Ch17
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Chapter 17 Plate Tectonics: Can we predict destructive earthquakes? 1. The Pacific coastline is found a. at the middle of a continental plate. b. where two tectonic plates move parallel. c. along divergent plate boundaries. d. near a subduction zone. e. associated with a hot spot. Ans: d Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Easy
2. Which of the following was used as evidence for plate tectonics? a. topographic profiles of the ocean floors b. maps on rock magnetism c. data classifying rocks by age d. sea floor spreading e. all of the above Ans: e Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Easy
3. The magnetic pattern from seafloor data recorded off the coast of Vancouver and Washington State a. were created by magnetite in fissure flows. b. are caused by hot spots. c. are indicators of past and future earthquake sites. d. have no one explanation accepted by scientists. e. always run perpendicular to the equator. Ans: a Link To: The Dynamic Earth Difficulty Level: Easy
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4. The continents of Eurasia and North America are currently moving apart at an average rate of a. 2 inches per century. b. 5 cm per year. c. 5 meters per year. d. 2 cm per century. e. 10 cm per decade. Ans: b Link To: The Dynamic Earth Difficulty Level: Easy
5. Which of the following describes earthquakes? a. Earthquakes are an abrupt release of energy. b. Prediction of earthquakes is an established science, which gives global citizens a chance to evacuate ahead of time. c. Earthquakes have never occurred in the middle of the USA. d. No earthquake has been measured higher than 7 on the Richter scale. e. All earthquakes happen within one kilometer of the Earth's surface. Ans: a Link To: The Dynamic Earth Difficulty Level: Easy
6. The North American Plate a. extends from coast to coast in the United States and is completely covered by land. b. extends from the middle of the Atlantic Ocean to the edge of the Pacific Plate. c. contains the eastern half of North America and parts of western Europe. d. has only subducting boundaries. e. contains only the western half of North and South America. Ans: b Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Easy
7. Which of the following is an example of a continental convergent plant boundary? a. the East African Rift Valley b. the San Andreas Fault c. the Atlantic east coast fall line d. Mount St. Helens in the northwest United States
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Chapter 17 e. the Himalayan Mountains Ans: e Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Easy
8. Divergent plate boundaries are associated with a. seafloor spreading. b. formation of new crust. c. volcanic action. d. shallow, low-energy earthquakes. e. all of the above Ans: e Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Easy
9. How often does the oceanic plate material of the Earth renew itself; i.e., go through one replacement cycle? a. every 100 million years b. every 200 million years c. every 1,000 years d. every 100,000 years e. The oceanic plate material never renews itself. Ans: b Link To: The Dynamic Earth Difficulty Level: Easy
10. The transform plate boundaries a. form new material at rates exceeding that of the divergent plate boundaries. b. are the location of island arcs and hot spots. c. created the Andes Mountains in South America. d. are exemplified by the San Andreas fault. e. are sites of major volcano ranges. Ans: d Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Medium
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11. Where is the longest mountain range on Earth? a. Mid-Atlantic Ocean Ridge b. Andes Mountains in South America d. Himalayas in India c. Appalachians in the eastern United States e. Urals in Russia Ans: a Link To: The Dynamic Earth Difficulty Level: Easy
12. Which formula would you use to determine the age of the Atlantic Ocean basin? a. E = mC2 b. D = R T. c. F= M A d. A = π r2 e. P = N R T Ans: b Link To: The Dynamic Earth Difficulty Level: Easy
13. What evidence convinced most scientists to accept the theory of plate tectonics? a. ocean topography b. magnetism of the ocean basin rocks c. discovery of the Mid-Atlantic Rift zone d. radiometric dating of the basaltic rocks e. all of the above Ans: e Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Easy
14. What causes the Ring of Fire, which borders much of the Pacific Ocean? a. plate subduction b. divergent plates c. sea floor spreading d. transform plates e. all of the above
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Chapter 17 Ans: a Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Easy
15. Which of these waves is classified as a type of seismic wave following earthquakes? a. transverse b. compressional c. longitudinal d. shear waves e. all of the above Ans: e Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Easy
16. Mountains on the Earth are continuously being formed. Ans: True Link To: The Dynamic Earth Difficulty Level: Easy
17. Energy from earthquakes is transmitted as light waves. Ans: False Link To: The Dynamic Earth Difficulty Level: Easy
18.A philosopher and a meteorologist laid the groundwork for the idea of moving continents. Ans: True Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Easy
280
19. Evidence for Earth's magnetic reversals has been found in the East African Rift Zone. Ans: False Link To: The Dynamic Earth Difficulty Level: Easy
20. An earthquake with a magnitude 7 on the Richter Scale releases 100 times the energy of an earthquake with a magnitude 5. Ans: True Link To: The Dynamic Earth Difficulty Level: Easy
21. The ocean floor is a flat plain collecting sediments from the continents. Ans. False Link To: The Dynamic Earth Difficulty Level: Easy
22. Rocks collected at the Mid-Atlantic Ridge and dated with radioactive isotopes are among the oldest rocks on earth. Ans: False Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Easy
23. Tidal waves come as frequently as the tides. Ans: False Link To: The Dynamic Earth Difficulty Level: Easy
24. Man may have evolved his upright stance from a need to adapt to divergent plate boundaries. Ans: True
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Chapter 17 Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Easy
25. The Appalachian Mountains are among the youngest on Earth. Ans: False Link To: The Dynamic Earth Difficulty Level: Easy
26. The specific surface features created by convergent plate boundaries depend on whether the plates are continental or oceanic. Ans: True Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Easy
27. The speed of a seismic wave depends partly on the type of seismic wave that is moving. Ans: True Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Easy
28. When Californians refer to “The Big One” what do they mean? Ans: Because of the stresses growing along the San Andreas and other faults, geologists predict that in the coming decades Californians will experience “The Big One,” an earthquake of greater magnitude than any they have had before. Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Easy
29. What are the surface features associated with convergent plate boundaries? Ans: Converging plates can result in deep ocean trenches, nonvolcanic mountains, or coastal mountain ranges with an ocean trench offshore.
282
Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Easy
30. How were the Hawaiian Islands formed? Ans: The Hawaiian Islands were created one at a time as the Pacific Plate moved toward the northwest over a stationary hot spot. Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Easy
31. What is always characteristic of a tectonic plate? a. made of basalt b. comprised of crust and some mantle material c. made of granite d. has a thickness of at least 35 km e. all of the above Ans: b Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Medium
32. Subduction zone regions are often the locations of a. active volcanoes. b. the disappearance of old plate material. c. the world's highest mountains. d. severe earthquakes. e. All of the above can be located at subduction zones. Ans: e Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Medium
33. What is the force that moves continents and tectonic plates? a. convection cells b. mantle convection c. radioactive decay d. heat energy left from the great bombardment e. all of the above
283
Chapter 17
Ans: e Link To: The Dynamic Earth Difficulty Level: Medium
34. Most mountains have not eroded to a flat plain in the last 500,000 years because a. under a thin veneer of soil, a mountain is solid rock. b. new mountains constantly emerge through rifts in the crustal material of oceans and continents. c. ozone depletion has decreased the rate of erosion. d. the mantle has a constant supply of granitic material e. mountains are reformed by tectonic uplift that is greater than or equal to the erosional forces. Ans: e Link To: The Dynamic Earth Difficulty Level: Medium
35. If you took a vacation driving to the oldest part of the North American continent you would need to bring a map of a. Wichita, Kansas. b. northeastern Canada. c. the Cascade Range of the Sierra Nevada Mountains. d. Baja, California. e. the Black Hills of South Dakota. Ans: b Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Medium
36. The only currently active plate boundary within the continental United States is the a. Marianas Trench. b. East-Pacific Rise. c. New Madrid Fault. d. San Andreas Fault. e. Mid-Atlantic Ridge. Ans: d Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Medium
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37. Which of the following would not be seen in the United States? a. chunks of land called terranes b. an old spreading "rift" plate boundary c. a “hot spot” with active volcanoes d. a mountain range created from the collision of two continents e. a mountain range formed when molten rock pushed up sediments Ans: b Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Medium
38. What part of the Hawaiian Island chain is the oldest? a. northwest b. southwest c. south d. east e. west Ans: a Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Medium
39. The difference between continental and ocean basin rock is a. ocean rocks are not as dense as continental rocks. b. ocean rocks are basaltic and continental rocks are granitic. c. continental rocks can be detected by Geiger counters. d. continental rocks were originally metamorphic rocks. e. continental rocks form thinner crustal material. Ans: b Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Medium
40. Earthquakes that measure around 8 on the Richter scale can be felt by most people but do little damage to buildings. Ans: False Link To: The Dynamic Earth Difficulty Level: Medium
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Chapter 17 41. The Grand Canyon is an example of what happens when two tectonic plates scrape past each other. Ans: False Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Medium
42. Compared to the oceanic plates, the continental plates are thicker and comprised of lower-density rock. Ans: True Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Medium
43. How can you tell the relative age of a mountain by its physical features? Ans: After much time, mountains that were once angular with steep slopes become more rounded by erosion processes; therefore, in general, rounded mountains may be older. Link To: The Dynamic Earth Difficulty Level: Medium
44. Describe the changes in curriculum organization in geology departments since 1960. What technologies and new information precipitated these changes? Ans: Magnetic measurements, images from high-flying airplanes, and so forth led to the acceptance of the theory of plate tectonics. Link To: The Dynamic Earth Difficulty Level: Medium
45. Briefly summarize the evidence scientists used to determine that the center of the Earth rotates at a different rate from the crust. Ans: Earthquake waves plus the idea that the more liquid mantle has more inertia than does the core. Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Medium
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46. Explain the wide range in age differences between the age of the continents measured in billions of years and the age of the ocean floor measured in millions of years. Ans: Answers will vary; the ocean floor is recycled via subduction into the Earth’s upper mantle, while the less dense continental crust is not subducted, so it remains on the surface. Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Medium
47. Explain how volcanoes situated over ‘hot spots’ would not be expected to be explosive in nature while volcanoes associated with subduction zones would be. Ans: Again the difference is in the amount (volume) of water available for steam resulting in explosive power. The subduction zone carries water with it into the melting zone. Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Medium
48. What would be an architectural specification for a skyscraper built in an earthquakeprone region? a. rigid and strong b. flexible with shock preservers c. soft and malleable d. corner angles locked to 90 degrees e. covered with rubber insulation Ans: b Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Hard
49. What evidence did Wegener use in proposing the idea of continental drift? Why were his ideas not accepted? Ans: In addition to observing and questioning the origin of the parallel coastlines on opposite sides of the Atlantic Ocean, Wegener identified matching rock formations and other geological evidence. The established geological community rejected his ideas because he proposed increase in average elevation of continents and had no mechanism for the movement of the continents. Link To: The Dynamic Earth Difficulty Level: Hard
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Chapter 17 50. What reasoning did scientists use to determine that the Atlantic Ocean is 160 million years old? Ans: Scientists used the distance/time/rate relationship. The time the ocean has expanded equals its age; the rate of movement (assumed constant) equals 5 cm/yr; the present distance between Eurasia and North America is about 7000 km. Distance divided by rate equals 140 million years for these data. Link To: The Dynamic Earth Difficulty Level: Hard
51. What attributes of granite and basalt have resulted in the shape of continents we see on a map? Ans: The continental plates are mostly granite capping the mantle, while the oceanic plates are basalt. Since granite is a lower-density rock than basalt, the continents “float” on top of the basalt and mantle rock. Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Hard
52. What are the processes that build stress in brittle rocks? Ans: Heated rocks expand; cooled rocks contract; rocks with changes in pressure from below or above can distort or rebound; rocks at plate boundaries absorb stress until one or more moves, causing earthquakes. Link To: The Dynamic Earth Difficulty Level: Hard
53. How do seismologists use the vibration energy released by earthquakes? Ans: Answers may vary. Seismologists around the world record the intensity and time of arrival of seismic waves generated by earthquakes. Using a computer, the scientists can analyze this information to learn more about the earthquake and about the material through which it passes. Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Hard
54. The Marianas Trench is the result of two convergent plates, with no continents on
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either plate, forming a subduction zone. Knowing these facts, what else can you say about the Marianas Trench? Ans: One plate will sink beneath the other, down into the Earth, where it can melt, producing magma and a volcanic environment beneath the ocean. Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Hard
55. Explain the statement “Good scientists will eventually accept the implications of their observations, whether those implications violate preconceived ideas or not.” Ans: Answers will vary but should include information about observations and testing/retesting experiments to confirm data. Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Hard
56. How does seismic tomography give scientists a three-dimensional view of the Earth? Ans: Data from seismic events are analyzed through computer imaging allowing for better analysis. Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Hard
57. The Earth’s magnetic field changes direction periodically over geologic time. Describe what evidence scientists have for this change and explain why they feel this evidence supports this theory. Ans: Magnetic field measurements showed alignment of north/south poles within rocks as they hardened after emerging from the mid-Atlantic Ridge. Link To: The Dynamic Earth Difficulty Level: Hard
58. Using your knowledge of Newton’s laws of motion and your knowledge of properties of materials, sketch both a high-rise and a one-story building that might be able to withstand an earthquake. Label the characteristics you have given your buildings that make them earthquake resistant. Indicate what will happen to your buildings when an earthquake hits.
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Chapter 17
Ans: Answers will vary but should include large-based, thin-topped flexible buildings. Link To: The Dynamic Earth Difficulty Level: Hard
59. Is “terra firma” an accurate description of the continents? If so, why? If not, use your imagination to come up with a more descriptive phrase. Ans: Answers will vary. From our perspective, the continents are not moving, except as evidenced by earthquakes and volcanoes. Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Hard
60. Describe the type of land formation that would be created at each of these plate boundaries and the processes that caused: continental divergent; ocean divergent; continental convergent; ocean convergent; subduction; and transform. Ans: Divergent—plates moving apart caused by convection currents moving away from each other, creating rifts and ridges; convergent—plates moving together caused by convection currents that move toward each other causing folded or uplifted mountains; subduction—heavy plate pulled under a light plate by converging convection currents causing trenches; transform—plates pushing by each other caused by plates pushed in opposite directions, forming faults. Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Hard
61. Which of the Earth's major cities are located in earthquake hazard areas? Is it more or less dangerous to live near an active volcano? Explain your answer. Ans: Answers will vary. San Francisco, Los Angeles, Nome, etc.; danger may be measured in several ways including loss of life and property. Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Hard
62. What would the Earth topography look like after 4.6 billion years if plate tectonics were not an active process? How do you know? Ans: Erosion would flatten some landforms and deepen others. Mountains would be
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eroded so that while the down-cutting ability of rivers would great in the beginning, they would lesson over time based on the decrease of slope. Link To: The Dynamic Earth Difficulty Level: Hard
63. Volcanoes are found all over the world, specifically in North America on both the east and west coasts. However it is the volcanoes on the west coast that concern earth scientists as geologic hazards. Why is this? Ans: The volcanoes are associated with active subduction zones and contain a significant amount of water, which turns into steam and thereby creates explosive eruptions. Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Hard
64. How is it that the deepest earthquakes do not go beyond a few tens of kilometers deep, that is there are no earthquakes in the mantle or core? Ans: Earthquakes only occur between and among brittle solid materials. In the mantle and outer core the material is not brittle, but has fluid characteristics so no stresses can build up. Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Hard
65. Explain the ‘Hollywood’ idea that California might ‘fall’ into the ocean. In what way is this a distortion of what geologists believe will be California’s geologic fate. Ans: First, California will not fall (downward motion), but will slip laterally along a transform fault—in this manner millions of years into the future, California will become a peninsula sticking into the Pacific northwest, eventually becoming an island. Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Hard
66. The text stresses the integration of and interconnectedness of various sciences, in what way is the modern plate tectonic model a product of scientific integration? Ans: Answers will vary; the raw data for the model came from many seemingly divergent fields within the earth sciences before they saw themselves as unified (mineral logy, paleontology, geomorphology, stratigraphy, structural geology, and even astronomy).
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Chapter 17 Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Hard
67. From the study of electricity and magnetism from previous chapters. What must be taking place in the Earth’s interior for the Earth’s magnetic poles to reverse? Ans: Magnetic fields are created when electrons move in uniform motion—the spinning metallic core provides the electrons and the uniform motion—so by some mechanism this would have to stop, and then the motion reverses in order to reverse the magnetic field. Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Hard
68. Assuming tsunamis are the result of earthquakes alone, and based on the nature of earthquakes at subduction zones and spreading zones, where would you predict would be the most likely geography for a large tsunami, the Atlantic Ocean or the Pacific Ocean? Explain your answer. Ans: The Pacific would be the most likely because the earthquakes associated with subduction zones are typically deeper, storing more energy than the shallow, spreading zone earthquakes. Link To: The Dynamic Earth Difficulty Level: Hard
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2. Which of the following was used as evidence for plate tectonics? a. topographic profiles of the ocean floors b. maps on rock magnetism c. data classifying rocks by age d. sea floor spreading e. all of the above Ans: e Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Easy
3. The magnetic pattern from seafloor data recorded off the coast of Vancouver and Washington State a. were created by magnetite in fissure flows. b. are caused by hot spots. c. are indicators of past and future earthquake sites. d. have no one explanation accepted by scientists. e. always run perpendicular to the equator. Ans: a Link To: The Dynamic Earth Difficulty Level: Easy
276
4. The continents of Eurasia and North America are currently moving apart at an average rate of a. 2 inches per century. b. 5 cm per year. c. 5 meters per year. d. 2 cm per century. e. 10 cm per decade. Ans: b Link To: The Dynamic Earth Difficulty Level: Easy
5. Which of the following describes earthquakes? a. Earthquakes are an abrupt release of energy. b. Prediction of earthquakes is an established science, which gives global citizens a chance to evacuate ahead of time. c. Earthquakes have never occurred in the middle of the USA. d. No earthquake has been measured higher than 7 on the Richter scale. e. All earthquakes happen within one kilometer of the Earth's surface. Ans: a Link To: The Dynamic Earth Difficulty Level: Easy
6. The North American Plate a. extends from coast to coast in the United States and is completely covered by land. b. extends from the middle of the Atlantic Ocean to the edge of the Pacific Plate. c. contains the eastern half of North America and parts of western Europe. d. has only subducting boundaries. e. contains only the western half of North and South America. Ans: b Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Easy
7. Which of the following is an example of a continental convergent plant boundary? a. the East African Rift Valley b. the San Andreas Fault c. the Atlantic east coast fall line d. Mount St. Helens in the northwest United States
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Chapter 17 e. the Himalayan Mountains Ans: e Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Easy
8. Divergent plate boundaries are associated with a. seafloor spreading. b. formation of new crust. c. volcanic action. d. shallow, low-energy earthquakes. e. all of the above Ans: e Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Easy
9. How often does the oceanic plate material of the Earth renew itself; i.e., go through one replacement cycle? a. every 100 million years b. every 200 million years c. every 1,000 years d. every 100,000 years e. The oceanic plate material never renews itself. Ans: b Link To: The Dynamic Earth Difficulty Level: Easy
10. The transform plate boundaries a. form new material at rates exceeding that of the divergent plate boundaries. b. are the location of island arcs and hot spots. c. created the Andes Mountains in South America. d. are exemplified by the San Andreas fault. e. are sites of major volcano ranges. Ans: d Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Medium
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11. Where is the longest mountain range on Earth? a. Mid-Atlantic Ocean Ridge b. Andes Mountains in South America d. Himalayas in India c. Appalachians in the eastern United States e. Urals in Russia Ans: a Link To: The Dynamic Earth Difficulty Level: Easy
12. Which formula would you use to determine the age of the Atlantic Ocean basin? a. E = mC2 b. D = R T. c. F= M A d. A = π r2 e. P = N R T Ans: b Link To: The Dynamic Earth Difficulty Level: Easy
13. What evidence convinced most scientists to accept the theory of plate tectonics? a. ocean topography b. magnetism of the ocean basin rocks c. discovery of the Mid-Atlantic Rift zone d. radiometric dating of the basaltic rocks e. all of the above Ans: e Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Easy
14. What causes the Ring of Fire, which borders much of the Pacific Ocean? a. plate subduction b. divergent plates c. sea floor spreading d. transform plates e. all of the above
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Chapter 17 Ans: a Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Easy
15. Which of these waves is classified as a type of seismic wave following earthquakes? a. transverse b. compressional c. longitudinal d. shear waves e. all of the above Ans: e Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Easy
16. Mountains on the Earth are continuously being formed. Ans: True Link To: The Dynamic Earth Difficulty Level: Easy
17. Energy from earthquakes is transmitted as light waves. Ans: False Link To: The Dynamic Earth Difficulty Level: Easy
18.A philosopher and a meteorologist laid the groundwork for the idea of moving continents. Ans: True Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Easy
280
19. Evidence for Earth's magnetic reversals has been found in the East African Rift Zone. Ans: False Link To: The Dynamic Earth Difficulty Level: Easy
20. An earthquake with a magnitude 7 on the Richter Scale releases 100 times the energy of an earthquake with a magnitude 5. Ans: True Link To: The Dynamic Earth Difficulty Level: Easy
21. The ocean floor is a flat plain collecting sediments from the continents. Ans. False Link To: The Dynamic Earth Difficulty Level: Easy
22. Rocks collected at the Mid-Atlantic Ridge and dated with radioactive isotopes are among the oldest rocks on earth. Ans: False Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Easy
23. Tidal waves come as frequently as the tides. Ans: False Link To: The Dynamic Earth Difficulty Level: Easy
24. Man may have evolved his upright stance from a need to adapt to divergent plate boundaries. Ans: True
281
Chapter 17 Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Easy
25. The Appalachian Mountains are among the youngest on Earth. Ans: False Link To: The Dynamic Earth Difficulty Level: Easy
26. The specific surface features created by convergent plate boundaries depend on whether the plates are continental or oceanic. Ans: True Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Easy
27. The speed of a seismic wave depends partly on the type of seismic wave that is moving. Ans: True Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Easy
28. When Californians refer to “The Big One” what do they mean? Ans: Because of the stresses growing along the San Andreas and other faults, geologists predict that in the coming decades Californians will experience “The Big One,” an earthquake of greater magnitude than any they have had before. Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Easy
29. What are the surface features associated with convergent plate boundaries? Ans: Converging plates can result in deep ocean trenches, nonvolcanic mountains, or coastal mountain ranges with an ocean trench offshore.
282
Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Easy
30. How were the Hawaiian Islands formed? Ans: The Hawaiian Islands were created one at a time as the Pacific Plate moved toward the northwest over a stationary hot spot. Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Easy
31. What is always characteristic of a tectonic plate? a. made of basalt b. comprised of crust and some mantle material c. made of granite d. has a thickness of at least 35 km e. all of the above Ans: b Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Medium
32. Subduction zone regions are often the locations of a. active volcanoes. b. the disappearance of old plate material. c. the world's highest mountains. d. severe earthquakes. e. All of the above can be located at subduction zones. Ans: e Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Medium
33. What is the force that moves continents and tectonic plates? a. convection cells b. mantle convection c. radioactive decay d. heat energy left from the great bombardment e. all of the above
283
Chapter 17
Ans: e Link To: The Dynamic Earth Difficulty Level: Medium
34. Most mountains have not eroded to a flat plain in the last 500,000 years because a. under a thin veneer of soil, a mountain is solid rock. b. new mountains constantly emerge through rifts in the crustal material of oceans and continents. c. ozone depletion has decreased the rate of erosion. d. the mantle has a constant supply of granitic material e. mountains are reformed by tectonic uplift that is greater than or equal to the erosional forces. Ans: e Link To: The Dynamic Earth Difficulty Level: Medium
35. If you took a vacation driving to the oldest part of the North American continent you would need to bring a map of a. Wichita, Kansas. b. northeastern Canada. c. the Cascade Range of the Sierra Nevada Mountains. d. Baja, California. e. the Black Hills of South Dakota. Ans: b Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Medium
36. The only currently active plate boundary within the continental United States is the a. Marianas Trench. b. East-Pacific Rise. c. New Madrid Fault. d. San Andreas Fault. e. Mid-Atlantic Ridge. Ans: d Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Medium
284
37. Which of the following would not be seen in the United States? a. chunks of land called terranes b. an old spreading "rift" plate boundary c. a “hot spot” with active volcanoes d. a mountain range created from the collision of two continents e. a mountain range formed when molten rock pushed up sediments Ans: b Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Medium
38. What part of the Hawaiian Island chain is the oldest? a. northwest b. southwest c. south d. east e. west Ans: a Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Medium
39. The difference between continental and ocean basin rock is a. ocean rocks are not as dense as continental rocks. b. ocean rocks are basaltic and continental rocks are granitic. c. continental rocks can be detected by Geiger counters. d. continental rocks were originally metamorphic rocks. e. continental rocks form thinner crustal material. Ans: b Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Medium
40. Earthquakes that measure around 8 on the Richter scale can be felt by most people but do little damage to buildings. Ans: False Link To: The Dynamic Earth Difficulty Level: Medium
285
Chapter 17 41. The Grand Canyon is an example of what happens when two tectonic plates scrape past each other. Ans: False Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Medium
42. Compared to the oceanic plates, the continental plates are thicker and comprised of lower-density rock. Ans: True Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Medium
43. How can you tell the relative age of a mountain by its physical features? Ans: After much time, mountains that were once angular with steep slopes become more rounded by erosion processes; therefore, in general, rounded mountains may be older. Link To: The Dynamic Earth Difficulty Level: Medium
44. Describe the changes in curriculum organization in geology departments since 1960. What technologies and new information precipitated these changes? Ans: Magnetic measurements, images from high-flying airplanes, and so forth led to the acceptance of the theory of plate tectonics. Link To: The Dynamic Earth Difficulty Level: Medium
45. Briefly summarize the evidence scientists used to determine that the center of the Earth rotates at a different rate from the crust. Ans: Earthquake waves plus the idea that the more liquid mantle has more inertia than does the core. Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Medium
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46. Explain the wide range in age differences between the age of the continents measured in billions of years and the age of the ocean floor measured in millions of years. Ans: Answers will vary; the ocean floor is recycled via subduction into the Earth’s upper mantle, while the less dense continental crust is not subducted, so it remains on the surface. Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Medium
47. Explain how volcanoes situated over ‘hot spots’ would not be expected to be explosive in nature while volcanoes associated with subduction zones would be. Ans: Again the difference is in the amount (volume) of water available for steam resulting in explosive power. The subduction zone carries water with it into the melting zone. Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Medium
48. What would be an architectural specification for a skyscraper built in an earthquakeprone region? a. rigid and strong b. flexible with shock preservers c. soft and malleable d. corner angles locked to 90 degrees e. covered with rubber insulation Ans: b Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Hard
49. What evidence did Wegener use in proposing the idea of continental drift? Why were his ideas not accepted? Ans: In addition to observing and questioning the origin of the parallel coastlines on opposite sides of the Atlantic Ocean, Wegener identified matching rock formations and other geological evidence. The established geological community rejected his ideas because he proposed increase in average elevation of continents and had no mechanism for the movement of the continents. Link To: The Dynamic Earth Difficulty Level: Hard
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Chapter 17 50. What reasoning did scientists use to determine that the Atlantic Ocean is 160 million years old? Ans: Scientists used the distance/time/rate relationship. The time the ocean has expanded equals its age; the rate of movement (assumed constant) equals 5 cm/yr; the present distance between Eurasia and North America is about 7000 km. Distance divided by rate equals 140 million years for these data. Link To: The Dynamic Earth Difficulty Level: Hard
51. What attributes of granite and basalt have resulted in the shape of continents we see on a map? Ans: The continental plates are mostly granite capping the mantle, while the oceanic plates are basalt. Since granite is a lower-density rock than basalt, the continents “float” on top of the basalt and mantle rock. Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Hard
52. What are the processes that build stress in brittle rocks? Ans: Heated rocks expand; cooled rocks contract; rocks with changes in pressure from below or above can distort or rebound; rocks at plate boundaries absorb stress until one or more moves, causing earthquakes. Link To: The Dynamic Earth Difficulty Level: Hard
53. How do seismologists use the vibration energy released by earthquakes? Ans: Answers may vary. Seismologists around the world record the intensity and time of arrival of seismic waves generated by earthquakes. Using a computer, the scientists can analyze this information to learn more about the earthquake and about the material through which it passes. Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Hard
54. The Marianas Trench is the result of two convergent plates, with no continents on
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either plate, forming a subduction zone. Knowing these facts, what else can you say about the Marianas Trench? Ans: One plate will sink beneath the other, down into the Earth, where it can melt, producing magma and a volcanic environment beneath the ocean. Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Hard
55. Explain the statement “Good scientists will eventually accept the implications of their observations, whether those implications violate preconceived ideas or not.” Ans: Answers will vary but should include information about observations and testing/retesting experiments to confirm data. Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Hard
56. How does seismic tomography give scientists a three-dimensional view of the Earth? Ans: Data from seismic events are analyzed through computer imaging allowing for better analysis. Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Hard
57. The Earth’s magnetic field changes direction periodically over geologic time. Describe what evidence scientists have for this change and explain why they feel this evidence supports this theory. Ans: Magnetic field measurements showed alignment of north/south poles within rocks as they hardened after emerging from the mid-Atlantic Ridge. Link To: The Dynamic Earth Difficulty Level: Hard
58. Using your knowledge of Newton’s laws of motion and your knowledge of properties of materials, sketch both a high-rise and a one-story building that might be able to withstand an earthquake. Label the characteristics you have given your buildings that make them earthquake resistant. Indicate what will happen to your buildings when an earthquake hits.
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Chapter 17
Ans: Answers will vary but should include large-based, thin-topped flexible buildings. Link To: The Dynamic Earth Difficulty Level: Hard
59. Is “terra firma” an accurate description of the continents? If so, why? If not, use your imagination to come up with a more descriptive phrase. Ans: Answers will vary. From our perspective, the continents are not moving, except as evidenced by earthquakes and volcanoes. Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Hard
60. Describe the type of land formation that would be created at each of these plate boundaries and the processes that caused: continental divergent; ocean divergent; continental convergent; ocean convergent; subduction; and transform. Ans: Divergent—plates moving apart caused by convection currents moving away from each other, creating rifts and ridges; convergent—plates moving together caused by convection currents that move toward each other causing folded or uplifted mountains; subduction—heavy plate pulled under a light plate by converging convection currents causing trenches; transform—plates pushing by each other caused by plates pushed in opposite directions, forming faults. Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Hard
61. Which of the Earth's major cities are located in earthquake hazard areas? Is it more or less dangerous to live near an active volcano? Explain your answer. Ans: Answers will vary. San Francisco, Los Angeles, Nome, etc.; danger may be measured in several ways including loss of life and property. Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Hard
62. What would the Earth topography look like after 4.6 billion years if plate tectonics were not an active process? How do you know? Ans: Erosion would flatten some landforms and deepen others. Mountains would be
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eroded so that while the down-cutting ability of rivers would great in the beginning, they would lesson over time based on the decrease of slope. Link To: The Dynamic Earth Difficulty Level: Hard
63. Volcanoes are found all over the world, specifically in North America on both the east and west coasts. However it is the volcanoes on the west coast that concern earth scientists as geologic hazards. Why is this? Ans: The volcanoes are associated with active subduction zones and contain a significant amount of water, which turns into steam and thereby creates explosive eruptions. Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Hard
64. How is it that the deepest earthquakes do not go beyond a few tens of kilometers deep, that is there are no earthquakes in the mantle or core? Ans: Earthquakes only occur between and among brittle solid materials. In the mantle and outer core the material is not brittle, but has fluid characteristics so no stresses can build up. Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Hard
65. Explain the ‘Hollywood’ idea that California might ‘fall’ into the ocean. In what way is this a distortion of what geologists believe will be California’s geologic fate. Ans: First, California will not fall (downward motion), but will slip laterally along a transform fault—in this manner millions of years into the future, California will become a peninsula sticking into the Pacific northwest, eventually becoming an island. Link To: Another Look at Volcanoes and Earthquakes Difficulty Level: Hard
66. The text stresses the integration of and interconnectedness of various sciences, in what way is the modern plate tectonic model a product of scientific integration? Ans: Answers will vary; the raw data for the model came from many seemingly divergent fields within the earth sciences before they saw themselves as unified (mineral logy, paleontology, geomorphology, stratigraphy, structural geology, and even astronomy).
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Chapter 17 Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Hard
67. From the study of electricity and magnetism from previous chapters. What must be taking place in the Earth’s interior for the Earth’s magnetic poles to reverse? Ans: Magnetic fields are created when electrons move in uniform motion—the spinning metallic core provides the electrons and the uniform motion—so by some mechanism this would have to stop, and then the motion reverses in order to reverse the magnetic field. Link To: Plate Tectonics: A Unifying View of Earth Difficulty Level: Hard
68. Assuming tsunamis are the result of earthquakes alone, and based on the nature of earthquakes at subduction zones and spreading zones, where would you predict would be the most likely geography for a large tsunami, the Atlantic Ocean or the Pacific Ocean? Explain your answer. Ans: The Pacific would be the most likely because the earthquakes associated with subduction zones are typically deeper, storing more energy than the shallow, spreading zone earthquakes. Link To: The Dynamic Earth Difficulty Level: Hard
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