. • Subduction creates the youngest seafloor. Explanation: When a continent breaks up and a new spreading center forms, seafloor spreading pushes the now-separated continents away from each other as new lithosphere is created on both sides of the spreading center (or mid-ocean ridge).

17. How does the seafloor become magnetized? • Accumulating sediment on the seafloor aligns with Earth’s magnetic field. • The seafloor becomes magnetized when the poles reverse. • When magnetic poles wander slightly around the geographic poles, the seafloor responds by becoming magnetized. • Magnetite crystals become aligned with Earth’s magnetic field as new oceanic crust cools from a molten state.

18. How does the seafloor become magnetized? • Accumulating sediment on the seafloor aligns with Earth’s magnetic field. • The seafloor becomes magnetized when the poles reverse. • When magnetic poles wander slightly around the geographic poles, the seafloor responds by becoming magnetized. • Magnetite crystals become aligned with Earth’s magnetic field as new oceanic crust cools from a molten state.

19. What is the ultimate cause of plate tectonics? • Heat transfer away from Earth’s interior. • Combined lunar and solar tides. • Seafloor spreading. • Continental drift.

20. What is the ultimate cause of plate tectonics? • Heat transfer away from Earth’s interior. • Combined lunar and solar tides. • Seafloor spreading. • Continental drift. Explanation: The ultimate cause is heat transfer from the interior—the cooling of the planet. If Earth had a uniform temperature throughout—in other words, it was completely cooled—there would be no mantle convection and no moving plates. Without moving plates, there could be no slab-pull or ridge-push.

21. Each tectonic plate is composed of • modified mantle rock. • crust and uppermost mantle. • crustal rock. • either modified mantle rock or crustal rock.

22. Each tectonic plate is composed of • modified mantle rock. • crust and uppermost mantle. • crustal rock. • either modified mantle rock or crustal rock. Explanation: The rigid lithosphere is composed of the crust and the top of the mantle. Earth’s lithosphere is divided into a number of pieces known as plates.

23. At which type of plate boundary is new lithosphere created? • Convergent boundaries. • Divergent boundaries. • Transform-fault boundaries.

24. At which type of plate boundary is new lithosphere created? • Convergent boundaries. • Divergent boundaries. • Transform-fault boundaries.

25. At which type of plate boundary is lithosphere neither created nor destroyed? • Convergent boundaries. • Divergent boundaries. • Transform-fault boundaries.

26. At which type of plate boundary is lithosphere neither created nor destroyed? • Convergent boundaries. • Divergent boundaries. • Transform-fault boundaries.

27. Water causes partial melting of the mantle at which type of plate boundary? • Convergent boundaries. • Divergent boundaries. • Transform-fault boundaries.

28. Water causes partial melting of the mantle at which type of plate boundary? • Convergent boundaries. • Divergent boundaries. • Transform-fault boundaries. Explanation: As a subducting oceanic plate descends into the mantle, water is driven from it into the overlying mantle. The water lowers the melting point of mantle rock, causing it to partially melt (mantle rock never melts completely).

29. Volcanoes do not form at which type of convergent plate boundary? • Oceanic–oceanic boundaries. • Oceanic–convergent boundaries. • Continental–continental convergent boundaries.

30. Volcanoes do not form at which type of convergent plate boundary? • Oceanic–oceanic boundaries. • Oceanic–convergent boundaries. • Continental–continental convergent boundaries. Explanation: Subduction does not occur at continental–continental convergent boundaries, so volcanoes do not form at such plate boundaries.

31. How can a food chain exist in a deep-ocean trench where it is completely dark and very cold? • Certain fish inadvertently bring down enough food to keep the base of the food chain viable. • Minute amounts of sunlight reach these frigid depths. • Deep-ocean organisms come to shallower depths to feed. • Hydrothermal vents emit chemicals that certain organisms can consume, forming the base of the food chain.

32. How can a food chain exist in a deep-ocean trench where it is completely dark and very cold? • Certain fish inadvertently bring down enough food to keep the base of the food chain viable. • Minute amounts of sunlight reach these frigid depths. • Deep-ocean organisms come to shallower depths to feed. • Hydrothermal vents emit chemicals that certain organisms can consume, forming the base of the food chain. Explanation: Some microorganisms are capable of chemosynthesis, which provides energy for growth. These chemosynthetic organisms produce organic carbon, on which higher organisms feed.

33. The Himalayan Mountains formed at which type of plate boundary? • Transform-fault boundary. • Oceanic–continental convergent boundary. • Divergent boundary. • Continental–continental convergent boundary.

34. The Himalayan Mountains formed at which type of plate boundary? • Transform-fault boundary. • Oceanic–continental convergent boundary. • Divergent boundary. • Continental–continental convergent boundary.

35. Transform-fault boundaries usually form • between two segments of a mid-ocean ridge. • between two other transform-fault boundaries. • between a mid-ocean ridge and a subduction zone. • in the rift of a mid-ocean ridge.

36. Transform-fault boundaries usually form • between two segments of a mid-ocean ridge. • between two other transform-fault boundaries. • between a mid-ocean ridge and a subduction zone. • in the rift of a mid-ocean ridge. Explanation: Transform-fault boundaries generally transform divergent motion from one ridge segment to the next. Thus, they usually occur between adjacent ridge segments.

37. Earthquakes are caused by • the friction between diverging plates. • the sudden release of energy that is stored elastically in deforming rocks. • the expansion of Earth’s crust. • the combined motion of tectonic plates.

38. Earthquakes are caused by • the friction between diverging plates. • the sudden release of energy that is stored elastically in deforming rocks. • the expansion of Earth’s crust. • the combined motion of tectonic plates. Explanation: Strain builds up in rocks in the form of elastic energy. Just as elastic energy is released when a rubber band is stretched (deformed) then suddenly released, earthquakes occur when elastic energy stored in rock is suddenly released. This occurs when rock can no longer deform without breaking.

39. At which of the following plate boundaries does a tsunami usually occur? • Transform-fault boundary. • Oceanic–continental convergent boundary. • Divergent boundary. • Continental–continental convergent boundary.

40. At which of the following plate boundaries does a tsunami usually occur? • Transform-fault boundary. • Oceanic–continental convergent boundary. • Divergent boundary. • Continental–continental convergent boundary. Explanation: Most tsunami (Japanese for harbor wave) occur at subduction zones. The overlying plate gets bent by sticking to the sinking plate. When the overlying plate can no longer bend, it snaps upward, hurling kilotons of water skyward. Tsunami can also occur at oceanic–oceanic convergent boundaries.