Test Bank For The Changing Earth Exploring Geology and Evolution, 6th Edition Chapter 1-24

Chapter 1—Understanding Earth: A Dynamic and Evolving Planet ESSAY 1. What distinguishes science from other forms of human inquiry?

ANS: Scientific ideas are based on data and observation. They are testable. Other forms of inquiry are based on faith, emotion, or something else that is nontestable.

PTS: 1

REF: 1.3. Geology and the Formulation of Theories

2. What is scientific method?

ANS: Scientific method is an orderly, logical approach to understanding our world that involves gathering and analyzing data about a natural phenomenon, formulating hypotheses to explain the phenomenon, testing the hypotheses, which, if it survives, is put forth as a theory.

PTS: 1

REF: 1.7. Origin of the Universe and Solar System, and Earth's Place in Them

3. How is a theory formulated?

ANS: Theories are formulated using scientific method. Observations and data are gathered to test the problem. Tentative explanations, also called hypotheses, are then formulated to explain the observations and data. More tests are done and the data are analyzed. If the data show that the hypothesis is not correct, it is tossed out. If the data support the hypothesis, there are no significant data refuting it, and it is accepted by scientists, it becomes a theory.

PTS: 1

REF: 1.7. Origin of the Universe and Solar System, and Earth's Place in Them

4. How have natural resources been important in history?

ANS: States, nations, and empires have risen and fallen, and they have fought for control of, or sometimes lost, natural resources.

PTS: 1

REF: 1.4. How Does Geology Relate to the Human Experience?

5. What is greenhouse effect and how does it work? What happens when greenhouse gas levels in the atmosphere increase?

ANS: Carbon dioxide and other greenhouse gases are natural components of the atmosphere. These gases allow sunlight to pass through the atmosphere but trap some of the heat that radiates outward from Earth's surface. This is greenhouse effect. If the amount of greenhouse gases in the atmosphere increases, they can trap more heat and the atmosphere warms.

PTS: 1

REF: 1.6. Global Geologic and Environmental Issues Facing Humankind

6. What are some of the predicted consequences of global warming?

ANS: Warmer temperatures overall; melting glaciers, ice caps, and sea ice; increased drought in some locations, increased precipitation in other locations; difficulty growing food in some agricultural areas; spread of tropical diseases into areas that have traditionally been too cold for them.

PTS: 1

REF: 1.6. Global Geologic and Environmental Issues Facing Humankind

7. Describe how the universe, galaxies, stars, and chemical elements formed.

ANS: Scientists believe that the universe originated with the Big Bang approximately 15 billion years ago.

At the moment of the Big Bang, there was only energy, no matter. In the first second following the Big Bang, the four basic forces separated and the universe experienced enormous expansion. Galaxies and stars came together because particles attracted to each other by gravity and angular momentum caused the material to rotate. In the early universe, the only chemical elements were hydrogen and helium.

Nuclear reactions in stars formed the heavier elements and star explosions scattered them around space.

PTS: 1

REF: 1.7. Origin of the Universe and Solar System, and Earth's Place in Them

8. Briefly explain the current theory of Earth's origin, including how and why it came to be differentiated by composition.

ANS: Formation began with uniform cold accretion of rocky material. Heat was generated by meteorite impacts, gravitational compression, and nuclear reactions. The heat caused the material to melt. Since it could now move, dense metals sank to the core and denser silicates to the mantle. Lighter silicates rose to form the crust.

PTS: 1

REF: 1.7. Origin of the Universe and Solar System, and Earth's Place in Them

9. How are the rock cycle and plate tectonics related?

ANS: Interactions between plates determine, to some extent, which of the three rock groups will form. Plates may melt to form igneous rocks, be altered to form metamorphic, or sink to allow sediments to become sedimentary rocks.

PTS: 1

REF: 1.9. The Rock Cycle

10. What is the basic tenet of the theory of organic evolution? What is the mechanism for organic evolution called and how does it work?

ANS: All living things are related and have descended with modification from organisms that lived in the past. The mechanism is called natural selection, which states that the organisms that are best adapted to their environment are the most likely to survive to reproduce and so their genes will be better represented in the next generation. It is these changes that cause species to evolve with time.

PTS: 1

REF: 1.10. Organic Evolution and the History of Life

11. Briefly explain how the themes of plate tectonics, organic evolution, and geologic time provide a cohesive history of Earth.

ANS: Earth has evolved internally and externally. As internal processes were established, they played a role in what was happening on the surface of Earth as the atmosphere, hydrosphere, and landmasses developed. Organic evolution was directly dependent on development of favorable conditions for different life forms. The net result of the physical, chemical, and biological evolution of Earth has been profound, particularly in light of the amount of time necessary for those changes to take place (synthesis).

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REF: various

12. Briefly explain how geologists can formulate theories about events that occurred on Earth before humans were here to make observations.

ANS: Geologists base their theories on two assumptions. First, that rocks record the processes that were involved in formation of those rocks. Second, that uniformitarianism is true, and the present is the key to the past. This means that basic physical, chemical, and biological processes have not changed, and that if we study and understand them today, we can apply what we learn to conditions in the past.

PTS: 1

REF: 1.11. Geologic Time and Uniformitarianism

13. Briefly explain the importance of the geologic time scale.

ANS: The geologic time scale is the result of work by many geologists worldwide who used fossils, the rock record, and radiometric dating techniques to determine a chronology for the evolution of Earth and its life through time.

PTS: 1

REF: 1.11. Geologic Time and Uniformitarianism

14. Briefly explain the importance of the Principle of Uniformitarianism to the study of historical geology.

ANS: Uniformitarianism provides the basis for interpreting the geologic history of Earth because geologists cannot travel back in time to study events. By using modern analogies, geologists can make reasonable interpretations about past events.

PTS: 1

REF: 1.11. Geologic Time and Uniformitarianism

SHORT ANSWER 1. What are two examples of geology-related environmental concerns? Briefly explain why geology holds an important position in environmental science.

ANS: Water quality and distribution, finding and exploiting energy resources, soil formation and erosion, climate change--there are many to choose from. Geology is concerned with all aspects of the physical Earth and their interactions with the biosphere.

PTS: 1

REF: 1.6. Global Geologic and Environmental Issues Facing Humankind

2. What is one way in which geologic knowledge is used to help humans?

ANS: There are several possible answers to this including finding mineral or energy resources, helping solve environmental problems, or predicting natural hazards.

PTS: 1

REF: various

3. What are planetesimals?

ANS: Accreting masses of gases, liquids, and solids that eventually become true planets.

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REF: 1.7. Origin of the Universe and Solar System, and Earth's Place in Them

4. What are the characteristics of the terrestrial planets?

ANS: The terrestrial planets  Mercury, Venus, Earth, and Mars  are all small and are composed of rock and metallic elements that condensed at the high temperatures of the inner solar nebula.

PTS: 1

REF: Geo-Insight. The Terrestrial and Jovian Planets

5. What are the characteristics of the Jovian planets?

ANS: The Jovian planets  Jupiter, Saturn, Uranus, and Neptune  are all large, gaseous bodies with rings and heavy atmospheres.

PTS: 1

REF: Geo-Insight. The Terrestrial and Jovian Planets

6. What is Pluto now that it is no longer a planet, and what are the characteristics of that type of body?

ANS: Pluto is now a dwarf planet. These bodies are similar to planets but they have not cleared their portion of space of debris. Pluto is found within the Kuiper belt of comets and other icy debris.

PTS: 1

REF: 1.7. Origin of the Universe and Solar System, and Earth's Place in Them

7. Why is Earth considered to be a dynamic (as opposed to static) planet?

ANS: Earth has been continuously changed through its 4.6 billion year existence.

PTS: 1

REF: 1.8. Why Earth is a Dynamic and Evolving Planet

8. On what bases are the concentric layers of Earth primarily distinguished?

ANS: density differences as a function of variations in pressure, temperature, and composition PTS: 1

REF: 1.8. Why Earth is a Dynamic and Evolving Planet

9. How is Earth unique among the planets of the solar system?

ANS: Earth supports life, has oceans of water, has a hospitable atmosphere, and has a variety of climate.

PTS: 1

REF: Geo-Insight. The Terrestrial and Jovian Planets

10. What is the difference between a rock and a mineral?

ANS: A rock is an aggregate of minerals. Minerals are naturally occurring, inorganic, crystalline solids that have definite physical and chemical properties.

PTS: 1

REF: 1.9. The Rock Cycle

11. What are the three major groups of rocks?

ANS: igneous, sedimentary, metamorphic PTS: 1

REF: 1.9. The Rock Cycle

12. What is the sequence of steps in the formation of sedimentary rocks?

ANS: weathering, erosion, transportation, deposition, and consolidation/lithification PTS: 1

REF: 1.9. The Rock Cycle

13. How do metamorphic rocks form?

ANS: The alteration of existing rocks is a result of heat, pressure, and chemical activity.

PTS: 1

REF: 1.9. The Rock Cycle

14. What is the basic premise of the principle of uniformitarianism?

ANS: Present-day processes have operated throughout geologic time.

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REF: 1.11. Geologic Time and Uniformitarianism

15. State the principle of uniformitarianism ANS: The physical and chemical laws of nature have remained the same over time and cannot be violated.

PTS: 1

REF: 1.11. Geologic Time and Uniformitarianism

16. What is the name of the method that is used to determine the absolute age of a rock body?

ANS: radiometric dating

PTS: 1

REF: 1.11. Geologic Time and Uniformitarianism

17. What is the definition of the word "theory" as used in science?

ANS: A theory is a coherent explanation for one or several related natural phenomena that is supported by a large body of objective evidence.

PTS: 1

REF: 1.3. Geology and the Formulation of Theories

18. What about Earth makes it suitable for a wide variety of life?

ANS: A hospitable atmosphere, lots of liquid water, and a variety of climate types.

PTS: 1

REF: Geo-Insight. The Terrestrial and Jovian Planets

COMPLETION 1. Earth's six principal subsystems are ____________________, ____________________, ____________________, ____________________, ____________________, and ____________________.

ANS: atmosphere, hydrosphere, biosphere, lithosphere, mantle, core PTS: 1

REF: 1.1. Introduction

2. A combination of related parts that interact in an organized fashion is a(n) ____________________.

ANS: system PTS: 1

REF: 1.1. Introduction

3. The two primary materials that geologists use as clues to understand Earth's past are ____________________ and ____________________.

ANS: rocks, fossils fossils, rocks PTS: 1

REF: 1.9. The Rock Cycle | 1.10. Organic Evolution and the History of Life

4. When the universe originated it was composed of 100 percent ____________________ and but now consists of ____________________ percent hydrogen and 2 percent ____________________ elements.

ANS: hydrogen and helium, 98, heavier PTS: 1

REF: 1.7. Origin of the Universe and Solar System, and Earth's Place in Them

5. The four basic forces are ____________________, ____________________, ____________________, and ____________________.

ANS: gravity, electromagnetic, strong nuclear, weak nuclear PTS: 1

REF: 1.7. Origin of the Universe and Solar System, and Earth's Place in Them

6. Any theory that explains the origin of the solar system must also explain the following properties of all or most of the planets: a(n) ____________________ direction of rotation and division into ____________________ planets and ____________________ planets, according to their chemical and physical properties.

ANS: counterclockwise, terrestrial, Jovian PTS: 1

REF: 1.7. Origin of the Universe and Solar System, and Earth's Place in Them

7. The increasing percentage of heavier elements in the later universe results from nuclear ____________________, during the evolution of ____________________.

ANS: fusion, stars PTS: 1

REF: 1.7. Origin of the Universe and Solar System, and Earth's Place in Them

8. Earth formed ______ billion years ago.

ANS: 4.6 PTS: 1

REF: 1.7. Origin of the Universe and Solar System, and Earth's Place in Them

9. The material in Earth's inner core is ____________________, while the outer core is ____________________.

ANS: solid, liquid PTS: 1

REF: 1.8. Why Earth is a Dynamic and Evolving Planet

10. Earth's solid portion is divided into concentric layers of rock and other materials that may be solid, liquid, or partially molten. From the center to the surface, these are known as the inner ____________________, outer ____________________, lower ____________________, upper ____________________, and ____________________.

ANS: core, core, mantle, mantle, crust PTS: 1

REF: 1.8. Why Earth is a Dynamic and Evolving Planet

11. The portion of Earth that has the largest volume is the ____________________.

ANS: mantle PTS: 1

REF: 1.8. Why Earth is a Dynamic and Evolving Planet

12. The crust and the underlying uppermost mantle make up the ____________________.

ANS: lithosphere PTS: 1

REF: 1.8. Why Earth is a Dynamic and Evolving Planet

13. The two types of crust are ____________________ and ____________________.

ANS: oceanic, continental continental, oceanic PTS: 1

REF: 1.8. Why Earth is a Dynamic and Evolving Planet

14. Plates of ____________________ move over the ____________________, partly as a result of ____________________ cells.

ANS: lithosphere, asthenosphere, convection PTS: 1

REF: 1.8. Why Earth is a Dynamic and Evolving Planet

15. Rocks that form from the crystallization of lava or magma are ____________________ rocks.

ANS: igneous PTS: 1

REF: 1.9. The Rock Cycle

MULTIPLE CHOICE 1. Which of the following statements about a scientific theory is not true? a. It is an explanation for some natural phenomena. b. It has a large body of supporting knowledge. c. It is testable. d. It is conjecture or guess. e. None of these ANS: D

PTS: 1

REF: 1.3. Geology and the Formulation of Theories

2. Most scientists argue that the greatest environmental problem facing the world today is what? a. climate change b. the ozone hole c. water pollution d. overpopulation e. overfishing ANS: D PTS: 1 REF: 1.6. Global Geologic and Environmental Issues Facing Humankind 3. The Big Bang took place approximately ____ years ago. a. 150 billion b. 50 billion c. 15 billion d. 15 million e. 10,000 ANS: C PTS: 1 REF: 1.7. Origin of the Universe and Solar System, and Earth's Place in Them 4. The age of the universe is estimated by ____.

a. b. c. d. e.

the temperature of the universal background radiation the age of comets formed in interstellar space the rate at which galaxies are moving away from one another the age of subatomic particles as determined by radioactive decay the age of the sun

ANS: C PTS: 1 REF: 1.7. Origin of the Universe and Solar System, and Earth's Place in Them 5. Among the evidence for the Big Bang origin of the universe is a. the separation of the four basic forces b. galaxies are all moving away from one another c. a universal background radiation slightly above zero d. the separation of the four basic forces AND a universal background radiation slightly above zero e. galaxies are all moving away from one another AND a universal background radiation slightly above zero ANS: E PTS: 1 REF: 1.7. Origin of the Universe and Solar System, and Earth's Place in Them 6. At the moment of the Big Bang, a. all matter and energy were compressed into an infinitely small high-temperature and highdensity state. b. all matter and energy were infinitely expanded and equaled the size of the universe. c. the universe was entirely made of infinitely dense matter; energy had not yet come into existence. d. the universe that had existed previously inverted on itself and became the current universe. e. all of the chemical elements that we see in the universe today were forged in the explosion.

ANS: A PTS: 1 REF: 1.7. Origin of the Universe and Solar System, and Earth's Place in Them 7. Identify the terrestrial planets. a. Jupiter, Saturn, Uranus, and Neptune b. Mercury, Venus, Earth, and Mars c. Earth, Mars, and Jupiter d. Uranus, Neptune, and Pluto e. Mercury, Earth, Mars, and Pluto ANS: B

PTS: 1

REF: Geo-Insight. The Terrestrial and Jovian Planets

8. The zone between the core and the crust is called what? a. innersphere b. lithosphere c. mantle d. convection center e. molten zone ANS: C

PTS: 1

REF: 1.8. Why Earth is a Dynamic and Evolving Planet

9. Earth's core is probably ____. a. composed of rock with high silica content b. hollow

c. molten throughout d. composed of potassium and aluminum rich silicates e. composed mostly of iron and nickel ANS: E

PTS: 1

REF: 1.8. Why Earth is a Dynamic and Evolving Planet

10. Which of the following statements about the asthenosphere is not true? a. It lies beneath the lithosphere. b. It is a rigid rock layer. c. It behaves plastically. d. It acts like a lubricating layer allowing plates to move. e. It has the same composition as the lower mantle.

ANS: B

PTS: 1

REF: 1.8. Why Earth is a Dynamic and Evolving Planet

11. The ocean crust is composed mostly of what? a. granite b. peridotite c. basalt d. sial e. gneiss ANS: C

PTS: 1

REF: 1.8. Why Earth is a Dynamic and Evolving Planet

12. The theory that all living organisms are descendants of different life forms that existed in the past is called ____. a. organic evolution b. astrology c. paleontology d. plate tectonics e. natural selection ANS: A

PTS: 1

REF: 1.10. Organic Evolution and the History of Life

13. Fossils are ____. a. useful for reconstructing past environmental conditions b. evidence that evolution has occurred c. evidence that Earth has a long history predating humans d. the remains or traces of once living organisms e. all of these ANS: E

PTS: 1

REF: 1.10. Organic Evolution and the History of Life

14. What are the three types of plate boundaries? a. mid-ocean ridge, trench, divergent b. mid-ocean ridge, divergent, convergent c. divergent, convergent, transform d. convergent, transform, trench ANS: C

PTS: 1

REF: 1.8. Why Earth is a Dynamic and Evolving Planet

15. Sudden or catastrophic events, such as volcanic eruptions and tsunami, can be explained by a. the big bang theory. b. the theory of natural selection. c. the third law of thermodynamics. d. the principle of uniformitarianism.

ANS: D

PTS: 1

REF: 1.11. Geologic Time and Uniformitarianism

TRUE/FALSE 1. The two types of crust are known as lithospheric and oceanic.

ANS: F

PTS: 1

REF: 1.8. Why Earth is a Dynamic and Evolving Planet

2. Scientists have proven that there is no supernatural or spiritual realm.

ANS: F

PTS: 1

REF: 1.3. Geology and the Formulation of Theories

3. The solar nebula theory of the formation of the solar system accounts for the differences in composition between the terrestrial and Jovian planets.

ANS: T PTS: 1 REF: 1.7. Origin of the Universe and Solar System, and Earth's Place in Them 4. Earth was originally of homogeneous composition.

ANS: T PTS: 1 REF: 1.7. Origin of the Universe and Solar System, and Earth's Place in Them 5. According to the theory of organic evolution, all living organisms are related and they descended, with some modifications, from organisms that lived in the past.

ANS: T

PTS: 1

REF: 1.10. Organic Evolution and the History of Life

6. The central thesis of the theory of organic evolution is that there has always been the same diversity of species on Earth in the past as today.

ANS: F

PTS: 1

REF: 1.10. Organic Evolution and the History of Life

7. Natural selection refers to survival of organisms that are best adapted to their environment.

ANS: T

PTS: 1

REF: 1.10. Organic Evolution and the History of Life

8. Natural selection refers to organisms choosing the habitat in which they feel most comfortable.

ANS: F

PTS: 1

REF: 1.10. Organic Evolution and the History of Life

9. In the 19th century, the geologic time scale was first developed using radiometric age dating techniques.

ANS: F

PTS: 1

REF: 1.11. Geologic Time and Uniformitarianism

10. In the 19th century, the geologic time scale was based primarily on sequence of fossils in the rock record.

ANS: T

PTS: 1

REF: 1.11. Geologic Time and Uniformitarianism

11. The Principle of Uniformitarianism is based on the idea that modern processes have operated throughout geologic time.

ANS: T

PTS: 1

REF: 1.11. Geologic Time and Uniformitarianism

12. According to the Principle of Uniformitarianism, processes have occurred at the same rates throughout geologic time.

ANS: F

PTS: 1

REF: 1.11. Geologic Time and Uniformitarianism

13. Geologists use the Principle of Uniformitarianism as a basis to interpret the past and predict the future.

ANS: T

PTS: 1

REF: 1.11. Geologic Time and Uniformitarianism

14. In order for geologists to use the Principle of Uniformitarianism to interpret the geologic record, they do not need to study modern geologic processes.

ANS: F

PTS: 1

REF: 1.11. Geologic Time and Uniformitarianism

Chapter 2—Plate Tectonics: A Unifying Theory ESSAY 1. What were the major lines of evidence for continental drift as presented by Wegener in the early 20 th century?

ANS: The glaciations on the Gondwana continents could only have occurred if the continents were joined since the centers of the glaciers would have been in the ocean if they were not. Also, the continents, such as South America and Africa, match like a jigsaw puzzle. Similar fossil plant and animals are separated by oceans leading to the assumption that they must have lived in adjacent regions when they were alive. Finally, similar rock sequences and mountain ranges could be connected across oceans.

PTS: 1

REF: 2.3. What is the Evidence for Continental Drift?

2. Explain how mountain ranges can be used as evidence to support continental drift.

ANS: A mountain range forms under the same geological conditions along its length. This means that the same or nearly the same rock types are found along the range's length in the same or nearly the same sequence. The processes that form mountain ranges tend to create somewhat linear, elevated features.

So a mountain range that has been split, even if it has been separated by an ocean, is fairly easy to recognize.

PTS: 1

REF: 2.3. What is the Evidence for Continental Drift?

3. How does fossil evidence support continental drift?

ANS:

The distribution of fossils is such that it would be impossible for the plants and animals not to have lived in contiguous land areas. Glossopteris seeds are too heavy to be dispersed by wind and would not have remained viable if they had traveled far across the oceans. The plants associated with Glossopteris do not match the climate zones the fossils are found in. As for the animals, it's hard to imagine a freshwater reptile like Mesosaurus swimming across the Atlantic. And the land-dwelling reptiles, Lystrosaurus and Cynognatuus, could not have swum at all!

PTS: 1

REF: 2.3. What is the Evidence for Continental Drift?

4. Briefly explain why apparent polar wandering is "apparent."

ANS: Paleomagnetic studies of ancient rocks point to different locations for the North Pole at different times.

When this is mapped out, it makes the pole appear to wander over time. The alternative to a wandering magnetic pole, for which there is no other evidence at all, is that the continents move and with them the rocks that contain the paleomagnetic data.

PTS: 1

REF: 2.6. Paleomagnetism and Polar Wandering

5. Briefly explain why the movement of continents over geologic time was the best explanation for polar wandering.

ANS: Since the Earth has only one magnetic north pole now, it was extremely unlikely that there would have been more than one in the past, though this would have been required to explain the different polar wander paths of the different continents. The only other possible explanation is that the continents were once joined and have since moved apart.

PTS: 1

REF: 2.6. Paleomagnetism and Polar Wandering

6. Briefly explain how magnetic reversals in oceanic crust and fossils in ocean sediments are used to construct a magnetic time scale.

ANS: A terrestrial sequence of magnetic reversal in volcanic deposits was dated radiometrically. These dates were extrapolated to regions which were not dated, but showed the same pattern of normal and reversed magnetic polarities. Ages of ocean-floor basalts lying within a zone of normal or reversed polarity are dated by the ages of the fossils found in the sediments which directly overlie the basaltic crust. These fossils have already been incorporated within a biostratigraphic zone.

PTS: 1

REF: 2.7. Magnetic Reversals and Seafloor Spreading

7. How are hot spots used for determining the absolute motions of plates?

ANS: Hot spots appear to be fixed in the mantle relative to each other so they can be used as a reference frame. If the age of a basalt and its distance from the hotspot is determined, then the rate of movement of that rock can be calculated. If a number of these samples are taken from various distances from the hotspot, the calculation can be quite accurate.

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REF: 2.10. Hot Spots and Mantle Plumes

8. Describe how the two models for the driving force of plate motion are the same. How are they different?

ANS: Both models involve thermal convection in the mantle. In both models, where two adjacent convection cells have upwelling limbs, there is a divergent plate boundary. Where there is a descending limb of a convection cell, there is a convergent boundary. The models differ in the location of the convection cells. In one, the convection cells are restricted to the asthenosphere. In the other, the convection cells take up the entire mantle.

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REF: 2.12. The Driving Mechanism of Plate Tectonics

9. Briefly explain the roles of magma and hydrothermal activity in forming ore deposits along convergent and divergent plate boundaries.

ANS: Magma contains valuable elements, some of which leave the magma in gases and fluids. These substances transport the elements and facilitate their exchange for other elements in the surrounding rock. The surrounding rock may then have enough of the valuable elements to become an ore deposit.

At convergent plate boundaries, partial melting at the subducting plate allows magma and valuable minerals to rise up in fluids and erupt as volcanoes or cool beneath the surface as plutons. At divergent plate boundaries, hydrothermal vents form. In these locations, seawater filters past hot magma, picks up valuable elements, and then the hot fluids flow onto the seafloor and drop their valuable elements.

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REF: 2.13. Plate Tectonics and the Distribution of Natural Resources

10. What are four of the many things that plate tectonics theory explains?

ANS: Plate tectonics explains, at least to some extent, all of the following phenomena: the distribution of earthquakes and volcanoes, the locations of ore deposits and mountain systems, climate and ocean circulation patterns, and the geographic distribution, evolution, and extinction of life forms.

PTS: 1

REF: various

11. Briefly explain why there is so much oil in the Persian Gulf region.

ANS: During the Mesozoic, the Persian Gulf was a broad, stable marine shelf. Countless microorganisms lived in the surface water and their remains accumulated in the bottom sediments and were buried. The collision between Arabia and Iran has tilted the Arabian plate and crumpled rocks on the edges of both plates. The tilting of Arabia allows oil to migrate upslope to accumulate in traps created by folding.

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REF: 2.13. Plate Tectonics and the Distribution of Natural Resources

12. How does the introduction of a geographic barrier encourage the evolution of species?

ANS: A population that is not separated will interbreed, and so there will be little opportunity for different species to form. If a barrier separates that population, and if conditions are different on either side of the barrier, natural selection will favor certain traits over others, and over time the two different populations of organisms may evolve to become different species.

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REF: 2.14. Plate Tectonics and the Distribution of Life

SHORT ANSWER 1. What was the principal reason why Wegener's theory of continental drift was rejected?

ANS: Wegener lacked a plausible mechanism to explain how continental crust could move through the sea floor.

PTS: 1

REF: 2.3. What is the Evidence for Continental Drift?

2. Why were glacially deposited strata important in the development of continental drift theory?

ANS: The glacial deposits indicated that all southern continents must have been contiguous and closer to the South Pole. Glaciers cannot form in the middle of an ocean, which is where they would have originated if the continents were not together.

PTS: 1

REF: 2.3. What is the Evidence for Continental Drift?

3. What was the principal reason why Wegener's theory of continental drift was rejected?

ANS: Wegener lacked a plausible mechanism to explain how continental crust could move through the sea floor.

PTS: 1

REF: 2.3. What is the Evidence for Continental Drift?

4. Describe the features of oceanic trenches. For what geological reasons do the trenches appear like this?

ANS: Oceanic trenches are long,steep sided depressions on the seafloor. They are found near convergent plate boundaries. The deep trench is caused by subduction of oceanic lithosphere beneath an oceanic or continental plate.

PTS: 1

REF: 2.4. Features of the Seafloor

5. What are the three possible explanations for the distribution of paleomagnetic data?

ANS: (1) The continent remained fixed and the north magnetic pole moved; (2) the north magnetic pole stayed still and the continent moved; (3) both the continent and north magnetic pole moved.

PTS: 1

REF: 2.6. Paleomagnetism and Polar Wandering

6. What evidence is there that ocean basins are young and old oceanic crust must be destroyed?

ANS: The maximum age for oceanic crust is 180 million years, but the continents contain rocks both younger and much older than 180 million years, so the older oceanic crust must go somewhere.

PTS: 1

REF: 2.7. Magnetic Reversals and Seafloor Spreading

7. What is one geologic method for determining the average rate of seafloor spreading?

ANS: The strips of oceanic crust can dated by reference to the ages of reversals in lava flows on land which have been radiometrically dated. Then the age with distance from the spreading ridge can be used to calculate the rate of plate motion and hence seafloor spreading.

PTS: 1

REF: 2.7. Magnetic Reversals and Seafloor Spreading

8. Briefly explain how convection transfers heat.

ANS: When a material is heated, it expands, and its density decreases so it rises. After having risen some distance, it begins to cool, contract, and become denser. Thus the material sinks and returns to the original level where it will eventually be heated and rise again.

PTS: 1

REF: 2.7. Magnetic Reversals and Seafloor Spreading

9. Briefly describe what happens when divergent plate boundaries form within a continent.

ANS: High heat flow elevates the continent and a rift valley forms, with normal faults and a central valley called a graben. Magma is intruded into fractures. As the plates diverge, basalt erupts in the rift, creating new ocean crust. Ultimately, as the plates continue to diverge, a new ocean basin forms.

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REF: 2.9. The Three Types of Plate Boundaries

10. Draw a cross-section of an oceanic-oceanic convergent plate boundary. Show the directions of relative plate motion. Put stars for the locations of earthquakes. Put triangles with smoke out the top for the locations of volcanoes. Label the trench, back arc basin, and subduction complex.

ANS: See Figure 2.18a PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

11. Draw a cross-section of an ocean-continent convergent plate boundary. Show the directions of relative plate motion. Put stars for the locations of earthquakes. Put triangles with smoke out the top for the locations of volcanoes. Label the trench and subduction complex.

ANS: See Figure 2.18b PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

12. Draw a cross-section of a continental-continental convergent plate boundary. Show the directions of relative plate motion. Put stars for the locations of earthquakes. Show the location of the mountain range. Label the subduction complex.

ANS: See Figure 2.18c PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

13. Why is plate tectonic theory so widely accepted?

ANS: Plate tectonic theory is supported by diverse lines of evidence from many scientific disciplines, such as geology and biology, and it explains many seemingly unrelated geological phenomena.

PTS: 1

REF: various

14. What is a method by which the present rate of motion between two plates can be measured accurately?

ANS: The travel of a laser beam can be timed from one plate to another by bouncing it from a satellite and by calculating the difference in arrival times of a quasar signal at two plates over a period of time.

PTS: 1

REF: 2.11. Plate Movement and Motion

15. What are the heat sources for each of the two mantle convection models for plate tectonics?

ANS: With whole mantle convection, the heat source is the core. With convection only in the asthenosphere, the heat source is harder to identify.

PTS: 1

REF: 2.12. The Driving Mechanism of Plate Tectonics

16. How does seafloor spreading explain the movement of the continents?

ANS: With seafloor spreading, the continents and oceanic crust move together as part of large plates. The plate is pushed by the formation of new ocean crust and pulled by the subduction of old ocean crust.

New crust forms due to seafloor spreading.

PTS: 1

REF: 2.12. The Driving Mechanism of Plate Tectonics

17. In what ways does plate tectonics theory have economic applications?

ANS: By understanding the geologic history of a region, geologists can predict whether it will be a worthwhile place to search for petroleum or ore deposits.

PTS: 1

REF: 2.13. Plate Tectonics and the Distribution of Natural Resources

COMPLETION 1. Paleomagnetism is the study of the ____________________ magnetism in rocks.

ANS: remnant PTS: 1

REF: 2.6. Paleomagnetism and Polar Wandering

2. When magma cools, the magnetic iron-bearing minerals align themselves with the Earth's magnetic field and record ____________________ and ____________________.

ANS: strength, direction of the North Pole PTS: 1

REF: 2.6. Paleomagnetism and Polar Wandering

3. The temperature at which iron-bearing minerals gain their magnetic property is the ____________________.

ANS: Curie point PTS: 1

REF: 2.6. Paleomagnetism and Polar Wandering

4. Paleomagnetic data plotted on a map suggested that the magnetic pole had moved through time; this phenomenon was called ____________________.

ANS: apparent polar wandering PTS: 1

REF: 2.6. Paleomagnetism and Polar Wandering

5. Magnetic stripes in oceanic basalts are ____________________ and ____________________ around ocean ridges.

ANS: parallel, symmetrical symmetrical, parallel PTS: 1

REF: 2.7. Magnetic Reversals and Seafloor Spreading

6. Radiometric dating shows that the oldest ocean crust is ____________________ years old, and the oldest continental crust is ____________________ years old.

ANS: 180 million, 3.96 billion PTS: 1

REF: 2.7. Magnetic Reversals and Seafloor Spreading

7. At deep sea trenches, ____________________ is subducted back into the ____________________.

ANS: lithosphere, mantle PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

8. At mid-oceanic ridges, hot magma rises from the ____________________ and forms new ____________________.

ANS: mantle, seafloor PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

9. The three kinds of boundaries there can be between adjacent plates are ____________________, ____________________, and ____________________.

ANS: divergent, convergent, transform PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

10. At divergent plate boundaries, plates are moving ____________________. At these locations, new ____________________ forms.

ANS: apart, lithosphere PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

11. Where divergent plate boundaries form beneath continental masses, low areas known as ____________________ form.

ANS: rift valleys PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

12. At a convergent plate boundary, oceanic crust is ____________________.

ANS: destroyed PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

13. The three types of convergent plate boundaries are ____________________-____________________, ____________________-____________________, and ________________________________________.

ANS: oceanic-oceanic, oceanic-continental, continental-continental PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

14. Volcanoes are found at these two types of plate boundaries: ____________________ and ____________________.

ANS: divergent, convergent convergent, divergent PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

15. The type of plate boundary that runs through California is called ____________________, and the name of this plate boundary is ____________________.

ANS: transform, the San Andreas Fault PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

16. The names of the plates on either side of the plate boundary that passes through California are ____________________ and ____________________.

ANS: Pacific, North American North American, Pacific PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

17. Mountain building events occur along ____________________-____________________ or ____________________-____________________ plate boundaries.

ANS:

oceanic-continental, continental-continental continental-continental, oceanic-continental PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

18. The type of plate boundary at which many of the world's major metallic ore deposits are associated is ____________________.

ANS: convergent PTS: 1

REF: 2.13. Plate Tectonics and the Distribution of Natural Resources

MULTIPLE CHOICE 1. One of the most general conclusions to be drawn from plate tectonic theory is that ____. a. the Earth is gradually losing heat b. the Earth's geography has continually changed c. the Earth is slowly expanding d. the Earth is slowly shrinking e. all the ocean basins are gradually enlarging ANS: B

PTS: 1

REF: various

2. Plate tectonic processes have influenced which of the following? a. the distribution of earthquakes and volcanoes b. the locations of ore deposits and mountain systems c. climatic patterns and ocean circulation d. the geographic distribution, evolution, and extinction of life forms e. all of these ANS: E

PTS: 1

REF: various

3. The first person to suggest that all of the continents had originally been joined together as the supercontinent Pangaea was who? a. Alexander du Toit, 1937 b. Frank Taylor, 1910 c. Alfred Wegener, 1912 d. Snider- Pelligrini, 1858 e. Harry Hess, 1962 ANS: C

PTS: 1

REF: 2.2. Early Ideas About Continental Drift

4. The name given to the northern supercontinent was ____. a. Laurasia b. Luentia c. Laurotia. d. Laurentia e. northern Pangaea ANS: A

PTS: 1

REF: 2.2. Early Ideas About Continental Drift

5. The southern supercontinent consisted of which current continents? a. South America, Africa, Australia, Antarctica, and India b. Africa, South America, Antarctica, and Australia

c. South America, Africa, India, and Australia d. South Africa, India, Africa, and Australia e. South America, Central America, India, Antarctica, Africa, and Australia ANS: A

PTS: 1

REF: 2.2. Early Ideas About Continental Drift

6. Which group of fossils is considered evidence for the former existence of Gondwana? a. Glossaurus b. Pecopteris c. Neuropteris d. Glossopteris e. Messopteris ANS: D

PTS: 1

REF: 2.3. What is the Evidence for Continental Drift?

7. Glacially deposited strata were important in the development of continental drift theory because ____. a. the distribution of glacial deposits indicated that the entire Earth must have been glaciated b. the distribution of coal-swamp deposits indicated that the entire Earth must have been very warm c. the glacial deposits indicated that there must have been many very large glaciers on several continents d. the glacial deposits indicated that all of the southern continents must have been closer to the South Pole and contiguous e. the glacial deposits indicated that climate can change dramatically over geologic time ANS: D

PTS: 1

REF: 2.3. What is the Evidence for Continental Drift?

8. That the northern continents were once joined and located along the equator was shown by what? a. the coal-age plant fossils of North America and Europe b. the Glossopteris flora c. the distribution of mountain ranges d. the distributions of Permian and Triassic reptiles e. the distributions of northern hemisphere glacial tillites ANS: A

PTS: 1

REF: 2.3. What is the Evidence for Continental Drift?

9. Which of the following was not evidence for Wegener's continental drift hypothesis? a. glacial deposits of Gondwana continents b. fit of African and South American shorelines c. paleomagnetic striping of the oceanic crust d. fossil plant and animal distributions e. similar rock sequences and mountain ranges ANS: C

PTS: 1

REF: 2.3. What is the Evidence for Continental Drift?

10. The proposal that the coastline fit of South America and Africa was evidence of continental drift was criticized because it could have been due to what? a. chance b. shoreline erosion c. the sinking of a land bridge d. ocean currents e. the distribution of resistant rock types ANS: B

PTS: 1

REF: 2.3. What is the Evidence for Continental Drift?

11. If the continents were once joined together, rocks and mountain ranges on the margins of each should have ____. a. formed under the same conditions b. formed the same sequences c. formed at the same time d. the same structural trends and forces e. all of these ANS: E

PTS: 1

REF: 2.3. What is the Evidence for Continental Drift?

12. Two sets of mountain ranges, which are continuous once the continents on either side of the Atlantic are joined, are located where? a. eastern North America and Greenland/ Australia and East Africa b. east Africa and Europe/ eastern North America and the Soviet Union c. Australia and Southeast Asia/ Arabia and the Persian Gulf d. South Africa and Brazil/ eastern North America and Great Britain e. Central and South America/ Central and North America ANS: D

PTS: 1

REF: 2.3. What is the Evidence for Continental Drift?

13. Glacial deposits gave strong evidence of the existence of Gondwana because ____. a. a single continent in high latitudes was more sensible than low latitude glaciation on several continents b. glacial striations showed that all glaciers on each continent had flowed from a central location c. fossil plants indicated tropical climate in the northern continents d. a single continent in high latitudes was more sensible than low latitude glaciation on several continents AND glacial striations showed that all glaciers on each continent had flowed from a central location e. a single continent in high latitudes was more sensible than low latitude glaciation on several continents AND fossil plants indicated tropical climate in the northern continents ANS: D

PTS: 1

REF: 2.3. What is the Evidence for Continental Drift?

14. Fossil evidence linking the Gondwana continents includes which animal fossils? a. lake-dwelling Mesosaurus and large land-dwelling reptile Lystrosaurus and Cynognathus b. freshwater Mesosaurus and dinosaurs Brontosaurus and Tyrannosaurus c. freshwater crocodiles and the large amphibian Eryops d. reptile Dimetrodon and the first bird Archaeopteryx e. lake-dwelling Mesosaurus and the large land-dwelling reptiles Dimetrodon and Edaphosaurus ANS: A

PTS: 1

REF: 2.3. What is the Evidence for Continental Drift?

15. Fossil evidence of the links among Gondwana continents was compelling because the species ____. a. should have been found over wide regions if they were able to migrate among continents b. should have exhibited evidence of tolerance for climatic extremes c. should have shown a mechanism for widespread dispersal d. should have been found over wide regions if they were able to migrate among continents AND should have shown a mechanism for widespread dispersal e. all of these ANS: E

PTS: 1

REF: 2.3. What is the Evidence for Continental Drift?

16. The transition zone from the exposed land to the ocean floor is called the

a. oceanic trench. b. continental margin.

ANS: B

PTS: 1

c. continental slope. d. abyssal plain.

REF: 2.4. Features of the Seafloor

17. A volcanic hill that is on the seafloor and has a flat top is best called a a. guyot. c. aseismic ridge. b. seamount. d. microcontinent.

ANS: A

PTS: 1

REF: 2.4. Features of the Seafloor

18. The Earth's magnetic field is due to ____. a. the presence of magnetic iron and nickel in the core b. gravity c. the occurrence of magnetite in all rocks d. convection in the liquid outer core e. none of these ANS: D

PTS: 1

REF: 2.5. Earth's Magnetic Field

19. The study of paleomagnetism is possible because ____. a. the magnetic minerals in rocks create the Earth's magnetic field b. most rocks contain no magnetic minerals c. the magnetic minerals in rocks disrupt the Earth's magnetic field d. the magnetic minerals in a cooling lava point toward the north magnetic pole e. none of these ANS: D

PTS: 1

REF: 2.6. Paleomagnetism and Polar Wandering

20. Certain rock types can be used to determine the locations of past magnetic poles because ____. a. the Earth's magnetic poles have reversed many times during its history b. the magnetic poles and geographic poles differ slightly c. iron-bearing minerals align themselves in the direction of the current magnetic field when the rock cools below the Curie point d. lava flows in Europe all showed that the continent was once located in the southern hemisphere e. the north magnetic poles of each continent are identical for each geological period ANS: C

PTS: 1

REF: 2.6. Paleomagnetism and Polar Wandering

21. What did the differing paleomagnetic records for each continent show? a. each continent had its own magnetic pole during successive geological periods b. that the magnetic poles for each continent had moved over geological time c. that the magnetic poles have remained in one location and each of the continents has moved d. that both the poles and the continents have moved over time e. none of these ANS: C

PTS: 1

REF: 2.6. Paleomagnetism and Polar Wandering

22. What do studies of paleomagnetism show? a. the northern and southern hemispheres have reversed position many times b. the ocean basins are young c. each continent once had its own magnetic pole d. the continents remain fixed and the north magnetic pole has moved e. all of these

ANS: B

PTS: 1

REF: 2.7. Magnetic Reversals and Seafloor Spreading

23. Magnetic iron-bearing minerals that crystallize out of magma ____. a. align themselves with the Earth's magnetic field and only record direction b. record the strength of the Earth's magnetic fields c. become easily altered and lose their magnetic properties d. record both direction and strength of the Earth's magnetic field at time of crystallization e. none of these ANS: D

PTS: 1

REF: 2.6. Paleomagnetism and Polar Wandering

24. Geologists know that oceanic ridges are geologically very active because they ____. a. have high heat flow b. have many small earthquakes c. are the site of recent volcanic eruptions d. have many small earthquakes and are the site of recent volcanic eruptions e. all of these ANS: E

PTS: 1

REF: 2.7. Magnetic Reversals and Seafloor Spreading

25. That the oceanic crust is geologically young and the parallel magnetic striping pattern of basalts is symmetrical about oceanic ridges was conclusively shown by what? a. radiometric dating of oceanic basalts and sequences from continents b. the unusually thin layer of oceanic sediments and ages of contained fossils c. the existence of the same magnetic anomaly patterns in all ocean basins d. radiometric dating of oceanic basalts and sequences from continents AND the unusually thin layer of oceanic sediments and ages of contained fossils e. all of these ANS: D

PTS: 1

REF: 2.7. Magnetic Reversals and Seafloor Spreading

26. The fact that no oceanic crust older than 180 million years (Jurassic) has been found indicates what? a. The break-up of Pangaea must have occurred before the Jurassic Period. b. The ocean basins must be older than Jurassic age. c. The movement of continents must have begun no earlier than the Jurassic Period. d. The break-up of Pangaea must have begun at about the same time as these oldest basalts were formed. e. The movement of continents must have begun no earlier than the Jurassic Period AND The break-up of Pangaea must have begun at about the same time as these oldest basalts were formed.

ANS: D

PTS: 1

REF: 2.7. Magnetic Reversals and Seafloor Spreading

27. The seafloor spreading hypothesis indicates what as the primary cause of continental movement? a. volcanism in the ocean crust b. convergence of tectonic plates c. the formation and destruction of ocean basins d. the convection of mantle heat e. the decay of radioactive isotopes ANS: C

PTS: 1

REF: 2.7. Magnetic Reversals and Seafloor Spreading

28. Who proposed the idea of seafloor spreading? a. Harry Hess b. Frederick Vine

c. Oliver and Sykes d. Fred Taylor e. Hess and Matthews ANS: A

PTS: 1

REF: 2.7. Magnetic Reversals and Seafloor Spreading

29. What is the driving mechanism for plate tectonics? a. heat deep within the Earth b. tidal forces caused by the moon c. volcanoes and earthquakes at plate boundaries d. a little man with a steering wheel in Tierra del Fuego e. none of these ANS: A

PTS: 1

REF: 2.7. Magnetic Reversals and Seafloor Spreading

30. What was the driving mechanism proposed by Hess to explain sea floor spreading? a. downwelling oceanic currents b. hydrothermal cells c. thermal convection cells d. motions in the outer core e. thermal convection cells AND motions in the outer core ANS: C

PTS: 1

REF: 2.7. Magnetic Reversals and Seafloor Spreading

31. Lithospheric plates move on the Earth's surface because ____. a. warm mantle ascends at ridges and cool mantle descends at subduction zones b. convection occurs only in the asthenosphere c. cool mantle ascends at ridges and warm mantle descends at subduction zones d. warm mantle ascends at ridges and cool mantle descends at subduction zones AND convection occurs only in the asthenosphere e. convection occurs only in the asthenosphere AND cool mantle ascends at ridges and warm mantle descends at subduction zones ANS: A

PTS: 1

REF: 2.7. Magnetic Reversals and Seafloor Spreading

32. Old, cold, and dense oceanic crust is ____. a. created at spreading ridges b. found closest to continental margins c. destroyed at subduction zones d. eventually becomes incorporated into continental crust e. always found on plate margins ANS: C

PTS: 1

REF: 2.7. Magnetic Reversals and Seafloor Spreading

33. Geologists recognize which three major types of plate boundaries? a. resurgent, divergent, and emergent b. convergent, divergent, and transform c. transcurrent, oblique, and resurgent d. emergent, transform, and convergent e. transform, transcurrent, and translateral ANS: B

PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

34. At divergent plate boundaries, what are the operating forces? a. compressional b. lateral shearing

c. tensional d. thrusting e. normal ANS: C

PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

35. At a mid-ocean ridge spreading center, what happens? a. the plates are moving past each other b. the plates are moving away from each other c. the plates are moving toward each other d. one plate is being subducted beneath another e. both plates are being subducted ANS: B

PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

36. Which are not associated with a mid-ocean ridge? a. old ocean crust b. shallow earthquakes c. volcanic eruptions d. transform faults e. hot water ANS: A

PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

37. Geologists locate plate boundaries ____. a. at continental margins b. at volcanoes c. by earthquake epicenters d. at volcanoes AND by earthquake epicenters e. All of these ANS: C

PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

38. The forces operating at continent-continent convergent boundaries are ____. a. transpressional b. compressional c. tensional d. lateral shearing e. compressional and tensional ANS: B

PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

39. When a continental plate diverges from another continental plate what happens? a. a new ocean basin forms b. a large mountain range forms c. a transform fault forms d. there are no earthquakes e. a subduction zone forms ANS: A

PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

40. At transform plate boundaries, ____. a. lithosphere is neither created or destroyed b. plates move laterally past each other c. active volcanism occurs d. plates move laterally past each other AND active volcanism occurs

e. all of these ANS: D

PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

41. A transform plate boundary may connect ____. a. a spreading ridge and subduction zone b. two spreading ridges c. two subduction zones d. a spreading ridge and subduction zone OR two spreading ridges e. all of these ANS: E

PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

42. The San Andreas Fault that runs through California ____. a. is a transform fault b. is a plate boundary c. is the location of large earthquakes d. is a transform fault that is the location of large earthquakes e. all of these ANS: D

PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

43. The Emperor Seamount-Hawaiian Island chain a. is a line of active volcanoes. b. is a line of extinct volcanic structures. c. results from volcanism along a mid-ocean ridge. d. records the direction of plate motion.

ANS: D

PTS: 1

REF: 2.10. Hot Spots and Mantle Plumes

44. Plate tectonics have affected biological evolution by ____. a. causing global climatic change with joining together or breaking apart of large landmasses b. causing more or fewer habitats to develop as continental masses come together or separate c. forming geographic barriers d. forming geographic corridors e. all of these ANS: E

PTS: 1

REF: 2.14. Plate Tectonics and the Distribution of Life

45. Olympus Mars, the largest volcano in the solar system, is a. on Venus. b. a shield volcano. c. covered with an ice cap. d. indicative of active plate tectonics.

ANS: B

PTS: 1

REF: Geo-Insight. Tectonics of the Terrestrial Planets

46. Jupiter’s moon, Io, has no impact craters. This means that the moon a. has been protected from meteors by Jupiter b. is geologically active. c. has too little gravity to attract meteors. d. has a liquid sulfur surface.

ANS: B

PTS: 1

REF: Geo-Insight. Tectonics of the Terrestrial Planets

TRUE/FALSE 1. The 2004 Indian Ocean tsunami, the 2010 Indonesian volcanic eruptions and the 2011 Japan earthquake and tsunami are all due to plate tectonics.

ANS: T

PTS: 1

REF: 2.1. Introduction

2. Oceanic ridges are geologically stable features where sediments are deposited and nothing much else takes place.

ANS: F

PTS: 1

REF: 2.4. Features of the Seafloor

3. Earth’s magnetic poles, where the lines of force leave and enter the planet, do not coincide with the geographic (rotational) poles).

ANS: T

PTS: 1

REF: 2.5. Earth's Magnetic Field

4. The cause of magnetic reversals is a change in the structure of the Earth's inner core.

ANS: F

PTS: 1

REF: 2.7. Magnetic Reversals and Seafloor Spreading

5. Earth’s lithosphere is divided into seven major plates and numerous smaller ones.

ANS: T

PTS: 1

REF: 2.8. Plate Tectonics: A Unifying Theory

6. Many seemingly unrelated geologic features and events are interrelated by plate tectonics processes.

ANS: T

PTS: 1

REF: 2.8. Plate Tectonics: A Unifying Theory

7. Active volcanism on Venus indicates that the planet has a geologically active interior.

ANS: F

PTS: 1

REF: Geo-Insight. Tectonics of the Terrestrial Planets

8. Features associated with ancient continental rift zones include andesite volcanoes and strike slip faulting.

ANS: F

PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

9. During the Triassic, a number of rift related fault basins formed along the eastern margin of North America.

ANS: T

PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

10. The west coast of South America is a convergent boundary.

ANS: T

PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

11. A transform plate boundary underlies the Alps in southern Europe.

ANS: F

PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

12. There is a divergent plate boundary within the region of east Africa.

ANS: T

PTS: 1

REF: 2.9. The Three Types of Plate Boundaries

13. There is active volcanism on bodies in the solar system besides Earth but only on other planets.

ANS: F

PTS: 1

REF: Geo-Insight. Tectonics of the Terrestrial Planets

14. Hot spots move with continental plates.

ANS: F

PTS: 1

REF: 2.10. Hot Spots and Mantle Plumes

15. Volcanic island chains that form along the trace of a hot spot are called aseismic ridges.

ANS: T

PTS: 1

REF: 2.10. Hot Spots and Mantle Plumes

16. To determine the rate of plate motion, geologists date the magnetic anomalies on the seafloor and determine the distance from the ridge axis to that magnetic anomaly. Then they divide the age by the distance to determine the rate of movement.

ANS: F

PTS: 1

REF: 2.11. Plate Movement and Motion

17. Geologists have an excellent understanding of plate movements since before Pangaea came together.

ANS: F

PTS: 1

REF: 2.11. Plate Movement and Motion

18. Slab pull and ridge push facilitate the movement of plates.

ANS: T

PTS: 1

REF: 2.12. The Driving Mechanism of Plate Tectonics

Chapter 3—Minerals--The Building Blocks of Rocks ESSAY 1. What is a mineral?

ANS: A mineral is a naturally-occurring, inorganic, crystalline solid with a definite chemical composition and characteristic physical properties.

PTS: 1

REF: 3.1. Introduction

2. For each of the following objects, state where it can be found, and what its charge is: proton, electron, nucleus.

ANS: Protons are found in the nucleus and have a positive charge; electrons orbit the nucleus and have a negative charge; the nucleus is found in the center of the atom and has a positive charge.

PTS: 1

REF: 3.2. Matter--What Is It?

3. The chemical formula of halite is NaCl. In simple terms, state how these atoms come together to form a solid mineral.

ANS:

Sodium has only one electron in its outer shell, whereas chlorine has seven. Atoms want to have a full outer shell so sodium gives its extra electron to chlorine creating two ions; sodium now has a positive charge and is Na+, and chlorine has a negative charge and is Cl . This is called ionic bonding.

PTS: 1

REF: 3.2. Matter--What Is It?

4. Discuss how carbon atoms come together to form diamonds.

ANS: The electron shells of adjacent carbon atoms overlap, and they share electrons. This is called covalent bonding. A carbon atom in a diamond shares all four of its outer electrons with a neighbor.

PTS: 1

REF: 3.2. Matter--What Is It?

5. Diamond and graphite are two minerals with the same chemical composition, but extremely different physical properties. Why is this?

ANS: They have a different crystal structure. In both, carbon is joined by covalent bonds, but in graphite the carbon atoms form sheets that are weakly bonded together. In diamond, the carbon forms a threedimensional framework.

PTS: 1

REF: 3.2. Matter--What Is It?

6. How do a rock and a mineral differ?

ANS: A rock is a naturally occurring aggregate of minerals, while minerals are naturally occurring, inorganic crystalline solids. Rocks are made up of minerals, not vice versa.

PTS: 1

REF: 3.6. Rock-Forming Minerals

7. The United States is totally dependent on imports of some resources. Some of these imports come from politically unstable parts of the world. What choices are there for resolving this problem?

ANS: Answers will vary. The U.S. could try to find the needed mineral resources within the country but some are not available in large enough quantities or would require mining in environmentally or culturally sensitive areas. The U.S. could try to find the resources in friendlier nations. Developing alternatives to these resources is another possibility. For example, we could try to become less dependent on petroleum by developing other types of energy resources.

PTS: 1

REF: 3.8. Natural Resources and Reserves

SHORT ANSWER 1. What is a rock?

ANS: A rock is a naturally-occurring aggregate of one or more minerals.

PTS: 1

REF: 3.1. Introduction

2. Name three properties commonly exhibited by minerals that have metallic bonding.

ANS: Choose any three of the following: metallic luster, electrical conductivity, thermal conductivity, higher specific gravity, malleability.

PTS: 1

REF: 3.2. Matter--What Is It?

3. Name one property commonly exhibited by minerals that have Van der Waals' bonding.

ANS: Flakiness, such as with graphite PTS: 1

REF: 3.2. Matter--What Is It?

4. Out of more than 100 chemical elements that have been identified in nature, how many are relatively abundant in Earth's crust?

ANS: eight PTS: 1

REF: 3.2. Matter--What Is It?

5. What are the eight chemical elements that make up over 99 percent of Earth's crust?

ANS: O, Si, Al, Fe, Mg, Ca, Na, K PTS: 1

REF: 3.2. Matter--What Is It?

6. What is meant when minerals are referred to as "crystalline solids?"

ANS: The constituent atoms are arranged in a regular, three-dimensional pattern.

PTS: 1

REF: 3.3. Explore the World of Minerals

7. Why do most minerals, as measured by rock volume, belong to the silicate group?

ANS: because oxygen and silicon are the two most abundant elements in the crust PTS: 1

REF: 3.3. Explore the World of Minerals

8. How many mineral have been identified and described?

ANS: more than 3,500 PTS: 1

REF: 3.4. Mineral Groups Recognized by Geologists

9. How many minerals are common?

ANS:

approximately two dozen PTS: 1

REF: 3.4. Mineral Groups Recognized by Geologists

10. Name one example for each of the following types of tetrahedra: isolated tetrahedra, single chain tetrahedra, double chain tetrahedra, sheet tetrahedra, and framework tetrahedral.

ANS: olivine, pyroxene, amphibole, biotite/muscovite/mica/clay, quartz/feldspar PTS: 1

REF: 3.4. Mineral Groups Recognized by Geologists

11. Give an example of a ferromagnesian silicate.

ANS: olivine/pyroxene/amphibole/biotite PTS: 1

REF: 3.4. Mineral Groups Recognized by Geologists

12. Give an example of a nonferromagnesian silicate.

ANS: quartz/feldspar/muscovite/clay PTS: 1

REF: 3.4. Mineral Groups Recognized by Geologists

13. Give one example of each of the carbonates, sulfates, sulfides, and halides.

ANS: calcite/dolomite, gypsum, pyrite/sphalerite/galena, halite/fluorite PTS: 1

REF: 3.4. Mineral Groups Recognized by Geologists

14. Give an example of a native element.

ANS: gold/silver/copper/diamond/graphite PTS: 1

REF: 3.4. Mineral Groups Recognized by Geologists

15. What is a simple chemical test that will distinguish calcite from non-carbonate minerals?

ANS: Calcite will effervesce in hydrochloric acid; the others will not.

PTS: 1

REF: 3.5. Mineral Identification

16. List, in increasing order of hardness, the minerals of the Mohs hardness scale.

ANS: talc, gypsum, calcite, fluorite, apatite, orthoclase/feldspar, quartz, topaz, corundum, diamond PTS: 1

REF: 3.5. Mineral Identification

17. What is the most distinctive physical property of the mineral halite?

ANS: the salty taste PTS: 1

REF: 3.5. Mineral Identification

18. If a diamond is the hardest naturally occurring substance, how can one be "cut"?

ANS: It is actually cleaved, along one of its four cleavage directions.

PTS: 1

REF: Geo-Focus. Gems and Gemstones.

19. Give an example of a rock that is composed of only one mineral.

ANS: Examples include limestone, dolostone, quartz sandstone, halite, chert, and gypsum PTS: 1

REF: various

20. Name three factors that determine whether a known mineral resource in an area can become a reserve.

ANS: any three of the following: market price, technology, cost (e.g., labor, transportation, location) PTS: 1

REF: 3.7. How Do Minerals Form?

21. How does a mineral reserve differ from a mineral resource?

ANS: A reserve is that part of a resource that can be extracted (mined) economically.

PTS: 1

REF: 3.7. How Do Minerals Form?

COMPLETION 1. Carbon-12 (C12), carbon-13 (C13), and carbon-14 (C14) are all ____________________ of the ____________________ carbon.

ANS: isotopes, element PTS: 1

REF: 3.2. Matter--What Is It?

2. Atoms of the same chemical element, carbon for example, always have the same number of ____________________ in the nucleus.

ANS: protons PTS: 1

REF: 3.2. Matter--What Is It?

3. C12 has 6 protons. How many protons does C13 have? ____ How many neutrons does C13 have? ____ Nitrogen-14 (N14) has 6 protons and 8 neutrons: true or false? ____________________

ANS: 6, 7, false PTS: 1

REF: 3.2. Matter--What Is It?

4. The number of electrons in an atom of an element is always equal to the number of ____________________.

ANS: protons PTS: 1

REF: 3.2. Matter--What Is It?

5. The atomic mass of an atom is defined as the sum of the number of its ____________________ plus ____________________.

ANS: protons, neutrons PTS: 1

REF: 3.2. Matter--What Is It?

6. Different isotopes of the same element differ from each other because they have different ____________________.

ANS: atomic masses PTS: 1

REF: 3.2. Matter--What Is It?

7. In the ____________________ type of chemical bonding, electrons are shared between adjacent atoms.

ANS: covalent PTS: 1

REF: 3.2. Matter--What Is It?

8. The chemical formula KAlS3O8 means that the mineral orthoclase is composed of one atom of K and one of Al for every ____ of Si and ____ of O. ANS: three, eight PTS: 1

REF: 3.2. Matter--What Is It?

9. ____________________ and ____________________ are mineral compounds which are commonly produced by animals and are known as calcium ____________________.

ANS: Calcite, aragonite, carbonate PTS: 1

REF: 3.3. Explore the World of Minerals

10. The two factors which determine whether or not an element can substitute for another element in the composition of a mineral are the ____________________ and ____________________ of the atoms.

ANS: size, charge charge, size

PTS: 1

REF: 3.3. Explore the World of Minerals

11. Minerals are chemically classified by their ____________________.

ANS: negative ion ion group PTS: 1

REF: 3.4. Mineral Groups Recognized by Geologists

12. The silicon atom of the silica tetrahedron has a (+/) ____________________ charge of ____ (number), and the oxygen atoms have a (+/) ____________________ charge of ____ (number).

Therefore, the ion group has an overall (+/) ____________________ charge of ____ (number).

ANS: positive, four, negative, two, negative, four positive, 4, negative, 2, negative, 4 PTS: 1

REF: 3.4. Mineral Groups Recognized by Geologists

13. The hardest, most chemically inert common rock-forming mineral is ____________________.

ANS: quartz PTS: 1

REF: 3.4. Mineral Groups Recognized by Geologists

14. The most abundant rock-forming minerals are the nonferromagnesian silicates called the ____________________.

ANS: feldspars PTS: 1

REF: 3.4. Mineral Groups Recognized by Geologists

15. The two basic types of luster are ____________________ and ____________________.

ANS: metallic, nonmetallic nonmetallic, metallic PTS: 1

REF: 3.5. Mineral Identification

MULTIPLE CHOICE 1. Which of the following is not true of minerals? They are (have) ____. a. crystalline b. organic c. naturally occurring d. definite chemical composition e. characteristic physical properties ANS: B 2. What is an atom?

PTS: 1

REF: 3.1. Introduction

a. a negatively charged particle that circles a nucleus b. a positively charged particle within a nucleus c. the smallest particle into which an element can be divided while still retaining the chemical characteristics of that element d. a combination of elements e. a negatively charged particle that orbits the nucleus ANS: C

PTS: 1

REF: 3.2. Matter--What Is It?

3. The relatively massive, positively-charged particles in the nucleus of an atom are called what? a. protons b. neutrons c. electrons d. megatrons e. none of these ANS: A

PTS: 1

REF: 3.2. Matter--What Is It?

4. Isotopes of the same element have ____. a. different numbers of protons but the same number of neutrons b. the same number of electrons and different numbers of neutrons c. different numbers of neutrons but the same number of protons d. different numbers of electrons but the same number of neutrons e. none of these ANS: C

PTS: 1

REF: 3.2. Matter--What Is It?

5. Ionic bonds occur when electrons ____. a. are transferred between atoms b. are shared by atoms c. have a neutral charge d. have a positive charge e. none of these ANS: B

PTS: 1

REF: 3.2. Matter--What Is It?

6. Covalent bonds differ from ionic bonds in that ____. a. ionic bonds arise from electrical attraction between positively and negatively charged ions b. covalent bonds arise from the sharing of one or more electrons c. covalent bonds can occur between atoms of the same element d. ionic bonds arise from electrical attraction between positively and negatively charged ions AND covalent bonds arise from the sharing of one or more electrons e. all of these ANS: E

PTS: 1

REF: 3.2. Matter--What Is It?

7. For a neutrally-charged atom to become a positively-charged atom of the same element it must do what? a. lose a proton b. lose an electron c. gain a proton d. gain an electron e. none of these ANS: B

PTS: 1

REF: 3.2. Matter--What Is It?

8. The positively charged atom in the above question is also called what? a. a positron b. a neutron c. an ion d. an isotope e. none of these ANS: C

PTS: 1

REF: 3.2. Matter--What Is It?

9. Elements bond together to form molecules because ____. a. they are most stable when their outer electron shell is filled b. they need to have a positive charge c. they need to have a negative charge d. they are glued together by positrons e. none of these ANS: A

PTS: 1

REF: 3.2. Matter--What Is It?

10. Amorphous minerals are a. without form. b. lacking an orderly arrangement of atoms. c. well-developed crystals. d. nonexistent.

ANS: D

PTS: 1

REF: 3.3. Explore the World of Minerals

11. In different specimens of the same type of mineral the interfacial angles between crystal faces are a. greater than 90 degrees. b. less than 90 degrees. c. identical. d. zero.

ANS: C

PTS: 1

REF: 3.3. Explore the World of Minerals

12. Which of the following are all examples of minerals? a. bronze, steel, glass, aluminum, pencil lead b. gold, silver, uranium, lead, silica, iron c. copper, ice, quartz, topaz, diamond, corundum d. water, mercury, metallic hydrogen, limestone e. petroleum, coal, iron, feldspar, basalt ANS: C

PTS: 1

REF: various

13. Cleavage is defined as a. planes of fracture resulting from weak bonds b. smooth, flat reflective surfaces c. surfaces of smooth, curved fracture d. planes of fracture resulting from strong bonds e. none of these ANS: A

PTS: 1

REF: 3.3. Explore the World of Minerals

14. Common examples of sulfide and sulfate minerals, respectively, are ____. a. galena and pyrite b. gypsum and anhydrite c. galena and gypsum

d. galena and hematite e. fluorite and pyrite ANS: C

PTS: 1

REF: 3.4. Mineral Groups Recognized by Geologists

15. Which of the following is an example of a mineral resource? a. sand b. gold c. petroleum d. salt e. all of these ANS: E

PTS: 1

REF: 3.7. How Do Minerals Form?

16. An example of a material which has been both a resource and a reserve, depending on abundance, economic conditions, and mining technology is which of the following? a. platinum b. gold c. petroleum d. iron e. all of these ANS: E

PTS: 1

REF: 3.7. How Do Minerals Form?

17. Placer deposits form because a. gold is lighter weight than other rocks and minerals and floats to the surface. b. hot fluids travel through bedrock and create mineral veins. c. minerals with covalent bonds transition to ionic bonding. d. running water separates and concentrates minerals and rock fragments by their density.

ANS: D

PTS: 1

REF: Geo-Insight. The Precious Metals

TRUE/FALSE 1. Ice is a mineral, but water is not.

ANS: T

PTS: 1

REF: 3.1. Introduction

2. Some naturally-occurring minerals have healing properties.

ANS: F

PTS: 1

REF: various

3. All minerals are compounds.

ANS: F

PTS: 1

REF: 3.2. Matter--What Is It?

4. Mica and clay minerals have a platy crystal form because they have a sheet-like structure of silica tetrahedra.

ANS: T

PTS: 1

REF: 3.2. Matter--What Is It?

5. Minerals of the amphibole group have their silica tetrahedra arranged in double chains.

ANS: T

PTS: 1

REF: 3.2. Matter--What Is It?

6. Noble gases are chemically inert because their outer electron shell is filled.

ANS: T

PTS: 1

REF: 3.2. Matter--What Is It?

7. Van der Waals bonds occur between atoms or compounds without free electrons.

ANS: T

PTS: 1

REF: 3.2. Matter--What Is It?

8. The number of neutrons in an atom always equals the number of protons.

ANS: F

PTS: 1

REF: 3.2. Matter--What Is It?

9. Minerals may have chemical compositions that vary within a range.

ANS: T

PTS: 1

REF: 3.3. Explore the World of Minerals

10. Olivine is an example of a mineral with isolated silica tetrahedra.

ANS: T

PTS: 1

REF: 3.4. Mineral Groups Recognized by Geologists

11. Specific gravity is the ratio of a mineral’s weight to the weight of an equal volume of water at 4degrees C. ANS: T

PTS: 1

REF: 3.5. Mineral Identification

12. The United States is self-sufficient in petroleum.

ANS: F

PTS: 1

REF: 3.8. Natural Resources and Reserves

13. The United States is self-sufficient in gold.

ANS: F

PTS: 1

Chapter 4—Igneous Rocks and Plutons

REF: 3.8. Natural Resources and Reserves

ESSAY 1. What are the "scratches" on Devil's Tower, Wyoming?

ANS: The scratches are the intersections of columnar joints and fractures that form in response to cooling and contraction that occurred in the magma.

PTS: 1

REF: 4.3. How Does Magma Originate and Change?

2. What phenomena does Bowen's Reaction Series help explain?

ANS: Bowen's Reaction Series explains how felsic magmas and rocks can come from mafic magmas, the order of mineral formation in a cooling magma, how the mineral composition of a magma changes with magma temperature, how magmas become enriched in Si, Al, and K, and the mineral associations that are common in igneous rocks.

PTS: 1

REF: 4.3. How Does Magma Originate and Change?

3. Briefly explain how it is possible for a single magma to yield rocks of felsic, intermediate, and mafic composition.

ANS: There are three ways for a single magma to yield rocks of vastly different composition. With crystal settling, the first crystals to form, the ferromagnesian minerals, settle to the bottom of the magma chamber, where they can cool to form a mafic rock. The remaining liquid is more intermediate and if the process continues, more felsic than the original magma. At any point, these liquids can cool to become an intermediate or felsic rock. Assimilation adds the country rock to a magma. If a magma is mafic, it can melt more felsic rock and change its composition from mafic to intermediate to felsic.

Magma mixing can combine magmas of different composition. If a mafic magma and a felsic magma mix, they will create a magma of intermediate composition. These three magmas can lead to three different rock types.

PTS: 1

REF: 4.3. How Does Magma Originate and Change?

4. What is a mantle plume, and what causes one to erupt?

ANS: A mantle plume is a cylindrical plume of hot rock that rises through the mantle, most likely from the core-mantle boundary. As the rock rises, the pressure on it declines and the melting temperature of the rock decreases. Melting begins and creates magma.

PTS: 1

REF: 4.3. How Does Magma Originate and Change?

5. What two types of volcanic features result from volcanism above a mantle plume? How are hot spots related to plate boundaries?

ANS: Mantle plumes are responsible for linear chains of volcanoes in the oceans, as seen in the HawaiiEmperor Chain. They are also responsible for flood basalts, vast flat-lying areas of overlapping lava flows. Hot spots are not related to plate boundaries; most cause intra-plate volcanism.

PTS: 1

REF: 4.3. How Does Magma Originate and Change?

6. Briefly explain why Bowen's reaction series predicts that mafic intrusive rocks should be much more common than felsic intrusive rocks.

ANS: If crystal settling produces the magma, there would need to be about ten times as much mafic magma present to yield the amount of felsic rock.

PTS: 1

REF: 4.3. How Does Magma Originate and Change?

7. When looking at a hand sample of an igneous rock, how would you tell if it is plutonic or volcanic?

ANS: If the texture is phaneritic, the magma cooled slowly, and the rock is plutonic. If the texture is aphanitic, the magma cooled rapidly, and the rock is volcanic.

PTS: 1

REF: 4.4. Igneous Rocks--Their Characteristics and Classification

8. How did Shiprock, New Mexico form?

ANS: Shiprock is a volcanic neck that is all that remains of an ancient volcano. The magma that fed the volcano with explosive eruptions penetrated the country rock, which has since eroded away.

PTS: 1

REF: 4.5. Intrusive Igneous Bodies--Plutons

9. Briefly explain batholith formation.

ANS: Most batholiths appear to have formed by upward intrusion of magma accompanied by fracturing and stoping, the shouldering-aside, and deformation of intruded country rock.

PTS: 1

REF: 4.6. The Origin of Batholiths

SHORT ANSWER 1. What is a pluton?

ANS: a body of rock which formed by cooling of magma below Earth's surface PTS: 1

REF: 4.1. Introduction

2. Name some common uses of granitic rocks.

ANS: building stone, tombstones, pedestals for statues, aggregate in cement PTS: 1

REF: Geo-Focus. Granite--Common, Attractive, and Useful

3. Give one reason why rhyolite flows are less common than basalt flows.

ANS: Rhyolitic magmas are more viscous than basaltic magmas and tend not to reach the surface as frequently.

PTS: 1

REF: 4.2. The Properties and Behavior of Magma and Lava

4. Why does lava retain heat so well?

ANS: because rocks conduct heat so poorly PTS: 1

REF: 4.2. The Properties and Behavior of Magma and Lava

5. How does lava differ from magma?

ANS: Lava is magma at Earth's surface.

PTS: 1

REF: 4.2. The Properties and Behavior of Magma and Lava

6. What is the average geothermal gradient for Earth?

ANS: about 25C per kilometer PTS: 1

REF: 4.3. How Does Magma Originate and Change?

7. Is the process of partial melting more likely to produce magmas which are more mafic or more felsic?

Why? ANS: Felsic rocks melt at lower temperatures than do mafic rocks.

PTS: 1

REF: 4.3. How Does Magma Originate and Change?

8. List three processes by which felsic and intermediate igneous rocks can be formed from more mafic magmas.

ANS: assimilation, magma mixing, crystal settling, and partial melting PTS: 1

REF: 4.3. How Does Magma Originate and Change?

9. What are flood basalts?

ANS: Flood basalts are vast flat-lying areas of overlapping lava flows that form at mantle plumes.

PTS: 1

REF: 4.3. How Does Magma Originate and Change?

10. Why can an intruding mafic magma assimilate felsic country rock, but an intruding felsic magma cannot assimilate mafic country rock?

ANS: Mafic magma has a higher temperature than felsic magma while felsic rock melts at lower temperatures than mafic rock.

PTS: 1

REF: 4.3. How Does Magma Originate and Change?

11. What does a phaneritic texture tell us about the history of an igneous rock?

ANS: The magma cooled slowly.

PTS: 1

REF: 4.4. Igneous Rocks--Their Characteristics and Classification

12. What does a glassy texture tell us about the history of an igneous rock?

ANS: The magma cooled very rapidly.

PTS: 1

REF: 4.4. Igneous Rocks--Their Characteristics and Classification

13. How do the holes form in vesicular igneous rocks, such as scoria and pumice?

ANS: They result from the entrapment of gases which come out of the liquid magma when the pressure is released.

PTS: 1

REF: 4.4. Igneous Rocks--Their Characteristics and Classification

14. Briefly explain how pegmatites form.

ANS: Pegmatites are extremely coarse-grained granitic rocks which form as dikes, sills, and stocks from the cooling of the liquid-vapor-rich phases of felsic magmas.

PTS: 1

REF: 4.4. Igneous Rocks--Their Characteristics and Classification

15. Why do pegmatite mineral crystals grow so large?

ANS: The vapor phase inhibits the formation of nuclei, but allows ions to move easily to those nuclei which do form, so large crystals can result.

PTS: 1

REF: 4.4. Igneous Rocks--Their Characteristics and Classification

16. How does a batholith differ from a stock?

ANS: A batholith has an exposed surface area greater than 100 square kilometers; a stock has an exposed surface area less than 100 square kilometers.

PTS: 1

REF: 4.5. Intrusive Igneous Bodies--Plutons

17. Explain how a laccolith is similar to a sill.

ANS: Both are near-surface concordant intrusive igneous bodies.

PTS: 1

REF: 4.5. Intrusive Igneous Bodies--Plutons

18. Explain how batholiths and stocks formed via plate tectonics.

ANS: Batholiths and stocks are products of partial melting of subducted oceanic crust that are emplaced in the continental crust above the subducted slab.

PTS: 1

REF: 4.5. Intrusive Igneous Bodies--Plutons

19. What role does stoping play in the emplacement of batholiths?

ANS: Fracturing and assimilation of country rock aid the upward movement of batholithic magma.

PTS: 1

REF: 4.6. The Origin of Batholiths

COMPLETION 1. The two main categories of igneous rocks are ____________________ and ____________________.

ANS: volcanic/extrusive, plutonic/intrusive plutonic/intrusive, volcanic/extrusive PTS: 1

REF: 4.2. The Properties and Behavior of Magma and Lava

2. ____________________ is the first ferromagnesian mineral to crystallize from a mafic magma.

ANS: Olivine PTS: 1

REF: 4.3. How Does Magma Originate and Change?

3. The only minerals in the continuous branch of Bowen's reaction series are the ____________________.

ANS: plagioclase feldspars PTS: 1

REF: 4.3. How Does Magma Originate and Change?

4. Partial melting of basalt, together with the processes of assimilation, ____________________settling, and ____________________ mixing are believed to explain the generation of felsic intrusive magmas from ____________________ magmas.

ANS: crystal, magma, mafic PTS: 1

REF: 4.3. How Does Magma Originate and Change?

5. The increase in Earth's temperature with depth is called the ____________________.

ANS: geothermal gradient PTS: 1

REF: 4.3. How Does Magma Originate and Change?

6. According to Bowen's reaction series, crystal settling should result in the magma being separated in lower layers rich in the early-formed ____________________ minerals, and upper layers enriched in later-formed ____________________ minerals.

ANS: mafic, felsic PTS: 1

REF: 4.3. How Does Magma Originate and Change?

7. Rapid cooling of magma results in a(n) ____________________ grained texture called ____________________.

ANS: fine, aphanitic PTS: 1

REF: 4.4. Igneous Rocks--Their Characteristics and Classification

8. Igneous rocks having a phaneritic texture have ____________________ grains that ____________________ be seen easily by the naked eye.

ANS: coarse, can PTS: 1

REF: 4.4. Igneous Rocks--Their Characteristics and Classification

9. An igneous rock in which large mineral grains called ____________________ are suspended in a finely crystalline groundmass is called a(n) ____________________.

ANS: phenocrysts, porphyry PTS: 1

REF: 4.4. Igneous Rocks--Their Characteristics and Classification

10. An example of a glassy igneous rock is ____________________.

ANS: obsidian PTS: 1

REF: 4.4. Igneous Rocks--Their Characteristics and Classification

11. Trapped gases in cooling lava form cavities called ____________________. Cinder cones may contain large amounts of ____________________ which contains more of these cavities than it does rock.

ANS: vesicles, scoria PTS: 1

REF: 4.4. Igneous Rocks--Their Characteristics and Classification

12. Basalt and gabbro are compositional equivalents, which means that they are made up of the same ____________________ but have different ____________________.

ANS: minerals, textures PTS: 1

REF: 4.4. Igneous Rocks--Their Characteristics and Classification

13. When magma cools slowly, crystal growth proceeds at a relatively ____________________ speed, and the resultant rock is ____________________ in texture.

ANS: slow, phaneritic PTS: 1

REF: 4.4. Igneous Rocks--Their Characteristics and Classification

14. The ultramafic rock composed predominantly of ____________________ is known as peridotite and is likely the rock that makes up the part of Earth known as the ____________________.

ANS: olivine, upper mantle PTS: 1

REF: 4.4. Igneous Rocks--Their Characteristics and Classification

15. Andesite and ____________________ are respectively, ____trusive and ____trusive rocks formed in volcanic chains along ____________________ plate boundaries.

ANS: diorite, ex-, in-, convergent

PTS: 1

REF: 4.4. Igneous Rocks--Their Characteristics and Classification

16. Rhyolite and granite are extrusive and intrusive rocks formed by volcanism and ____________________, which form at or near plate boundaries as the result of ____________________ and/or ____________________ of plates.

ANS: plutonism, subduction, collision PTS: 1

REF: 4.4. Igneous Rocks--Their Characteristics and Classification

17. Concordant tabular sheetlike plutons are called ____________________, whereas discordant tabular plutons are called ____________________.

ANS: sills, dikes PTS: 1

REF: 4.5. Intrusive Igneous Bodies--Plutons

18. ____________________ are concordant, mushroom-shaped plutons.

ANS: Laccoliths PTS: 1

REF: 4.5. Intrusive Igneous Bodies--Plutons

19. The largest intrusive bodies are called ____________________ and by definition, they must have at least ______ square kilometers of surface area.

ANS: batholiths, 100 PTS: 1

REF: 4.5. Intrusive Igneous Bodies--Plutons

20. The Columbia Plateau basalts issued from fissures which are now preserved as ____________________.

ANS: dikes PTS: 1

REF: 4.5. Intrusive Igneous Bodies--Plutons

21. Batholiths and stocks can be important sources of minerals such as ____________________ and ____________________.

ANS: gold, copper copper, gold PTS: 1

REF: 4.5. Intrusive Igneous Bodies--Plutons

MULTIPLE CHOICE 1. Most plutons form ____. a. well within plates b. at plate boundaries c. without regard to plate boundaries d. above the land surface

e. all of these ANS: B

PTS: 1

REF: 4.1. Introduction

2. Intrusive igneous (plutonic) rocks ____. a. solidify below the surface of the ground b. solidify above the surface of the ground c. form by crystallization of magmas intruded into surrounding rocks d. solidify below the surface AND form by crystallization of intruded magmas e. solidify above the surface AND form by crystallization of intruded magmas ANS: D

PTS: 1

REF: 4.1. Introduction

3. A dark colored igneous rock with no visible crystals cooled ____. a. slowly in a magma chamber b. quickly in a magma chamber c. slowly on the Earth's surface d. quickly on the Earth's surface e. none of these ANS: D PTS: 1 REF: 4.2. The Properties and Behavior of Magma and Lava 4. Where are mantle plumes primarily found? a. divergent plate boundaries b. convergent plate boundaries c. transform plate boundaries d. not at plate boundaries e. none of these ANS: D

PTS: 1

REF: 4.3. How Does Magma Originate and Change?

5. The process of assimilation ____. a. includes melting and incorporation of inclusions b. includes the inclusion of country rock in an intrusive magma c. can explain some of the felsic mineral enrichment of a mafic magma d. results in the cooling of a magma body e. all of these ANS: E

PTS: 1

REF: 4.3. How Does Magma Originate and Change?

6. The most widely accepted explanation for chains of volcanoes in the oceans and lines of volcanoes on land is that they formed at ____. a. divergent plate boundaries b. normal faults c. hot spots d. convergent plate boundaries e. transform faults ANS: C

PTS: 1

7. Most igneous rocks are classified by what? a. texture b. composition c. size d. texture and composition

REF: 4.3. How Does Magma Originate and Change?

e. size and composition ANS: D PTS: 1 REF: 4.4. Igneous Rocks--Their Characteristics and Classification 8. Although all compositions are represented, most plutons are ____. a. felsic rocks b. intermediate rocks c. mafic rocks d. felsic and mafic rocks e. none of these ANS: A PTS: 1 REF: 4.4. Igneous Rocks--Their Characteristics and Classification 9. Aphanitic, phaneritic, and porphyritic are textural terms that ____. a. refer to fine-grained, course-grained, and mixed grained crystal sizes, respectively. b. refer to formation by slow cooling, fast cooling, and mixed cooling rates, respectively. c. are indicative of volcanic, plutonic, and mixed plutonic-volcanic origins, respectively. d. are fine-grained, coarse grained, and mixed-grained crystal sizes respectively and are indicative of volcanic, plutonic and mixed plutonic-volcanic origins respectively e. all of these ANS: E PTS: 1 REF: 4.4. Igneous Rocks--Their Characteristics and Classification 10. Large crystals found in a fine-grained groundmass can indicate what? a. origin from a magma with an early intrusive phase followed by an extrusive phase b. origin from a magma with an early extrusive phase followed by an intrusive phase c. a rock of mixed volcanic-plutonic origin d. intrusive slow cooling e. origin from a magma with an early intrusive phase followed by an extrusive phase; a rock of mixed volcanic-plutonic origin ANS: E PTS: 1 REF: 4.4. Igneous Rocks--Their Characteristics and Classification 11. Igneous rocks with a two-stage intrusive-extrusive origin are recognized by a texture which is ____. a. aphanitic b. porphyritic c. glassy d. phaneritic e. pyroclastic ANS: B PTS: 1 REF: 4.4. Igneous Rocks--Their Characteristics and Classification 12. Igneous rocks with a texture that is so fine-grained that the crystals are too small to see is ____. a. aphanitic b. porphyritic c. glassy d. phaneritic e. pyroclastic ANS: A PTS: 1 REF: 4.4. Igneous Rocks--Their Characteristics and Classification

13. Natural glass such as obsidian forms when magma does what? a. cools too rapidly for crystals to form b. cools rapidly and very tiny crystals form c. cools too slowly for crystals to form d. doesn't cool e. none of these ANS: A PTS: 1 REF: 4.4. Igneous Rocks--Their Characteristics and Classification 14. Igneous rocks formed by explosive volcanic activity have a texture that is termed what? a. aphanitic b. porphyritic c. glassy d. phaneritic e. pyroclastic ANS: E PTS: 1 REF: 4.4. Igneous Rocks--Their Characteristics and Classification 15. What is a vesicular felsic rock called? a. pumice b. scoria c. obsidian d. tuff e. volcanic breccia ANS: A PTS: 1 REF: 4.4. Igneous Rocks--Their Characteristics and Classification TRUE/FALSE 1. Any individual volcano always erupts magmas of the same type.

ANS: F PTS: 1 REF: 4.2. The Properties and Behavior of Magma and Lava 2. Bowen's Reaction Series explains the order of mineral formation with decreasing temperature.

ANS: T

PTS: 1

REF: 4.3. How Does Magma Originate and Change?

3. Bowen's Reaction Series explains why Si-rich minerals are the last to crystallize from a magma.

ANS: T

PTS: 1

REF: 4.3. How Does Magma Originate and Change?

4. Geologists agree that hot-spot volcanism results from a rising mantle plume.

ANS: F

PTS: 1

REF: 4.3. How Does Magma Originate and Change?

5. The process of assimilation partly explains why felsic intrusive rocks are much more common than mafic intrusive rocks.

ANS: T

PTS: 1

REF: 4.3. How Does Magma Originate and Change?

6. The process of assimilation includes the incorporation of felsic country rock.

ANS: T

PTS: 1

REF: 4.3. How Does Magma Originate and Change?

7. Granite and rhyolite are extrusive and intrusive igneous rocks of the same composition.

ANS: F PTS: 1 REF: 4.4. Igneous Rocks--Their Characteristics and Classification 8. Pegmatites are rocks of felsic composition that are similar to granite.

ANS: F PTS: 1 REF: 4.4. Igneous Rocks--Their Characteristics and Classification 9. Laccoliths are sills that inflate, causing the overlying rock to bow upward.

ANS: T

PTS: 1

REF: 4.5. Intrusive Igneous Bodies--Plutons

10. Batholiths are emplaced by forceful injection as magma moves upward through country rock.

ANS: T

PTS: 1

Chapter 5—Volcanoes and Volcanism

REF: 4.6. The Origin of Batholiths

ESSAY 1. How is volcanism destructive? What are two reasons that it is primarily a constructive process?

ANS: Some volcanic eruptions are explosive and they blow a lot of material outward so volcanism can be considered destructive. But volcanism also builds up material, including at the volcanoes themselves and at lava flows. Large islands in the ocean, such as Hawaii, are constructed entirely of material from volcanic eruptions. New seafloor is created by volcanic processes. Also, the early atmosphere and oceans were filled with gases that came from the interior of the Earth, through the mechanism of volcanism.

PTS: 1

REF: 5.1. Introduction

2. How could carbon dioxide gas cause so many deaths in Cameroon?

ANS: The gas erupted from the caldera and flowed downhill because it was dense. The gas was so fast, it flattened trees. Thousands of animals and many people were asphyxiated by the CO 2.

PTS: 1

REF: 5.2. Volcanoes and Volcanism

3. How could you distinguish a volcanic crater from a caldera?

ANS: A crater is a conical or funnel-shaped depression, usually less than 1 km in diameter at the summit of a volcano. A caldera is a larger, steep-sided depression which formed by collapse of the summit following explosive eruptions.

PTS: 1

REF: 5.3. Types of Volcanoes

4. Mauna Loa volcano in Hawaii is huge and has gentle slopes. Mt. Rainier in Washington is tall, with much steeper slopes. Paricutin in Mexico is smaller and has very steep slopes composed of loose pyroclastic material. What type of volcano does each one represent, and what kind of volcanic activity produced it?

ANS: Mauna Loa is a shield volcano composed of fluid lava flows. Mt. Rainier is a composite volcano made of a combination of lava flows and explosive (pyroclastic) eruptions. Paricutin is a cinder cone made from short-lived pyroclastic activity.

PTS: 1

REF: 5.3. Types of Volcanoes

5. What causes the configuration of the islands that make up Santorini? How has volcanism at Santorini affected the people who live there?

ANS: Santorini is a giant caldera that erupted about 3,600 years ago. The eruption is at least partially responsible for the demise of the Minoan culture on Crete. This may be responsible for Plato's story of the lost city of Atlantis.

PTS: 1

REF: 5.5. Volcano Belts

6. Briefly explain how magma can originate at spreading zones if temperatures at such shallow depths cannot produce melting alone.

ANS: The material is kept from melting because the lithostatic pressure of the overlying rock raises its melting temperature. The divergence of the plates and the fracturing that accompanies it reduces the pressure and lowers the material's melting temperature, which allows the rock to melt and become magma.

PTS: 1

REF: 5.7. Plate Tectonics, Volcanoes, and Plutons

7. Briefly explain why volcanism occurs at subduction zones.

ANS: Water in the subducting oceanic crust and sediments reduces the melting temperature of the subducting slab, and friction with the overlying slab and mantle wedge also causes heating.

PTS: 1

REF: 5.7. Plate Tectonics, Volcanoes, and Plutons

8. Discuss what volcanologists look for in trying to determine if a volcano is about to erupt.

ANS: Volcanologists monitor and measure volcanoes they think might erupt. They look for any evidence that magma is moving upward in the volcano, such as changes in the slope or horizontal distances of volcanic cones. They also look for changes in magnetic or electrical fields and for gas emissions. Most importantly, they look for harmonic tremors. These are not the sharp earthquakes that commonly occur but they can last for hours and indicate magma movement.

PTS: 1

REF: 5.8. Volcanic Hazards, Volcano Monitoring, and Forecasting Eruptions

SHORT ANSWER 1. What is the difference between an active volcano and a dormant volcano?

ANS: An active volcano has erupted during historic time; a dormant volcano has not erupted recently but may do so in the future.

PTS: 1

REF: 5.1. Introduction

2. What other bodies in the solar system are thought to possess active volcanoes?

ANS: Io, a moon of Jupiter, and perhaps Triton, a moon of Neptune PTS: 1

REF: 5.2. Volcanoes and Volcanism

3. What produces columnar jointing in lava flows?

ANS: contraction during cooling PTS: 1

REF: 5.2. Volcanoes and Volcanism

4. How do pillow lavas form?

ANS: A lava is erupted into water and rapidly chilled.

PTS: 1

REF: 5.2. Volcanoes and Volcanism

5. Distinguish aa from pahoehoe flows.

ANS: Aa has a rough, jagged, "clinkery" surface and moves slowly; pahoehoe has a smoother "ropy" surface and can move very rapidly.

PTS: 1

REF: 5.2. Volcanoes and Volcanism

6. Would you rather be chased by a pahoehoe flow or an aa flow? Explain.

ANS: Aa, because pahoehoe can move rapidly; aa moves slowly.

PTS: 1

REF: 5.2. Volcanoes and Volcanism

7. How did the recent eruptions of Mt. Pinatubo, in the Philippines, and Kilauea, in Hawaii, differ?

ANS: Mt. Pinatubo's eruption was explosive, while Kilauea had quiet lava flows.

PTS: 1

REF: 5.3. Types of Volcanoes

8. Why is Crater Lake in Oregon considered to be misnamed?

ANS: It is actually a caldera not a crater.

PTS: 1

REF: 5.3. Types of Volcanoes

9. Which type of volcano is Mt. St. Helens?

ANS: composite volcano PTS: 1

REF: 5.3. Types of Volcanoes

10. What type of eruption is mainly responsible for producing plateau basalts?

ANS: fissure eruptions PTS: 1

REF: 5.3. Types of Volcanoes

11. Why are some places (e.g., northern California) more likely to experience volcanic eruptions than others (e.g., New York)?

ANS: Volcanoes are located on convergent or divergent plate boundaries. Places within plates may experience volcanism if they are over a hotspot.

PTS: 1

REF: 5.7. Plate Tectonics, Volcanoes, and Plutons

12. Why are there volcanoes on the west coast of North America but not on the east coast?

ANS: The west coast is an active margin of the North American plate; from Northern California northward it a convergent margin. The east coast is a passive margin.

PTS: 1

REF: 5.7. Plate Tectonics, Volcanoes, and Plutons

13. Why does most volcanism at spreading ridges go undetected?

ANS: because almost all of it occurs below sea level PTS: 1

REF: 5.7. Plate Tectonics, Volcanoes, and Plutons

14. What does harmonic tremor indicate is happening beneath the surface of a volcano?

ANS: Magma is moving.

PTS: 1

REF: 5.8. Volcanic Hazards, Volcano Monitoring, and Forecasting Eruptions

15. Besides monitoring, what other knowledge helps geologists determine what to expect for eruptions from a given volcano?

ANS: knowledge about the past history of the volcano PTS: 1

REF: 5.8. Volcanic Hazards, Volcano Monitoring, and Forecasting Eruptions

COMPLETION 1. The eruption that buried the city of Pompeii, Italy in 79 A.D. was that of Mount ____________________, which prior to the eruption had been quiet for at least ______ years.

ANS: Vesuvius, 300 PTS: 1

REF: 5.1. Introduction

2. The dominant gas emitted from volcanoes is ____________________.

ANS: water vapor PTS: 1

REF: 5.2. Volcanoes and Volcanism

3. One common but dangerous gas emitted from volcanoes, which is responsible for many deaths in Cameroon, is ____________________.

ANS: carbon dioxide PTS: 1

REF: 5.2. Volcanoes and Volcanism

4. At Laki fissure in Iceland, the eruption of the gas ____________________ caused about 75 percent of the nation's livestock to die, 25 percent of the population to die, and crops to fail.

ANS: sulfur dioxide PTS: 1

REF: 5.2. Volcanoes and Volcanism

5. Columnar joints caused by the contraction of lava as it cools form typically in a(n) ____________________ shape.

ANS: hexagonal six-sided PTS: 1

REF: 5.2. Volcanoes and Volcanism

6. Pahoehoe is lava erupted by Hawaiian volcanoes that has a(n) ____________________ viscosity and a(n) ____________________ appearance.

ANS: low, ropy PTS: 1

REF: 5.2. Volcanoes and Volcanism

7. Pyroclastic material that is less than 2 mm in diameter is called ____________________. Particles ranging from 2 to 64 mm in diameter are known as ____________________, while ____________________ are pieces larger than 64 mm in diameter.

ANS: ash, lapilli, bombs or blocks PTS: 1

REF: 5.2. Volcanoes and Volcanism

8. Lavas of ____________________ composition are more likely to produce lava domes.

ANS: felsic PTS: 1

REF: 5.3. Types of Volcanoes

9. Shield volcanoes are composed largely of lavas of ____________________ composition; they commonly have slopes that are ____________________, and their eruptions tend to be ____________________ in explosivity.

ANS: basaltic, gentle, quiet PTS: 1

REF: 5.3. Types of Volcanoes

10. Cinder cones rarely reach heights greater than ____________________; they are composed of ____________________ material of ____________________ composition.

ANS: 400 m, pyroclastic, basaltic (mafic) PTS: 1

REF: 5.3. Types of Volcanoes

11. Composite volcanoes are also known as ____________________ and are composed of both ____________________ flows and ____________________ material.

ANS: stratovolcanoes, lava, pyroclastic PTS: 1

REF: 5.3. Types of Volcanoes

12. Sometimes the pyroclastic material that flows from a volcano is so hot that it fuses together to form a deposit known as ____________________.

ANS: welded tuff PTS: 1

REF: 5.4. Other Volcanic Landforms

13. The type of volcano that is the most common in the two major volcanic belts on Earth is ____________________.

ANS: composite PTS: 1

REF: 5.5. Volcano Belts

14. Mount Vesuvius is part of a chain of volcanoes along Italy's south coast where the ____________________ plate is being subducted beneath the ____________________ plate.

ANS: African, Eurasian

PTS: 1

REF: 5.5. Volcano Belts

15. The one place on earth where mid-ocean ridge volcanism occurs above sea level is ____________________.

ANS: Iceland PTS: 1

REF: 5.7. Plate Tectonics, Volcanoes, and Plutons

16. Volcanic activity that takes place away from plate boundaries is the result of volcanism at a(n) ____________________. In the U.S., an example of this type of volcanism in the ocean is ____________________; an example on land is ____________________.

ANS: hot spot, Hawaii, Yellowstone PTS: 1

REF: 5.7. Plate Tectonics, Volcanoes, and Plutons

MULTIPLE CHOICE 1. An extinct volcano is one that ____. a. existed during a past geological period or epoch b. has not erupted during recorded history c. has shown no evidence of activity over recorded history d. has not erupted during recorded history and has shown no evidence of activity over recorded history e. all of these ANS: D

PTS: 1

REF: 5.1. Introduction

2. What are the three main types of volcanoes? a. cinder cones, clastic cones, and stratocones b. cinder cones, composite cones, and shield volcanoes c. shield volcanoes, composite volcanoes, and Hawaiian-style volcanoes d. clastic cones, stratocones, and Hawaiian-style volcanoes e. none of these ANS: B

PTS: 1

REF: 5.3. Types of Volcanoes

3. Give an example of a caldera. a. Mount St. Helens, Washington b. Paricutin, Mexico c. El Chichon, Mexico d. Krakatau, Java e. Crater Lake, Oregon ANS: E

PTS: 1

REF: 5.3. Types of Volcanoes

4. What is an example of a composite volcano? a. Fujiyama, Japan b. Nevado del Ruiz, Columbia c. Mount Vesuvius, Italy d. Mount St. Helens, Washington e. All of these

ANS: E

PTS: 1

REF: 5.3. Types of Volcanoes

5. Name an example of a cinder cone volcano. a. Mount St. Helens, Washington b. Mayon, Philippines c. Eldfell, Iceland d. Vesuvius, Italy e. Mazama, Oregon ANS: C

PTS: 1

REF: 5.3. Types of Volcanoes

6. Supervolcanoes ____. a. are enormous peaky volcanic cones b. produce enormous volcanic eruptions c. erupt about once a century d. are enormous peaky volcanic cones that produce enormous volcanic eruptions e. all of these ANS: B

PTS: 1

REF: 5.3. Types of Volcanoes

7. What do lava domes form from? a. mafic magma b. intermediate magma c. viscous magma d. pyroclastic materials e. basalt ANS: C

PTS: 1

REF: 5.3. Types of Volcanoes

8. Nuee ardentes erupt from ____. a. supervolcanoes b. shield volcanoes c. fissures d. lava domes e. cinder cones ANS: D

PTS: 1

REF: 5.3. Types of Volcanoes

9. Basalt plateaus erupt from ____. a. supervolcanoes b. shield volcanoes c. fissures d. lava domes e. cinder cones ANS: C

PTS: 1

REF: 5.3. Types of Volcanoes

10. Where are most volcanoes located? a. the Mediterranean belt b. the mid-oceanic ridges c. the circum-Pacific belt d. the East African Rift Zone e. Indonesia ANS: C

PTS: 1

REF: 5.5. Volcano Belts

11. Which is the correct ranking of regions with the most active volcanoes and volcanic activity?

1.

2.

3.

4.

Circum-Pacific belt Mid-oceanic ridges Mediterranean Belt isolated sites like the Hawaiian Islands

a. b. c. d. e.

2, 1, 3, 4 1, 3, 2, 4 2, 3, 4, 1 1, 2, 3, 4 3, 2, 1, 4

ANS: B

PTS: 1

REF: 5.5. Volcano Belts

12. The volcanic explosivity index (VEI) is intended to do what? a. describe the frequency of volcanoes b. be used to forecast eruptions c. prevent fatalities and property damage d. document the size of eruptions e. encourage people not to live near active volcanoes ANS: D PTS: 1 REF: 5.8. Volcanic Hazards, Volcano Monitoring, and Forecasting Eruptions 13. Most of the approximately 3,300 historic eruptions lasted how long? a. less than one month b. one to six months c. one to two years d. more than two years e. none of these ANS: B PTS: 1 REF: 5.8. Volcanic Hazards, Volcano Monitoring, and Forecasting Eruptions 14. Ozone depletion in the stratosphere is caused by a. CFCs and other manmade compounds. b. carbon dioxide from fossil fuel burning. c. volcanic gases like HCl. d. all of these.

ANS: A PTS: 1 REF: Geo-Focus. Do Volcanic Gases Cause Ozone Depletion?

15. Alaska’s volcanoes are a. composite with huge calderas. b. fissure with large lava flows. c. the result of seafloor spreading. d. all dormant or extinct.

ANS: B TRUE/FALSE

PTS: 1

REF: 5.6. North America's Active Volcanoes

1. The chemical composition of all lavas is the same.

ANS: F

PTS: 1

REF: various

2. Earth is the only body in our solar system that is volcanically active.

ANS: F

PTS: 1

REF: 5.2. Volcanoes and Volcanism

3. Crater Lake in Oregon is an example of a caldera.

ANS: T

PTS: 1

REF: 5.3. Types of Volcanoes

4. A nuée ardente is composed of fiery hot gases and dust.

ANS: T

PTS: 1

REF: 5.3. Types of Volcanoes

5. The volcanic explosivity index (VEI) can be correlated with the number of deaths caused by an eruption.

ANS: F PTS: 1 REF: 5.8. Volcanic Hazards, Volcano Monitoring, and Forecasting Eruptions 6. Andesite is the type of lava most likely to erupt in a fissure eruption.

ANS: F

PTS: 1

REF: 5.3. Types of Volcanoes

7. A lahar is a volcanic mud flow.

ANS: T

PTS: 1

REF: 5.3. Types of Volcanoes

8. The ozone hole is the region of depleted stratospheric ozone that is found over the equatorial region.

ANS: F PTS: 1 REF: Geo-Focus. Do Volcanic Gases Cause Ozone Depletion?

9. Pyroclastic sheet deposits were formed by enormous ash falls.

ANS: F

PTS: 1

REF: 5.4. Other Volcanic Landforms

10. The eruption of Mount St. Helens was one of the largest and deadliest in the world in historic times.

ANS: F

PTS: 1

REF: 5.6. North America's Active Volcanoes

11. The lateral blast associated with the 1980 Mount St. Helens eruption traveled at speeds possibly greater than 1000 km/hr.

ANS: T

PTS: 1

REF: 5.6. North America's Active Volcanoes

12. Lava flows are the greatest hazard of volcanoes.

ANS: F PTS: 1 REF: 5.8. Volcanic Hazards, Volcano Monitoring, and Forecasting Eruptions

Chapter 6—Weathering, Erosion, and Soil

ESSAY 1. Briefly explain how exfoliation domes form.

ANS: Exfoliation domes form from pressure release and are typically found in granite. Igneous intrusive rocks form at tremendous depth and pressure. When they are uplifted, the pressure is released and the rock can expand. It does so along fractures called sheet joints that more or less parallel the existing rock surface. Slabs of rock, bounded by sheet joints, slide off the parent rock, leaving behind a dome.

PTS: 1

REF: 6.3. Mechanical Weathering--Disaggregation of Earth Materials

2. Briefly explain why water is such an important agent in chemical weathering.

ANS: Water is a remarkable solvent because of the asymmetrical shape of the molecule and the difference in charge between the two sides of the molecule. The negative side of the water molecule attracts positive ions from a mineral, and the positive side attracts negative ions, which results in the eventual dissolution of the mineral.

PTS: 1

REF: 6.4. Chemical Weathering--Decomposition of Earth Materials

3. Explain why the ferromagnesian minerals most susceptible to chemical weathering are those formed early in the continuous branch of Bowen's reaction series.

ANS: The minerals that form first in Bowen's reaction series form under the highest temperatures and pressures, which are least like equilibrium conditions at the surface of Earth. These minerals are most susceptible to weathering because they are stable at conditions that are the furthest from those found at the surface.

PTS: 1

REF: 6.4. Chemical Weathering--Decomposition of Earth Materials

4. Briefly explain the sequence in which a soil develops.

ANS: Soil formation begins at the surface and proceeds downward. The process begins with the weathering of bedrock, a stage which resembles soil horizon "C" and proceeds from increased leaching, organic activity, and organic material content to the formation of humus, or soil horizon "O".

PTS: 1

REF: 6.5. Soil and Its Origin

5. How do soils that form in semi-arid to arid regions differ in their basic characteristics from soils that form in humid regions?

ANS: Soils that form in semi-arid to arid region contain less organic matter and more unstable minerals in horizon A than the soils of more humid areas, so horizon A is lighter colored and contains more unstable minerals because of less intense chemical weathering. Calcium carbonate precipitates in horizon B, forming caliche, as soil water evaporates. Soils that form in humid regions have most of their soluble minerals leached from horizon A, but that horizon contains abundant organic matter.

Aluminum-rich clays and iron oxides tend to accumulate in horizon B.

PTS: 1

REF: 6.5. Soil and Its Origin

6. Explain why, and give two examples of how, climate is more effective in determining soil type than parent rock type.

ANS: Laterites are the product of intense and continual leaching of organic material and all but the most stable elements from soils. This can occur only in warm and humid climates. Soils with an accumulation of Ca and Na-rich material can occur only in the absence of abundant water and the presence of intense evaporation.

PTS: 1

REF: 6.5. Soil and Its Origin

7. How does loss of soil fertility exacerbate soil erosion?

ANS: Loss of fertility reduces the amount of plant cover, and thus increases temperature due to loss of the cooling effects of plants and excess water. Without binding, irrigation, and aeration of soil by plants, soil becomes exposed and hardened, thus more susceptible to large losses from sheet runoff.

PTS: 1

REF: 6.6. Expansive Soils and Soil Degradation

8. What factors and sequence of events commonly lead to soil erosion in rainforests?

ANS: Land is deforested for use in farming by a process known as slash-and-burn agriculture. Farming decreases fertility, water content, and plant cover. Farming is abandoned for ranching. Livestock tramples and hardens soil and remaining plants. Both reduce the soil's ability to retain moisture and gases, and further reduce plant cover and fertility. These factors increase regional temperature and rates of soil erosion, which in turn, prevent re-establishment of forests and renewal of soil.

PTS: 1

REF: 6.6. Expansive Soils and Soil Degradation

9. List the agricultural practices which reduce the rate of soil erosion and explain why each does so.

ANS: Crop rotation prevents loss of soil fertility; contour plowing and terracing prevent massive down slope erosion of soil; windbreaks prevent wind erosion of soil; and no-till planting prevents soils from lying exposed to wind and water erosion when crops are not effectively binding the soil.

PTS: 1

REF: 6.6. Expansive Soils and Soil Degradation

10. What processes lead to soil degradation?

ANS: Soil is lost by erosion, a process that is usually balanced by soil formation. However, removing natural vegetation by plowing, overgrazing, and excess deforestation have increased the soil erosion rate substantially. Soil undergoes chemical deterioration when its nutrients are depleted and its productivity decreases. Pollutants can also bring about the chemical deterioration of soil. Soil deteriorates physically when it is compacted by heavy machinery and livestock, especially cattle. Soil must be taken care of by avoiding the practices mentioned above.

PTS: 1

REF: 6.6. Expansive Soils and Soil Degradation

11. Describe the human activities that produce acid rain.

ANS: Burning fossil fuels releases carbon dioxide and nitrogen oxide that create acids in the atmosphere.

Burning coal releases sulfur dioxide that reacts with oxygen and water droplets in the atmosphere to form sulfuric acid, the main component of acid rain.

PTS: 1

REF: Geo-Focus: Industrialization and Acid Rain

12. What environmental effects are being seen that result from acid rain? In which environments are these effects lessened? Where are they most seen?

ANS: Acid rain water is neutralized in areas where carbonates or alkaline rocks and soils are found. Rock types that do not neutralize acids, like granite, show a greater effect. Acid rain damage is seen on buildings, monuments and tombstones made of carbonates and to a lesser degree, sandstone. Forests downwind of coal plants are damaging forests.

PTS: 1

REF: Geo-Focus. Industrialization and Acid Rain

SHORT ANSWER 1. Define weathering.

ANS: Weathering is the physical disintegration and/or chemical decomposition of rocks at or near Earth's surface as they are exposed to the atmosphere, hydrosphere, and/or biosphere.

PTS: 1

REF: 6.1. Introduction

2. How does weathering differ from erosion?

ANS: Weathering is the breakdown of material in place; erosion is the removal of the weathered materials.

PTS: 1

REF: 6.1. Introduction

3. List some ways in which organisms contribute to mechanical weathering.

ANS: burrowing/particle mixing/root wedging/reduction of particle size PTS: 1

REF: 6.3. Mechanical Weathering--Disaggregation of Earth Materials

4. How does mechanical weathering differ from chemical weathering?

ANS: In mechanical weathering, physical forces break the rock materials into smaller pieces that retain their chemical composition; in chemical weathering the composition is altered.

PTS: 1 REF: 6.3. Mechanical Weathering--Disaggregation of Earth Materials | 6.4. Chemical Weathering--

Decomposition of Earth Materials 5. Name an important physical property about water that makes it unique among liquids, and why is this property important in the weathering of rocks?

ANS: It increases in volume when it freezes (changes from a liquid to a solid state). The expanding volume creates pressures which may break rocks and minerals into smaller pieces.

PTS: 1

REF: 6.3. Mechanical Weathering--Disaggregation of Earth Materials

6. List some examples of mechanical weathering processes.

ANS: frost action/pressure release/thermal expansion and contraction/salt crystal growth/activities of organisms PTS: 1

REF: 6.3. Mechanical Weathering--Disaggregation of Earth Materials

7. In what climatic conditions is frost action most effective?

ANS: Frost action is most effective in areas where temperatures fluctuate commonly above and below freezing.

PTS: 1

REF: 6.3. Mechanical Weathering--Disaggregation of Earth Materials

8. How can organisms contribute to chemical weathering?

ANS: by the removal of ions from soil water; release of organic acids PTS: 1

REF: 6.4. Chemical Weathering--Decomposition of Earth Materials

9. What are the major factors that control the rate of chemical weathering?

ANS: presence of fractures, particle size, climate, parent material PTS: 1

REF: 6.4. Chemical Weathering--Decomposition of Earth Materials

10. Why do small particles weather more rapidly than large particles?

ANS: Chemical weathering occurs on the surface of a rock or mineral, and small particles have larger surface areas per given volume.

PTS: 1

REF: 6.4. Chemical Weathering--Decomposition of Earth Materials

11. How does mechanical weathering aid chemical weathering?

ANS: Mechanical weathering produces smaller particles, with more surface area for the given volume, and chemical weathering operates on the surface of the material.

PTS: 1

REF: 6.4. Chemical Weathering--Decomposition of Earth Materials

12. Carbon dioxide levels in the atmosphere are rising due to the burning of fossil fuels. How might this increased level of carbon dioxide affect rates of weathering?

ANS: Increased amounts of atmospheric carbon dioxide will increase the amount of carbonic acid that forms in the atmosphere and result in an increase of chemical weathering.

PTS: 1

REF: 6.4. Chemical Weathering--Decomposition of Earth Materials

13. Briefly explain how hydrolysis results in the weathering of some minerals.

ANS: In hydrolysis, hydrogen ions replace positive ions in minerals and the released mineral ions go into solution, changing the mineral's composition.

PTS: 1

REF: 6.4. Chemical Weathering--Decomposition of Earth Materials

14. How does regolith differ from soil?

ANS: Regolith is unconsolidated rock material that covers the land surface. Soil is regolith that includes weathered material, water, air, organic matter, (and can support plant growth).

PTS: 1

REF: 6.5. Soil and Its Origin

15. What are the principle controls on soil formation?

ANS: climate, parent material, organic activity, relief (and slope), time PTS: 1

REF: 6.5. Soil and Its Origin

16. What is soil degradation?

ANS: Soil degradation includes any soil losses that exceed the rate of soil formation, any decrease in soil fertility, or loss of soil by erosion.

PTS: 1

REF: 6.6. Expansive Soils and Soil Degradation

17. What three types of soil degradation are recognized?

ANS: erosion, chemical deterioration, and physical deterioration PTS: 1

REF: 6.6. Expansive Soils and Soil Degradation

18. What factors lead to the development of the "Dust Bowl" during the 1930s in the United States?

ANS:

Farming resulted in the loss of natural soil cover; improper farming practices resulted in increased soil erosion; and drought exacerbated the soil erosion.

PTS: 1

REF: 6.6. Expansive Soils and Soil Degradation

19. Any process that removes soil or makes it less productive is called _______ _______.

ANS: soil degradation PTS: 1

REF: 6.6. Expansive Soils and Soil Degradation

COMPLETION 1. Weathering is an essential part of the _______ _______ because parent material must break down into smaller pieces or perhaps dissolve to become sediment.

ANS: rock cycle PTS: 1

REF: 6.1. Introduction

2. Large, rounded masses of rock from which joint-bounded slabs of rock have slipped off are _______ _______.

ANS: exfoliation domes PTS: 1

REF: 6.3. Mechanical Weathering--Disaggregation of Earth Materials

3. The chemical weathering process that produces most of the red, yellow, and brown colors seen in soils and many sedimentary rocks is called ____________________.

ANS: oxidation PTS: 1

REF: 6.4. Chemical Weathering--Decomposition of Earth Materials

4. Three important chemical processes involved in chemical weathering are ____________________, ____________________, and ____________________.

ANS: solution, oxidation, hydrolysis PTS: 1

REF: 6.4. Chemical Weathering--Decomposition of Earth Materials

5. Carbonate minerals, like calcite, dissolve readily in a solution that is _______.

ANS: acidic PTS: 1

REF: 6.4. Chemical Weathering--Decomposition of Earth Materials

6. The process that decomposes rocks and minerals by altering the makeup of the parent material is called _______ _______.

ANS: chemical weathering

PTS: 1

REF: 6.4. Chemical Weathering--Decomposition of Earth Materials

7. ____________________ is an essential component of soil as it provides nutrients to plants and increases the ability of the soil to retain ____________________.

ANS: Humus, moisture PTS: 1

REF: 6.5. Soil and Its Origin

8. A(n) ____________________ soil forms where the parent material has weathered, whereas ____________________ soil develops from eroded material that was weathered at another location.

ANS: residual, transported PTS: 1

REF: 6.5. Soil and Its Origin

9. Soils that are a result of intense weathering and are typically found in the tropics are ____________________.

ANS: laterite PTS: 1

REF: 6.5. Soil and Its Origin

10. Because quartzite is (more/less) ____________________ chemically stable than granite, it will be covered by a (thicker/thinner) ____________________ layer of soil than will an adjacent body of granite.

ANS: more, thinner PTS: 1

REF: 6.5. Soil and Its Origin

11. Under similar climatic conditions, soil will develop (faster/slower) ____________________ on solid bedrock than it will on unconsolidated sediment.

ANS: slower PTS: 1

REF: 6.5. Soil and Its Origin

12. The most important factor controlling soil formation is ____________________.

ANS: climate PTS: 1

REF: 6.5. Soil and Its Origin

13. ____________________ erosion occurs when water carves small channels into a soil bed.

ANS: Rill PTS: 1

REF: 6.6. Expansive Soils and Soil Degradation

14. The actions of ____________________ and ____________________ are responsible for most soil erosion.

ANS:

wind, water water, wind PTS: 1

REF: 6.6. Expansive Soils and Soil Degradation

15. The economically valuable mineral resource produced by intense chemical weathering that is found only in laterite soils is called ____________________.

ANS: bauxite aluminum ore PTS: 1

REF: 6.7. Weathering and Resources

16. On a pH scale, the pH value of something neutral is _______; the pH of normal rain is _____ and acid rain is less than _____.

ANS: 7; 5.6; 5.0 PTS: 1

REF: Geo-Focus. Industrialization and Acid Rain

MULTIPLE CHOICE 1. What is erosion? a. movement of weathered material from its source site b. decomposition of rock c. disintegration of rock d. weathering of rock and transportation of sediment e. disintegration of soil ANS: A

PTS: 1

REF: 6.1. Introduction

2. Weathering that takes place at different rates even in the same area is called a. mechanical weathering. b. differential weathering. c. chemical weathering. d. original weathering.

ANS: B

PTS: 1

REF: 6.2. Alteration of Minerals and Rocks

3. Weathering is classified into which of the following categories? a. mechanistic and compositional b. mechanical and physical c. chemical and physical d. physical and chemical e. organic and inorganic ANS: C

PTS: 1

REF: 6.2. Alteration of Minerals and Rocks

4. Which of the following contribute to weathering? a. organisms such as worms, bacteria, and trees b. oxygen and carbon dioxide in the air c. rain water d. organic acids

e. all of these ANS: E PTS: 1 REF: 6.3. Mechanical Weathering--Disaggregation of Earth Materials | 6.4. Chemical Weathering-Decomposition of Earth Materials 5. Which of the following is a means of mechanical weathering? a. frost wedging b. pressure release c. thermal expansion and contraction d. burrowing and root wedging e. all of these ANS: E PTS: 1 REF: 6.3. Mechanical Weathering--Disaggregation of Earth Materials 6. Frost wedging in the mountains produces which type of material? a. tailings b. talus c. conglomerate d. exfoliation e. regolith ANS: B PTS: 1 REF: 6.3. Mechanical Weathering--Disaggregation of Earth Materials 7. Under which conditions does pressure release occur? a. humid and seasonal b. hot and arid c. cold and humid d. where there is uplift and erosion e. where there is faulting and seismic activity ANS: D PTS: 1 REF: 6.3. Mechanical Weathering--Disaggregation of Earth Materials 8. What does pressure release weathering result in? a. sheet jointing b. rock bursts c. exfoliation d. exfoliation domes e. all of these ANS: D PTS: 1 REF: 6.3. Mechanical Weathering--Disaggregation of Earth Materials 9. Thermal expansion and contraction occur most commonly in which of the following conditions? a. cold and hot b. arid and cold c. humid and hot d. arid and hot e. humid and cold ANS: A PTS: 1 REF: 6.3. Mechanical Weathering--Disaggregation of Earth Materials

10. What is a source of carbon dioxide for carbonic acid? a. the atmosphere b. soil c. groundwater d. surface water e. all of these ANS: E PTS: 1 REF: 6.4. Chemical Weathering--Decomposition of Earth Materials 11. Hydrolysis is particularly effective in weathering ____. a. limestone b. sandstone c. quartz d. calcite e. feldspar ANS: E PTS: 1 REF: 6.4. Chemical Weathering--Decomposition of Earth Materials 12. The important weathering product(s) of hydrolysis of feldspar is (are) ____. a. ferromagnesian minerals b. sand minerals c. dissolved calcium d. clay minerals e. accessory minerals ANS: D PTS: 1 REF: 6.4. Chemical Weathering--Decomposition of Earth Materials 13. Which of the following is not a factor influencing the rate of chemical weathering? a. climate b. particle size c. parent material d. humidity e. gravity ANS: E PTS: 1 REF: 6.4. Chemical Weathering--Decomposition of Earth Materials 14. Carbonic acid forms from the combination of a. water and bicarbonate ion. b. water and carbon dioxide. c. carbon dioxide and hydrogen ion. d. calcium ion and bicarbonate ion.

ANS: B PTS: 1 REF: 6.4. Chemical Weathering--Decomposition of Earth Materials 15. Hydrolysis is the chemical reaction between a mineral’s ions and a. water molecules. b. hydrogen and oxygen ions. c. hydrogen and hydroxyl ions. d. hydroxide ions.

ANS: C

PTS: 1

REF: 6.4. Chemical Weathering--Decomposition of Earth Materials 16. Clay particles in soil are important to soil development because ____. a. They hold soil particles apart. b. They allow water and gases to enter soil. c. They retain water and supply nutrients. d. They allow the flow of groundwater. e. They drain poorly.

ANS: C

PTS: 1

REF: 6.5. Soil and Its Origin

17. Humus ____. a. is the material always comprising the topmost soil horizon b. is dark, organic-rich material formed by bacterial decay c. is leaf-litter d. must include sediments e. none of these ANS: B

PTS: 1

REF: 6.5. Soil and Its Origin

18. What is caliche? a. a layer of silica cement within a pedalfer b. a layer of precipitated calcium carbonate in horizon B c. a layer of rock between soil layers C and D d. a deposit formed in alkali soils e. a light colored layer of unstable minerals ANS: B

PTS: 1

REF: 6.5. Soil and Its Origin

19. In soil, the A horizon is a. low in organic matter. b. the site of little biological activity. c. full of sand and gravel. d. composed mostly of clays and stable minerals.

ANS: D

PTS: 1

REF: 6.5. Soil and Its Origin

20. The biggest problem areas for acid rain include a. the eastern United States and much of Europe. b. China and Australia. c. western Europe and the western United States. d. the Amazon, Congo and Pacific rainforests.

ANS: A

PTS: 1

REF: Geo-Focus. Industrialization and Acid Rain

TRUE/FALSE 1. Mechanical weathering produces no change in the chemical composition of the parent rock.

ANS: T PTS: 1 REF: 6.3. Mechanical Weathering--Disaggregation of Earth Materials 2. Pressure release is a mechanical weathering process that occurs often in intrusive rocks such as those formed in batholiths.

ANS: T PTS: 1 REF: 6.3. Mechanical Weathering--Disaggregation of Earth Materials 3. Thermal expansion and contraction occur because rock is an excellent conductor of heat.

ANS: F PTS: 1 REF: 6.3. Mechanical Weathering--Disaggregation of Earth Materials 4. Salt crystals can exert enough force to widen cracks and dislodge particles in some rocks.

ANS: T PTS: 1 REF: 6.3. Mechanical Weathering--Disaggregation of Earth Materials 5. Sheet joints, created by pressure release, form roughly parallel to the rock surface.

ANS: T PTS: 1 REF: 6.3. Mechanical Weathering--Disaggregation of Earth Materials 6. A rock may be subjected to either mechanical or chemical weathering but never both at the same time.

ANS: F PTS: 1 REF: 6.4. Chemical Weathering--Decomposition of Earth Materials 7. Laterite soils are rich in organic matter.

ANS: F

PTS: 1

REF: 6.5. Soil and Its Origin

8. Laterite soils are not very fertile.

ANS: T

PTS: 1

REF: 6.5. Soil and Its Origin

9. Laterite soils can support extended periods of farming.

ANS: F

PTS: 1

REF: 6.5. Soil and Its Origin

10. Laterite soils are typical of rainforests.

ANS: T

PTS: 1

REF: 6.5. Soil and Its Origin

11. Laterite soils are the product of intense leaching.

ANS: T

PTS: 1

REF: 6.5. Soil and Its Origin

12. The most stable shape a stone can form is a rectangle.

ANS: F PTS: 1 REF: 6.4. Chemical Weathering--Decomposition of Earth Materials 13. Acid rain is a problem in regions near the source of the emissions but, unlike global warming, it is not a worldwide problem.

ANS: F

PTS: 1

REF: Geo-Focus. Industrialization and Acid Rain

14. A soil that is rich in clay and expands by more than 6% is an expansive soil.

ANS: T

PTS: 1

REF: 6.6. Expansive Soils and Soil Degradation

Chapter 7—Sediment and Sedimentary Rocks ESSAY

1. How do detrital sedimentary rocks differ from chemical sedimentary rocks?

ANS: Detrital sedimentary rocks are made from the fragments of preexisting rocks. The cement may be new material but otherwise the material forming them predates the formation of the rock. Chemical sedimentary rocks precipitate from a solution; they are made of new material that forms for that rock.

PTS: 1

REF: 7.1. Introduction

2. Briefly explain how coal forms.

ANS: Coal forms from the accumulation of generations of dead plants in a swamp. The plants never decay fully because there is no oxygen for the decomposers to use. As the plants are buried by sediments and other plants, they are lithified and become coal.

PTS: 1

REF: 7.4. Types of Sedimentary Rocks

3. What are the four major types of coal, and which is the most valuable?

ANS: The types of coal include bituminous, lignite, subbituminous, and anthracite. Anthracite is the best because it burns more cleanly and efficiently than the other types.

PTS: 1

REF: 7.4. Types of Sedimentary Rocks

4. Briefly explain why the study of sedimentary environments is important in the study of historical geology.

ANS: Historical geology is concerned with understanding what events have taken place in the history of the Earth and in what order. By using sedimentary rocks and the study of their depositional environments, geologists can determine what processes have occurred on the surface of the Earth and when they occurred.

PTS: 1

REF: 7.6. Reading the Story in Sedimentary Rocks

5. Explain how fossils, and especially microfossils, can be used to help determine ancient depositional environments.

ANS: Marine versus terrestrial organisms are relatively easy to distinguish, based on a comparison with their living counterparts. Strong invertebrate shells usually indicate a high energy environment, such as the intertidal zone; deep sea fossils are microscopic and fragile. Marine microfossils are particularly important because so many can be retrieved in a single core sample. Coral reef deposits are bounded in depth, as well as latitude, and are always marine.

PTS: 1

REF: 7.6. Reading the Story in Sedimentary Rocks

6. What are some ways in which fossils are useful?

ANS: Fossils are useful in correlating and determining the age of strata, in determining types of depositional environments, and in telling us about extinct forms of life.

PTS: 1

REF: 7.6. Reading the Story in Sedimentary Rocks

7. How are oil and gas trapped in rock strata? What are these traps called?

ANS: Rock strata that can trap oil and gas are known as stratigraphic traps. A reservoir rock has an overlying cap rock, and it is the difference between the rock types that traps the hydrocarbons. Structural traps result when rocks are deformed by folding, fracturing, or both. The hydrocarbons migrate to the tops of these structures. These require only a good reservoir rock to hold the oil and gas.

PTS: 1

REF: 7.7. Important Resources in Sedimentary Rocks

8. Explain why understanding the depositional environments of sedimentary rocks are sometimes economically important.

ANS: Important economic resources, such as mineral deposits, oil, and gas, are found in sedimentary rocks.

By understanding how these resources are related to sedimentary processes, geologists can more effectively predict where these deposits will occur.

PTS: 1

REF: 7.7. Important Resources in Sedimentary Rocks

SHORT ANSWER 1. What makes up a chemical sediment?

ANS: Chemical sediment is material precipitated from solution by inorganic or organic processes.

PTS: 1

REF: 7.1. Introduction

2. What are the two most common cements in sedimentary rocks?

ANS: calcium carbonate and silicon dioxide PTS: 1

REF: 7.3. How Does Sediment Become Sedimentary Rock?

3. Briefly explain how dolostone is formed.

ANS: Dolostone is formed by the replacement by magnesium of some of the calcium in calcite of limestones.

PTS: 1

REF: 7.4. Types of Sedimentary Rocks

4. What is an example of an evaporite sedimentary rock?

ANS: rock salt/rock gypsum PTS: 1

REF: 7.4. Types of Sedimentary Rocks

5. Under what conditions does coal form?

ANS: Coal forms when plant material accumulates faster than it decays, or when levels of dissolved oxygen in the water are low and aerobic bacterial decay is inhibited.

PTS: 1

REF: 7.4. Types of Sedimentary Rocks

6. Under what conditions do carbonates form?

ANS: Carbonates form at warm temperatures in the absence of detrital sediments and usually in shallow water.

PTS: 1

REF: 7.4. Types of Sedimentary Rocks

7. What are sedimentary facies?

ANS: Sedimentary facies are bodies of sediment or sedimentary rock with a distinctive set of physical, chemical, and biological attributes.

PTS: 1

REF: 7.5. Sedimentary Facies

8. What are some of the characteristics of sedimentary rocks that are used in determining the depositional environment represented by a facies?

ANS: fossils/sedimentary textures/geometry of the facies/sedimentary structures PTS: 1

REF: 7.5. Sedimentary Facies

9. What are some examples of sedimentary structures?

ANS: bedding/ripple marks/mud cracks PTS: 1

REF: 7.6. Reading the Story in Sedimentary Rocks

10. How does graded bedding form?

ANS: A fast-moving current first deposits only coarser sediments, but as it slows it deposits continually finer sediments.

PTS: 1

REF: 7.6. Reading the Story in Sedimentary Rocks

11. What two sedimentary structures can be useful in determining paleocurrent directions?

ANS: current ripple marks and cross-bedding PTS: 1

REF: 7.6. Reading the Story in Sedimentary Rocks

12. What can mud cracks tell us if we find them preserved in ancient rocks?

ANS: The area was wet then the area dried, so the surface must have been exposed to air.

PTS: 1

REF: 7.6. Reading the Story in Sedimentary Rocks

13. What is a fossil?

ANS: the remains or traces of ancient organisms PTS: 1

REF: 7.6. Reading the Story in Sedimentary Rocks

14. What are the requirements for a rock body to serve as a reservoir rock for hydrocarbons?

ANS: The rock must be capable of transmitting fluids through pore spaces (i.e., permeable), and it must contain a large amount of pore space.

PTS: 1

REF: 7.7. Important Resources in Sedimentary Rocks

15. What are three ways in which hydrocarbons can be trapped in reservoir rock?

ANS: stratigraphic traps, structural traps, salt domes PTS: 1

REF: 7.7. Important Resources in Sedimentary Rocks

16. Is banded iron formation a chemical or detrital sedimentary rock? Explain.

ANS: Banded iron formation is a chemical sedimentary rock, the precipitation of which was induced by the presence of free oxygen in ocean water and the atmosphere reacting with reduced iron in sea water.

PTS: 1

REF: 7.7. Important Resources in Sedimentary Rocks

17. Describe how compaction lithifies sediments.

ANS: A sediment has water in its pore spaces. The sediment is overlain by the weight of all the sediments on top of it, which squeezes the water from the pores. When the grains fit tightly together the rock is lithified.

PTS: 1

REF: 7.3. How Does Sediment Become Sedimentary Rock?

COMPLETION 1. The two major types of sediments that may become sedimentary rocks are ____________________ and ____________________.

ANS: detrital, chemical chemical, detrital PTS: 1

REF: 7.1. Introduction

2. Sedimentary deposits formed by wind tend to be very ____________________ sorted.

ANS: well PTS: 1

REF: 7.2. Sediment Sources, Transport, and Deposition

3. The steam channel, floodplain, lake, beach or deep seafloor where a sediment is laid down is known as its _______ _______.

ANS: depositional environment PTS: 1

REF: 7.2. Sediment Sources, Transport, and Deposition

4. The basis for classifying detrital sediments and their rocks is ____________________.

ANS: particle size PTS: 1

REF: 7.2. Sediment Sources, Transport, and Deposition

5. The designation of sediment grain size, from largest to smallest, is _______, _______, _______, _______.

ANS: gravel, sand, silt, clay PTS: 1

REF: 7.2. Sediment Sources, Transport, and Deposition

6. Sediment becomes sedimentary rock by the process known as _______.

ANS: lithification PTS: 1

REF: 7.3. How Does Sediment Become Sedimentary Rock?

7. Two processes that can create a rock from sediment are _______, in which grains are squeezed and water is lost, and _______ in which material is precipitated in pore spaces and binds grains together.

ANS: compaction, cementation PTS: 1

REF: 7.3. How Does Sediment Become Sedimentary Rock?

8. A sedimentary rock with gravel-sized particles that are angular is a _______; a sedimentary rock with rounded particles is a _______.

ANS: breccia; conglomerate PTS: 1

REF: 7.4. Types of Sedimentary Rocks

9. All detrital sedimentary rocks have a _______ texture.

ANS: clastic PTS: 1

REF: 7.4. Types of Sedimentary Rocks

10. A vertical sequence of a(n) ____________________ facies shows an offshore facies superposed on nearshore facies.

ANS: transgressive PTS: 1

REF: 7.5. Sedimentary Facies

11. A vertical sequence of a(n) ____________________ facies records the landward advance of the sea.

ANS: transgressive PTS: 1

REF: 7.5. Sedimentary Facies

12. Rock units with sheet-like geometry were most likely deposited during marine ____________________ or ____________________.

ANS: transgression, regression regression, transgression PTS: 1

REF: 7.5. Sedimentary Facies

13. A vertical sequence of regressive facies shows _______ facies superposed on _______ facies.

ANS: offshore, nearshore PTS: 1

REF: 7.5. Sedimentary Facies

14. ____________________ ripple marks form in response to wind or water moving in one direction.

ANS: Current PTS: 1

REF: 7.6. Reading the Story in Sedimentary Rocks

15. ____________________form when layers are deposited at an angle to the surface and the layers dip in direction of ____________________.

ANS: Cross-beds, flow PTS: 1 MULTIPLE CHOICE

REF: 7.6. Reading the Story in Sedimentary Rocks

1. Sediments are classified as ____. a. detrital, clastic, and chemical b. detrital and clastic c. detrital and chemical d. particulate and crystalline e. organic, particulate, and crystalline ANS: C

PTS: 1

REF: 7.1. Introduction

2. If all of the grains in a sedimentary rock are about the same size, shape, and composition, what can the rock can be characterized as? a. cemented b. compacted c. cross bedded d. graded e. well-sorted ANS: E

PTS: 1

REF: 7.2. Sediment Sources, Transport, and Deposition

3. What is the most common and effective agent for transporting sediment? a. wind b. waves and currents c. glaciers d. storms e. running water ANS: E

PTS: 1

REF: 7.2. Sediment Sources, Transport, and Deposition

4. What are the properties used to describe detrital sediment? a. size b. sorting c. rounding d. size and rounding e. All of these ANS: E

PTS: 1

REF: 7.2. Sediment Sources, Transport, and Deposition

5. What does poorly-sorted sediment have? a. no sharp edges b. restricted size range c. only particles larger than sand d. great size variation e. only particles smaller than sand ANS: D

PTS: 1

REF: 7.2. Sediment Sources, Transport, and Deposition

6. If all the grains in a sedimentary rock are about the same size, the rock can be characterized as ____. a. poorly sorted b. well-sorted c. compacted d. poorly graded e. cemented ANS: B

PTS: 1

REF: 7.2. Sediment Sources, Transport, and Deposition

7. Sedimentary rocks can undergo lithification by a. compaction b. cementation c. dissolution d. compaction and cementation ANS: D PTS: 1 REF: 7.3. How Does Sediment Become Sedimentary Rock?

8. Chemical sedimentary rocks generally have an interlocking grain texture called what? a. clastic b. porphyritic c. particulate d. crystalline e. detrital ANS: D

PTS: 1

REF: 7.4. Types of Sedimentary Rocks

9. Which coal contains the most carbon and is the hottest burning? a. lignite b. anthracite c. bituminous d. peat e. subbituminous ANS: B

PTS: 1

REF: 7.4. Types of Sedimentary Rocks

10. A rock composed almost entirely of fragmented seashells is called a. coquina. b. ooid. c. limestone. d. carbonate.

ANS: A

PTS: 1

REF: 7.4. Types of Sedimentary Rocks

11. In a marine environment, the largest sediments are found ____. a. just offshore because the largest sediments come from the continents b. in the deep sea because the largest sediments fall down from the sea surface c. in the deep sea because the largest sediments come out from continents d. in the deep sea because the largest sediments are brought out by glaciers e. nowhere; there are no large sediments in the ocean basins ANS: A

PTS: 1

REF: 7.5. Sedimentary Facies

12. Sedimentary structures refer to what? a. sedimentary rock folded and faulted after lithification b. features that form as a result of physical or biological processes operating in the depositional environment c. only layering in sedimentary rocks d. only grain size and textural features in sedimentary rocks e. none of these ANS: B

PTS: 1

REF: 7.6. Reading the Story in Sedimentary Rocks

13. Graded bedding forms when ____. a. erosion planes off a portion of the sea bottom

b. c. d. e.

sediment is deposited on a steep slope or grade turbidity currents deposit first coarse sediment then fine sediment cross-bedding is truncated turbidity currents deposit first fine sediment followed by coarse sediment

ANS: C

PTS: 1

REF: 7.6. Reading the Story in Sedimentary Rocks

14. Hydrocarbons are formed largely from what? a. the remains of dinosaurs b. any type of fossil c. microorganisms like algae d. the same types of plants which form coal deposits e. marine invertebrate animals ANS: C

PTS: 1

REF: 7.7. Important Resources in Sedimentary Rocks

15. Any mass of material that can be easily separated from the enclosing rock is a a. primary sedimentary structure. b. septaria. c. geode. d. concretion.

ANS: D

PTS: 1

REF: Geo-Focus. Concretions and Geodes

TRUE/FALSE 1. Wind blown deposits tend to be very well sorted.

ANS: T

PTS: 1

REF: 7.2. Sediment Sources, Transport, and Deposition

2. A detrital rock that is made mostly made of quartz sand is called arkose.

ANS: F

PTS: 1

REF: 7.4. Types of Sedimentary Rocks

3. Chert is hard rock consisting of microscopic crystals of silica that was shaped into sharp cutting tools by early humans.

ANS: T

PTS: 1

REF: 7.4. Types of Sedimentary Rocks

4. A vertical sequence of transgressive facies shows an offshore facies, superposed on nearshore facies.

ANS: T

PTS: 1

REF: 7.5. Sedimentary Facies

5. A vertical sequence of transgressive and regressive facies records the rise and fall of sea level.

ANS: T

PTS: 1

REF: 7.5. Sedimentary Facies

6. Graded beds refer to sedimentary beds that show an increase in grain size from bottom to top.

ANS: F

PTS: 1

REF: 7.6. Reading the Story in Sedimentary Rocks

7. Sedimentary layers in which grain size decreases from bottom to top are called graded beds.

ANS: T

PTS: 1

REF: 7.6. Reading the Story in Sedimentary Rocks

8. Cross-beds indicate that current flow changed direction and that the new direction flows across the old direction at an angle.

ANS: F

PTS: 1

REF: 7.6. Reading the Story in Sedimentary Rocks

9. Glacial deposits tend to be well sorted.

ANS: F

PTS: 1

REF: 7.6. Reading the Story in Sedimentary Rocks

10. Current flow direction can be determined by cross-beds and ripple marks.

ANS: T

PTS: 1

REF: 7.6. Reading the Story in Sedimentary Rocks

11. The uranium used in nuclear reactors comes largely from precipitated deposits in rocks such as black shale containing abundant organic matter.

ANS: T

PTS: 1

REF: 7.7. Important Resources in Sedimentary Rocks

12. The United States is the world's largest producer and exporter of uranium.

ANS: F

PTS: 1

REF: 7.7. Important Resources in Sedimentary Rocks

13. Fossil “shoe prints” are evidence that humans and dinosaurs coexisted.

ANS: F

PTS: 1

REF: Geo-Focus. Concretions and Geodes

Chapter 8—Metamorphism and Metamorphic Rocks ESSAY

1. Asbestos has been linked to lung cancer, yet why would removing all asbestos from all buildings be a bad idea?

ANS: There are several types of asbestos, and crocidolite is the variety that's associated with most lung disease. Since 95 percent of the asbestos that's in buildings is chrysotile, it is unnecessary to remove most of the asbestos that is found in buildings. To remove it all would cost about $100 billion.

PTS: 1

REF: Geo-Focus. Asbestos: Good or Bad?

2. Why is crocidolite asbestos harmful to lungs but chrysotile is not?

ANS: Crocidolite has thin, long, straight fibers that lodge in the lungs and stay there. Over time, they are a major irritant and can lead to lung cancer. chrysotile has long, curly fibers that do not become lodged in the lungs, and the fibers are soluble and disappear in the tissue.

PTS: 1

REF: Geo-Focus. Asbestos: Good or Bad?

3. What are some uses of metamorphic rocks such as marble, slate, sulfide ore, talc, graphite, and clay?

ANS:

Marble is used as a building stone; some of the world's most beautiful sculptures have been carved from it. Slate is also used as a building stone; in some regions where it is commonly found, it makes up the roofs of all the buildings. Sulfide ore minerals are some of the most important metals that we use in modern society. In addition, we use talc for talcum powder, graphite for pencils, garnets and corundum for gemstones or abrasives, some high temperature clay minerals for ceramics, and some temperature-resistant minerals for sparkplugs and other hot jobs.

PTS: 1

REF: various

4. How do metamorphic processes form ore deposits? What are some of the ores that are formed?

ANS: Ore deposits result from contact metamorphism, in which hot, ion-rich fluids migrate from igneous intrusions into the surrounding rock. Sulfide ore minerals include bornite, chalcopyrite, galena, pyrite, sphalerite, hematite, magnetite, tin, and tungsten.

PTS: 1

REF: 8.7. Metamorphism and Natural Resources

SHORT ANSWER 1. Some of the oldest known rocks, which have been dated at 3.96 billion years, are metamorphic. What does this tell us about the age of Earth?

ANS: Earth must be older than this, because there had to be a preexisting rock for it to become metamorphosed.

PTS: 1

REF: 8.1. Introduction

2. What physical properties have made asbestos an important industrial mineral?

ANS: noncombustibility and flexibility of the fibers PTS: 1

REF: Geo-Focus. Asbestos: Good or Bad?

3. Why might the health hazard of asbestos be less widespread than previously believed?

ANS: The majority of asbestos used in industry and in products is chrysotile, the mineral which has long curly fibers and does not become lodged in tissue.

PTS: 1

REF: Geo-Focus. Asbestos: Good or Bad?

4. Name five of the more than 3,000 uses for asbestos.

ANS: Examples of uses for asbestos include brake lining, fireproof fabrics, shingles, acid equipment, chemical equipment, clutch facings, insulation, binders for plasters, porcelains, and electrical insulators.

PTS: 1

REF: Geo-Focus. Asbestos: Good or Bad?

5. Metamorphism can be caused by increased temperatures. How can temperatures be raised, geologically, to bring about metamorphism?

ANS: Possibilities include burial and igneous activity (intrusion, etc.)

PTS: 1

REF: 8.2. The Agents of Metamorphism

6. How does lithostatic pressure differ from differential pressure?

ANS: Lithostatic pressure is equal in all directions; differential pressure is not.

PTS: 1

REF: 8.2. The Agents of Metamorphism

7. What are three possible sources of water and other fluids that are active in metamorphism?

ANS: water trapped in pore spaces of rocks, dehydration of water-bearing minerals, magmatic fluids PTS: 1

REF: 8.2. The Agents of Metamorphism

8. Why is heat an important agent of metamorphism?

ANS: Heat increases the rate of chemical reactions, and it may promote the growth of new minerals which are stable at higher temperatures.

PTS: 1

REF: 8.2. The Agents of Metamorphism

9. Why is time important in metamorphism?

ANS: Chemical reactions, especially those involving silicate minerals, proceed very slowly.

PTS: 1

REF: 8.2. The Agents of Metamorphism

10. What are some important types of ore deposits that may have resulted from movement of metallic ions in hydrothermal solutions?

ANS: copper, gold, iron ores, tin, zinc PTS: 1

REF: 8.3. The Three Types of Metamorphism

11. List some of the minerals commonly used as index minerals for metamorphic zones.

ANS: chlorite, biotite, garnet, staurolite, kyanite, sillimanite PTS: 1

REF: 8.3. The Three Types of Metamorphism

12. What does increasing grade of metamorphism mean in terms of the conditions which produced a sequence of metamorphic rocks?

ANS: increasing pressure, temperature PTS: 1

REF: 8.3. The Three Types of Metamorphism

13. What is the difference between slate and phyllite?

ANS: Grain size. Phyllite grains are larger, although they are still too small to be seen. The grains give the rock a glossy or lustrous sheen.

PTS: 1

REF: 8.4. How Are Metamorphic Rocks Classified?

14. Foliated metamorphic rocks are further classified on the basis of what observable properties?

ANS: Foliated rocks are classified by the size and shape of their mineral grains.

PTS: 1

REF: 8.4. How Are Metamorphic Rocks Classified?

15. What are some examples of nonfoliated metamorphic rocks?

ANS: marble, quartzite, greenstone, hornfels, anthracite PTS: 1

REF: 8.4. How Are Metamorphic Rocks Classified?

16. What is the significance of foliation in a metamorphic rock? (Not what is foliation, but what does it mean in terms of the rock's history?

ANS: Foliation indicates that the rock was metamorphosed under conditions of differential pressures.

PTS: 1

REF: 8.4. How Are Metamorphic Rocks Classified?

17. What is a metamorphic zone?

ANS: A metamorphic zone is the region between index mineral isograds.

PTS: 1

REF: 8.5. Metamorphic Zones and Facies

18. What is an isograd?

ANS: An isograd is a line connecting areas of equal metamorphic intensity.

PTS: 1

REF: 8.5. Metamorphic Zones and Facies

19. At which type(s) of tectonic plate boundaries does heat sufficient to cause metamorphism occur?

ANS: convergent, divergent

PTS: 1

REF: 8.6. Plate Tectonics and Metamorphism

20. What are some types of ore deposits that have formed in association with contact metamorphism?

ANS: copper, iron, lead, zinc, tin, tungsten PTS: 1

REF: 8.7. Metamorphism and Natural Resources

21. Name five metamorphic rocks or minerals for which there is an economic use. Name that use.

ANS: talc: cosmetics, paint, lubricant; garnet: gemstones, abrasives; asbestos: insulation, fireproofing; kyanite: refractory materials; graphite: pencil leads, lubricant; marble: building stone, sculpture; slate: building stone PTS: 1

REF: various

COMPLETION 1. One plate tectonic process that causes very widespread metamorphism is ____________________.

ANS: subduction PTS: 1

REF: 8.2. The Agents of Metamorphism

2. The most important fluid promoting metamorphism is ____________________.

ANS: water PTS: 1

REF: 8.2. The Agents of Metamorphism

3. What are two different types of pressures to which rocks can be subjected and can cause metamorphism? ____________________ ____________________, ANS: lithostatic, differential differential, lithostatic PTS: 1

REF: 8.2. The Agents of Metamorphism

4. The three types of metamorphism are ____________________, ____________________, and ____________________.

ANS: contact, dynamic, regional PTS: 1

REF: 8.3. The Three Types of Metamorphism

5. The concentric zones surrounding an igneous intrusion, and in which contact metamorphism has taken place, are called ____________________.

ANS: aureoles

PTS: 1

REF: 8.3. The Three Types of Metamorphism

6. The type of metamorphism that is common in fault zones in which rocks are subjected to high differential pressures is called ____________________.

ANS: dynamic PTS: 1

REF: 8.3. The Three Types of Metamorphism

7. The type of metamorphism that typically produces the hard, dense, fine-grained rocks called mylonites is called ____________________.

ANS: dynamic PTS: 1

REF: 8.3. The Three Types of Metamorphism

8. The type of metamorphism that occurs over large areas, commonly at convergent plate margins, and is responsible for the production of most metamorphic rocks is ____________________.

ANS: regional PTS: 1

REF: 8.3. The Three Types of Metamorphism

9. Metamorphism is most common along ____________________ plate boundaries.

ANS: convergent PTS: 1

REF: 8.3. The Three Types of Metamorphism

10. Contact metamorphism is found at the boundary between country rock and _______.

ANS: plutons PTS: 1

REF: 8.3. The Three Types of Metamorphism

11. Metamorphic rocks are commonly divided into these two groups, based on their textures: ____________________ and ____________________.

ANS: foliated, nonfoliated nonfoliated, foliated PTS: 1

REF: 8.4. How Are Metamorphic Rocks Classified?

12. Slate, phyllite, schist, gneiss, amphibolite, and migmatite are examples of _______ metamorphic rocks.

ANS: nonfoliated PTS: 1

REF: 8.4. How Are Metamorphic Rocks Classified?

13. A rock that has both igneous and metamorphic characteristics is called _______. These rocks form as the result of _______ temperatures.

ANS: migmatite; (extremely) high PTS: 1

REF: 8.4. How Are Metamorphic Rocks Classified?

14. The region between two _______ makes up a single metamorphic _______.

ANS: isograds; zone PTS: 1

REF: 8.5. Metamorphic Zones and Facies

15. Many ore deposits, including tin and tungsten, are associated with ____________________ metamorphism.

ANS: contact PTS: 1

REF: 8.7. Metamorphism and Natural Resources

MULTIPLE CHOICE 1. Metamorphic rocks are those that ____. a. are claimed to have certain metaphysical properties (e.g., quartz crystals) b. have different mineral compositions due to increased temperature and pressure c. have textures due to water and volatile magmatic fluids d. have different chemical compositions due to organisms and sediments e. have different mineral compositions due to increased temperature and pressure AND have textures due to water and volatile magmatic fluids ANS: E

PTS: 1

REF: 8.2. The Agents of Metamorphism

2. Metamorphism takes place ____. a. in the liquid state, melted by contact with magma b. in the solid state with or without fluid activity c. only at great depth d. in the liquid state, melted by contact with magma, and only at great depth e. all of these ANS: B

PTS: 1

REF: 8.2. The Agents of Metamorphism

3. Metamorphism is a physical and chemical change that occurs in such a way that ____. a. disequilibrium is reached with the new physical and chemical environment b. a dynamic equilibrium is reached c. equilibrium with the new environment is disturbed d. the rock reaches equilibrium with its new environment e. the rock's chemistry and texture become increasingly unstable ANS: D

PTS: 1

REF: 8.2. The Agents of Metamorphism

4. What are the two most important sources of heat for metamorphism? a. intrusive magma bodies and deep burial b. intrusive magma bodies and heat from the core c. deep burial and volcanism d. radioactive decay and volcanism e. radioactive decay and deep burial

ANS: A

PTS: 1

REF: 8.2. The Agents of Metamorphism

5. Which of the following correctly lists metamorphic mineral assemblages in order of decreasing temperature/pressure of formation? a. chlorite, biotite, garnet, staurolite, kyanite, sillimanite b. biotite, garnet, chlorite, staurolite, sillimanite, kyanite c. garnet, biotite, chlorite, sillimanite, staurolite, kyanite d. sillimanite, staurolite, kyanite, garnet, biotite, chlorite e. sillimanite, garnet, kyanite, staurolite, biotite, chlorite ANS: E

PTS: 1

REF: 8.3. The Three Types of Metamorphism

6. What is the reaction of country rock with solutions from a cooling magma known as? a. hydrothermal solution b. hydroxide alteration c. geothermal alteration d. hydrothermal alteration e. hydrostatic alteration ANS: D

PTS: 1

REF: 8.3. The Three Types of Metamorphism

7. An example of a region where mylonites are formed is ____. a. the Cascade Range b. the mid-oceanic ridges c. the San Andreas Fault Zone d. the Valles Marianas Rift Zone e. the Mendocino Fracture Zone ANS: C

PTS: 1

REF: 8.3. The Three Types of Metamorphism

8. What may the intensity of regional metamorphism be recognized by? a. index of recrystallization b. index fossils c. index minerals d. index polymorphs e. index cards ANS: C

PTS: 1

REF: 8.3. The Three Types of Metamorphism

9. Kyanite, andalusite, and sillimanite ____. a. are index minerals formed from clay-rich parent rocks b. form from the same parent rocks under different combinations of pressure and temperature c. can transform from one to the other depending on changes in temperature and pressure d. have the same chemical composition e. all of these ANS: E

PTS: 1

REF: 8.3. The Three Types of Metamorphism

10. Which of the following lists of foliated rock types is arranged according to increasing coarseness of texture? a. slate, phyllite, gneiss, schist b. slate, amphibolite, schist, phyllite c. schist, phyllite, gneiss, slate d. slate, phyllite, schist, gneiss e. schist, phyllite, amphibolite, gneiss

ANS: D

PTS: 1

REF: 8.4. How Are Metamorphic Rocks Classified?

11. When minerals in a metamorphic rock are arranged in a parallel manner this means that the rock was exposed to a. pressure perpendicular to the mineral alignment. b. pressure parallel to the mineral alignment. c. pressure coming equally from all sides. d. pressure perpendicular and parallel to the mineral alignment.

ANS: D

PTS: 1

REF: 8.4. How Are Metamorphic Rocks Classified?

12. Marble is a. an extremely hard rock. b. the result of dynamic metamorphism. c. metamorphosed limestone or dolostone. d. an extremely hard rock AND metamorphosed limestone or dolostone.

ANS: C

PTS: 1

REF: 8.4. How Are Metamorphic Rocks Classified?

13. A metamorphic rock with more than 50% platy and elongated minerals, all of which are visible to the naked eye is a a. phyllite. b. gneiss. c. slate. d. schist.

ANS: D

PTS: 1

REF: 8.4. How Are Metamorphic Rocks Classified?

14. A group of metamorphic rocks that formed under the same broad conditions of temperature and pressure is a a. metamorphic zone. b. isograd. c. metamorphic facies. d. contact zone.

ANS: C

PTS: 1

REF: 8.5. Metamorphic Zones and Facies

15. Divergent plate boundaries are characterized by ____. a. hydrothermal alteration and contact metamorphism b. regional and contact metamorphism c. regional and dynamic metamorphism d. dynamic and contact metamorphism e. hydrothermal alteration and dynamic metamorphism ANS: A

PTS: 1

REF: 8.6. Plate Tectonics and Metamorphism

16. Blueschist facies indicate a. formation at high temperature and high pressure. b. evidence of an ancient subduction zone. c. migmatite melting in a subduction zone. d. all of these ANS: B

PTS: 1

REF: 8.6. Plate Tectonics and Metamorphism

17. Which mineral group is the source of most commercial asbestos?

a. b. c. d.

serpentine amphibole chrysotile serpentine and amphibolite

ANS: D

PTS: 1

REF: Geo-Focus. Asbestos: Good or Bad?

18. Why is asbestos considered a health hazard? a. The fibers can cause lung cancer. b. Smoke from burning asbestos can cause lung cancer. c. Particles are toxic when ingested. d. Asbestos mining is hazardous for the miners.

ANS: A

PTS: 1

REF: Geo-Focus. Asbestos: Good or Bad?

TRUE/FALSE 1. Metamorphic rocks are most common in the flat-lying rocks overlying the stable shields of continents.

ANS: F

PTS: 1

REF: 8.1. Introduction

2. Metamorphic rocks are very common in the crystalline basement rocks of shields.

ANS: T

PTS: 1

REF: 8.1. Introduction

3. Metamorphic rocks have formed throughout all geological periods.

ANS: T

PTS: 1

REF: 8.1. Introduction

4. Metamorphic rocks indicate that an even older parent rock once existed in that place.

ANS: T

PTS: 1

REF: 8.1. Introduction

5. Metamorphic rocks can indicate the chemical changes that have occurred at various depths.

ANS: T

PTS: 1

REF: 8.2. The Agents of Metamorphism

6. Contact metamorphism along sills and dikes may produce metamorphosed zones many kilometers wide.

ANS: F

PTS: 1

REF: 8.2. The Agents of Metamorphism

7. The temperature of the intrusive magma has little effect on the metamorphic minerals formed.

ANS: F

PTS: 1

REF: 8.2. The Agents of Metamorphism

8. Aureoles surrounding felsic bodies will contain higher temperature metamorphic minerals than will mafic magmas.

ANS: F

PTS: 1

REF: 8.3. The Three Types of Metamorphism

9. Only magmatic fluids, not pore fluids of the country rock, have an effect on contact metamorphism.

ANS: F

PTS: 1

REF: 8.3. The Three Types of Metamorphism

10. The various colors of slate result from differing intensities of deformation.

ANS: F

PTS: 1

REF: 8.3. The Three Types of Metamorphism

11. A greenstone is a metamorphosed clay-rich sedimentary rock.

ANS: F

PTS: 1

REF: 8.4. How Are Metamorphic Rocks Classified?

12. Gneiss is a high-grade metamorphic rock that is streaked or has segregated bands of light and dark minerals.

ANS: T

PTS: 1

REF: 8.4. How Are Metamorphic Rocks Classified?

13. Isograds separate different metamorphic zones.

ANS: T

PTS: 1

REF: 8.5. Metamorphic Zones and Facies

14. Granulites are low temperature but high pressure metamorphic facies.

ANS: F

PTS: 1

REF: 8.6. Plate Tectonics and Metamorphism

15. Migmatites can form at convergent plate boundaries.

ANS: T

PTS: 1

REF: 8.6. Plate Tectonics and Metamorphism

Chapter 9—Earthquakes and Earth's Interior ESSAY

1. How does elastic rebound theory explain when earthquakes occur?

ANS: Where the rocks on the opposite side of a fault are on pieces of crust that are moving in different directions, the rocks are initially locked in place by their strength and friction. The rocks do not move but they do deform. As the pressure builds, the strength of the rocks is eventually exceeded. They rebound to their original shape, but the crust on either side of the fault has moved to a new location.

PTS: 1

REF: 9.2. Elastic Rebound Theory

2. Why do most earthquakes occur along the circum-Pacific belt?

ANS: Convergent plate boundaries line the Pacific basin since the Pacific is shrinking and the Atlantic is growing due to plate tectonics motions. As plates subduct, they create earthquakes along their distance.

The Pacific basin also has some transform faults along it, including the San Andreas in California.

PTS: 1

REF: 9.4. Where Do Earthquakes Occur, and How Often?

3. How would you locate an earthquake epicenter using three seismograms, a map, and a protractor?

ANS:

First, determine the difference in first arrival time for P- and S-waves from the three seismogram locations. Second, using a time-distance graph, determine the distance the epicenter is from each of the seismogram stations. Use a protractor to draw a circle of points the distance of the epicenter from the location of the seismic station. The point where the three circles intersect is the earthquake epicenter.

PTS: 1

REF: 9.6. Locating an Earthquake

4. What causes tsunami, and why are they so destructive?

ANS: Many tsunami are caused by the displacement of ocean water caused by crustal movement or slumping as the result of faulting. They are very destructive because they are incredibly fast-moving waves with long wavelengths. These waves reach large sizes only where they enter water shallow enough for them to touch bottom (1/2 wave length), and thus the wave amplitude increases.

PTS: 1

REF: 9.8. What Are the Destructive Effects of Earthquakes?

5. Explain why the portions of the San Andreas fault that are "locked" are or are not safer than the parts where the two plates slide more or less continually. What is the name of the theory that deals with this issue?

ANS: The locked portions of a fault are probably less safe than those that slide regularly. The locked portions are storing energy in the surrounding rocks, which will ultimately be released in a large earthquake. The portions that slide frequently build up much less energy since they release it frequently. The name of the theory is seismic gap theory.

PTS: 1

REF: 9.9. Earthquake Prediction

6. Why has it been suggested that large earthquakes might be prevented by injecting water along isolated portions of fault zones, which have been inactive for an unusually long time? When was this technique discovered?

ANS: Local increase of fluid pressure can cause small earthquakes, which release stresses that would otherwise build up to cause a larger earthquake. This phenomenon was first recognized when it was discovered that liquid waste disposal by deep-well injection at Rocky Mountain Arsenal near Denver, Colorado, was responsible for numerous small earthquakes in the area.

PTS: 1

REF: 9.10. Earthquake Control

7. What is the purpose of trenching across an active fault?

ANS: Geologists can find evidence of previous earthquakes in the ancient soil layers to determine the frequency of past earthquakes, and the time of the last earthquake to determine the probability of a future earthquake.

PTS: 1

REF: Geo-Focus. Paleoseismology

8. What is the evidence that Seattle is prone to earthquakes since there have been no quakes in historic times?

ANS:

Evidence for a large quake dating from less than 1,100 years ago has been found, including a marine terrace that had been uplifted 7m, tsunami evidence around the Pacific, rock avalanches in the Olympic Mountains that dammed streams and downed trees, and resuspended and redeposited sediments in Lake Washington.

PTS: 1

REF: Geo-Focus. Paleoseismology

9. Compare the continental crust with oceanic crust in terms of composition and thickness.

ANS: Continental crust is complex, consisting of all rock types but is usually described as granitic. It averages 35 km thick. Oceanic crust is comparatively simple, consisting of gabbro in its lower part and overlain by basalt. Its thickness ranges from five to 10 km.

PTS: 1

REF: 9.16. Earth's Crust

SHORT ANSWER 1. What is the cause of most earthquakes?

ANS: Most earthquakes are caused by the sudden release of energy by displacement of rocks along faults.

PTS: 1

REF: 9.1. Introduction

2. Why are most intermediate- to deep-focus earthquakes generated at convergent plate boundaries?

ANS: The convergent plates generate compressional forces as a result of plate subduction. The downgoing plate undergoes phase changes as it descends into the mantle.

PTS: 1

REF: 9.3. Seismology

3. Why are there so few earthquakes within plate interiors?

ANS: At plate boundaries, adjacent plates are moving in different directions, which build up stresses that are ultimately relieved by earthquakes.

PTS: 1

REF: 9.4. Where Do Earthquakes Occur, and How Often?

4. What is a possible cause of intraplate earthquakes?

ANS: Intraplate earthquakes may be caused by localized stresses that build up along ancient faults that are generated by plate movements elsewhere.

PTS: 1

REF: 9.4. Where Do Earthquakes Occur, and How Often?

5. Within which belt or zone do the majority of earthquakes occur?

ANS: the circum-Pacific belt

PTS: 1

REF: 9.4. Where Do Earthquakes Occur, and How Often?

6. Why are earthquakes more likely to occur in Tokyo, Anchorage, and Los Angeles than they are in New York, London, or Paris?

ANS: The first three cities lie along or very near the margins of plates; the other cities are farther from the edges.

PTS: 1

REF: 9.4. Where Do Earthquakes Occur, and How Often?

7. What are two major and very useful differences between P- and S-waves?

ANS: P-waves move faster; they can travel through solids, liquids, and gases. S-waves only travel through solids.

PTS: 1

REF: 9.5. Seismic Waves

8. Explain how geologists calculate the distance between the epicenter of an earthquake and a given seismograph.

ANS: by measuring the difference between the arrival times of P-waves and S-waves at a seismograph location and using a time-distance graph PTS: 1

REF: 9.6. Locating an Earthquake

9. Which type(s) of seismic waves do seismographs record?

ANS: P-waves; S-waves; surface-waves PTS: 1

REF: 9.6. Locating an Earthquake

10. Besides the distance to the epicenter of an earthquake, what are two other things that a seismograph can tell us?

ANS: A seismograph records that there was an earthquake, the time of the earthquake, and the magnitude of the earthquake.

PTS: 1

REF: 9.6. Locating an Earthquake

11. Explain the differences between the magnitude and the intensity of an earthquake, in terms of cause and effect.

ANS: Magnitude is a measure of the cause of the earthquake (the energy released), while intensity is a measure of the effect (damage) produced by the earthquake.

PTS: 1

REF: 9.7. Measuring the Strength of an Earthquake

12. Why do earthquakes of similar size often have such large differences in their destructiveness? Why are they so different in the number of people they kill?

ANS: Earthquakes do more damage in places where the population density is high and the structures are not especially well built. More people are killed if they are out on the road and at work than if they are home in bed.

PTS: 1

REF: 9.7. Measuring the Strength of an Earthquake

13. Explain the differences between the magnitude and the intensity of an earthquake, in terms of how each is measured or observed.

ANS: Magnitude is measured by instruments (seismographs), while intensity is measured by people's reactions and observations.

PTS: 1

REF: 9.7. Measuring the Strength of an Earthquake

14. Explain the differences between the magnitude and the intensity of an earthquake, in terms of how many intensities and magnitudes a single earthquake can have.

ANS: An earthquake can have only one magnitude, but it will have different intensities in different locations.

PTS: 1

REF: 9.7. Measuring the Strength of an Earthquake

15. Why do structures located on thick, soft sediment, especially water-saturated or artificial fill, suffer much greater damage than structures built on bedrock?

ANS: Surface waves cause this material to shake, lose its cohesiveness, and collapse. Sometimes they mix with water and move like a fluid, in a process called liquefaction.

PTS: 1

REF: 9.8. What Are the Destructive Effects of Earthquakes?

16. Why are the paths of seismic waves curved?

ANS: Density and elasticity vary with depth causing the waves to be continually refracted.

PTS: 1

REF: 9.11. What Is Earth's Interior Like?

17. What is Earth's average density, what are the average surface rock densities, and what does this tell us about the interior of Earth?

ANS: Earth's average density is 5.5 g/cm, surface rocks range between 2.5 and 3.0 g/cm, therefore the interior must be denser than the crust.

PTS: 1

REF: 9.12. The Core

18. What evidence do scientists use to estimate the density and composition of the core?

ANS: The composition of the core is estimated by studying the composition of meteorites, information from seismic waves, laboratory experiments, and Earth's density.

PTS: 1

REF: 9.12. The Core

19. What is the highest temperature found on or in Earth, and why is that location so hot?

ANS: The temperature at the center of the core is about 6,000C, close to the temperature at the surface of the sun. It is so hot because of the immense pressure of gravity pulling all the material that surrounds it in toward it.

PTS: 1

REF: 9.12. The Core

20. What happens to P-waves and S-waves when they encounter the core-mantle boundary, and what does this change in behavior indicate about the core?

ANS: P-wave velocity abruptly decreases, and S-waves disappear, meaning that at least the outer core must be liquid.

PTS: 1

REF: 9.12. The Core

21. For what purpose is seismic tomography used?

ANS: to develop three-dimensional models of Earth's interior PTS: 1

REF: 9.14. Seismic Tomography

22. Why do we know that the geothermal gradient near the surface cannot continue very deeply into Earth?

ANS: If the geothermal gradient near the surface continued at depth, the temperature at only 100 km depth would be so high that all known rocks would melt despite the high pressure.

PTS: 1

REF: 9.15. Earth's Internal Heat

23. What is paleoseismology, and why is it important?

ANS: P-wave velocity abruptly decreases, and S-waves disappear, meaning that at least the outer core must be liquid.

PTS: 1

REF: Geo-Focus. Paleoseismology

COMPLETION 1. The theory of elastic rebound was proposed as a result of studies following the ____________________ earthquake in the year ____________________.

ANS: San Francisco, 1906 PTS: 1

REF: 9.2. Elastic Rebound Theory

2. The elastic rebound theory of earthquakes postulates that rocks store the energy of ____________________ by bending until their internal strength is surpassed and they ____________________ and return to their former place.

ANS: deformation, rupture/break/fault/fracture PTS: 1

REF: 9.2. Elastic Rebound Theory

3. The study of earthquakes is called ____________________.

ANS: seismology PTS: 1

REF: 9.3. Seismology

4. An instrument that detects, records, and measures vibrations produced by an earthquake is called a(n) ____________________.

ANS: seismograph PTS: 1

REF: 9.3. Seismology

5. Almost all intermediate- to deep-focus earthquakes occur along ____________________ plate boundaries.

ANS: convergent PTS: 1

REF: 9.3. Seismology

6. The ____________________ or focus of an earthquake is the location within the crust where the energy of an earthquake is released. The ____________________ is the point on Earth's surface directly above the focus.

ANS: hypocenter, epicenter PTS: 1

REF: 9.3. Seismology

7. The two major types of seismic waves are ____________________ waves and ____________________ waves.

ANS: surface, body PTS: 1

REF: 9.5. Seismic Waves

8. Seismic waves that cause a rolling or swaying motion of the surface of the ground are called ____________________.

ANS: surface PTS: 1

REF: 9.5. Seismic Waves

9. The velocity of S-waves is ____________________ than that of P-waves. S-waves cannot pass through materials that are ____________________ or ____________________.

ANS: slower, liquid, gas PTS: 1

REF: 9.5. Seismic Waves

10. The number of seismograph records needed to locate the epicenter of an earthquake is ______.

ANS: three PTS: 1

REF: 9.6. Locating an Earthquake

11. For every integer increase of magnitude on the Richter Scale, ______ times more energy is released by the earthquake.

ANS: thirty PTS: 1

REF: 9.7. Measuring the Strength of an Earthquake

12. The term that best describes most tsunamis is ____________________.

ANS: seismic sea wave PTS: 1

REF: 9.8. What Are the Destructive Effects of Earthquakes?

13. The structural layer that the P- and S-wave low-velocity zone, in the upper part of the mantle, closely corresponds to is the ____________________.

ANS: asthenosphere PTS: 1

REF: 9.11. What Is Earth's Interior Like?

14. The velocities of P- and S-waves are determined by these two properties of the material they are passing through: ____________________ and ____________________.

ANS: density, elasticity PTS: 1

REF: 9.11. What Is Earth's Interior Like?

15. If you could drill from the outer surface of Earth all the way to the center, you would pass through the major divisions of Earth, the ____________________, the ____________________, and finally the ____________________.

ANS: crust, mantle, core PTS: 1

REF: 9.11. What Is Earth's Interior Like?

16. The study of ancient earthquakes is known as ____________________.

ANS: paleoseismology PTS: 1

REF: Geo-Focus. Paleoseismology

17. The structural layer of earth that is liquid is the ____________________.

ANS: outer core PTS: 1

REF: 9.12. The Core

18. The depth to the Mohorovicic discontinuity is ______ km beneath the continents and between ______ and ______ km beneath the seafloor.

ANS: 35, 5, 10 PTS: 1

REF: 9.13. Earth's Mantle

19. The energy used in seismic tomography is ____________________.

ANS: seismic waves PTS: 1

REF: 9.14. Seismic Tomography

20. The increase of temperature with depth is known as the ____________________.

ANS: geothermal gradient PTS: 1

REF: 9.15. Earth's Internal Heat

MULTIPLE CHOICE 1. According to the elastic rebound theory, ____. a. rocks will bend before they break b. rocks will snap back into their original shape after faulting c. rocks will break when their capacity to store energy of deformation has been exceeded d. rocks will bend before they break AND snap back into their original shape after faulting e. all of these ANS: E

PTS: 1

REF: 9.2. Elastic Rebound Theory

2. The focal depth ranges for shallow focus, intermediate focus, and deep focus earthquakes, respectively is a. <70 km; 70 to 300 km; >300 km b. <5 km; 5-50 km; >50 km c. <1 km; 1-10 km; >10 km d. <20 m; 20 m -100 m; >100 m ANS: A

PTS: 1

REF: 9.3. Seismology

3. Seismology has produced a great amount of information about ____. a. the mechanisms of plate tectonics b. the physical and chemical state of Earth's interior c. the causes of mountain building d. earthquakes e. all of these ANS: E

PTS: 1

REF: 9.3. Seismology

4. The focus of the most destructive earthquakes is almost always ____. a. shallow b. intermediate c. deep d. intermediate and deep e. none of these ANS: A

PTS: 1

REF: 9.3. Seismology

5. The percentage of all earthquakes that occur along a plate boundary is nearly what? a. 100 percent b. 95 percent c. 80 percent d. 55 percent e. 25 percent ANS: B PTS: 1 REF: 9.4. Where Do Earthquakes Occur, and How Often?

6. Only 5 percent of all earthquakes occur within ____. a. the Mediterranean-Asiatic Belt b. the Circum-Mediterranean Belt c. the interiors of plates and mid-oceanic ridges d. the passive margins of continents and mid-oceanic ridges e. the shields of continents and mid-oceanic ridges ANS: C PTS: 1 REF: 9.4. Where Do Earthquakes Occur, and How Often?

7. One of the strongest earthquakes ever recorded in North America was the intraplate quake known as the a. 1811 New Madrid, Missouri, earthquake b. 1886 Charleston, Carolina, earthquake c. 1906 San Francisco earthquake d. 1964 Anchorage, Alaska, earthquake e. 1984 Mount St. Helens, Washington, earthquake ANS: A PTS: 1 REF: 9.4. Where Do Earthquakes Occur, and How Often?

8. The two types of body waves are _______ and _______ waves. a. Raleigh; Love b. compressional; extensional c. secondary; primary d. tensional; extensional ANS: C

PTS: 1

REF: 9.5. Seismic Waves

9. Which of the following is not a factor affecting earthquake intensity? a. distance from the epicenter b. depth of the hypocenter c. population density d. duration of shaking e. the time elapsed since the last earthquake ANS: E

PTS: 1

REF: 9.7. Measuring the Strength of an Earthquake

10. What does the magnitude of an earthquake measure? a. intensity b. the damage created c. the energy released d. the duration of trembling e. intensity and the duration of trembling ANS: C

PTS: 1

REF: 9.7. Measuring the Strength of an Earthquake

11. The most damage from the 1906 San Francisco earthquake was caused by what? a. fire b. a tsunami c. ground shaking d. cracks opening up e. landslides ANS: A PTS: 1 REF: 9.8. What Are the Destructive Effects of Earthquakes?

12. A seismic risk map can be used to a. predict when an earthquake will take place in an area. b. choose locations for hospitals and other important buildings. c. determine the most likely location of the epicenter of the next earthquake. d. show seismic gaps.

ANS: B

PTS: 1

REF: 9.9. Earthquake Prediction

13. The major discontinuity that occurs at a depth of 2,900 km below earth's surface is the ____. a. low velocity zone b. Moho c. inner core outer core transition d. core-mantle boundary e. none of these ANS: D

PTS: 1

REF: 9.12. The Core

14. What is the composition of the mantle? a. peridotite b. basalt c. granite d. iron e. iron and nickel metal ANS: A

PTS: 1

REF: 9.13. Earth's Mantle

15. Scientists use seismic tomography to a. develop 3-dimensional models of Earth’s interior. b. determine the location of an earthquake’s epicenter. c. predict the timing and intensity of a future earthquake. d. determine the depth of an earthquake.

ANS: A

PTS: 1

REF: 9.14. Seismic Tomography

16. The average geothermal gradient near Earth's surface is what? a. 100C/km

b. c. d. e.

50C/km 25C/km 25C/km 50C/km

ANS: C

PTS: 1

REF: 9.15. Earth's Internal Heat

17. What is the estimated average geothermal gradient in the mantle? a. 10C/km b. 5C/km c. 1C/km d. 2C/km e. 5C/km ANS: C

PTS: 1

REF: 9.15. Earth's Internal Heat

18. The temperature range at the core-mantle boundary is estimated to be between ____. a. 2,500 to 5,000C b. 5,000 to 6,500C c. 7,000 to 8,500C d. 8,500 to 10,000C e. 10,000 to 11,500C ANS: A

PTS: 1

REF: 9.15. Earth's Internal Heat

19. The temperature of the core of Earth is estimated to be very close to that of the ____. a. interior of the Sun b. surface of the Sun c. Earth's mantle d. Earth's oceanic crust e. outer space ANS: B

PTS: 1

REF: 9.15. Earth's Internal Heat

20. Seattle, Washington ____. a. has not had an earthquake historically b. is very unlikely to have a large earthquake because there have been none in historic times c. has frequent small earthquakes and so is very unlikely to have a large earthquake d. has large earthquakes about once every century e. has large earthquakes very infrequently but will likely have one again ANS: A

PTS: 1

REF: Geo-Focus. Paleoseismology

TRUE/FALSE 1. Although most aftershocks are smaller than the initial earthquake, an aftershock may be as big and may cause considerable damage.

ANS: T

PTS: 1

REF: 9.1. Introduction

2. According to elastic rebound theory, rocks deform and bend. When their internal strength is exceeded they rupture. This energy release is called an earthquake.

ANS: T

PTS: 1

REF: 9.2. Elastic Rebound Theory

3. Approximately 90% of all earthquake foci are at depths of greater than 100 km.

ANS: F

PTS: 1

REF: 9.3. Seismology

4. The second major seismic belt, accounting for 15% of all earthquakes is the Mediterranean-Asiatic belt.

ANS: T PTS: 1 REF: 9.4. Where Do Earthquakes Occur, and How Often?

5. Subtracting the arrival time of the first S-wave from the arrival time of the first P-wave gives the P-S time interval for each seismic station.

ANS: F

PTS: 1

REF: 9.6. Locating an Earthquake

6. On the Richter Scale, an earthquake of 6.0 releases ten times as much energy as an earthquake of 5.0.

ANS: F

PTS: 1

REF: 9.7. Measuring the Strength of an Earthquake

7. The Modified Mercalli Scale is a quantitative measure of an earthquake’s intensity.

ANS: F

PTS: 1

REF: 9.7. Measuring the Strength of an Earthquake

8. Seismologists most commonly report the magnitude of an earthquake using the Richter Scale.

ANS: F

PTS: 1

REF: 9.7. Measuring the Strength of an Earthquake

9. The opening of large crevasses that open up and swallow people is a significant source of danger created by earthquakes.

ANS: F PTS: 1 REF: 9.8. What Are the Destructive Effects of Earthquakes?

10. Landslides and ground liquefaction are significant sources of danger created by earthquakes.

ANS: T PTS: 1 REF: 9.8. What Are the Destructive Effects of Earthquakes?

11. Tsunami are significant sources of danger created by earthquakes.

ANS: T PTS: 1 REF: 9.8. What Are the Destructive Effects of Earthquakes?

12. The odd behavior of many kinds of animals is a scientifically accepted method used to predict earthquakes.

ANS: F

PTS: 1

REF: 9.9. Earthquake Prediction

13. The analysis of the alignment of the planets and moon is a scientifically accepted method used to predict earthquakes.

ANS: F

PTS: 1

REF: 9.9. Earthquake Prediction

14. Monitoring changes in electrical conductivity is a scientifically accepted method used to predict earthquakes.

ANS: T

PTS: 1

REF: 9.9. Earthquake Prediction

15. Chinese seismologists have successfully predicted several earthquakes and are now confident that they can predict most quakes within China.

ANS: F

PTS: 1

REF: 9.9. Earthquake Prediction

16. We know that the mantle is not molten because P-waves can travel through it.

ANS: F

PTS: 1

REF: 9.13. Earth's Mantle

17. Seattle's most important buildings--schools, hospitals, etc.--are built to State of California earthquake standards.

ANS: F

PTS: 1

REF: Geo-Focus. Paleoseismology

18. The temperature range at the base of the crust is 1,000 to 1,500 degrees C. ANS: F

PTS: 1

REF: 9.15. Earth's Internal Heat

Chapter 10—Deformation, Mountain Building, and Earth's Crust ESSAY

1. What type of information is found on geologic maps, and what are some of the possible uses for geologic maps?

ANS: Geologic maps include information on the distribution of rock types, age relationships among rock units, and geologic structures. Uses are varied. Economic uses include locating petroleum, ore deposits, and sand and gravel deposits; hazard planning includes locating potential volcanic activity, landslides, and earthquake faults; city planning includes placing landfills; and engineering uses includes placing dams, highways, nuclear reactors, and tunnels.

PTS: 1

REF: 10.3. Strike and Dip--The Orientation of Deformed Rock Layers

2. Describe the plate tectonics processes and associated stresses that have led to the formation of the Himalayas, the world's largest mountain range?

ANS: The Indian plate has moved northward into Eurasia, causing compression. First there was subduction of the seafloor that separated the two continents, which formed continental arc volcanoes. Then when the continental plates met, India continued to push into Eurasia. The motions resulted in thrust faulting, reverse faulting, and folding, which thickened the crust to make the mountains.

PTS: 1

REF: 10.5. Deformation and the Origin of Mountains

3. What is isostatic rebound? Give an example.

ANS:

Isostatic rebound is the re-equilibration of the crust by rebounding to the level at which it "floats" again in the mantle after a mass has been removed. The melting of glaciers after the end of the ice age has caused the crust they were sitting on to rebound upward.

PTS: 1

REF: 10.6. Earth's Crust

4. If the mantle transmits S-waves, then how can it behave like a liquid, as implied by the principle of isostasy?

ANS: The mantle responds to short term stresses, such as seismic waves, like a solid, but responds to long term stresses, such as those of isostatic rebound, like a viscous liquid.

PTS: 1

REF: 10.6. Earth's Crust

5. Briefly explain why, according to the principle of isostasy, continental crust should be thicker than oceanic crust.

ANS: A mass such as the continental crust that "floats" on an underlying mass, should do so at an equilibrium level, such that it extends at least as far beneath the upper level of the underlying material as it does above the surface of that material.

PTS: 1

REF: 10.6. Earth's Crust

SHORT ANSWER 1. What is meant when rocks are said to be deformed (fractured or folded)?

ANS: Their shape and/or their volume is altered by the stress of an applied force that is greater than the rock's internal strength.

PTS: 1

REF: 10.2. Rock Deformation--How Does It Occur?

2. What are the three types of stress?

ANS: compression, tension, and shear stress PTS: 1

REF: 10.2. Rock Deformation--How Does It Occur?

3. What does compression stress result from?

ANS: Compression stress results from external forces directed toward one another.

PTS: 1

REF: 10.2. Rock Deformation--How Does It Occur?

4. What does tension stress result from?

ANS: Tension stress results from forces acting in opposite directions along the same line.

PTS: 1

REF: 10.2. Rock Deformation--How Does It Occur?

5. What does shear stress result from?

ANS: Shear stresses result from forces acting parallel to one another but in opposite directions.

PTS: 1

REF: 10.2. Rock Deformation--How Does It Occur?

6. What is the difference between brittle and ductile rocks?

ANS: Brittle rocks show little or no plastic strain before fracture, while ductile rocks show much plastic strain.

PTS: 1

REF: 10.2. Rock Deformation--How Does It Occur?

7. If the foci of most earthquakes lie at depths of less than 30 km, what does this indicate about the behavior of rocks in terms of brittle and ductile deformation?

ANS: Rocks are more likely to deform in a brittle fashion above this depth and in a ductile fashion below this depth.

PTS: 1

REF: 10.2. Rock Deformation--How Does It Occur?

8. What is the difference between elastic and plastic deformation?

ANS: After elastic deformation, the material returns to its original shape; after plastic deformation, the material stays deformed.

PTS: 1

REF: 10.2. Rock Deformation--How Does It Occur?

9. What is the dip of an inclined layer of rock?

ANS: Dip is the maximum angular deviation of the plane from horizontal.

PTS: 1

REF: 10.3. Strike and Dip--The Orientation of Deformed Rock Layers

10. What is the difference between faults and joints?

ANS: Faults show evidence of movement parallel to the fracture surface; joints do not.

PTS: 1

REF: 10.4. Deformation and Geologic Structures

11. How do geologists stabilize a slope for highway construction?

ANS: Slopes can be stabilized by building retaining walls or drainage systems to keep the slope dry, planting vegetation, or rerouting the road if it would be too costly to stabilize the slope.

PTS: 1

REF: Geo-Focus. Engineering and Geology

12. What role do geologists play in engineering large structures like bridges and power plants?

ANS: Geologists must be sure slopes are stable and that the ground can support a large structure.

PTS: 1

REF: Geo-Focus. Engineering and Geology

13. What is the distinction between the hanging wall and the footwall of a fault?

ANS: The hanging wall is the block which overlies the fault plane, and the footwall is the block which underlies the fault plane.

PTS: 1

REF: 10.4. Deformation and Geologic Structures

14. What is the difference between a thrust fault and a reverse fault?

ANS: A thrust fault is a special case of reverse fault where the dip of the fault is less than 45.

PTS: 1

REF: 10.4. Deformation and Geologic Structures

15. What are some ways in which mountains form?

ANS: Mountains form by volcanic activity, the intrusion of batholiths plutons, block faulting, thrust faulting, and/or reverse faulting.

PTS: 1

REF: 10.5. Deformation and the Origin of Mountains

16. What are some geologic processes which accompany orogenesis at oceanic-oceanic plate boundaries?

ANS: Orogenic activity at oceanic-oceanic plate boundaries includes subduction, deformation, igneous activity, and metamorphism.

PTS: 1

REF: 10.5. Deformation and the Origin of Mountains

17. What are some of the ways in which terranes differ from surrounding strata?

ANS: Terranes are different rock from the surrounding strata so they can differ in many ways including rock type, fossil content, stratigraphic sequence, structural features, and paleomagnetic signature.

PTS: 1

REF: 10.5. Deformation and the Origin of Mountains

COMPLETION 1. Force applied to a given area is known as ____________________.

ANS: stress PTS: 1

REF: 10.2. Rock Deformation--How Does It Occur?

2. Deformation caused by stress that exceeds a material's internal strength is known as ____________________.

ANS: strain PTS: 1

REF: 10.2. Rock Deformation--How Does It Occur?

3. The direction of a line formed by the intersection of a horizontal plane with the plane of a layer of rock is called ____________________.

ANS: strike PTS: 1

REF: 10.3. Strike and Dip--The Orientation of Deformed Rock Layers

4. A fold is the result of ____________________ deformation.

ANS: plastic PTS: 1

REF: 10.4. Deformation and Geologic Structures

5. A simple bend or flexure, in an otherwise horizontal rock layer, is called a(n) ____________________.

ANS: monocline PTS: 1

REF: 10.4. Deformation and Geologic Structures

6. Sedimentary rocks that are now tilted were deposited ____________________.

ANS: horizontally PTS: 1

REF: 10.4. Deformation and Geologic Structures

7. A(n) ____________________ divides a fold into two halves.

ANS: axial plane PTS: 1

REF: 10.4. Deformation and Geologic Structures

8. Each half of a fold is known as a(n) ____________________.

ANS: limb PTS: 1

REF: 10.4. Deformation and Geologic Structures

9. If both limbs of a fold dip in the same direction, the fold is ____________________.

ANS: overturned PTS: 1

REF: 10.4. Deformation and Geologic Structures

10. In an anticline, the beds in its axial region are ____________________ in age than the beds of its limbs, and all strata dip ____________________ the axis.

ANS: older, away from PTS: 1

REF: 10.4. Deformation and Geologic Structures

11. The type of fold that traps most of the world's produced petroleum is a(n) ____________________.

ANS: anticline PTS: 1

REF: 10.4. Deformation and Geologic Structures

12. A circular or oval fold in which the strata are up-arched, and the marginal strata are ____________________ in age than that of the interior is known as a(n) ____________________.

ANS: younger, dome PTS: 1

REF: 10.4. Deformation and Geologic Structures

13. Strike-slip faults are caused by ____________________ forces.

ANS: shearing PTS: 1

REF: 10.4. Deformation and Geologic Structures

14. A fault with both dip-slip and strike-slip movement is classified as a(n) ________________________________________ fault.

ANS: oblique-slip PTS: 1

REF: 10.4. Deformation and Geologic Structures

15. In a(n) ____________________, the youngest rocks are in the center and the oldest are on the outside.

In a(n) ____________________, the oldest rocks are in the center and the youngest are on the outside.

ANS: basin, dome PTS: 1

REF: 10.4. Deformation and Geologic Structures

16. An episode of mountain building is known as a(n) ____________________.

ANS: orogeny PTS: 1

REF: 10.5. Deformation and the Origin of Mountains

17. Small accreted lithospheric blocks of foreign origin that differ completely from the rocks in surrounding regions are called ____________________.

ANS: terranes PTS: 1

REF: 10.5. Deformation and the Origin of Mountains

18. The principle that Earth's crust is in floating equilibrium with the denser mantle below is known as ____________________.

ANS: isostasy PTS: 1

REF: 10.6. Earth's Crust

MULTIPLE CHOICE 1. If you're standing on ice above a pond and you hear a crack, what should you do? a. remain as motionless until the cracking stops b. lie down on the ice to distribute your weight more broadly on the ice c. run as fast as you can to shore d. not worry because the ice will not break e. prepare for a swim ANS: B

PTS: 1

REF: 10.2. Rock Deformation--How Does It Occur?

2. The type of strain which occurs depends not only on the kind of stress applied, but also on what? a. the amount of pressure and degree of temperature b. the rock type c. the duration of the stress d. the amount of pressure, the degree of temperature and the duration of the stress e. the amount of pressure, the degree of temperature and the rock type ANS: C

PTS: 1

REF: 10.2. Rock Deformation--How Does It Occur?

3. In a reverse fault, the ____. a. hanging wall goes up relative to the footwall b. hanging wall goes down relative to the footwall c. hanging wall and footwall remain in the same position vertically d. two sides of the fault slide past each other horizontally e. two sides of the fault move away from each other ANS: A

PTS: 1

REF: 10.2. Rock Deformation--How Does It Occur?

4. Dip-slip faults include ____. a. normal faults b. reverse faults c. thrust faults d. normal and reverse faults e. All of these ANS: D

PTS: 1

REF: 10.2. Rock Deformation--How Does It Occur?

5. The San Andreas Fault is a ____ fault. a. normal b. reverse c. thrust d. strike slip e. recumbent ANS: D

PTS: 1

6. Movement along the San Andreas is ____.

REF: 10.2. Rock Deformation--How Does It Occur?

a. b. c. d. e.

compressional tensional right lateral left lateral vertical

ANS: C

PTS: 1

REF: 10.2. Rock Deformation--How Does It Occur?

7. Rocks that are tilted were deposited ____. a. on a slope in their present orientation b. in an unknown orientation and then were tilted into their current position c. horizontally and then were tilted into their current orientation d. vertically and then were tilted into their current orientation e. on the continental shelf and then uplifted ANS: C PTS: 1 REF: 10.3. Strike and Dip--The Orientation of Deformed Rock Layers 8. On a geologic map the number adjacent to the strike and dip symbol is a. the strike angle. c. the strike direction. b. the dip angle. d. the dip direction.

ANS: B PTS: 1 REF: 10.3. Strike and Dip--The Orientation of Deformed Rock Layers 9. In what type of fault does the hanging wall move up relative to the footwall at an angle of less than 45 degrees? a. normal c. reverse b. strike-slip d. thrust ANS: D

PTS: 1

REF: 10.4. Deformation and Geologic Structures

10. The forces that produce block-faulted mountains, such as the Basin and Range Province of the Western United States, are a. extensional c. elastic b. compressional d. shear ANS: A

PTS: 1

REF: 10.4. Deformation and Geologic Structures

11. The zone of rubble found along a fracture that has had movement on both sides is called a. conglomerate. c. fracture rubble. b. angular unconformity. d. fault breccia.

ANS: D

PTS: 1

REF: 10.4. Deformation and Geologic Structures

12. Pretend that you are standing with one foot on either side of a strike-slip fault and the right block moves toward you. This can be called a(n) _______ strike slip fault. a. left-lateral c. dip-slip b. right-lateral d. thrust ANS: B

PTS: 1

13. What are uplifted blocks called? a. tensional blocks b. grabens c. horsts

REF: 10.4. Deformation and Geologic Structures

d. fault blocks e. graves ANS: B

PTS: 1

REF: 10.5. Deformation and the Origin of Mountains

14. Volcanic island arcs are characteristic of which type of convergent plate boundaries? a. continental-continental b. continental-oceanic c. oceanic-oceanic d. continental-oceanic AND oceanic-oceanic e. All of these ANS: C

PTS: 1

REF: 10.5. Deformation and the Origin of Mountains

15. When an isolated mountain range occurs in the interior of a continent, one may infer that the range formed by what? a. the collision of two continental plates b. compressive forces acting on the opposing margins of a single plate c. the rifting of the continent d. the growth of a volcanic arc e. the collision of two continental plates AND the growth of a volcanic arc ANS: A

PTS: 1

REF: 10.5. Deformation and the Origin of Mountains

16. Continents grow and evolve by addition of felsic and mafic crust; a process known as what? a. addition b. accretion c. concretion d. convergence e. conformation ANS: B

PTS: 1

REF: 10.5. Deformation and the Origin of Mountains

17. Which of the following have become terranes? a. island arcs and ocean ridges b. seamounts c. fragments of other continents d. island arcs, ocean ridges and seamounts e. all of these ANS: E

PTS: 1

REF: 10.5. Deformation and the Origin of Mountains

18. Where is the thickest crust found? a. beneath mountains b. at the old stable portions of the continents c. at the continental margins d. at the old stable portions of the ocean basins e. at the mid-oceanic ridge spreading centers ANS: A

PTS: 1

REF: 10.6. Earth's Crust

TRUE/FALSE 1. Fracturing of rock can occur to depths as great as 900 km.

ANS: F

PTS: 1

REF: 10.2. Rock Deformation--How Does It Occur?

2. Most folding of rocks occurs near the surface.

ANS: F

PTS: 1

REF: 10.2. Rock Deformation--How Does It Occur?

3. Because movement along a strike-slip fault is just horizontal, quakes along these faults are small and do not do much damage.

ANS: F

PTS: 1

REF: 10.4. Deformation and Geologic Structures

4. All mountains are made of continental crust.

ANS: F

PTS: 1

REF: 10.5. Deformation and the Origin of Mountains

5. The most active orogenic belts today are the Alpine-Himalayan belt and the circum-Pacific belt.

ANS: T

PTS: 1

REF: 10.5. Deformation and the Origin of Mountains

6. Divergent plate boundaries are responsible for most orogenesis.

ANS: F

PTS: 1

REF: 10.5. Deformation and the Origin of Mountains

7. Most orogenesis takes place on oceanic-oceanic convergent plate boundaries.

ANS: F

PTS: 1

REF: 10.5. Deformation and the Origin of Mountains

8. The Andes formed as result of oceanic-continental convergence.

ANS: T

PTS: 1

REF: 10.5. Deformation and the Origin of Mountains

9. An important means of continental accretion is plutonism.

ANS: T

PTS: 1

REF: 10.5. Deformation and the Origin of Mountains

10. Continental crust is always thicker than oceanic crust.

ANS: T

PTS: 1

Chapter 11—Mass Wasting

REF: 10.6. Earth's Crust

ESSAY 1. Why is La Conchita, California particularly vulnerable to landslides?

ANS: The slope behind the small community is composed of soft, weak, and porous sediments that are not well lithified. An avocado orchard that sits at the top of the hill introduces irrigation water into the slope; this part of California sometimes experiences heavy rainfall, and the slope has been undercut by a road.

PTS: 1

REF: Geo-Focus. Southern California Landslides

2. Why is the Uniform Building Code important for reducing mass wasting losses?

ANS: Chapter 70 of the code deals with slopes and the alteration of landscapes. The chapter deals with slope angle and the direction of slope in relation to bedding planes, faults, folds, and other geologic structures. It specifies drainage requirements. By adhering to the building codes, there is a decrease in the loss of structures built on hillsides and other unstable areas.

PTS: 1

REF: 11.4. Recognizing and Minimizing the Effects of Mass Wasting

3. In what ways are slope stability maps useful to planners and developers?

ANS: Slope stability maps are used to determine where certain types of buildings and other structures should or should not be built and to indicate how slope stability might be improved, if structures are built where stability is compromised.

PTS: 1

REF: 11.4. Recognizing and Minimizing the Effects of Mass Wasting

SHORT ANSWER 1. What factors collectively define a slope's shear strength?

ANS: Shear strength is defined by the material's strength and cohesion, internal inter-grain friction, and its external slope support.

PTS: 1

REF: 11.1. Introduction

2. What types of changes in a slope can lead to mass wasting?

ANS: Mass wasting can occur due to changes in slope gradient or vegetation cover, increased water content, weakening by weathering, and overloading.

PTS: 1

REF: 11.2. Factors that Influence Mass Wasting

3. What are some ways by which a slope can become oversteepened?

ANS: Slopes are oversteepened by undercutting caused by streams or waves, or excavations by human activities.

PTS: 1

REF: 11.2. Factors that Influence Mass Wasting

4. How can vegetation affect the likelihood of mass wasting?

ANS: Vegetation can absorb water, and roots may help bind soil and bedrock; both effects decrease the likelihood of mass wasting.

PTS: 1

REF: 11.2. Factors that Influence Mass Wasting

5. What are the most common triggering mechanisms for mass wasting?

ANS: The most common triggering mechanisms are vibrations due to earthquakes and a sudden influx of excessive water.

PTS: 1

REF: 11.2. Factors that Influence Mass Wasting

6. Briefly explain why saturated clay is a very unstable slope material.

ANS: Clay grains are platy and tend to align with their larger flat surfaces parallel to one another. Clay also absorbs water and traps it between grains. These properties make clay very susceptible to slippage along grain surfaces.

PTS: 1

REF: 11.2. Factors that Influence Mass Wasting

7. On the basis of what three criteria are mass movements classified?

ANS: rate of movement, type of movement, and type of material PTS: 1

REF: 11.3. Types of Mass Wasting

8. How can slow mass movements be detected?

ANS: Slow mass movements can be detected by their effects, such as tilted trees and cracked foundations.

PTS: 1

REF: 11.3. Types of Mass Wasting

9. How does a slump differ from a rock slide?

ANS: A slump involves movement along a curved surface, with backward rotation, while a rock slide involves movement along an essentially planar surface.

PTS: 1

REF: 11.3. Types of Mass Wasting

10. Why can mudflows be very dangerous?

ANS: They can form quickly, move rapidly, and transport both small and very large objects.

PTS: 1

REF: 11.3. Types of Mass Wasting

11. Briefly explain why a region that is tectonically active may be particularly vulnerable to mass wasting.

ANS: Such a region is likely to contain faults and highly fractured bedrock, have young steep slopes, and experience many earthquakes.

PTS: 1

REF: 11.3. Types of Mass Wasting

12. What is the most important step that can be taken to minimize or eliminate mass wasting or damage from it?

ANS: make a thorough geological investigation of the area PTS: 1

REF: 11.4. Recognizing and Minimizing the Effects of Mass Wasting

13. Because water can be so important in mass movement, what is one of the most effective and inexpensive ways of reducing mass wastage risk and damage?

ANS: installing an effective drainage system PTS: 1

REF: 11.4. Recognizing and Minimizing the Effects of Mass Wasting

14. What is a slope stability map?

ANS: A slope stability map portrays the mass wasting hazards of an area.

PTS: 1

REF: 11.4. Recognizing and Minimizing the Effects of Mass Wasting

15. What methods can be used to stabilize a hillside?

ANS: Methods include installing subsurface drainage, diversion of surface waters, reducing the slope by cutand-fill or benching, constructing retaining walls, and planting vegetation.

PTS: 1

REF: 11.4. Recognizing and Minimizing the Effects of Mass Wasting

16. If you were surveying hillside property on which you planned to build a home, what are some of the evidences of former mass wasting you would look for?

ANS: You should look for evidence of former landslides such as scarps, open fissures, displaced or tilted objects, and sudden changes in vegetation.

PTS: 1

REF: 11.4. Recognizing and Minimizing the Effects of Mass Wasting

17. What human activities contribute to or cause mass wasting?

ANS: Activities such as undercutting slopes (to build roads for example), overloading slopes by construction, adding water, and removing or replacing vegetation.

PTS: 1

REF: 11.4. Recognizing and Minimizing the Effects of Mass Wasting

18. Give an example of a way in which mass wasting can affect human activity.

ANS: by destroying buildings and other structures or by causing fatalities PTS: 1

REF: 11.4. Recognizing and Minimizing the Effects of Mass Wasting

COMPLETION 1. Geologists call the down slope movement of material under the direct influence of gravity ____________________.

ANS: mass wasting PTS: 1

REF: 11.1. Introduction

2. A rapid down slope mass movement of snow and ice is called a(n) ____________________.

ANS: avalanche PTS: 1

REF: 11.2. Factors that Influence Mass Wasting

3. The steepest angle a slope can maintain without collapsing is known as the slope’s ______________.

ANS: angle of repose PTS: 1

REF: 11.2. Factors that Influence Mass Wasting

4. _______ adds weight to the slope material, decreases inter-grain friction, and lubricates the base of an unstable slope.

ANS: Water PTS: 1

REF: 11.2. Factors that Influence Mass Wasting

5. When a slope dips in the same direction as the strata or a prominent joint set the type of mass wasting that is likely to occur is _______ _______.

ANS: block slides PTS: 1

REF: 11.3. Types of Mass Wasting

6. A flow that is up to 30 percent water and at least 50 percent clay-sized particles is a _______. A flow with less water but larger particles is a _______.

ANS: mudflow; debris flow PTS: 1

REF: 11.3. Types of Mass Wasting

7. The material accumulated at the base of cliffs where rocks fall is known as ____________________.

ANS: talus PTS: 1

REF: 11.3. Types of Mass Wasting

8. Mass movement in which rocks fall through the air are known as ____________________.

ANS: rockfall

PTS: 1

REF: 11.3. Types of Mass Wasting

9. Clays that spontaneously liquefy and flow like water are called ____________________ clays.

ANS: quick PTS: 1

REF: 11.3. Types of Mass Wasting

10. Ground that remains permanently frozen is called ____________________.

ANS: permafrost PTS: 1

REF: 11.3. Types of Mass Wasting

11. Creep is most effective and significant in a(n) ____________________climate.

ANS: humid PTS: 1

REF: 11.3. Types of Mass Wasting

12. Mass movement in which material move as a viscous fluid or plastically is termed _______.

ANS: flow PTS: 1

REF: 11.3. Types of Mass Wasting

13. Periodic freezing and thawing of the upper ground surface when the weather is cold can lead to _______.

ANS: solifluction PTS: 1

REF: 11.3. Types of Mass Wasting

14. ____________________ are sometimes used to fasten unstable bedrock to stable strata.

ANS: Rock bolts PTS: 1

REF: 11.4. Recognizing and Minimizing the Effects of Mass Wasting

15. In the ____________________ method of protecting slopes, material is removed from the top of the slope and used as fill at the base.

ANS: cut and fill PTS: 1

REF: 11.4. Recognizing and Minimizing the Effects of Mass Wasting

MULTIPLE CHOICE 1. Damage to homes by mass wasting a. strikes wealthy and poor people equally. b. is rare because the potential dangers on different slopes are well studied. c. is more likely to affect poor people since they cannot afford to build on the most stable slopes.

d. is most likely to strike urban areas.

ANS: C

PTS: 1

REF: 11.1. Introduction

2. Landslide is a. a general term for mass movements of earth materials. b. a specific term for a mass movement of a defined type and speed. c. a specific term used for mass movements on a volcano. d. a specific term for the rapid movement of snow and ice downslope.

ANS: A

PTS: 1

REF: 11.2. Factors that Influence Mass Wasting

3. A slope material’s strength and cohesion, the amount of internal friction between grains, and any external support of the slope define a slope’s a. mass wasting. b. angle of repose. c. dynamic equilibrium. d. shear strength.

ANS: D

PTS: 1

REF: 11.2. Factors that Influence Mass Wasting

4. Most mass wasting is enhanced or promoted by ____. a. erosion b. weathering c. flash floods d. wind erosion e. plate tectonics ANS: B

PTS: 1

REF: 11.2. Factors that Influence Mass Wasting

5. Mass wasting does NOT occur on ____. a. unstable material b. near-level slopes c. steep slopes. d. gradual slopes. e. It occurs on all of these.

ANS: E

PTS: 1

REF: 11.2. Factors that Influence Mass Wasting

6. All other factors being equal, what is the chance of mass wasting increased by? a. the amount of material involved b. the lack of friction on the slope c. the angle of the slope d. the kind of event which initiates the mass wasting e. whether there exists a positive or negative gravity anomaly ANS: C

PTS: 1

REF: 11.2. Factors that Influence Mass Wasting

7. Water a. decreases friction between grains. b. causes a loss of cohesion. c. adds weight. d. all of these.

ANS: D

PTS: 1

REF: 11.2. Factors that Influence Mass Wasting

8. After gravity, what is the major cause of mass wasting? a. slope gradient b. weakening by weathering c. overloading d. vegetation loss e. increased water content ANS: A

PTS: 1

REF: 11.2. Factors that Influence Mass Wasting

9. Mass wasting is most likely to occur in what climate? a. arid warm regions b. humid tropical regions c. arctic regions d. temperate regions e. none of these ANS: B

PTS: 1

REF: 11.2. Factors that Influence Mass Wasting

10. The type of mass wasting that is responsible for the greatest amount of property damage is what? a. creep b. slumps c. rock fall d. slides e. avalanches ANS: A

PTS: 1

REF: 11.3. Types of Mass Wasting

11. Most major landslides ____. a. are caused by earthquakes b. are caused by volcanic eruptions c. have natural causes d. are due to human activity and poor engineering e. none of these ANS: C

PTS: 1

REF: 11.3. Types of Mass Wasting

12. Among the types of slides are ____. a. slumps b. block slides c. mudflows d. slumps and block slides e. all of these ANS: D

PTS: 1

REF: 11.3. Types of Mass Wasting

13. Permafrost lies beneath ____ percent of the land surface on Earth. a. 0 b. 10 c. 20 d. 40 e. 50 ANS: C

PTS: 1

14. Drainage on a slope a. reduces the weight of material.

REF: 11.3. Types of Mass Wasting

b. lowers pore pressure. c. is effective and inexpensive. d. All of these.

ANS: D PTS: 1 REF: 11.4. Recognizing and Minimizing the Effects of Mass Wasting 15. In the cut-and-fill method, a. benches are cut into a hillside. b. material is removed from the up a slope and placed at the base. c. retaining walls are constructed and anchored into bedrock. d. rock bolts are fastened to stable bedrock.

ANS: B PTS: 1 REF: 11.4. Recognizing and Minimizing the Effects of Mass Wasting TRUE/FALSE 1. Solifluction is not a serious economic problem because it occurs mainly in unpopulated areas.

ANS: F

PTS: 1

REF: 11.2. Factors that Influence Mass Wasting

2. The removal of vegetation is a significant cause of slope failure and mass wasting.

ANS: T

PTS: 1

REF: 11.2. Factors that Influence Mass Wasting

3. A loud thunderclap may be sufficient to trigger a landslide of an unstable slope.

ANS: T

PTS: 1

REF: 11.2. Factors that Influence Mass Wasting

4. Some mass wasting occurs at almost imperceptibly slow rates.

ANS: T

PTS: 1

REF: 11.3. Types of Mass Wasting

5. Creep occurs only on weathered or soil-covered surfaces of moderate slope.

ANS: F

PTS: 1

REF: 11.3. Types of Mass Wasting

6. Creep is the most economically damaging and widespread type of material flow.

ANS: T

PTS: 1

REF: 11.3. Types of Mass Wasting

7. Slow mass movement transports a greater volume of material than does rapid mass movement.

ANS: T

PTS: 1

REF: 11.3. Types of Mass Wasting

8. Slumps occur most commonly in well-consolidated material.

ANS: F

PTS: 1

REF: 11.3. Types of Mass Wasting

9. Most block slides occur because the strata are highly fractured.

ANS: F

PTS: 1

REF: 11.3. Types of Mass Wasting

10. Falls, slumps, and slides may turn into flows.

ANS: T

PTS: 1

REF: 11.3. Types of Mass Wasting

11. Most large mass movements can be prevented given sufficient study and planning.

ANS: F PTS: 1 REF: 11.4. Recognizing and Minimizing the Effects of Mass Wasting 12. Geologists choose the one best method for stabilizing a slope among the many that are available.

ANS: F PTS: 1 REF: 11.4. Recognizing and Minimizing the Effects of Mass Wasting

Chapter 12—Running Water--Streams and Rivers ESSAY 1. Describe the hydrologic cycle.

ANS: Water is evaporated from the ocean, lakes, and streams and becomes water vapor in the atmosphere.

Then it precipitates and ends up back on land. On land it may end up in glaciers, in the oceans, in lakes or streams, or it may spend a long period of time underground as groundwater. Water also works its way through plants by evaporation and through animals, where it is used for many processes.

PTS: 1

REF: 12.2. Water on Earth

2. Describe where flow velocity is highest in a semi-straight channel. Why is this the case?

ANS: Flow velocity is highest in the center of the channel, just below the surface, where there is little friction. At the bottom and sides of the channel, the roughness of the channel bed, due to sediments, slows the water down. There is even some frictional resistance where the water meets the air.

PTS: 1

REF: 12.3. Running Water

3. Is it possible to change the velocity of a stream but have it maintain the same discharge? Explain.

ANS: Yes. The discharge (Q) is a product of the velocity (V) and the cross-sectional area (A); that is, Q = V ?

A. To maintain the same discharge while changing the velocity, it is necessary to change the crosssectional area at the same time, and in the opposite manner. For example, if the velocity is increased, the cross-sectional area would need to be decreased by an appropriate amount.

PTS: 1

REF: 12.3. Running Water

4. Briefly explain why braided streams are common in regions adjacent to glaciers.

ANS: Braided streams form when there is an excess of sediment load for the amount of water available and the depth of the stream channel. Glaciers provide a great deal of sediment in comparison to the amount of meltwater they release.

PTS: 1

REF: 12.5. Deposition by Running Water

5. If the formation of an oxbow lake results in an increase in stream velocity, explain what causes a stream to meander.

ANS: A stream meanders when the volume and velocity of a stream is too great for its gradient. An increase in the distance traveled, by virtue of a meandering path, balances volume and velocity with a low gradient.

PTS: 1

REF: 12.5. Deposition by Running Water

6. What is a 20-year flood?

ANS: Based on records of stream behavior through time, agencies determine how often a flood of a certain size is likely to happen. For a 20-year flood, a flood of that magnitude is predicted to happen about once every 20 years.

PTS: 1

REF: 12.6. Can Floods Be Predicted and Controlled?

7. Briefly explain the trade-offs that accompany any flood control project.

ANS: The obvious benefits of controlling flooding are offset by loss of sediment deposition area, loss of wetland habitat, loss of the natural evolution of a drainage basin (natural changes in the stream channel such as meandering), increased soil erosion, and decreased natural ability to moderate effects of floods.

PTS: 1

REF: 12.6. Can Floods Be Predicted and Controlled?

8. Briefly explain how a stream might adjust toward an equilibrium state following a heavy rain.

ANS: A heavy rain will increase stream volume and velocity. The channel and gradient will be temporarily too small and low, respectively, for the increased volume. Stretches of the stream with a low gradient will experience erosion, and stretches farther downstream may experience deposition as the gradient of the upstream portion is adjusted (increased).

PTS: 1

REF: 12.7. Drainage Systems

SHORT ANSWER 1. What has been the effect of the Aswan Dam on farming in Egypt?

ANS: Without the annual floods, the floodplain is not nourished, and Egyptian farmers have to apply chemical fertilizers.

PTS: 1

REF: 12.1. Introduction

2. What was the importance of the Nile River to ancient Egypt?

ANS: The Nile floodplain provided the only fertile farmland in the region, and the river was the main avenue of commerce.

PTS: 1

REF: 12.1. Introduction

3. What evidence is there that reveals that water may once have been abundant on Mars?

ANS: Images from spacecraft show areas with winding valleys that apparently were eroded by running water.

PTS: 1

REF: 12.1. Introduction

4. What are some of the reasons running water is important to humans?

ANS: Water is important for domestic uses, industry, agriculture, power, and transportation corridors.

PTS: 1

REF: 12.1. Introduction

5. In the hydrologic cycle, what happens to the precipitation that falls on the land?

ANS: It becomes runoff; it evaporates or is transpired; or it is absorbed (becomes groundwater).

PTS: 1

REF: 12.2. Water on Earth

6. What powers the hydrologic cycle?

ANS: The hydrologic cycle is powered by heat from solar radiation and gravity.

PTS: 1

REF: 12.2. Water on Earth

7. Briefly explain what property of water makes hydrologic cycling possible.

ANS: Water changes phase from liquid to solid to vapor all within the normal range of Earth's surface temperatures.

PTS: 1

REF: 12.2. Water on Earth

8. In what ways can water be temporarily stored, from a few years to a few thousand years, on land areas, before returning to the oceans?

ANS: Water can be stored in lakes, snow fields, glaciers, or as groundwater.

PTS: 1

REF: 12.2. Water on Earth

9. On what factors does the infiltration capacity of a surface depend?

ANS: Infiltration capacity depends on the existing degree of water saturation, the duration and intensity of rainfall, and the degree of soil consolidation.

PTS: 1

REF: 12.2. Water on Earth

10. Distinguish sheet flow from channel flow.

ANS: With sheet flow, water moves in a more-or-less continuous film over the surface. With channel flow, the runoff is confined to long, trough-like depressions.

PTS: 1

REF: 12.3. Running Water

11. What is the gradient of a stream?

ANS: Stream gradient is the slope over which the stream flows, or the vertical drop through which the stream moves, divided by the horizontal distance the water moves.

PTS: 1

REF: 12.3. Running Water

12. Why does the velocity of a stream generally increase downstream even though the gradient decreases?

ANS: Velocity generally increases downstream because channels are generally smoother downstream and because stream volume tends to increase as more tributaries enter downstream.

PTS: 1

REF: 12.3. Running Water

13. What is the difference between the velocity and the discharge of a stream?

ANS: The velocity is the rate at which the stream is moving; the discharge is the total volume of water in the stream moving past some point in a given period of time.

PTS: 1

REF: 12.3. Running Water

14. What is (are) the source(s) of the dissolved load in most streams?

ANS: The dissolution of stream bed and banks, sheet flow, and groundwater flow into the stream.

PTS: 1

REF: 12.4. Running Water, Erosion, and Sediment Transport

15. Under what conditions will a braided stream develop?

ANS: Braided streams develop when the stream is supplied with excessive sediment.

PTS: 1

REF: 12.5. Deposition by Running Water

16. What causes a delta to form?

ANS: The stream's velocity decreases rapidly when it flows into another body of water and deposition occurs.

PTS: 1

REF: 12.5. Deposition by Running Water

17. What are the three types of beds characteristically exhibited by a prograding delta?

ANS: bottomset beds, foreset beds, and topset beds PTS: 1

REF: 12.5. Deposition by Running Water

18. Since levees can protect many areas during floods, why are they controversial?

ANS: In addition to being expensive, levees in many cases make problems worse, by restricting the flow of water that otherwise would have spread over a floodplain.

PTS: 1

REF: 12.6. Can Floods Be Predicted and Controlled?

19. Briefly explain how a stream can apparently have a bed that extends onto the continental shelf or to the shelf-slope break.

ANS: The stream valley must have been established when sea level was lower.

PTS: 1

REF: 12.7. Drainage Systems

20. Briefly explain what will happen to a stream's behavior if one drains a lake that is a temporary base level for that stream.

ANS: Drainage of a lake, which serves as a temporary base level, will lower the base level for the part of the stream above the lake. The stream may respond by eroding, in an attempt to reach its new base level.

PTS: 1

REF: 12.7. Drainage Systems

21. The ideal graded stream has a balance among what five factors?

ANS: gradient, discharge, flow velocity, channel characteristics, sediment load PTS: 1

REF: 12.7. Drainage Systems

22. Name three of the processes involved in the evolution of valleys.

ANS: downcutting, lateral erosion, mass wasting, sheet wash, headward erosion PTS: 1

REF: 12.8. The Evolution of Valleys

23. Briefly explain the sequence of events that leads to the formation of a stream terrace.

ANS: Alternating high and low sea levels will raise or lower a stream's base level, respectively, causing it to deposit or erode. These changes would result in a high terrace cut by a younger channel.

PTS: 1

REF: 12.8. The Evolution of Valleys

24. Briefly explain how a meandering stream can become incised in solid bedrock.

ANS: A stream with a previously established meandering pattern may become incised into solid bedrock which is uplifted, or the same stream may be responding to a relative lowering of its base level.

PTS: 1

REF: 12.8. The Evolution of Valleys

COMPLETION 1. Water that returns to the oceans as surface flow from streams is ____________________.

ANS: runoff PTS: 1

REF: 12.2. Water on Earth

2. The two types of flow are ____________________ flow and ____________________ flow.

ANS: laminar, turbulent PTS: 1

REF: 12.2. Water on Earth

3. ____________________ flow is characteristic of almost all streams.

ANS: Turbulent PTS: 1

REF: 12.2. Water on Earth

4. The gradient of streams tends to be ____________________ in their upper reaches and ____________________ in their lower reaches.

ANS: steeper, gentler PTS: 1

REF: 12.3. Running Water

5. When infiltration capacity is exceeded and water begins to move rapidly down slope, a continuous film of water known as ____________________ flow develops. This type of flow can cause ____________________.

ANS: sheet, sheet erosion PTS: 1

REF: 12.3. Running Water

6. In meandering streams, the water velocity tends to be greatest in the ____________________ portion of the meander.

ANS: outer

PTS: 1

REF: 12.5. Deposition by Running Water

7. The outer bank of a meander in a meandering stream is called the ____________________ ____________________, where (erosion, deposition) ____________________ takes place. The deposit on the opposite side of the channel is called the ____________________, which is where (erosion, deposition) ____________________ occurs.

ANS: cut bank, erosion, point bar, deposition PTS: 1

REF: 12.5. Deposition by Running Water

8. Former meanders that have been cut off from the stream are called ____________________.

ANS: oxbow lakes PTS: 1

REF: 12.5. Deposition by Running Water

9. Ridges of alluvium left along a stream's margins by repeated deposition during floods are called ____________________.

ANS: natural levees PTS: 1

REF: 12.5. Deposition by Running Water

10. The types of marine deltas that are recognized, based on the relative importance of the processes involved in their formation are ____________________-dominated, ____________________dominated, and ____________________-dominated.

ANS: stream, wave, tide PTS: 1

REF: 12.5. Deposition by Running Water

11. A fan-shaped deposit of alluvium that forms adjacent to highlands in arid or semiarid climates is called a(n) ____________________.

ANS: alluvial fan PTS: 1

REF: 12.5. Deposition by Running Water

12. The total surface region that provides runoff to a stream system is known as a(n) ____________________.

ANS: drainage basin PTS: 1

REF: 12.7. Drainage Systems

13. The lower limit to which the stream can erode is its ____________________.

ANS: base level PTS: 1

REF: 12.7. Drainage Systems

14. The renewal of erosion which results in creation of stream terraces is generally attributed to a change in ____________________ level, or a change in climate resulting in greater ____________________, and thus discharge.

ANS: base, runoff PTS: 1

REF: 12.7. Drainage Systems

15. Lateral erosion creates conditions along a stream valley that promotes movement of material by another geologic process known as ____________________.

ANS: mass wasting PTS: 1

REF: 12.8. The Evolution of Valleys

16. An uplifted erosional remnant of a floodplain that formed when a stream was flowing at a higher level is called a(n) ____________________.

ANS: stream terrace PTS: 1

REF: 12.8. The Evolution of Valleys

17. A change in base level leading to formation of stream terraces can come about by ____________________ of the land over which the stream flows or a(n) ____________________ of sea level.

ANS: uplift, lowering PTS: 1

REF: 12.8. The Evolution of Valleys

MULTIPLE CHOICE 1. The percentage of Earth's water that is in the oceans is ____. a. 100 percent b. 97 percent c. 93 percent d. 55 percent e. 50 percent ANS: B

PTS: 1

REF: 12.1. Introduction

2. The percentage of the Earth's water that is fresh water and is not frozen is ____. a. 5 percent b. 3 percent c. 1 percent d. 0.65 percent e. 0.01 percent ANS: D

PTS: 1

REF: 12.1. Introduction

3. Flow in which there is no mixing between parallel layers in the water is known as what? a. turbulent flow b. outflow c. intermittent flow

d. laminar flow e. stream flow ANS: D

PTS: 1

REF: 12.2. Water on Earth

4. The primary factor that determines whether water moves by turbulent or laminar flow is ____. a. discharge b. gradient c. velocity d. area e. none of these ANS: C

PTS: 1

REF: 12.2. Water on Earth

5. A stream erodes material from its banks and bed by ____. a. suspension b. hydraulic action c. abrasion d. suspension and hydraulic action e. hydraulic action and abrasion ANS: E PTS: 1 REF: 12.4. Running Water, Erosion, and Sediment Transport 6. What do the solid particles of a stream include? a. bed load b. suspended load c. solution load d. bed load and suspended load e. suspended load and solution load ANS: D PTS: 1 REF: 12.4. Running Water, Erosion, and Sediment Transport 7. Streams do most of their erosion, transportation of sediment, and deposition of sediment during ____. a. day-to-day flow movement b. icy winters c. flooding d. rainstorms e. wind storms ANS: C PTS: 1 REF: 12.4. Running Water, Erosion, and Sediment Transport 8. A delta with long, fingerlike sand bodies, each deposited in a distributary channel that progrades far seaward, such as the Mississippi River, is typically formed as a(n) ____-dominated delta. a. avian b. stream c. wave d. tide e. sediment ANS: B

PTS: 1

REF: 12.5. Deposition by Running Water

9. A delta that has islands reworked by waves on the seaward side, such as the Nile delta, is typically formed as a(n) ____-dominated delta.

a. b. c. d. e.

avian stream wave tide sediment

ANS: C

PTS: 1

REF: 12.5. Deposition by Running Water

10. The Mississippi Delta is a good example of a a. tide-dominated delta. b. distributary channel. c. stream-dominated delta. d. mixed delta.

ANS: C

PTS: 1

REF: 12.5. Deposition by Running Water

11. To predict floods, scientists a. monitor a stream’s water levels. b. evaluate a stream’s past behavior. c. assume the same behavior as last year. d. monitor water levels and evaluate past behavior for a stream.

ANS: D

PTS: 1

REF: 12.6. Can Floods Be Predicted and Controlled?

12. What is the ultimate base level for a stream? a. sea level b. the nearest lake c. the nearest stream d. the nearest spring e. the nearest valley ANS: A

PTS: 1

REF: 12.7. Drainage Systems

13. When a stream’s equilibrium profile shows a delicate balance among gradient, discharge, flow velocity, channel shape and sediment load the stream is a. superposed. b. incised. c. graded. d. divided.

ANS: C

PTS: 1

REF: 12.7. Drainage Systems

14. In all types of power plants a. potential energy converts to kinetic energy to generate electricity. b. a spinning turbine connected to a generator containing a coil of wire produces electricity. c. fossil fuels are burned to generate electricity. d. water is heated to generate steam, which turns turbines and generates electricity.

ANS: B PTS: 1 REF: Geo-Focus. Dams, Reservoirs, and Hydroelectric Power Plants 15. Headward erosion cuts through a drainage divide and diverts part of the drainage to another stream.

This process is called a. stream erosion. b. stream piracy. c. downcutting.

d. stream terracing.

ANS: B

PTS: 1

REF: 12.8. The Evolution of Valleys

TRUE/FALSE 1. By percentage volume, most of the hydrologic cycle is limited to ocean-atmosphere transference.

ANS: T

PTS: 1

REF: 12.2. Water on Earth

2. Streams with broad, shallow channels and narrow, deep channels have a higher flow velocity than do those with semi-circular channels.

ANS: F

PTS: 1

REF: 12.3. Running Water

3. Flow at all but the slowest velocities is turbulent.

ANS: T

PTS: 1

REF: 12.2. Water on Earth

4. A dry surface has a higher infiltration capacity than a moist surface.

ANS: F

PTS: 1

REF: 12.2. Water on Earth

5. The Mississippi River is an example of channel flow.

ANS: T

PTS: 1

REF: 12.3. Running Water

6. A stream's velocity varies only along its length.

ANS: F

PTS: 1

REF: 12.3. Running Water

7. The average channel velocity increases downstream where the gradient is lower.

ANS: T

PTS: 1

REF: 12.3. Running Water

8. Most of a stream's kinetic energy is involved in eroding and transporting sediment.

ANS: F PTS: 1 REF: 12.4. Running Water, Erosion, and Sediment Transport 9. Mass wasting can be an important source of sediment carried in a stream.

ANS: T PTS: 1 REF: 12.4. Running Water, Erosion, and Sediment Transport 10. Alluvial fans form best in humid climates.

ANS: F

PTS: 1

REF: 12.5. Deposition by Running Water

11. Meandering streams have semi-circular cross-sections along most of their length.

ANS: F

PTS: 1

REF: 12.5. Deposition by Running Water

12. In each state in the U.S., hydroelectric power accounts for 6.4% of the electricity generated.

ANS: F PTS: 1 REF: Geo-Focus. Dams, Reservoirs, and Hydroelectric Power Plants

Chapter 13—Groundwater ESSAY

1. What is a cone of depression, where is it found, and what causes it? Why can large cones of depression be a serious problem?

ANS: A cone of depression is where the water table is lower in a cone shape in the area around a well. It is caused by excess groundwater pumping; that is when discharge from a water well exceeds recharge or the rate of groundwater flow. Large cones of depression are a problem because they can cause shallow wells in the immediate vicinity to go dry.

PTS: 1

REF: 13.6. Springs, Water Wells, and Artesian Systems

2. Briefly explain the role of streams in the formation of caverns, and the process by which several levels of vertically connected caves may form.

ANS: Water can percolate into limestone bedrock and cavern systems from surface streams. Streams may connect with a cavern system and disappear beneath the ground. Fluctuating rainfall levels can cause fluctuating groundwater levels, thus forming cavern systems at different depths.

PTS: 1

REF: 13.7. Groundwater Erosion and Deposition

3. How are stalactites different from stalagmites? Why do they typically form in pairs and often merge to form a column?

ANS: Stalactites are dripstone formations shaped like icicles that hang from the roof of a cave. Stalagmites are dripstone formations that project upward from the floor of a cave. They form in pairs because they are from the same dripping source, and the two may continue growing until they merge.

PTS: 1

REF: 13.7. Groundwater Erosion and Deposition

4. Why does the Leaning Tower of Pisa lean? Is it likely to lean so much it will some day fall over?

ANS: One reason the tower leans is groundwater subsidence. It began to lean shortly after construction due to compaction of the ground beneath it. The tilt increased in the 1960s as the community withdrew groundwater from the underlying aquifer. The tower is not likely to fall over because the withdrawal of groundwater is now well regulated and the base of the tower has been stabilized so the tower should stand for several more centuries.

PTS: 1

REF: 13.8. Modification of the Groundwater System and Its Effects

5. What are the health effects of drinking water with high concentrations of arsenic?

ANS: Several types of cancer are linked to arsenic, as are damage to the central and peripheral nervous systems, birth defects. and reproductive problems.

PTS: 1

REF: Geo-Focus. Arsenic and Old Lace

6. What is hard water? How is it found, and what are its negative effects?

ANS: Hard water contains dissolved calcium and magnesium ions. It is found primarily in areas that are underlain by carbonate rocks. The ions precipitate in water pipes, water heaters, and even on glasses and dishes.

PTS: 1

REF: 13.8. Modification of the Groundwater System and Its Effects

SHORT ANSWER 1. What are the three major uses for groundwater?

ANS: irrigation, industry, domestic needs PTS: 1

REF: 13.1. Introduction

2. What are the major problems that exist with, or are related to, groundwater supply?

ANS: ground subsidence, saltwater intrusion, and pollution by landfills, toxic waste, and from agricultural products in runoff PTS: 1

REF: 13.1. Introduction

3. Contrast porosity and permeability.

ANS: Porosity is the percentage of open space within the rock or sediment, while permeability is the capacity of a material for transmitting fluids.

PTS: 1

REF: 13.3. Porosity and Permeability

4. Why are porosity and permeability important when considering groundwater?

ANS: They affect both the amount of groundwater which can be stored within an aquifer and the availability and movement of the groundwater within an aquifer.

PTS: 1

REF: 13.3. Porosity and Permeability

5. Briefly explain how some limestone and other carbonate rocks can have high porosity and permeability.

ANS:

Carbonate rocks may have bedding planes, joints, and solution cavities through which water can move and dissolve rock to make larger pathways.

PTS: 1

REF: 13.3. Porosity and Permeability

6. What factors affect the surface configuration of the water table in an area?

ANS: The water table is affected by rainfall, permeability, and the rate of groundwater movement.

PTS: 1

REF: 13.4. The Water Table

7. Under what conditions will an artesian well flow freely at the surface?

ANS: An artesian well will flow freely if the elevation of ground surface at the well is less than that of the artesian-pressure surface.

PTS: 1

REF: 13.6. Springs, Water Wells, and Artesian Systems

8. Briefly explain why the artesian-pressure surface slopes.

ANS: Friction reduces the pressure of the aquifer water and consequently the level to which artesian water rises.

PTS: 1

REF: 13.6. Springs, Water Wells, and Artesian Systems

9. How can limestone be dissolved by groundwater when it is almost insoluble in pure water?

ANS: Most groundwater naturally contains some carbonic acid and is slightly acidic.

PTS: 1

REF: 13.7. Groundwater Erosion and Deposition

10. What is karst topography?

ANS: The topography of regions underlain by limestone and having numerous rounded surface depressions and caves formed by groundwater erosion.

PTS: 1

REF: 13.7. Groundwater Erosion and Deposition

11. What are some possible consequences of modifications to the groundwater system caused by human usage?

ANS: Possible consequences include lowering of the groundwater table, loss of water pressure, ground subsidence, saltwater encroachment or intrusion, and contamination.

PTS: 1

REF: 13.8. Modification of the Groundwater System and Its Effects

12. What are the most common sources of groundwater contamination?

ANS: sewage, landfills, toxic waste disposal sites, and agriculture PTS: 1

REF: 13.8. Modification of the Groundwater System and Its Effects

13. What causes the subsidence that sometimes accompanies groundwater use?

ANS: As the water is withdrawn from pore spaces in poorly consolidated sedimentary materials, the water pressure between grains is reduced, and the materials become compacted.

PTS: 1

REF: 13.8. Modification of the Groundwater System and Its Effects

14. What is one method that can be used in the construction of a landfill which will make it less likely to contaminate groundwater? Why is this done?

ANS: The site can be lined with an impermeable material such as clay, which will keep fluids from flowing through it.

PTS: 1

REF: 13.8. Modification of the Groundwater System and Its Effects

15. What factors contribute to the high degree of local variability in the amount of groundwater arsenic?

ANS: Groundwater arsenic depends on local geology, type of aquifer, and well depth.

PTS: 1

REF: Geo-Focus. Arsenic and Old Lace

16. In what ways are geysers and undersea hydrothermal vent sites similar?

ANS: Both are powered by water that enters a system of faults and joints from the surface, and then descends to a level where it is superheated under pressure by the surrounding hot rock lying close to a shallow magma chamber.

PTS: 1

REF: 13.9. Hydrothermal Activity

COMPLETION 1. The water stored in the open spaces within underground rocks and unconsolidated material is called ____________________.

ANS: groundwater PTS: 1

REF: 13.2. Groundwater and the Hydrologic Cycle

2. The major source of the water stored as groundwater is ____________________.

ANS: precipitation PTS: 1

REF: 13.2. Groundwater and the Hydrologic Cycle

3. Groundwater is one reservoir of the ____________________ cycle.

ANS: hydrologic PTS: 1

REF: 13.2. Groundwater and the Hydrologic Cycle

4. The percentage of open space within a rock or sediment is known as its ____________________.

ANS: porosity PTS: 1

REF: 13.3. Porosity and Permeability

5. The capacity of a material for transmitting fluids is known as its ____________________.

ANS: permeability PTS: 1

REF: 13.3. Porosity and Permeability

6. A permeable layer that transports water is called a(n) ____________________.

ANS: aquifer PTS: 1

REF: 13.3. Porosity and Permeability

7. An impermeable layer which prevents the passage of groundwater is a(n) ____________________ ANS: aquiclude PTS: 1

REF: 13.3. Porosity and Permeability

8. The boundary between the zone of aeration and the zone of saturation is known as the ____________________.

ANS: water table PTS: 1

REF: 13.3. Porosity and Permeability

9. A place where groundwater flows/seeps out of the ground is a(n) ____________________.

ANS: spring PTS: 1

REF: 13.6. Springs, Water Wells, and Artesian Systems

10. Groundwater under high fluid pressure is called a(n) ____________________ system. It is confined by rock bodies called ____________________.

ANS: artesian, aquicludes PTS: 1

REF: 13.6. Springs, Water Wells, and Artesian Systems

11. During times of drought, the water table ____________________.

ANS: falls

flattens PTS: 1

REF: 13.4. The Water Table

12. Within the zone of saturation, groundwater flows from the region of ____________________ pressure to the region of ____________________ pressure.

ANS: highest, lowest PTS: 1

REF: 13.4. The Water Table

13. The addition of water to the zone of saturation is known as ____________________.

ANS: recharge PTS: 1

REF: 13.4. The Water Table

14. One common, widespread sedimentary rock that is readily dissolved by groundwater is ____________________.

ANS: limestone PTS: 1

REF: 13.7. Groundwater Erosion and Deposition

15. Rounded depressions common in regions having limestone bedrock are known as ____________________.

ANS: sinkholes PTS: 1

REF: 13.7. Groundwater Erosion and Deposition

16. A very large cave or system of interconnected caves is called a(n) ____________________.

ANS: cavern PTS: 1

REF: 13.7. Groundwater Erosion and Deposition

17. A stream that just disappears has flowed ____________________.

ANS: into a sinkhole PTS: 1

REF: 13.7. Groundwater Erosion and Deposition

18. The Leaning Tower of Pisa leans largely because of ____________________.

ANS: subsidence PTS: 1

REF: 13.8. Modification of the Groundwater System and Its Effects

MULTIPLE CHOICE 1. Which of the following is most porous? a. sand

b. c. d. e.

soil gravel silt clay

ANS: E

PTS: 1

REF: 13.3. Porosity and Permeability

2. Which of the following is most permeable? a. sand b. soil c. gravel d. silt e. clay ANS: C

PTS: 1

REF: 13.3. Porosity and Permeability

3. An example of a rock/sediment type which could be an effective aquiclude is ____. a. quartz sandstone b. fractured granite c. gravel d. shale e. graywacke ANS: D

PTS: 1

REF: 13.3. Porosity and Permeability

4. In regions of moderate to high rainfall, the top of a stream is the same as the ____. a. top of the zone of aeration b. top of the zone of saturation c. bottom of the aquifer d. bottom of the zone of aeration e. top of the water table ANS: E

PTS: 1

REF: 13.4. The Water Table

5. What is the average rate of groundwater flow? a. a few kilometers a day b. a few meters a day c. a few centimeters a day d. a few millimeters a day e. imperceptible ANS: C

PTS: 1

REF: 13.5. Groundwater Movement

6. Where does groundwater discharge naturally? a. only in the ocean b. only in springs c. only in streams d. only in aquifers e. wherever the groundwater table intersects the ground surface ANS: E

PTS: 1

REF: 13.6. Springs, Water Wells, and Artesian Systems

7. A local aquiclude within a larger aquifer results in a(n) ____. a. cone of depression b. perched water table c. artesian aquifer

d. zone of aeration e. zone of saturation ANS: B

PTS: 1

REF: 13.6. Springs, Water Wells, and Artesian Systems

8. States in which there is extensive karst topography include which of the following? a. Ohio, Pennsylvania, Virginia, and West Virginia b. Florida, Kentucky, Tennessee, Indiana, and Missouri c. Minnesota, Iowa, Nebraska, and Kansas d. Wyoming, Arizona, Colorado, and Utah e. Michigan, New York, and Ohio ANS: B

PTS: 1

REF: 13.7. Groundwater Erosion and Deposition

9. What conditions are needed for the development of karst topography? a. humid climate b. arid climate c. carbonate bedrock at a shallow depth d. humid climate and carbonate bedrock at a shallow depth e. all of these ANS: D

PTS: 1

REF: 13.7. Groundwater Erosion and Deposition

10. What is the general term for deposits of calcite and/or aragonite within caves? a. stalactites b. stalagmites c. spears d. dripstone e. calcite-stone ANS: D

PTS: 1

REF: 13.7. Groundwater Erosion and Deposition

11. Groundwater erupting from geysers that contain dissolved calcium carbonate will form deposits of what? a. stalactites b. stalagmites c. travertine d. quartz e. sulfides ANS: C

PTS: 1

REF: 13.7. Groundwater Erosion and Deposition

12. Groundwater in an aquifer is sometimes called fossil water because a. the water has been in the aquifer for thousands of years. b. the water is not being replenished at anywhere near the same rate as when it formed. c. tiny microorganisms living in the aquifer are living fossils. d. the water has been in the aquifer for a long time and is not being rapidly replenished.

ANS: D PTS: 1 REF: 13.8. Modification of the Groundwater System and Its Effects 13. What is a natural fountain that intermittently ejects hot water and steam into the air? a. hot spring b. volcano c. hydrothermal vent d. geyser

e. aquiclude ANS: D

PTS: 1

REF: 13.9. Hydrothermal Activity

14. What is the heat source for hydrothermal activity on land? a. earthquake faults b. recent or current volcanic activity c. deep heat in Earth's interior d. earthquake faults and recent or current volcanic activity e. recent or current volcanic activity and deep heat in Earth’s interior ANS: C

PTS: 1

REF: 13.9. Hydrothermal Activity

15. The maximum level of arsenic permitted in drinking water by the U.S. Environmental Protection Agency is a. 10 parts per million b. 10% c. 0.010 parts per million d. 1% ANS: C

PTS: 1

REF: Geo-Focus. Arsenic and Old Lace

TRUE/FALSE 1. Groundwater will move through any rock/sediment or soil that is porous.

ANS: F

PTS: 1

REF: 13.3. Porosity and Permeability

2. Rocks such as limestone, granite, and gneiss cannot be groundwater reservoirs.

ANS: F

PTS: 1

REF: 13.3. Porosity and Permeability

3. By definition, the porosity of rocks/sediments consists of pore spaces between particles/grains.

ANS: T

PTS: 1

REF: 13.3. Porosity and Permeability

4. Most detrital rocks are neither porous nor permeable.

ANS: F

PTS: 1

REF: 13.3. Porosity and Permeability

5. A poorly sorted porous rock/sediment is as permeable as a well-sorted porous rock/sediment.

ANS: F

PTS: 1

REF: 13.3. Porosity and Permeability

6. In hilly country, the groundwater table's highest elevation occurs in stream valleys and around lakes.

ANS: F

PTS: 1

REF: 13.4. The Water Table

7. The zone of saturation extends to an indefinite depth.

ANS: F

PTS: 1

REF: 13.4. The Water Table

8. Caves do not form in marble because it is a dense and hard rock.

ANS: F

PTS: 1

REF: 13.7. Groundwater Erosion and Deposition

9. About 22 percent of all usable water in the United States comes from groundwater.

ANS: T

PTS: 1

REF: 13.2. Groundwater and the Hydrologic Cycle

10. Saltwater incursion occurs primarily along coastlines.

ANS: T PTS: 1 REF: 13.8. Modification of the Groundwater System and Its Effects

Chapter 14—Glaciers and Glaciation ESSAY

1. Why do scientists study glaciers to better understand climate change? What do studies of glaciers contribute to our understanding of current climate trends?

ANS: Glaciers are sensitive to even short-term changes in climate so whether they advance, retreat, or remain stationary is important. Glaciers are retreating and in some cases have nearly or completely disappeared. This means that climate is warming.

PTS: 1

REF: Geo-Focus. Glaciers and Global Warming

2. Explain the origin of varves and their significance in the chronologies of glacial lake deposits.

ANS: Varves are laminated silts and clays that are deposited in glacial lakes and marine waters beneath regions of fluctuating sea ice cover. The darker layers are deposited at the end of the summer season when the summer's life dies and becomes incorporated in the accumulating sediment. The lighter and finer-grained layers are deposited during the winter when the water is still, lacking abundant life, and receiving little sediment. Thus, each light and dark pair represents one year's accumulation.

PTS: 1

REF: 14.6. Glacial Deposits

3. How does the Milankovitch theory explain intermediate-term climatic events like the Pleistocene glaciation? According to Milankovitch, variations in what three parameters of Earth's orbit were responsible for the onset of Pleistocene glaciation?

ANS: According to the Milankovitch theory, there is a 100,000 year cycle of eccentricity (departure from a perfect circle) of Earth's orbit in three areas: the precession of equinoxes, changes in axial tilt, and orbital eccentricity. This affects the amount of solar radiation coming in at different latitudes, sometimes resulting in cooling.

PTS: 1

REF: 14.7. What Causes Ice Ages?

SHORT ANSWER 1. From the human perspective, what climatic effect of the Little Ice Age had the greatest impact?

ANS:

shorter, cooler, and wetter summers PTS: 1

REF: Geo-Insight. The Little Ice Age

2. Under what conditions can glaciers exist in the equatorial latitudes?

ANS: Glaciers can occur even at equatorial latitudes, at high enough elevations.

PTS: 1

REF: 14.2. The Kinds of Glaciers

3. How does the water bound in glaciers eventually re-enter the hydrologic cycle?

ANS: by calving and melt water runoff PTS: 1

REF: 14.3. Glaciers--Moving Bodies of Ice on Land

4. Is ice a mineral? Explain.

ANS: Yes, ice is a mineral. It is a naturally-occurring, inorganic substance with a distinct chemical composition and physical structure.

PTS: 1

REF: 14.3. Glaciers--Moving Bodies of Ice on Land

5. How can the boundary between the zones of accumulation and wastage on a glacier be located during the spring and summer?

ANS: The boundary can be found by locating the firn limit; that is, the elevation to which snow recedes during a wastage season.

PTS: 1

REF: 14.4. The Glacial Budget

6. Why do continental glaciers generally flow more slowly than valley glaciers?

ANS: Continental glaciers are relatively slow because there is little basal meltwater in the high latitudes where they occur, and thus, basal slip is limited.

PTS: 1

REF: 14.4. The Glacial Budget

7. Name some erosional landforms that might help you recognize that a valley had previously been occupied by a valley glacier.

ANS: U-shaped valley trough, truncated spurs, fiords, hanging valleys, cirques, tarns, arêtes, horns PTS: 1

REF: 14.5. Erosion and Sediment Transport by Glaciers

8. What are some of the characteristics of large ice-scoured plains, such as those of the Canadian Shield region?

ANS: Ice-scoured plains have deranged drainage, little or no soil, extensive bedrock exposures, low relief, and numerous lakes and swamps.

PTS: 1

REF: 14.5. Erosion and Sediment Transport by Glaciers

9. How does a fiord form?

ANS: A fiord was a glacier filled valley when sea level was much lower. When glaciers melted and sea level rose the valley was flooded.

PTS: 1

REF: 14.5. Erosion and Sediment Transport by Glaciers

10. Briefly explain how a hanging valley forms.

ANS: A hanging valley forms from the eroded valley of a tributary valley glacier which met the trunk valley glacier at an elevation high above the valley floor of the latter.

PTS: 1

REF: 14.5. Erosion and Sediment Transport by Glaciers

11. Explain how medial moraines develop.

ANS:

Medial moraines develop by the coalescence of two lateral moraines when two glaciers merge.

PTS: 1

REF: 14.5. Erosion and Sediment Transport by Glaciers

12. What are eskers and how do they form?

ANS: Eskers are long, sinuous ridges of stratified drift. They form in tunnels beneath stagnant ice and in meltwater channels on the surface of glaciers.

PTS: 1

REF: 14.6. Glacial Deposits

13. What are dropstones, and what do they indicate?

ANS: Dropstones are gravel- to boulder-sized rocks found in otherwise fine-grained glacial lake deposits. They indicate transport of the rocks into the lake by icebergs that eventually melted, releasing the coarser sediment.

PTS: 1

REF: 14.6. Glacial Deposits

14. Briefly explain the origin of drumlins.

ANS: Drumlins form beneath moving ice that molded glacial drift into a characteristic streamlined shape.

PTS: 1

REF: 14.6. Glacial Deposits

15. What is a possible explanation for long-term variations in Earth's climate?

ANS:

plate tectonic movement of continents PTS: 1

REF: 14.7. What Causes Ice Ages?

COMPLETION 1. The climatic event that began with cooling in about AD 1300 and lasted until the middle 1800s is known as the Little ____________________.

ANS: Ice Age PTS: 1

REF: Geo-Insight. The Little Ice Age

2. An ice mass of compacted and recrystallized snow that flows under its own weight on land is called a(n) ____________________.

ANS: glacier PTS: 1

REF: 14.2. The Kinds of Glaciers

3. The present glacial landscapes mainly formed during the ____________________ Epoch, which lasted from ____________________ years to ____________________ years ago.

ANS: Pleistocene, 1.8 million, 10,000 PTS: 1

REF: 14.1. Introduction

4. When snow thaws and refreezes, which results in a loss of air and pore spaces, the result is ____________________.

ANS: firn PTS: 1

REF: 14.3. Glaciers--Moving Bodies of Ice on Land

5. Glaciers move primarily by ____________________ flow.

ANS: plastic PTS: 1

REF: 14.3. Glaciers--Moving Bodies of Ice on Land

6. The three stages involved in the formation of a glacier are the precipitation of ____________________; the formation of ____________________ by partial thawing, refreezing, and crystallization; and compaction and recrystallization to produce ____________________.

ANS: snow, firn, glacial ice PTS: 1

REF: 14.3. Glaciers--Moving Bodies of Ice on Land

7. The two major types of glaciers are ____________________ and ____________________.

ANS: continental, valley valley, continental PTS: 1

REF: 14.2. The Kinds of Glaciers

8. A glacier that is now longer flowing is called a(n) ____________________ glacier.

ANS: stagnant PTS: 1

REF: 14.4. The Glacial Budget

9. The distal end or edge of the glacier is called its ____________________.

ANS: terminus

PTS: 1

REF: 14.4. The Glacial Budget

10. The zone of ____________________ is the portion of a glacier where additions exceed losses.

ANS: accumulation PTS: 1

REF: 14.4. The Glacial Budget

11. The zone of wastage is the portion of a glacier where ____________________ exceed ____________________.

ANS: losses, accumulation PTS: 1

REF: 14.4. The Glacial Budget

12. In general, rates of glacial flow are greatest in the zone of ____________________.

ANS: accumulation PTS: 1

REF: 14.4. The Glacial Budget

13. The presence of ____________________ in the upper 40 m or so of a glacier indicates that this portion behaves not as a plastic, but as a(n) ____________________ solid.

ANS: crevasses, brittle PTS: 1

REF: 14.3. Glaciers--Moving Bodies of Ice on Land

14. The fine, clay- and silt-sized particles that result from glacial pulverization of rock is known as ____________________.

ANS: rock flour

PTS: 1

REF: 14.5. Erosion and Sediment Transport by Glaciers

15. The Matterhorn in Switzerland is a glacial ____________________ landform known as a(n) ____________________.

ANS: erosional, horn PTS: 1

REF: 14.5. Erosion and Sediment Transport by Glaciers

16. Any sediment deposited as a result of glacial activity is known as glacial ____________________.

ANS: drift PTS: 1

REF: 14.6. Glacial Deposits

17. Finely laminated, alternating light and dark layers of sediment deposited in a glacial lake are known as glacial ____________________.

ANS: varves PTS: 1

REF: 14.6. Glacial Deposits

MULTIPLE CHOICE 1. When did the Pleistocene Ice Age end? a. 1.8 million years ago b. 10,000 years ago c. 1,300 years ago d. 200 years ago e. It still hasn't ended.

ANS: B

PTS: 1

REF: 14.1. Introduction

2. Where is the largest existing glacier located? a. Greenland b. Alaska c. The Alps d. Patagonia e. Antarctica

ANS: E

PTS: 1

REF: 14.2. The Kinds of Glaciers

3. Which is the only continent that does not presently have glaciers? a. South America b. North America c. Africa d. Europe e. Australia

ANS: E

PTS: 1

REF: 14.2. The Kinds of Glaciers

4. A glacier that is unconfined by topography and has tributaries is a a. ice cap. b. tributary glacier. c. continental glacier. d. valley glacier.

ANS: D

PTS: 1

5. In the process of sublimation

REF: 14.2. The Kinds of Glaciers

a. ice melts to become liquid water, which then evaporates. b. fresh snow becomes firn and then glacial ice. c. ice changes directly into water vapor. d. white ice becomes denser so that blue wavelengths are transmitted and scattered and the ice appears blue.

ANS: C

PTS: 1

REF: 14.3. Glaciers--Moving Bodies of Ice on Land

6. A glacier begins to flow when the ice reaches what critical thickness? a. 100 meters b. 40 meters c. 20 meters d. 10 meters e. 5 meters

ANS: B

PTS: 1

REF: 14.3. Glaciers--Moving Bodies of Ice on Land

7. If glacial ice were a rock it would be a(n) _______ rock. a. igneous b. sedimentary c. metamorphic d. glacial ice cannot be a rock

ANS: C

PTS: 1

REF: 14.3. Glaciers--Moving Bodies of Ice on Land

8. A glaciers budget is balanced when a. additions to the zone of accumulation equal losses in the zone of wastage. b. losses in the zone of accumulation equal additions to the zone of wastage. c. the zone of accumulation receives more input than the zone of wastage. d. the zone of wastage does not lose material.

ANS: A

PTS: 1

REF: 14.4. The Glacial Budget

9. In a cross-section of a glacier, where do the greatest flow velocities occur? a. at the surface b. in the few tens of meters below the surface c. in the few tens of meters above the base d. at the base e. in the center of the flow

ANS: B

PTS: 1

REF: 14.4. The Glacial Budget

10. A glacial landform produced primarily by plucking rocks on the downstream side and smoothing by the glacier on the upstream side is called a(n) ____. a. roche moutonnée b. esker c. kame d. terminal moraine e. cirque

ANS: A

PTS: 1

REF: 14.5. Erosion and Sediment Transport by

Glaciers 11. A glacial landform that forms at the head of glacial valleys or troughs is called a(n) ____. a. roche moutonnée b. esker c. kame d. arête e. cirque

ANS: E

PTS: 1

REF: 14.5. Erosion and Sediment Transport by

Glaciers 12. Straight scratches on rock surfaces created by glacial abrasion are known as what? a. rock flour b. glacial striations c. glacial till d. varves e. moraines

ANS: B

PTS: 1

REF: 14.5. Erosion and Sediment Transport by

Glaciers 13. What is a lake formed within a cirque called? a. arête b. esker c. tarn d. fjord e. drumlin

ANS: C

PTS: 1

REF: 14.5. Erosion and Sediment Transport by

Glaciers 14. Glacial till is ____. a. any sediment deposited as a result of glacial activity b. boulders transported long distances and deposited by glaciers c. an elongated spoon-shaped hill that has been shaped by an overriding glacier d. unstratified sediment deposited directly by a glacier e. a lake within an outwash plain.

ANS: D

PTS: 1

REF: 14.6. Glacial Deposits

15. Ice Ages a. have been common through Earth history. b. have glacial episodes separated by very short interglacial stages. c. are caused primarily by plate tectonics. d. are the result of variations in the amount of solar heat received.

ANS: D

PTS: 1

REF: 14.7. What Causes Ice Ages?

TRUE/FALSE 1. The Little Ice Age ended in the mid to late 1800s.

ANS: T

PTS: 1

REF: 14.1. Introduction

2. Glaciers are geologically important because they erode, transport, and deposit so much material.

ANS: T

PTS: 1

REF: 14.1. Introduction

3. Basal slip becomes a more important means of glacier movement in warmer months when more meltwater collects at a glacier's base.

ANS: T

PTS: 1

REF: 14.3. Glaciers--Moving Bodies of Ice on Land

4. A steep-walled, pyramidal peak formed by headward erosion of cirques.

ANS: T Glaciers

PTS: 1

REF: 14.5. Erosion and Sediment Transport by

5. Valleys carved by glaciers are distinctive because they are V-shaped in cross-section.

ANS: F

PTS: 1

REF: 14.5. Erosion and Sediment Transport by

Glaciers 6. A conical hill of stratified drift is an esker.

ANS: F

PTS: 1

REF: 14.6. Glacial Deposits

7. End moraines continue to grow as long as the ice front remains stationary.

ANS: T

PTS: 1

REF: 14.6. Glacial Deposits

8. A strong correlation has been established between periods of intense volcanism and shortterm glacial cooling.

ANS: F

PTS: 1

REF: 14.7. What Causes Ice Ages?

9. Earth’s orbit varies from nearly circular to more elliptical in a roughly 100,000-year cycle.

ANS: T

PTS: 1

REF: 14.7. What Causes Ice Ages?

10. There is good evidence that variation in solar energy, as evinced by sunspot activity cycles, is responsible for short-term climatic variations.

ANS: F

PTS: 1

REF: 14.7. What Causes Ice Ages?

11. The decade from 2000 to 2009 was the hottest on record so far.

ANS: T

PTS: 1

REF: Geo-Focus. Glaciers and Global Warming

Chapter 15—The Work of Wind and Deserts

ESSAY

1. Explain how air masses are set into motion.

ANS: The mechanism is the convection of heat. Air near the ground surface is warmed, becomes less dense and rises, pulling air in from the surrounding region. As the air rises, it cools, and eventually moves outward. It continues to cool until it becomes dense enough to sink. This describes a convection cell.

PTS: 1

REF: 15.5. Air-Pressure Belts and Global Wind Patterns

2. Briefly explain how a rain-shadow desert forms.

ANS: Air masses are forced to rise over mountains. As they do, they cool and moisture condenses and falls as precipitation. Upon descending the lee side of the mountain range, this air mass is dry. It heats and its aridity causes increased evaporation.

PTS: 1

REF: 15.6. The Distribution of Deserts

3. Briefly explain how mesas and buttes form.

ANS: A nearly horizontal resistant layer of rock is breached by weathering and erosion, allowing the underlying less resistant layers to be rapidly eroded. The flat-topped steep-sided erosional remnants are mesas, and further erosion leaves the pillar-like structures called buttes.

PTS: 1

REF: 15.8. Desert Landforms

SHORT ANSWER 1. What are some of the human-caused factors that may be initiators of desertification?

ANS: Factors include clearing of natural vegetation for crops/firewood, overgrazing, drilling water wells and irrigation, soil salinization, and overpopulation.

PTS: 1

REF: 15.1. Introduction

2. Besides deserts, where is the wind a significant geologic agent?

ANS: Wind is significant anyplace where exposure of sediment and soil is widespread, such as on shorelines and plains.

PTS: 1

REF: 15.2. Sediment Transport by Wind

3. Explain how wind can be a significant intercontinental agent of erosion and deposition.

ANS: Wind can lift silt- and clay-sized particles high into the atmosphere and transport this material large distances.

PTS: 1

REF: 15.2. Sediment Transport by Wind

4. Briefly explain why sand is moved by wind before clay and silt during wind erosion.

ANS: Sand grains protrude above the surface and are more easily caught by the wind, while clay and silt grains lie closer to the surface where there is a stationary layer of air, unless this is disturbed.

PTS: 1

REF: 15.2. Sediment Transport by Wind

5. What are deflation hollows?

ANS: Deflation hollows are shallow depressions created by differential wind erosion of surface materials.

PTS: 1

REF: 15.3. Wind Erosion

6. What factors affect the type of dune that forms?

ANS: Factors include vegetation coverage, direction and velocity of wind, and the amount of available sand.

PTS: 1

REF: 15.4. Wind Deposits

7. What are the four major dune types generally recognized?

ANS: barchan, longitudinal, transverse, parabolic PTS: 1

REF: 15.4. Wind Deposits

8. Briefly explain why there are extensive deposits of loess in China, Mississippi Valley, and north-central states of the United States.

ANS: The source for the loess deposits in China are the extensive deserts in Central Asia. The loess deposits of the Mississippi Valley and north-central states are derived from glacial outwash deposits.

PTS: 1

REF: 15.4. Wind Deposits

9. Briefly explain how the geological conditions that produced and deposited loess have determined the sites of the world's major grain belts.

ANS: Because loess derived soils are some of the most fertile in the world, the locations where large loess deposits have occurred have developed into some of the most productive farmland.

PTS: 1

REF: 15.4. Wind Deposits

10. Equatorial regions receive the most heat, while polar regions receive the least. Therefore, what air pressures would you expect to be characteristic of these regions?

ANS: low pressures in the equatorial regions, high pressures in the polar regions PTS: 1

REF: 15.5. Air-Pressure Belts and Global Wind Patterns

11. What can lithified sand dunes tell us?

ANS: Dunes indicate that they were deposited by wind, and they reflect the direction of prevailing winds when they were deposited.

PTS: 1

REF: 15.4. Wind Deposits

12. Briefly explain why most deserts develop in the mid-latitude, dry climate zone.

ANS: It is at this latitude that high pressure ridges form, and as air that is already dry descends, it becomes warmer, causing increased evaporation.

PTS: 1

REF: 15.5. Air-Pressure Belts and Global Wind Patterns

13. What are some of the ways in which desert plants have adapted to the conditions in which they live?

ANS: Some have widespread and shallow root systems, stems and leaves are usually hard and waxy, and many have the ability to lie dormant for long periods between rainfalls.

PTS: 1

REF: 15.7. Characteristics of Deserts

14. How is rock/desert varnish produced?

ANS: This varnish is produced by windblown iron and manganese dust or precipitates of microorganisms.

PTS: 1

REF: 15.7. Characteristics of Deserts

15. What type of weathering is dominant in deserts, and why?

ANS: Mechanical weathering is dominant because the agents of mechanical weathering, such as water and vegetation, are less abundant than in other climatic regions.

PTS: 1

REF: 15.7. Characteristics of Deserts

16. What factors enhance water erosion in deserts?

ANS: Erosion is enhanced by little vegetation cover and the inability of dry sparse soil and regolith to rapidly absorb water.

PTS: 1

REF: 15.7. Characteristics of Deserts

17. Since most deserts have internal drainage, why are there through-flowing streams such as the Nile, Niger, Indus, Colorado Rivers in some deserts?

ANS: The headwaters of these rivers are outside the desert, and there is enough water to compensate for losses by evaporation and infiltration.

PTS: 1

REF: 15.7. Characteristics of Deserts

18. Why are flash floods and sheet flows common in deserts?

ANS: The lack of vegetation, relative lack of soil, abundance of regolith, and hardness of the soil surface prevents water from filtering into the soil.

PTS: 1

REF: 15.7. Characteristics of Deserts

19. How does the topography of the water table in deserts with through-flowing streams result in the restriction of much of the vegetation to the stream banks?

ANS: Water tables in deserts tend to be located at great depth and not associated with streams. Very limited infiltration of water from streams does, however, allow a zone of vegetation to develop along stream valleys.

PTS: 1

REF: 15.7. Characteristics of Deserts

20. Explain the ways in which alluvial fans and deltas are similar.

ANS: Both are deposited by running water that abruptly encounters a dramatic reduction in velocity, and both spread laterally as a fan-shaped deposit.

PTS: 1

REF: 15.8. Desert Landforms

21. Briefly explain how a pediment is formed.

ANS: Pediments are erosional features developed on bedrock, formed in association with gradual erosion of mountains by streams and sheet flooding and subsequent burial of their remnants in the eroded sediment.

PTS: 1

REF: 15.8. Desert Landforms

22. Why are large alluvial fan deposits of importance to human residents of deserts?

ANS: They can be a source of otherwise scarce groundwater, and the outer edges can have soil for farming.

PTS: 1

REF: 15.8. Desert Landforms

COMPLETION 1. The transformation of formerly productive lands into deserts is called ____________________.

ANS: desertification PTS: 1

REF: 15.1. Introduction

2. The size of material that is frequently carried as suspended load by wind is ____________________ and ____________________.

ANS: silt, clay clay, silt

PTS: 1

REF: 15.2. Sediment Transport by Wind

3. Stones whose polished, pitted, faceted surfaces have been produced by wind erosion are called ____________________.

ANS: ventifacts PTS: 1

REF: 15.3. Wind Erosion

4. Although loess forms in only a few environments, it covers approximately ______ percent of Earth's land surface.

ANS: 10 PTS: 1

REF: 15.4. Wind Deposits

5. Air flows from ____________________ pressure regions to ____________________ pressure regions.

ANS: high, low PTS: 1

REF: 15.5. Air-Pressure Belts and Global Wind Patterns

6. The deflection of a moving mass from a straight line is known as ____________________.

ANS: Coriolis effect PTS: 1

REF: 15.5. Air-Pressure Belts and Global Wind Patterns

7. The Coriolis effect causes winds to be deflected to the ____________________ of their direction of motion in the Northern Hemisphere and to the ____________________ of their direction of motion in the Southern Hemisphere.

ANS: right, left PTS: 1

REF: 15.5. Air-Pressure Belts and Global Wind Patterns

8. High pressure troughs exist where cooler, denser air begins to descend at about ______ to ______ degrees latitude, N and S. ANS: 20, 30 PTS: 1

REF: 15.5. Air-Pressure Belts and Global Wind Patterns

9. Deserts receive less than ______ centimeters of rain per year, on average.

ANS: 25 PTS: 1

REF: 15.6. The Distribution of Deserts

10. The drainage characteristic of most deserts, in which streams dry up and do not have enough water to become integrated and reach outside their drainage areas, is called ____________________ drainage.

ANS: internal PTS: 1

REF: 15.7. Characteristics of Deserts

11. The most effective agent of erosion in the deserts is ____________________.

ANS: water PTS: 1

REF: 15.7. Characteristics of Deserts

12. A saline, temporary lake in a desert is known as a(n) ____________________ lake.

ANS: playa PTS: 1

REF: 15.8. Desert Landforms

13. A playa forms by ____________________ of a playa lake.

ANS: evaporation PTS: 1

REF: 15.8. Desert Landforms

14. Alluvial fans are composed of sediment that is ______-sorted and ____________________ stratified.

ANS: un, poorly PTS: 1

REF: 15.8. Desert Landforms

15. Crescent shaped dunes whose tips point downward are _______ dunes.

ANS: barchan PTS: 1

REF: 15.4. Wind Deposits

MULTIPLE CHOICE 1. How much land area is converted to deserts globally each year? a. 10,000 square kilometers b. 25,000 square kilometers c. 40,000 square kilometers d. 55,000 square kilometers e. 70,000 square kilometers

ANS: E

PTS: 1

REF: 15.1. Introduction

2. What is the size of particles that are usually the first to be set in motion by wind? a. silt b. clay c. sand d. pebbles e. boulders

ANS: C

PTS: 1

REF: 15.2. Sediment Transport by Wind

3. During sandstorms, how high can sand be lifted into the air? a. a few inches b. about one foot c. about three feet d. about 10 feet e. hundreds of feet.

ANS: C

PTS: 1

REF: 15.2. Sediment Transport by Wind

4. What does wind erode by? a. saltation b. abrasion c. deflation d. saltation and abrasion e. abrasion and deflation

ANS: E

PTS: 1

REF: 15.2. Sediment Transport by Wind

5. What are elongated, streamlined rock ridges in wind-dominated erosional areas called?

a. ventifacts b. barchan dunes c. longitudinal dunes d. yardangs e. desert pavement

ANS: D

PTS: 1

REF: 15.3. Wind Erosion

6. The close-fitting mosaic of pebbles, cobbles, and boulders covering the floor of many deserts and semi-arid regions is called what? a. ventifacts b. desert pavement c. longitudinal dunes d. yardangs e. barchan dunes

ANS: B

PTS: 1

REF: 15.3. Wind Erosion

7. What are windblown deposits of silt and clay called? a. dunes b. loess c. ventifacts d. yardangs e. till

ANS: B

PTS: 1

REF: 15.4. Wind Deposits

8. Loess is important because it ____. a. is an important source of building material b. is rich in important ore deposits

c. sometimes contains petroleum d. makes fertile soil e. is an important source of groundwater

ANS: D

PTS: 1

REF: 15.4. Wind Deposits

9. Which are the most mobile dunes? a. longitudinal b. transverse c. barchan d. parabolic e. none of these

ANS: C

PTS: 1

REF: 15.4. Wind Deposits

10. Dunes that form when vegetation cover is broken by deflation and the dune tips point upwind are ____. a. longitudinal b. transverse c. barchan d. parabolic e. none of these

ANS: D

PTS: 1

REF: 15.4. Wind Deposits

11. Loess a. must be stabilized by moisture and vegetation. b. is most common in desert regions. c. is very fine-grained and bad for crops. d. all of these.

ANS: A

PTS: 1

REF: 15.4. Wind Deposits

12. What is Coriolis effect caused by? a. wind shear between water and the atmosphere b. the axial tilt of the Earth c. the rotation of the Earth d. differences in air pressure in different regions e. Milankovitch cycles

ANS: C

PTS: 1

REF: 15.5. Air-Pressure Belts and Global Wind

Patterns 13. Deserts mostly occur at ____ latitudes. a. low b. middle c. high d. low and middle e. middle and high

ANS: D

PTS: 1

REF: 15.5. Air-Pressure Belts and Global Wind

Patterns 14. What is a common mode of mass wasting in deserts? a. mud flows b. rock fall c. creep d. slumps e. slides

ANS: A

PTS: 1

REF: 15.7. Characteristics of Deserts

15. A broad alluvial apron formed by the coalescence of alluvial fans is called a(n) ____. a. alluvium b. bajada c. playa d. plain e. pediment

ANS: B

PTS: 1

REF: 15.8. Desert Landforms

16. Fan-shaped landforms that develop in deserts adjacent to highlands are known as ____ fans. a. alluvial b. bajada c. playa d. plain e. pediment

ANS: A

PTS: 1

REF: 15.8. Desert Landforms

17. What is an isolated mountain that rises from the flat plain of a desert called? a. mesa b. butte c. inselberg d. drumlin e. yardang

ANS: C

PTS: 1

REF: 15.8. Desert Landforms

TRUE/FALSE 1. All dunes originate in desert conditions.

ANS: F

PTS: 1

REF: 15.4. Wind Deposits

2. Although loess may originate in deserts, it is not deposited in them.

ANS: T

PTS: 1

REF: 15.4. Wind Deposits

3. All dunes have crests oriented perpendicular to the direction of wind movement.

ANS: F

PTS: 1

REF: 15.4. Wind Deposits

4. Sand covers approximately 75 percent of the world's deserts.

ANS: F

PTS: 1

REF: 15.7. Characteristics of Deserts

5. The water table in deserts with through-flowing streams slopes toward the streams.

ANS: F

PTS: 1

REF: 15.7. Characteristics of Deserts

6. The major topographic features of western United States deserts formed in the last 8,000 years.

ANS: F

PTS: 1

REF: 15.7. Characteristics of Deserts

7. Deserts are the one environment where wind erosion is more important than water erosion.

ANS: F

PTS: 1

REF: 15.7. Characteristics of Deserts

8. Wind is as effective an agent of landform creation, as is water.

ANS: F

PTS: 1

REF: 15.7. Characteristics of Deserts

9. Surface creep is a common type of mass wasting in deserts.

ANS: F

PTS: 1

REF: 15.7. Characteristics of Deserts

10. The same geological agents work in all deserts, so landforms of various deserts are similar.

ANS: F

PTS: 1

REF: 15.8. Desert Landforms

11. The finest-grained material in an alluvial fan is found along its margins.

ANS: T

PTS: 1

REF: 15.8. Desert Landforms

12. Alluvial fan sediment is deposited by flashflood, sheetflow, mudflow, and debris flow.

ANS: T

PTS: 1

REF: 15.8. Desert Landforms

Chapter 16—Oceans, Shorelines, and Shoreline Processes

ESSAY 1. List the primary ways that oceanographers learn about the seafloor and briefly explain each.

ANS: Echo sounding is a technique in which sound waves are used to create a topographic map of the seafloor. Seismic profiling is similar but uses strong waves from an energy source to create the picture. Sampling can be done by sending down a piece of equipment to pick up rocks or by sending people down in a submersible to observe and pick up samples. Direct observation can be done by sending people down or by sending a remotely operated vehicle down, which has a camera and sampling ability.

PTS: 1

REF: 16.2. Exploring the Oceans

2. Explain how a seismic profile is created and what types of information it provides.

ANS: Strong waves from an energy source are emitted from a research ship. These waves that reflect from the surfaces of rock layers are recorded as they return. The seismic wave velocity and magnitude data are used to construct a computerized image of the rock sequence that lies below the seafloor. This profile shows the differing properties of the rock layers such as thicknesses, extents, dips, attitudes, and internal structure.

PTS: 1

REF: 16.2. Exploring the Oceans

3. What two phenomena cause the tides? Which of these is stronger, and why?

ANS: The tides are caused by the gravitational attraction of the moon and sun on the ocean surface.

The moon exerts a stronger force because although the sun is 27 million times more massive than the moon, it is 390 times as far from Earth. Consequently, the sun exerts a tidegenerating force only 46 percent as strong as the Moon's.

PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

4. Briefly explain how the functions and locations of groins and jetties differ.

ANS: A groin is a structure built at right angles to the shore to widen a beach by inducing deposition or to prevent erosion. A jetty is a seaward projecting structure designed to prevent closing of a bay entrance by deposition by longshore currents.

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

5. What caused the bulk of the damage that was done by Hurricane Katrina to the City of New Orleans? Why was New Orleans so vulnerable?

ANS: Parts of New Orleans were built well below sea level since the city was built on swampy, subsiding land. The city was (and is) protected by a system of levees. Hurricane Katrina did not do the bulk of the damage directly, rather it caused the levees to break, which allowed water to flood the city. The pumps were overwhelmed and were useless when the city lost electrical power.

PTS: 1

REF: 16.7. The Perils of Living Along a Shoreline

6. Briefly explain what the effects of rising sea level are on the barrier islands along the United States coastlines, and why coastal communities are concerned.

ANS: Rising sea levels cause erosion, shoreward migration of barrier islands, and even submergence of barrier islands. This is of concern because so many expensive properties are located on barrier islands, and barrier islands protect the mainland from erosion and flooding and are a part of the natural coastal wetland habitat.

PTS: 1

REF: 16.7. The Perils of Living Along a Shoreline

SHORT ANSWER 1. What is the difference between a fringing reef and a barrier reef?

ANS: A fringing reef is one that is solidly attached to the margins of an island or continent, while a barrier reef is separated from a landmass by a lagoon.

PTS: 1

REF: 16.3. Seawater and Oceanic Circulation

2. What path do water particles in a wave ideally follow?

ANS:

They move in circular paths with little or no net movement.

PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

3. What is wave base, and how deep is it?

ANS: Wave base is the depth at which wave-generated movement of water particles is essentially zero; it is reached at a depth equal to one-half the wave length.

PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

4. How are most waves generated?

ANS: Most waves are generated by wind blowing over the water surface.

PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

5. How does wave behavior on lakes differ from that of seas?

ANS: Lakes have waves only when winds blow, whereas oceans have residual wave activity.

PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

6. Why are waves in ponds and lakes smaller than those in oceans?

ANS: Winds blow over a greater distance in the ocean; that is, they have a larger fetch and can generate larger waves.

PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

7. Why do waves bend or refract as they approach shorelines?

ANS: Waves rarely approach parallel to a shore, and therefore, one portion of a wave will reach wave base before another.

PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

8. In what direction do longshore currents flow?

ANS: Longshore currents flow in the same direction as the approaching waves and parallel to the shoreline.

PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

9. What three factors interact to create rip currents?

ANS: wave refraction, longshore currents, and surf zone backwash PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

10. Briefly explain how longshore and rip currents are related.

ANS: Rip currents are formed by the combined outward flow of water from opposing longshore currents.

PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

11. If you were caught in a rip current, how would you attempt to reach shore?

ANS: Swim parallel to shore a short distance before swimming toward shore.

PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

12. What are some depositional features of shorelines?

ANS: beaches, spits, baymouth bars, barrier islands PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

13. What determines the characteristics of beaches?

ANS: The characteristics of beaches are determined by wave energy. Beaches are modified by waves and longshore currents.

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

14. What provides most of the sediment of a beach?

ANS: Longshore currents moving sediment in the nearshore zone.

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

15. Give a possible reason why beach residents might construct a groin on a beach. What is a probable negative effect of such a construction?

ANS:

A groin would be constructed to widen the beach and to prevent erosion of the beach. The downside is that there would be erosion on the downcurrent side of the groin.

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

16. What are the most important reasons for changes in beach profiles?

ANS: Beach profiles change due to seasonal variations in wave energy and storms.

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

17. How does the budget or volume of sand on a given beach change through the year?

ANS: The volume remains more or less constant by sand moving from offshore bars in winter to the foreshore in summer.

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

18. Under what conditions do barrier islands form?

ANS: Barrier islands form where sand is abundant and wave energy and tidal range are low.

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

19. What are two models that may explain the formation of barrier islands?

ANS: Barrier islands may be formed from the separation of spits from the mainland or from beach ridges on subsiding coasts.

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

20. What is one major problem for residents on barrier islands?

ANS: The islands are migrating landward.

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

21. Briefly explain how a tombolo forms.

ANS: A tombolo forms on the shoreward side of an island as wave refraction around the island creates converging currents that turn seaward and deposit a sandbar.

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

22. What are two ways (one natural and one human-induced) in which the sediment budget of a coastline can become negative?

ANS: The sediment source could be eliminated by rising sea level, a change in shoreline topography, or a change in drainage pattern. Human-made dams across streams which feed sediment to the shore can starve a shoreline of sediment.

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

23. What characteristics along a seacoast indicate that erosion predominates over deposition?

ANS: When erosion predominates over deposition, beaches are lacking or poorly developed and sea cliffs erode.

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

24. How are sea cliffs eroded?

ANS: Seacliffs are eroded by corrosion or chemical weathering, hydraulic action, and abrasion.

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

25. How do marine terraces form?

ANS: They are old wave-cut platforms that have been elevated above sea level.

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

26. What is a wave-cut platform, and how does one develop?

ANS: A wave-cut platform is the gently seaward-sloping beveled surface that has resulted from the undercutting and retreat of a sea cliff.

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

27. Briefly explain how sea level could fall in one region while it is generally rising elsewhere.

ANS: Sea level can be generally rising while regional tectonic uplift or glacial eustatic rebound causes the local sea level to fall.

PTS: 1

REF: 16.6. Types of Coasts

28. What are the two factors that control the absolute rate of sea level rise in a particular shoreline?

ANS: The two factors are the volume of water in the ocean basins and the rate of subsidence or uplift of the coastal area.

PTS: 1

REF: 16.7. The Perils of Living Along a Shoreline

29. How would a country such as Bangladesh be affected by a 2 m rise in sea level?

ANS: As much as 20 percent of the country would be under water, causing the refugee migration of many millions of people. The remaining land area would be susceptible to storm-generated flooding.

PTS: 1

REF: 16.7. The Perils of Living Along a Shoreline

30. What options do geologists and engineers have in combating the effects of rising sea level?

ANS: Options include building sea walls, restoring beaches by moving sand, building groins and jetties to reduce erosion rates, constructing onshore features to prevent shoreline erosion, and preventing development of shoreline properties.

PTS: 1

REF: 16.7. The Perils of Living Along a Shoreline

31. Why must shoreline government officials understand the geologic processes of shorelines?

ANS: Shoreline communities must realize that shorelines are dynamic environments that are constantly changing as the result of several interacting processes, which may or may not be modified to minimize the detrimental effects of change.

PTS: 1

REF: 16.7. The Perils of Living Along a Shoreline

COMPLETION 1. A(n) ____________________ is the location where land meets the sea; a(n) ____________________ is the same, in addition to the land both seaward and landward of it.

ANS: shoreline, coast PTS: 1

REF: 16.1. Introduction

2. Shoreline erosion is common in many parts of the world, in part because sea level is ____________________.

ANS: rising PTS: 1

REF: 16.1. Introduction

3. The apparent deflection of a moving object from its anticipated course resulting from Earth's rotation is called _______ _______.

ANS: Coriolis effect PTS: 1

REF: 16.3. Seawater and Oceanic Circulation

4. The rising tide is also known as the ____________________ tide. The falling tide is known as the ____________________ tide.

ANS: flood, ebb PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

5. Tidal ranges are lowest where the sea bottom slope is _______ in slope and the inlet is _______ in width and are highest where the slope is _______ in slope and the inlet is _______ in width.

ANS: gradual, wide, steep, narrow PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

6. Orbiting molecules of water in a wave touch the sea or lake floor at the depth of the ____________________.

ANS: wave base PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

7. The ____________________ of a wave is the time necessary for two successive ____________________ or ____________________ to pass.

ANS: period, crests, troughs PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

8. The velocity of a wave is calculated as the ____________________ multiplied by the ____________________.

ANS: wavelength, period PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

9. Regularly-sized waves with long, rounded crests are known as ____________________.

ANS: swells

PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

10. Energy is transferred from wind to water to create waves by ____________________.

ANS: friction PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

11. When wave base is reached, wave velocity and wave _______ decrease, while wave _______ increases.

ANS: length, height PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

12. The two important types of near shore currents are ____________________ currents and ____________________ currents.

ANS: longshore, rip PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

13. The zone that extends to just beyond where the waves break is called the ____________________ zone.

ANS: nearshore PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

14. The bending of waves toward shore as they approach from an oblique angle is called wave ____________________.

ANS: refraction

PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

15. A structure built perpendicular to shore to enlarge a beach or prevent erosion is a(n) ____________________.

ANS: groin PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

16. A spit that has lengthened until it closes the mouth of a bay is a(n) ____________________.

ANS: baymouth bar PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

17. If hydraulic action and abrasion undercut headlands, structures known as ____________________ may form. When these join they form a(n) ____________________, which might later collapse to give a(n) ____________________.

ANS: sea caves, sea arch, sea stack PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

18. Wave-cut platforms along northern coastlines of North America and the Great Lakes are exposed as the result of ____________________.

ANS: isostatic rebound PTS: 1 MULTIPLE CHOICE

REF: 16.6. Types of Coasts

1. Scientists today calculate the depth to the seafloor using a. the time it takes for sound waves to travel from a ship to the seafloor and back. b. seismic waves that reflect from the seafloor. c. a very long line with a weight attached. d. trips to the seafloor in modern submersibles.

ANS: A

PTS: 1

REF: 16.2. Exploring the Oceans

2. Salinity of seawater is a measure of a. the total sodium and chloride. b. the total quantity of dissolved solids. c. the trace elements. d. the sodium and chlorine.

ANS: B

PTS: 1

REF: 16.3. Seawater and Oceanic Circulation

3. Geologic evidence suggests that oceans were present by at least a. 4.6 billion years ago. b. 3.5 billion years ago. c. 4.6 million years ago. d. 1.5 billion years ago.

ANS: B

PTS: 1

REF: 16.3. Seawater and Oceanic Circulation

4. Most of the chemical elements in seawater come from a. outgassing. b. ocean life. c. the seafloor. d. the continents.

ANS: C

PTS: 1

REF: 16.3. Seawater and Oceanic Circulation

5. The aphotic zone is a. a thin layer, about 100 m or less. b. organic substances rain down from the photic zone. c. where plants receive enough light to photosynthesize. d. all of these.

ANS: B

PTS: 1

REF: 16.3. Seawater and Oceanic Circulation

6. Vertical ocean circulation, in which water moves from deep to shallow, is called a. surface currents. b. deep currents. c. downwelling. d. upwelling.

ANS: D

PTS: 1

REF: 16.3. Seawater and Oceanic Circulation

7. Spring tides are tides ____. a. that result from the combined gravitational force of the aligned Moon and Sun b. that occur when the Sun and Moon are disposed at right angles to one another c. that occur in springtime when floodwaters are high d. with a relatively small range e. that are high only once per day

ANS: A

PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

8. Water in waves is displaced from the circular orbits when ____. a. waves enter progressively shallower water

b. seas become swells c. waves reach great heights d. waves reach great lengths e. winds reach a critical velocity

ANS: A

PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

9. The distance wave-producing winds blow over a continuous body of water is the ____. a. wavelength b. trough c. height d. fetch e. velocity

ANS: D

PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

10. What are narrow surface currents that flow in the same general direction as the approaching waves? a. rip currents b. nearshore currents c. longshore currents d. upwelling currents e. refraction currents

ANS: A

PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

11. A deposit of unconsolidated sediment that extends landward from low tide to a change in topography or to where permanent vegetation begins is a(n) ____. a. spit b. tombolo

c. barrier island d. beach e. baymouth bar

ANS: D

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

12. A beach with a small berm, coarser sediment, and offshore sand bars is a(n) ____. a. summer beach b. winter beach c. high energy beach d. tide-dominated beach e. sediment-poor beach

ANS: B

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

13. What is a spit that connects an island to the mainland called? a. hook b. tombolo c. barrier island d. beach e. baymouth bar

ANS: B

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

14. Sediment is lost from the nearshore zone by ____. a. wind erosion b. deposition into submarine canyons c. offshore transport d. deposition into submarine canyons and offshore transport e. All of these

ANS: E

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

15. What is a coast that is straight and has marine terraces called? a. depositional coast b. erosional coast c. submergent coast d. emergent coast e. none of these

ANS: D

PTS: 1

REF: 16.6. Types of Coasts

16. The amount of oil from U.S. production that comes from the Gulf of Mexico is a. 10% b. 30% c. 65% d. 100%

ANS: B

PTS: 1

REF: Geo-Focus. The Deepwater Horizon Oil Spill

TRUE/FALSE 1. Ocean currents move in the direction of local winds.

ANS: F

PTS: 1

REF: 16.1. Introduction

2. The saltiness of seawater has been a state of dynamic equilibrium for at least 1.5 billion years.

ANS: T

PTS: 1

REF: 16.3. Seawater and Oceanic Circulation

3. The diameter of a water molecule orbit increases with depth until the wave reaches the seafloor.

ANS: F

PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

4. Wave size depends entirely on wind velocity and duration.

ANS: F

PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

5. Rip currents commonly develop in regions where wave heights are highest.

ANS: F

PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

6. Rip currents tend to develop over regions where the sea/lake floor is slightly deeper.

ANS: T

PTS: 1

REF: 16.4. Shorelines and Shoreline Processes

7. Winter beach profiles can actually develop during any season.

ANS: T

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

8. By definition, beaches are composed of sand.

ANS: F

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

9. Nearly all beach sand is quartz.

ANS: F

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

10. Barrier islands migrate landward.

ANS: T

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

11. Spits, baymouth bars, and tombolos form only along ocean shores because lakes have insufficient supplies of sand.

ANS: F

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

12. The most effective means of sea cliff erosion is hydraulic action.

ANS: T

PTS: 1

REF: 16.5. Erosion and Deposition Along Shorelines

13. During the past century, sea level has risen 12 centimeters.

ANS: T

PTS: 1

REF: 16.7. The Perils of Living Along a Shoreline

Chapter 17—Geologic Time: Concepts and Principles

ESSAY 1. What is the principle of uniformitarianism? Why does the principle of uniformitarianism lead to the conclusion that Earth's age is great?

ANS: Present-day processes have operated throughout geologic time; the laws of physics, chemistry, and biology have operated throughout geologic time. Geologists can observe that the processes which are currently shaping, and previously shaped, Earth occur very slowly or infrequently and cannot be accommodated by an historic time scale.

PTS: 1

REF: 17.4. James Hutton and the Recognition of Geologic Time

2. What is the principle of superposition, and what is its importance? Who is credited with discovering it?

ANS:

In an undisturbed succession of sedimentary rocks, the oldest layer is at the bottom and the youngest is at the top. This principle, discovered by Nicholas Steno, is the basis for determining relative ages of strata and their contained fossils.

PTS: 1

REF: 17.5. Relative Dating Methods

3. What is the principle of fossil succession, and what is its importance? Who is credited its discovery?

ANS: The principle of fossil succession states that fossil assemblages succeed one another through time in a regular and predictable order and was recognized by William Smith. This principle allows correlation of rock units, by relative age, from one area to another.

PTS: 1

REF: 17.5. Relative Dating Methods

4. How are zones of rocks that are deposited during equivalent time intervals constructed using fossil assemblages?

ANS: Because an assemblage of fossils occurring over a large region can be taken to represent a period of time during which each species was contemporaneous, the rock units in which these assemblage range zones occur represent rock formed of sediments deposited during the interval of time over which the species in question existed.

PTS: 1

REF: 17.5. Relative Dating Methods

5. Why is it necessary to employ lithologic and fossil correlation to establish a relative sequence of geologic time?

ANS:

Most bodies of rock cannot be recognized as having been deposited during a short interval in geologic time in which the upper and lower surfaces of the rock body were contemporaneously deposited everywhere. The overlapping geologic ranges of fossil species allow definition of time intervals because each species is unique and had a definite duration.

PTS: 1

REF: 17.5. Relative Dating Methods

6. What types of deposits are considered marker beds? What is the importance of a marker bed?

ANS: Marker beds include unusual lithologies such as bedded chert, evaporites, conglomerates, volcanic ashes, lava flows, turbidites, or any lithology that has unique features, such as caves or concretions, or was deposited in a very brief period of time. Marker beds are important because they can be used for correlation.

PTS: 1

REF: 17.8. Development of the Geologic Timescale

7. Describe how stalagmites are used to reconstruct past climate.

ANS: Stalagmites are made of calcium carbonate. The oldest layers are on the inside of the stalagmite and the layers get progressively younger toward the outside. Uranium-234 sometimes substitutes for calcium. It decays to Th-230 at a known rate so the layer of the stalagmite can be radiometrically dated. Oxygen-16 is lighter than oxygen-18 so it evaporates more easily. As climate warms and evaporation increases more O-16 evaporates and the O18/O16 ratio rises. Temperature can then be correlated with age to reconstruct past temperatures.

PTS: 1

REF: 17.10. Geologic Time and Climate Change

SHORT ANSWER 1. How does relative dating differ from absolute dating?

ANS: Relative dating involves placing events in a sequential order. Absolute dating results in specific dates for events, expressed in years before the present.

PTS: 1

REF: 17.2. How Geologic Time is Measured

2. Why was Lord Kelvin's argument for the age of Earth fundamentally in error?

ANS: He assumed that Earth cooled from a molten state, and he did not know about Earth's internal heat source  radioactivity.

PTS: 1

REF: 17.4. James Hutton and the Recognition of Geologic Time

3. What are the six fundamental geologic principles which are used in relative dating?

ANS: superposition, original horizontality, lateral continuity, cross-cutting relationships, inclusions, fossil succession PTS: 1

REF: 17.5. Relative Dating Methods

4. How does the sequence of events differ between an angular unconformity and a disconformity?

ANS: An angular unconformity involves not only uplift resulting in erosion but also the tilting of originally horizontal strata. Such tilting does not occur in the production of a disconformity.

PTS: 1

REF: 17.5. Relative Dating Methods

5. A clast of granite taken from a conglomerate is determined by radiometric dating to be one hundred million years old. What, if anything, does this tell you about the age of the conglomerate?

ANS: The sedimentary rock is less than 100 million years old.

PTS: 1

REF: 17.5. Relative Dating Methods

6. What criteria are used to correlate rock units in different areas?

ANS: similar lithology, similar position in a sequence, fossil assemblages PTS: 1

REF: 17.6. Correlating Rock Units

7. What are the requirements for a useful guide fossil?

ANS: A guide fossil should be easily identified, geographically widespread, and should be from an organism that existed for a relatively short period of geologic time.

PTS: 1

REF: 17.6. Correlating Rock Units

8. Explain why correlation by fossils is necessary to demonstrate time equivalence of strata.

ANS: Each life form is indicative of a specific interval of geologic time.

PTS: 1

REF: 17.6. Correlating Rock Units

9. What is the goal of subsurface correlation techniques that is used in the search for oil and gas?

ANS: Subsurface correlation techniques correlate rock units in regions where they are not exposed at the surface. They can be used to discover structural disturbances or facies that are likely to contain fossil fuels.

PTS: 1

REF: 17.6. Correlating Rock Units

10. What are seismic profiles?

ANS: Seismic profiles are graphic displays of the return arrival times and strengths of explosive device-created sound waves that reflect differentially from rock layers of differing properties.

PTS: 1

REF: 17.6. Correlating Rock Units

11. Earlier Precambrian rocks could not be correlated over great distances from one area to another (e.g., from Canada to Europe) but younger rocks were correlated in the same areas with a high degree of confidence. Why was this?

ANS: The Precambrian rocks lack fossils which can be used for correlation.

PTS: 1

REF: 17.6. Correlating Rock Units

12. What fact makes radiocarbon dating possible?

ANS: Life forms stop accumulating carbon 14 when they die.

PTS: 1

REF: 17.7. Absolute Dating Methods

13. Why don't the sources of uncertainty in radiometric dating invalidate or lend suspicion to the results obtained?

ANS: The geologic conditions that can produce error are easily recognized, and all other sources of error are of the same types (measuring and sampling) that are present in statistical measurements of all other types.

PTS: 1

REF: 17.7. Absolute Dating Methods

14. What kind of rocks (igneous, sedimentary, metamorphic) have been most important in determining absolute age dates for the geologic time scale? Explain why.

ANS: Igneous rocks because they can be radiometrically dated.

PTS: 1

REF: 17.7. Absolute Dating Methods

15. Which of the major rock types were most important originally in developing the geologic time scale, and why?

ANS: Sedimentary rocks, because they follow the principles of historical geology, and they contain fossils.

PTS: 1

REF: 17.8. Development of the Geologic Timescale

16. How are marker beds used to determine the age of strata in a region that has no marker beds but does contain strata with the same fossil assemblage zone?

ANS: Marker beds are dated with radiometric techniques. Marker beds that encompass a fossil zone in one region can then be used to define the duration of that zone in regions where the marker beds do not occur.

PTS: 1

REF: 17.8. Development of the Geologic Timescale

17. If the dating technique is used correctly, how reliable are the radiometric dates derived from individual layers of stalagmites using ratios of uranium 234 to thorium 230?

ANS: The dates are very precise and reliable back to about 500,000 years.

PTS: 1

REF: 17.10. Geologic Time and Climate Change

COMPLETION 1. ____________________ dating is used to obtain absolute age dates.

ANS: Radiometric PTS: 1

REF: 17.2. How Geologic Time is Measured

2. The placement of events into a sequential order based upon their position in the rock record is referred to as ____________________ dating.

ANS: relative PTS: 1

REF: 17.2. How Geologic Time is Measured

3. A body of rock that is intruded by another rock must be ____________________ in age than the intrusion.

ANS: older PTS: 1

REF: 17.5. Relative Dating Methods

4. A sedimentary rock that shows evidence of contact metamorphism must be ____________________ in age than the igneous rock with which it is in contact, even if it lies above the igneous rock.

ANS: older PTS: 1

REF: 17.5. Relative Dating Methods

5. Fragments of a rock that are contained in a layer of another rock must be ____________________ in age than the layer of rock which surrounds them.

ANS: older PTS: 1

REF: 17.5. Relative Dating Methods

6. An interval of geologic time not represented by strata in a particular area is a(n) ____________________.

ANS: hiatus PTS: 1

REF: 17.5. Relative Dating Methods

7. A surface of discontinuity representing a break in the depositional record or a discontinuity representing erosion or nondeposition is a(n) ____________________.

ANS: unconformity PTS: 1

REF: 17.5. Relative Dating Methods

8. The principle of ____________________ states that rock layers extend laterally in all directions unless or until they terminate in one of a number of natural means.

ANS: lateral continuity

PTS: 1

REF: 17.5. Relative Dating Methods

9. To determine the age of sedimentary rocks containing fossils, ____________________ zones are established, plotting the overlapping geologic ranges of different species of fossils.

ANS: concurrent range PTS: 1

REF: 17.6. Correlating Rock Units

10. In order to correlate age-equivalent rock units of dissimilar composition or to correlate rock units over a large area, ____________________ and the principle of ____________________ must be used.

ANS: fossils, fossil succession PTS: 1

REF: 17.5. Relative Dating Methods

11. Different varieties of an atom that have a different number of neutrons in their nuclei are ____________________.

ANS: isotopes PTS: 1

REF: 17.7. Absolute Dating Methods

12. The half-life of a radioactive element is the amount of time it takes for ____________________ of the atoms of the unstable ____________________ element to decay to atoms of a new, more stable ____________________ element.

ANS: half, parent, daughter PTS: 1

REF: 17.7. Absolute Dating Methods

13. The most accurate radiometric dates are obtained from ____________________ rocks. Only in very unusual circumstances can ____________________ rocks be radiometrically dated.

ANS: igneous, sedimentary/metamorphic PTS: 1

REF: 17.7. Absolute Dating Methods

14. Long-lived radioactive isotope pairs used in radiometric dating have half-lives of the magnitude of ____________________ or ____________________ of years.

ANS: millions, billions PTS: 1

REF: 17.7. Absolute Dating Methods

15. The time necessary for half of the atoms of the unstable parent element to decay to the new, more stable daughter element is the isotope's ____________________.

ANS: half-life PTS: 1

REF: 17.7. Absolute Dating Methods

16. Prior to the discovery of radioactivity in the late ______ century, geologists were able to develop a(n) ____________________ geologic time scale.

ANS: 19th, relative PTS: 1

REF: 17.8. Development of the Geologic Timescale

MULTIPLE CHOICE 1. What is the approximate length of time preserved in Grand Canyon rocks? a. 10,000 years b. 100,000 years

c. 1 million years d. 1 billion years e. 10 billion years

ANS: D

PTS: 1

REF: 17.1. Introduction

2. Once the concept of a linear time and history were established, the earliest estimates of Earth's age were based on ____. a. inference from the Bible b. inference from the rates of observable geologic processes c. direct statements from the Bible d. faith e. none of these

ANS: A

PTS: 1

REF: 17.3. Early Concepts of Geologic Time and the Age of Earth 3. What is the age of the Earth? a. 12.6 billion years b. 12.6 million years c. 4.6 billion years d. 4.6 million years e. 10,000 years

ANS: C

PTS: 1

REF: 17.3. Early Concepts of Geologic Time and the Age of Earth 4. Whose work was the basis for the principle of uniformitarianism and the unavoidable necessity of a great age for Earth? a. Charles Lyell

b. William Smith c. James Hutton d. Lord Kelvin e. John Joly

ANS: C

PTS: 1

REF: 17.4. James Hutton and the Recognition of Geologic Time 5. Who, by virtue of a mathematical model, concluded that Earth could not be older than 100 million years and no younger than 20 million years? a. Charles Lyell b. William Smith c. James Hutton d. Lord Kelvin e. John Joly

ANS: D

PTS: 1

REF: 17.4. James Hutton and the Recognition of Geologic Time 6. A surface of erosion on metamorphic or igneous rocks, below sedimentary rocks is a(n) ____. a. nonconformity b. disconformity c. angular unconformity d. anticonformity e. none of these

ANS: B

PTS: 1

REF: 17.5. Relative Dating Methods

7. What principle states that in an undisturbed succession of sedimentary rocks, the oldest layer is at the bottom and the youngest is at the top?

a. principle of cross-cutting relationships b. principle of inclusions c. principle of fossil succession d. principle of uniformitarianism e. principle of superposition

ANS: E

PTS: 1

REF: 17.5. Relative Dating Methods

8. What principle states that fragments of one rock contained within another rock are older than the containing rock? a. principle of cross-cutting relationships b. principle of inclusions c. principle of fossil succession d. principle of uniformitarianism e. principle of superposition

ANS: B

PTS: 1

REF: 17.5. Relative Dating Methods

9. Which principle states that fossil assemblages succeed one another through time in a regular and predictable order? a. principle of cross-cutting relationships b. principle of inclusions c. principle of fossil succession d. principle of uniformitarianism e. principle of superposition

ANS: C

PTS: 1

REF: 17.5. Relative Dating Methods

10. The time equivalence of strata is determined by ____. a. correlation of unusual lithologies

b. correlation of key beds c. correlation of fossils d. lateral tracing e. superposition

ANS: C

PTS: 1

REF: 17.6. Correlating Rock Units

11. What is the loss of two protons and two neutrons from the nucleus called? a. alpha decay b. beta decay c. electron decay d. electron capture e. half-life decay

ANS: A

PTS: 1

REF: 17.7. Absolute Dating Methods

12. If an isotope has a half-life of 50 million years, and 1/8 of the sample remaining consists of that isotope, what is the age of the rock from which it was taken? a. 400 million years b. 300 million years c. 150 million years d. 800 million years e. none of these

ANS: C

PTS: 1

REF: 17.7. Absolute Dating Methods

13. Sources of uncertainty in radioactive dating do not include ____. a. loss of daughter isotope b. uncertainty in decay constants c. experimental and sample error

d. addition of parent isotope e. questions about metamorphism

ANS: B

PTS: 1

REF: 17.7. Absolute Dating Methods

14. What is the maximum age limit for radiocarbon dating of fossils? a. 70,000 years b. 700,000 years c. 7 million years d. 70 million years e. 700 million years

ANS: A

PTS: 1

REF: 17.7. Absolute Dating Methods

15. The geologic time scale was initially put together by a. radiometric dating and correlation. b. superposition, fossil succession and correlation. c. lithostratigraphy and biostratigraphy. d. carbon-14 age dating and lithostratigraphy.

ANS: B

PTS: 1

REF: 17.8. Development of the Geologic Timescale

16. Stalagmites can be radiometrically dated because a. like tree rings, the calcium carbonate layers vary in thickness by year. b. carbon-14 decays to nitrogen 14 in the carbonate. c. uranium-234 substitutes for calcium and decays to thorium-230. d. fission tracks in apatite in the structures can be dated.

ANS: C

PTS: 1

REF: 17.10. Geologic Time and Climate Change

17. Climate changes in a region because a. continents are carried to different latitudes. b. continental movement affects ocean circulation patterns. c. continental movement affects atmospheric circulation patterns. d. all of these.

ANS: D

PTS: 1

REF: Geo-Focus. Denver's Weather--280 Million Years Ago! TRUE/FALSE 1. Fossils cannot usually be dated directly because they are not composed of minerals that naturally contain radioactive isotopes.

ANS: F

PTS: 1

REF: 17.5. Relative Dating Methods

2. A fossil that is particularly useful for correlation is an evolutionary fossil.

ANS: F

PTS: 1

REF: 17.6. Correlating Rock Units

3. Lithostratigraphic units are defined by physical attributes of the rocks.

ANS: T

PTS: 1

REF: 17.9. Stratigraphy and Stratigraphic

Terminology 4. The basic lithostratigraphic unit is the series.

ANS: F

PTS: 1

REF: 17.9. Stratigraphy and Stratigraphic

Terminology 5. Biostratigraphic units are defined by fossil content.

ANS: T

PTS: 1

REF: 17.9. Stratigraphy and Stratigraphic

Terminology 6. Time-stratigraphic units are units of rock sharing a specific lithology.

ANS: F

PTS: 1

REF: 17.9. Stratigraphy and Stratigraphic

Terminology 7. Denver 280 million years ago was covered by glaciers.

ANS: F

PTS: 1

REF: Geo-Focus. Denver's Weather--280 Million Years Ago! 8. The fossils of plants and animals indicate something about the environment and climate at the time the organisms were living.

ANS: T

PTS: 1

REF: Geo-Focus. Denver's Weather--280 Million Years Ago! 9. Stratigraphy is the study of the composition, origin, aereal distribution and age relationships of layered rocks.

ANS: T

PTS: 1

REF: 17.9. Stratigraphy and Stratigraphic

Terminology 10. Geologists are correlating past geologic events to see if there are correlations with climate changes.

ANS: T

PTS: 1

REF: 17.10. Geologic Time and Climate Change

Chapter 18—Organic Evolution--The Theory and Its Supporting Evidence

ESSAY

1. Briefly explain why critics did not readily accept the Darwin-Wallace theory of natural selection. What possibilities did they ignore?

ANS: Critics thought that a partially evolved eye or wing would not be useful, and therefore the eye and the wing could not have evolved but must have been created as a whole. They ignored the possibility that the eye or wing was used for something else before it evolved to where it is today. For example, a wing might have been used for stability.

PTS: 1

REF: 18.2. Organic Evolution: What Does It Mean?

2. How can traits in organisms evolve over time?

ANS: Evolution occurs because there is genetic variation in populations, and alleles are redistributed from generation to generation. Natural selection brings out the most favorable alleles, which then appear to greater degree in subsequent generations.

PTS: 1

REF: 18.4. The Modern View of Organic Evolution

3. Briefly state the factors that entered into the modern view or modern synthesis of the concept of evolution by natural selection.

ANS: Scientists from several disciplines contributed to this modern view, including paleontologists, geneticists, and biologists. They incorporated the chromosome theory of inheritance as the mechanism to explain the Darwin-Wallace theory of natural selection. In doing so, they discarded Lamarck's theory of inheritance of acquired characteristics. They recognized that mutations are common and important in change.

PTS: 1

REF: 18.4. The Modern View of Organic Evolution

4. Describe allopatric speciation.

ANS: In allopatric speciation, a new species arises when a small part of a population is geographically isolated from its parent population by some type of barrier. The subset of the population must adapt to somewhat different conditions, and ultimately, it becomes a new species.

PTS: 1

REF: 18.4. The Modern View of Organic Evolution

5. Briefly explain how the concept of punctuated equilibrium is compatible with the fossil record.

ANS: The fossil record is incomplete by virtue of the process of fossilization. Organisms that exist over long periods of time have a much greater chance of being preserved than the transitional species which developed and lived during a very short time span, as small geographically isolated populations.

PTS: 1

REF: 18.4. The Modern View of Organic Evolution

6. What role does the process of extinction play in the evolution of life?

ANS: When one species goes extinct, the disappearance of that species from a habitat opens the possibility for other organisms to expand into that habitat. Without extinction, there would not be the diversity of organisms on Earth and in the fossil record that we see today.

PTS: 1

REF: 18.4. The Modern View of Organic Evolution

SHORT ANSWER 1. Describe the DNA molecule.

ANS: DNA is a complex, double-stranded helix.

PTS: 1

REF: 18.3. Mendel and the Birth of Genetics

2. If Parent 1 has the genetic makeup AA, meaning that he carries the dominant gene for trait A twice, and parent 2 has the genetic makeup aa, meaning that she carries the recessive gene for trait A twice, what is the chance that the offspring of these two parents will have the recessive form of trait A? Explain.

ANS: Zero. Any offspring will have the genetic makeup Aa and the dominant A gene will be expressed.

PTS: 1

REF: 18.3. Mendel and the Birth of Genetics

3. If the offspring of the above situation with Aa mates with an individual with the makeup aa, what are the chances that an offspring will express the recessive trait? Explain.

ANS: 50%. Aa + aa = Aa, Aa, aa, aa. So 50% of offspring on average will have the makeup aa and will express the recessive trait.

PTS: 1

REF: 18.3. Mendel and the Birth of Genetics

4. What is phyletic gradualism?

ANS: Phyletic gradualism is the concept that evolution occurs because of minor changes that eventually bring about changes from one species to another.

PTS: 1

REF: 18.4. The Modern View of Organic Evolution

5. What is punctuated equilibrium?

ANS: Punctuated equilibrium is the concept that there is little or no evolutionary change in a population, and then suddenly the change is rapid.

PTS: 1

REF: 18.4. The Modern View of Organic Evolution

6. Describe divergent evolution.

ANS: In divergent evolution, an interbreeding population gives rise to diverse descendant types of organisms that ultimately make more than one descendent species.

PTS: 1

REF: 18.4. The Modern View of Organic Evolution

7. Evolution by natural selection is a two step process. What are those two steps?

ANS: Variation must be present or must arise in a population. The variations that are favorable in the environment in which the organism lives will survive and those that are not favorable will ultimately be eliminated.

PTS: 1

REF: 18.4. The Modern View of Organic Evolution

8. What is a mass extinction?

ANS: In a mass extinction, extinction rates are accelerated and sharply reduce Earth’s biotic diversity.

PTS: 1

REF: 18.4. The Modern View of Organic Evolution

9. When was the greatest extinction of all time and what was the consequence of that extinction?

ANS: The greatest extinction was at the end of the Paleozoic Era when 90% of all species died out.

PTS: 1

REF: 18.4. The Modern View of Organic Evolution

10. Briefly explain how the phylogeny of an extinct group can be determined.

ANS: If sufficient fossil material is available for a significant amount of geologic time, a group’s evolutionary trend may be determined by changes in internal or external skeletal features.

PTS: 1

REF: 18.4. The Modern View of Organic Evolution

11. What is cladistics? How does cladistics group organisms?

ANS: Cladistics is a type of biological analysis in which organisms are grouped together based on derived characteristics. Evolutionary novelties, which are unique, are used to differentiate a group.

PTS: 1

REF: 18.4. The Modern View of Organic Evolution

12. In addition to fossils, what are other types of evidence for evolutionary theory?

ANS: Other types of evidence for evolution include shared characteristics, biochemistry, comparative anatomy, and the small-scale evolution of living organisms.

PTS: 1

REF: 18.5. Evidence Supporting Evolutionary Theory

13. What are body fossils?

ANS: Body fossils are fossilized hard skeletal parts, such as bones, teeth, and shells.

PTS: 1

REF: 18.5. Evidence Supporting Evolutionary Theory

14. What are vestigial structures?

ANS: Vestigial structures are nonfunctional remnants of organs that were functional in their ancestors.

PTS: 1

REF: 18.5. Evidence Supporting Evolutionary Theory

15. Name some types of trace fossils.

ANS: Trace fossils include tracks, trails, burrows, borings, nests, or other indications of the activities of organisms.

PTS: 1

REF: 18.5. Evidence Supporting Evolutionary Theory

COMPLETION 1. ____________________ are the only record of prehistoric life.

ANS: Fossils PTS: 1

REF: 18.1. Introduction

2. Genes controlling the same trait are called ____________________.

ANS: alleles PTS: 1

REF: 18.3. Mendel and the Birth of Genetics

3. If in a cell, R is the dominant allele and represents blue flowers and r is the recessive allele and represents yellow flowers, what color flower will an organism which inherits the pair Rr have? ____________________ ANS: blue PTS: 1

REF: 18.3. Mendel and the Birth of Genetics

4. Complex, double-stranded, helical molecules of DNA are called ____________________.

ANS: chromosomes PTS: 1

REF: 18.3. Mendel and the Birth of Genetics

5. Cell division that results in cells containing only one chromosome from each pair is ____________________.

ANS: meiosis PTS: 1

REF: 18.3. Mendel and the Birth of Genetics

6. DNA is an abbreviation for ____________________.

ANS: deoxyribonucleic acid PTS: 1

REF: 18.3. Mendel and the Birth of Genetics

7. The number of chromosomes is ____________________ for a given species but ____________________ among different species.

ANS: fixed, varies PTS: 1

REF: 18.3. Mendel and the Birth of Genetics

8. The type of cell division in which resulting cells contain one chromosome from each pair is called ____________________.

ANS: meiosis PTS: 1

REF: 18.3. Mendel and the Birth of Genetics

9. The process in which changes occur in genes passed from one generation to another is called ____________________.

ANS: mutation PTS: 1

REF: 18.3. Mendel and the Birth of Genetics

10. The process that involves changes in the genetic makeup of a population is ____________________.

ANS: speciation PTS: 1

REF: 18.4. The Modern View of Organic Evolution

11. According to the concept of ____________________, an ancestral species changes gradually and continuously and grades imperceptibly into a descent species.

ANS: phyletic gradualism PTS: 1

REF: 18.4. The Modern View of Organic Evolution

12. Two types of evolution that occur because organisms develop similar evolutionary paths are ____________________ and ____________________.

ANS: convergent, parallel parallel, convergent PTS: 1

REF: 18.4. The Modern View of Organic Evolution

13. ____________________ evolution is the development of ____________________ characteristics in distantly related organisms.

ANS: Convergent, similar PTS: 1

REF: 18.4. The Modern View of Organic Evolution

14. Parallel evolution is the development of ____________________ characteristics in ____________________ related organisms.

ANS: similar, closely PTS: 1

REF: 18.4. The Modern View of Organic Evolution

15. The Linnaean classification scheme from broadest to most specific is ____________________, ____________________, ____________________, ____________________, ____________________, ____________________, ____________________.

ANS: kingdom, phylum, class, order, family, genus, species PTS: 1

REF: 18.5. Evidence Supporting Evolutionary Theory

16. The fossil record is biased because of selective preservation of organisms with ____________________ parts.

ANS: hard PTS: 1

REF: 18.5. Evidence Supporting Evolutionary Theory

MULTIPLE CHOICE 1. What led Darwin to change his beliefs about fixity of species? a. renewed interest in the biblical account of creation b. observation of language variation in human populations in the British Isles c. observations of no documentable difference in plant and animal population over wide geographic areas d. observations that distinct but closely related groups of plants and animals inhabited isolated islands e. none of these

ANS: D

PTS: 1

REF: 18.1. Introduction

2. Who demonstrated that many plants and animals had become extinct through time and that fossils differed through time? a. Thomas Malthus b. Georges Cuvier c. Jean Baptiste de Lamarck d. Charles Darwin e. Carolus Linnaeus

ANS: B

PTS: 1

REF: 18.2. Organic Evolution: What Does It Mean?

3. Lamarck's theory of inheritance of acquired characteristics was based on what?

a. discovery of DNA b. discovery of genes c. discovery of mitochondria d. observation and interpretation e. experiments

ANS: D

PTS: 1

REF: 18.2. Organic Evolution: What Does It Mean?

4. Which of the following is not a component of the Darwin-Wallace theory of natural selection? a. All populations contain heritable variations. b. Some variations are more favorable than others. c. Not all young survive to maturity. d. Those with favorable variations are most likely to survive and pass those variations on to their offspring. e. All organisms can knowingly select their genetic direction.

ANS: E

PTS: 1

REF: 18.2. Organic Evolution: What Does It Mean?

5. What led to changes in scientific thought in the 17th and 18th centuries? a. development of radiometric age dating techniques b. discovery of fossils c. lesser influence of the church in all matters d. opening of universities specifically dedicated to sciences e. all of these

ANS: C

PTS: 1

REF: 18.2. Organic Evolution: What Does It Mean?

6. Whose original concept of inheritance did Lysenko's ideas reflect? a. Thomas Malthus b. Georges Cuvier

c. Jean Baptiste de Lamarck d. Charles Darwin e. Carolus Linnaeus

ANS: C

PTS: 1

REF: Geo-Focus. The Tragic Lysenko Affair

7. If in a pea plant, R is the dominant allele and represents a red flower and r is the recessive allele and represents a white flower, an organism that inherits the pair Rr will have which color flower? a. red b. pink c. white d. red and white e. It's impossible to know.

ANS: A

PTS: 1

REF: 18.3. Mendel and the Birth of Genetics

8. The important aspects of Mendel's genetic studies include which of the following? a. Chance is the most important factor in change. b. Genes controlling traits do not blend during inheritance but are transmitted as discrete entities. c. The traits which an organism inherits are the average of the end member alleles. d. If particular traits do not appear within two generations, they are lost from the species. e. all of these

ANS: B

PTS: 1

REF: 18.3. Mendel and the Birth of Genetics

9. The important aspect(s) of mutation is(are) that they ____. a. only occur because of outside influences on an organism

b. occur in sex cells that are inheritable c. only occur in the weakest organisms d. are random in terms of fitness of organisms e. occur in sex cells that are inheritable AND are random in terms of fitness of organisms

ANS: E

PTS: 1

REF: 18.4. The Modern View of Organic Evolution

10. What are populations that have similar individuals that can interbreed and produce fertile offspring called? a. mating pairs b. families c. breeding stock d. species e. none of these

ANS: D

PTS: 1

REF: 18.4. The Modern View of Organic Evolution

11. A clade is a. a group of organisms and its most recent common ancestor. b. a group of organisms on a phylogenetic tree.

c. a group of organisms that can interbreed and have fertile offspring. d. a group of organisms in an evolutionary line from ancestor to descendent.

ANS: A

PTS: 1

REF: 18.4. The Modern View of Organic Evolution

12. Who proposed the modern biological classification scheme? a. Thomas Malthus b. Georges Cuvier

c. Jean Baptiste de Lamarck d. Charles Darwin e. Carolus Linnaeus

ANS: E

PTS: 1

REF: 18.5. Evidence Supporting Evolutionary

Theory 13. With the Linnaean classification scheme, as one moves down the hierarchy, the categories become more ____. a. exclusive b. poorly defined c. inclusive d. general e. broad

ANS: A

PTS: 1

REF: 18.5. Evidence Supporting Evolutionary

Theory 14. Linnaeus devised his classification scheme to provide a ____. a. basis for the theory of evolution b. basis for understanding the biblical creation theory c. means to refute the theory of biblical creation d. means to refute the theory of evolution e. means to categorize organisms with like characteristics

ANS: E

PTS: 1

REF: 18.5. Evidence Supporting Evolutionary

Theory 15. Structures which are superficially dissimilar but have the same structure in terms of bones, muscles, nerves, and blood vessels are ____.

a. heterologous b. homologous c. vestigial d. analogous e. exogenous

ANS: B

PTS: 1

REF: 18.5. Evidence Supporting Evolutionary

Theory 16. Features that serve the same purpose on very dissimilar organisms are called ____. a. heterologous b. exogenous c. homologous d. analogous e. vestigial

ANS: D

PTS: 1

REF: 18.5. Evidence Supporting Evolutionary

Theory 17. The fossil record shows a sequence of variations based on what? a. density of organisms b. shape of organisms c. size of organisms d. different life forms e. none of these

ANS: D

PTS: 1

REF: 18.5. Evidence Supporting Evolutionary

Theory 18. All of the following are trace fossils except ____.

a. trails b. bones c. burrows d. coprolites (fossil feces) e. nests

ANS: B

PTS: 1

REF: 18.5. Evidence Supporting Evolutionary

Theory TRUE/FALSE 1. Lysenko and his colleagues increased food production significantly.

ANS: F

PTS: 1

REF: Geo-Focus. The Tragic Lysenko Affair

2. Lysenko's research was endorsed by the Soviet government because it seemed compatible with Marxist-Leninist philosophy.

ANS: T

PTS: 1

REF: Geo-Focus. The Tragic Lysenko Affair

3. The Lysenko affair shows the absurdity of basing scientific theories on philosophic or political beliefs.

ANS: T

PTS: 1

REF: Geo-Focus. The Tragic Lysenko Affair

4. The father of modern genetics is Alfred Wallace.

ANS: F

PTS: 1

REF: 18.3. Mendel and the Birth of Genetics

5. The science of genetics was developed based on experimental studies using fruit flies.

ANS: F

PTS: 1

REF: 18.3. Mendel and the Birth of Genetics

6. The controlling factor in variation in organisms is based on the presence or absence of genes.

ANS: F

PTS: 1

REF: 18.4. The Modern View of Organic Evolution

7. Alleles are the pair of controlling factors in genes, and both have equal dominance.

ANS: F

PTS: 1

REF: 18.4. The Modern View of Organic Evolution

8. Whether a mutation is harmful or beneficial can only be judged in respect to the conditions in which the organism lives.

ANS: T

PTS: 1

REF: 18.4. The Modern View of Organic Evolution

9. All mutations are either harmful or beneficial.

ANS: F

PTS: 1

REF: 18.4. The Modern View of Organic Evolution

10. Populations that can interbreed and produce fertile offspring are called species.

ANS: T

PTS: 1

REF: 18.4. The Modern View of Organic Evolution

11. Vestigial structures are those that have only small pieces remaining on an organism.

ANS: F

PTS: 1

REF: 18.5. Evidence Supporting Evolutionary

Theory 12. Homologous structures probably indicate descent with modifications from a common ancestor.

ANS: T Theory

PTS: 1

REF: 18.5. Evidence Supporting Evolutionary

13. For evolution to occur, variation must occur and favorable conditions must exist for the variations to survive.

ANS: T

PTS: 1

REF: 18.5. Evidence Supporting Evolutionary

Theory 14. The only factor necessary for evolution to occur is that there must be variation in organisms in a population.

ANS: F

PTS: 1

REF: 18.5. Evidence Supporting Evolutionary

Theory 15. Cladistics and cladograms work well for constructing relationships among fossil organisms.

ANS: F

PTS: 1

REF: 18.4. The Modern View of Organic Evolution

Chapter 19—Precambrian Earth and Life History

ESSAY 1. What are the three major units found in greenstone belts from bottom to top, and what type dominates the lower two-thirds? In the upper third?

ANS: The three major units are argillite and graywacke, layered cherts, and ultramafic lava. The lower portion is volcanic rocks, and the upper portion is sedimentary rocks.

PTS: 1

REF: 19.4. Archean Earth History

2. Why are ultramafic volcanics rare in rocks that are much younger than Archean in age?

ANS:

Earth has cooled from its early stages because radiogenic heat production decreased. The Archean near-surface temperatures have not been high enough for ultramafic magma to reach the surface.

PTS: 1

REF: 19.4. Archean Earth History

3. Briefly explain the difference between the tectonic setting of shield areas during the Precambrian and since the onset of the Phanerozoic.

ANS: During the Precambrian, the areas that are now part of the shield were tectonically active with volcanism, metamorphism, and folding and faulting. During that time, continents grew by accretion. Since the beginning of the Phanerozoic, these areas have been tectonically inactive and have been eroded to topographically flat, stable areas.

PTS: 1

REF: 19.5. Proterozoic Earth History

4. What do the Ediacaran fauna represent, and why are they important?

ANS: The Ediacaran fauna represent the first multi-celled organisms found in the fossil record. They are important because they represent a transition faunal assemblage between generally lifepoor Proterozoic and the Paleozoic with its sudden appearance of many life forms.

PTS: 1

REF: 19.7. Life--Its Origin and Early History

SHORT ANSWER 1. What are the two main rock types that characterize Archean shield areas?

ANS: greenstone and granite-gneiss complexes

PTS: 1

REF: 19.4. Archean Earth History

2. What is the basic difference between the Archean and the Proterozoic?

ANS: the style of crustal evolution PTS: 1

REF: 19.4. Archean Earth History

3. How did Laurentia evolve?

ANS: Archean cratons were sutured together by a series of island arc and microcontinent collisions.

PTS: 1

REF: 19.5. Proterozoic Earth History

4. Sandstone-carbonate-shale assemblages are characteristic of sedimentation at what type of plate margin? Describe when they form in the Wilson cycle, and what types of environments they represent?

ANS: They are found at passive margins during the late continental rifting phase of the Wilson cycle, when passive margins develop. They are indicative of fluvial, tidal flat, and shallow marine environments.

PTS: 1

REF: 19.5. Proterozoic Earth History

5. What are banded iron formations composed mainly of?

ANS: thinly layered chert and iron oxides PTS: 1

REF: 19.5. Proterozoic Earth History

6. What does the appearance of red beds in the geologic record indicate about the atmosphere?

ANS: It was oxidizing.

PTS: 1

REF: 19.5. Proterozoic Earth History

7. What two processes, which began during the Archean, can account for the introduction of free oxygen into the atmosphere?

ANS: photochemical dissociation and photosynthesis PTS: 1

REF: 19.6. Origin and Evolution of the Atmosphere and Hydrosphere

8. How does photochemical dissociation of water vapor occur?

ANS: Water molecules are broken up by ultraviolet radiation in the upper atmosphere.

PTS: 1

REF: 19.6. Origin and Evolution of the Atmosphere and Hydrosphere

9. What are two examples that demonstrate the difficulty of adopting absolute minimal criteria for deciding whether or not something is alive?

ANS: viruses and microspheres PTS: 1

REF: 19.7. Life--Its Origin and Early History

10. What are monomers?

ANS: simple organic molecules PTS: 1

REF: 19.7. Life--Its Origin and Early History

11. Why is it believed that cyanobacteria must have been preceded by even simpler organisms?

ANS: Cyanobacteria were photosynthesizing organisms that should have been preceded by simpler nonphotosynthesizing organisms.

PTS: 1

REF: 19.7. Life--Its Origin and Early History

12. What are prokaryotic organisms?

ANS: They are unicellular organisms that lack a nucleus.

PTS: 1

REF: 19.7. Life--Its Origin and Early History

13. What is an anaerobic organism?

ANS: One that does not need oxygen.

PTS: 1

REF: 19.7. Life--Its Origin and Early History

14. What are heterotrophic organisms?

ANS: Organism that are completely dependent upon an external source of nutrients.

PTS: 1

REF: 19.7. Life--Its Origin and Early History

15. Besides the origin of life itself, what was the most significant biological event of the Archean?

ANS: The most significant biological event of the Archean was the development of the autotrophic process of photosynthesis.

PTS: 1

REF: 19.7. Life--Its Origin and Early History

16. What is symbiosis?

ANS: Symbiosis is the living together of two or more organisms.

PTS: 1

REF: 19.7. Life--Its Origin and Early History

COMPLETION 1. Most of the Precambrian is divided into the following two eons _______ and _______, with the earlier part of the time interval being the _______.

ANS: Archean, Proterozoic; Hadean PTS: 1

REF: 19.1. Introduction

2. Continents are cored by large areas of exposed ancient rocks called ____________________, which are tectonically ____________________ regions.

ANS: shields, inactive PTS: 1 Cratons

REF: 19.3. The Foundations of Continents--Shields, Platforms, and

3. Areas of buried shield rock and younger sedimentary cover are collectively called ____________________, which are tectonically ____________________ and ____________________.

ANS: cratons, inactive, stable PTS: 1

REF: 19.3. The Foundations of Continents--Shields, Platforms, and

Cratons 4. The ____________________ forms the core of North America and has been tectonically ____________________.

ANS: Canadian Shield, inactive PTS: 1

REF: 19.3. The Foundations of Continents--Shields, Platforms, and

Cratons 5. The Grenville orogeny occurred between ______ to ______ billion years ago ANS: 1.3, 1.0 PTS: 1

REF: 19.5. Proterozoic Earth History

6. Continental growth during the Early Proterozoic development of Laurentia was related to ____________________ of ____________________ age cratons.

ANS: accretion, Archean PTS: 1

REF: 19.5. Proterozoic Earth History

7. The ____________________ orogen is the earliest that documents a complete ____________________ cycle of opening and closing ocean basins.

ANS: Wopmay, Wilson PTS: 1

REF: 19.5. Proterozoic Earth History

8. Sandstone-carbonate-shale assemblages were deposited along _______ continental margins.

ANS: rifted PTS: 1

REF: 19.5. Proterozoic Earth History

9. Between 1.3 and 1.0 billion years ago, the __________ orogeny occurred in the supercontinent __________.

ANS: Grenville; Laurentia PTS: 1

REF: 19.5. Proterozoic Earth History

10. The Grenville orogen probably resulted from closure of a(n) __________, the final stage in a __________ cycle.

ANS: ocean basin; Wilson PTS: 1

REF: 19.5. Proterozoic Earth History

11. The formation of the Midcontinent rift was ____________________ in time with the Grenville orogeny.

ANS: contemporaneous PTS: 1

REF: 19.5. Proterozoic Earth History

12. Sandstone-carbonate-shale assemblages comprise ______ percent of the Proterozoic rock record and indicate ____________________ tectonics.

ANS: 60, rift PTS: 1

REF: 19.5. Proterozoic Earth History

13. The assemblage of sandstone-carbonate-shale is probably indicative of ____________________ (in depth) water shelf environment.

ANS: shallow PTS: 1

REF: 19.5. Proterozoic Earth History

14. The deposition of banded iron formations primarily occurred about ______ to ______ billion years ago.

ANS: 2.5, 2.0 PTS: 1

REF: 19.5. Proterozoic Earth History

15. The process by which gases within Earth are emitted and eventually accumulate into an atmosphere is called ____________________.

ANS: outgassing PTS: 1

REF: 19.6. Origin and Evolution of the Atmosphere and Hydrosphere

16. Evidence for oxygen deficient atmosphere during the Archean includes the presence of detrital ____________________ and ____________________ in ____________________ rocks.

ANS: pyrite, uraninite, sedimentary PTS: 1

REF: 19.6. Origin and Evolution of the Atmosphere and Hydrosphere

17. Early gases which had begun to accumulate around Earth during the Early Archean were lost because of a lack of a(n) ____________________.

ANS: magnetosphere PTS: 1

REF: 19.6. Origin and Evolution of the Atmosphere and Hydrosphere

18. Early organisms played a role in the accumulation of free oxygen through the process of ____________________, which combines carbon dioxide and ____________________ to make organic molecules, and ____________________ is given off as waste.

ANS: photosynthesis, water, oxygen PTS: 1

REF: 19.6. Origin and Evolution of the Atmosphere and Hydrosphere

MULTIPLE CHOICE 1. What are time divisions in the Precambrian based on? a. distinct fossil assemblages b. metamorphic assemblages c. radiometric age dates d. time-stratigraphic units e. none of these

ANS: C

PTS: 1

REF: 19.1. Introduction

2. The Precambrian comprises what percent of geologic time? a. 99 percent b. 88 percent c. 77 percent d. 66 percent e. 55 percent

ANS: B

PTS: 1

REF: 19.1. Introduction

3. The heat reservoir of the early history of Earth was generated by all but which of the following? a. radioactive decay b. compression of material c. meteorite bombardment d. continental collision and accretion e. none of these

ANS: D

PTS: 1

REF: 19.2. What Happened During the Hadean?

4. During the Archean, how long was the length of a day on Earth? a. 36 hours b. 10 hours c. the same as the length of a day on modern Earth d. like the present but there was no day, it was all darkness e. like the present but there was no darkness, it was all daylight

ANS: B

PTS: 1

REF: 19.2. What Happened During the Hadean?

5. The Precambrian history of Earth is difficult to determine for all but which of the following reasons? a. There is Precambrian rock exposed only on three continents. b. Precambrian rock is complexly deformed. c. Precambrian rock is metamorphosed. d. In many places the rock is deeply buried. e. There are few fossils in the Precambrian record.

ANS: A

PTS: 1

REF: various

6. Shield areas of continents are found in modern ____. a. subduction zones b. continent-continent plate boundaries c. tectonically inactive regions d. divergent plate boundaries e. transform plate boundaries

ANS: C

PTS: 1

REF: 19.3. The Foundations of Continents--Shields, Platforms, and Cratons 7. All but which of the following are features of greenstone belts? a. volcanic and sedimentary rocks b. key index fossil assemblages c. granitic intrusions d. complex folding and faulting e. abundant chlorite

ANS: B

PTS: 1

REF: 19.4. Archean Earth History

8. Most of the volcanism associated with greenstone belts was ____. a. subaqueous b. basalt pillow lavas c. ultramafic lava d. subaqueous and ultramafic lava e. all of these

ANS: E

PTS: 1

REF: 19.4. Archean Earth History

9. Sedimentary rocks are abundant in the ____ portion of greenstone belts and consist largely of ____ and ____. a. bottom, argillite, graywacke b. upper, argillite, graywacke c. middle, argillite, graywacke d. top, argillite, limestone e. bottom, argillite, limestone.

ANS: B

PTS: 1

REF: 19.4. Archean Earth History

10. Which is the correct sequence of events in the development of a back-arc basin style greenstone belt?

1.

granitic intrusion and metamorphism

2.

basin opening

3.

basin closing

4.

extension

5.

compression

6.

volcanism and sedimentation

a. 2, 4, 6, 3, 5, 1 b. 2, 6, 5, 4, 3, 1 c. 6, 4, 2, 5, 1, 3 d. 6, 1, 2, 4, 3, 5 e. 1, 2, 3, 4, 5, 6

ANS: A

PTS: 1

REF: 19.4. Archean Earth History

11. The large Proterozoic landmass known as Laurentia was composed of ____. a. Europe, Asia, Scandinavia, NW Scotland

b. North America, South America, Greenland, Baltic Shield c. North America, Greenland, NW Scotland, Baltic Shield d. Greenland, NW Scotland, Baltic Shield, Europe e. Greenland, Iceland, Nova Scotia, Baltic Shield

ANS: C

PTS: 1

REF: 19.5. Proterozoic Earth History

12. By ____ years ago, much of Greenland, central Canada, and the north central United States formed one large craton. a. 1.8 million b. 2.0 billion c. 1.6 billion d. 1.6 million e. 1.8 billion

ANS: E

PTS: 1

REF: 19.5. Proterozoic Earth History

13. The iron in banded iron formations was primarily in which iron-bearing minerals? a. iron sulfide b. iron oxides c. iron silicate d. iron carbonate e. none of these

ANS: B

PTS: 1

REF: 19.5. Proterozoic Earth History

14. What factor(s) led to the enormous scale of banded iron deposition during the Proterozoic? a. abundance of dissolved iron in seawater b. increase in photosynthesizing bacteria c. chemical affinity of iron to combine with available oxygen

d. all of these e. none of these

ANS: D

PTS: 1

REF: 19.5. Proterozoic Earth History

15. The earliest atmosphere of Earth was ____. a. the same as the modern atmosphere b. composed entirely of nitrogen c. composed of ozone and hydrogen d. blown into space by solar wind e. composed of ozone and hydrogen AND blown into space by solar wind

ANS: D

PTS: 1

REF: 19.6. Origin and Evolution of the Atmosphere and Hydrosphere 16. The Archean atmosphere could be described as what? a. oxygen rich b. nitrogen rich c. ozone rich d. oxygen deficient e. carbon dioxide rich

ANS: D

PTS: 1

REF: 19.6. Origin and Evolution of the Atmosphere and Hydrosphere 17. The increase in atmospheric oxygen during the Proterozoic was related to what? a. decreased world wide volcanism b. decrease in size of oceans c. photosynthesis by bacteria d. appearance of land plants

e. none of these

ANS: C

PTS: 1

REF: 19.6. Origin and Evolution of the Atmosphere and Hydrosphere 18. There is chemical evidence that life appeared by ____ and fossils by ____. a. 3.8 billion years, 2.5 billion years b. 4.6 billion years, 2.5 billion years c. 3.8 million years, 3.5 million years d. 3.8 billion years, 3.5 billion years e. 4.6 million years, 3.5 million years

ANS: D

PTS: 1

REF: 19.7. Life--Its Origin and Early History

19. All organisms are composed mostly of all but which of the following? a. oxygen b. nitrogen c. calcium d. carbon e. hydrogen

ANS: C

PTS: 1

REF: 19.7. Life--Its Origin and Early History

20. Which factors likely played a role in the development of early life? a. presence of carbon, hydrogen, nitrogen, and oxygen b. ultraviolet light c. lightning d. ultraviolet light and lightning only e. all of these

ANS: E

PTS: 1

REF: 19.7. Life--Its Origin and Early History

21. What are small molecules composed of multiple amino acids called? a. monomers b. protobionts c. bacteria d. proteinoids e. none of these

ANS: D

PTS: 1

REF: 19.7. Life--Its Origin and Early History

22. What are molecules which are intermediate between inorganic compounds and living organisms called? a. protobionts b. proteinoids c. bacteria d. amino acids e. monomers

ANS: A

PTS: 1

REF: 19.7. Life--Its Origin and Early History

23. The oldest eukaryotes in the fossil record are at least how old? a. 2.0 billion years old b. 1.2 billion years old c. 1.0 billion years old d. 3.4 billion years old e. 5.0 billion years old

ANS: B

PTS: 1

REF: 19.7. Life--Its Origin and Early History

24. Which of the following might be considered advantages that multi-celled organisms have over single celled organisms? a. They can grow larger. b. Specialized cells are more efficient. c. Cells can be replaced, thus they live longer. d. Specialized cells for reproduction aid in population growth. e. all of these

ANS: E

PTS: 1

REF: 19.7. Life--Its Origin and Early History

25. The Ediacaran fauna include representatives of the modern phyla ____. a. Proterozoa, Annelida, and Arthropoda b. Annelida, Arthropoda, and Cnidaria c. Proterozoa, Porifera, and Cnidaria d. Coelenterata, Annelida, and Cnidaria e. Coelenterata, Proterozoa, and Porifera

ANS: B

PTS: 1

REF: 19.7. Life--Its Origin and Early History

26. Archean age rocks are important sources for all but which of the following commodities? a. chrome b. gold c. platinum d. lead e. nickel

ANS: D

PTS: 1

REF: 19.8. Resources in Precambrian Rocks

27. Pegmatites are associated with ____ rocks and contain ____, ____, and ____.

a. greenstone belt volcanic, copper, lead, zinc b. greenstone belt volcanic, rubidium, beryllium, lithium c. granitic, lithium, zinc, gold d. granitic, lithium, beryllium, rubidium e. sedimentary, gold, chrome, platinum

ANS: D

PTS: 1

REF: 19.8. Resources in Precambrian Rocks

28. The Sudbury Basin is one of the richest mining areas in the world because it a. is a banded-iron formation. b. is a meteorite impact site. c. is a layered intrusion. d. is a stromatolite. e. all of these

ANS: B

PTS: 1

REF: Geo-Focus. The Sudbury Meteorite Impact and Its Aftermath TRUE/FALSE 1. The boundaries of subunits or smaller cratons within the shield are based on topographic expression of different rock types.

ANS: F

PTS: 1

REF: 19.3. The Foundations of Continents--Shields, Platforms, and Cratons 2. Subunits within the shield are delineated by radiometric ages and structural trends.

ANS: T

PTS: 1

REF: 19.3. The Foundations of Continents--Shields, Platforms, and Cratons

3. In the back-arc basin model for greenstone belt evolution, metamorphism and deformation are closely tied to basin opening.

ANS: F

PTS: 1

REF: 19.4. Archean Earth History

4. Ophiolites are abundant in Archean age rock sequences.

ANS: F

PTS: 1

REF: 19.4. Archean Earth History

5. The rate of plate motion was probably slower in the Archean.

ANS: F

PTS: 1

REF: 19.4. Archean Earth History

6. The presence of thick sections of carbonate and sandstone indicates that Archean continents had well-developed shelf environments.

ANS: F

PTS: 1

REF: 19.4. Archean Earth History

7. The rapid rate of plate motion was probably the most important factor in rapid continental growth in the Late Archean.

ANS: T

PTS: 1

REF: 19.4. Archean Earth History

8. Archean and Proterozoic greenstone belts formed in similar tectonic settings.

ANS: T

PTS: 1

REF: 19.4. Archean Earth History

9. Rocks associated with the Wopmay orogen document the oldest complete Wilson cycle.

ANS: T

PTS: 1

REF: 19.5. Proterozoic Earth History

10. The Grenville orogeny was the culminating event of the amalgamation of Laurentia.

ANS: T

PTS: 1

REF: 19.5. Proterozoic Earth History

11. Sandstone-carbonate-shale assemblages occur along continental rift margins and intracratonic basins.

ANS: T

PTS: 1

REF: 19.5. Proterozoic Earth History

12. Banded iron formations are composed of almost 99 percent silica with only minor iron impurities that give a streaked or banded appearance.

ANS: F

PTS: 1

REF: 19.5. Proterozoic Earth History

13. Sandstone-carbonate-shale assemblages are restricted to the Proterozoic.

ANS: F

PTS: 1

REF: 19.5. Proterozoic Earth History

14. The enormous amount of banded iron formation deposited during the period of 2.5 to 2.0 billion years ago signifies a transition from oxidizing to reducing atmosphere on Earth.

ANS: F

PTS: 1

REF: 19.6. Origin and Evolution of the Atmosphere and Hydrosphere 15. Both the presence of banded iron formations and red beds are evidence that the atmosphere and hydrosphere changed from oxidizing to reducing in the Proterozoic.

ANS: F

PTS: 1

REF: 19.6. Origin and Evolution of the Atmosphere and Hydrosphere 16. Stromatolites are the product of organic activity.

ANS: T

PTS: 1

REF: 19.7. Life--Its Origin and Early History

17. The buildup of cyanobacteria entrapping sand grains explains the origin of stromatolites.

ANS: T

PTS: 1

REF: 19.7. Life--Its Origin and Early History

18. The oldest stromatolites are 4.1 billion years old.

ANS: F

PTS: 1

REF: Geo-Focus. The Sudbury Meteorite Impact and Its Aftermath 19. In order for monomers to polymerize, they need to be immersed in an aqueous solution.

ANS: F

PTS: 1

REF: 19.7. Life--Its Origin and Early History

20. Stromatolites are the first life form with skeletal structure.

ANS: F

PTS: 1

REF: 19.7. Life--Its Origin and Early History

21. Multi-celled organisms are those composed of many cells, all of which function independently.

ANS: F

PTS: 1

REF: 19.7. Life--Its Origin and Early History

22. The transition from single to multi-celled organisms may have started with cell colonies.

ANS: T

PTS: 1

REF: 19.7. Life--Its Origin and Early History

23. All known Proterozoic animals were soft-bodied.

ANS: T

PTS: 1

REF: 19.7. Life--Its Origin and Early History

24. Material such as chitin may have formed semi-durable chitinous exoskeletons.

ANS: T

PTS: 1

REF: 19.7. Life--Its Origin and Early History

25. Banded iron formations, although rich in iron, are not economical to mine because of the chert.

ANS: F

PTS: 1

REF: 19.8. Resources in Precambrian Rocks

26. Proterozoic layered igneous complexes are important sources for pegmatites.

ANS: F

PTS: 1

REF: 19.8. Resources in Precambrian Rocks

27. Proterozoic layered igneous intrusions are the world's major source of chrome and platinum.

ANS: T

PTS: 1

REF: 19.8. Resources in Precambrian Rocks

28. The Sudbury Basin was the site of two meteorite impacts that occurred at roughly the same time.

ANS: F

PTS: 1

REF: Geo-Focus. The Sudbury Meteorite Impact and Its Aftermath Chapter 20—Paleozoic Earth History

ESSAY 1. Describe how the first geologic map was created.

ANS: William Smith was building canals to transport coal around England. He noted that the same rocks and fossils kept appearing in the same order, and he could predict which sequences would be encountered where. His map allowed diggers to predict which rocks they would be digging through.

PTS: 1

REF: 20.1. Introduction

2. Describe a clastic wedge. How can a clastic wedge be used as evidence for an orogeny?

ANS: A clastic wedge is an extensive accumulation of mostly detriatal sediments deposited adjacent to an uplifted area. The wedge is thickest nearest the uplift and thins with distance from the uplift. These sediments eventually grade into carbonate cratonic facies. The existence of the wedge indicates that there was once a highland because of the thick sediments at one end and thinned sediments at the other. A highland indicates that there was once an orogeny.

PTS: 1

REF: 20.9. History of the Paleozoic Mobile Belts

3. What role did microplates and terranes play in the formation of Pangaea? Give an example.

ANS: Numerous terranes or microplates of various sizes were involved in Paleozoic orogenic events. For example, the microcontinent of Avalonia separated from Gondwana in the Early Ordovician and existed as a separate continent until it collided with Baltica during the Late Ordovician-Early Silurian and then with Laurentia later in the Silurian. During the times when the microplates were separate from the larger continental masses they developed their own unique floral and faunal assemblages.

PTS: 1 REF: 20.10. What Role Did Microplates and Terranes Play in the Formation of Pangaea?

SHORT ANSWER 1. What are mobile belts of a continent?

ANS: elongated areas of mountain-building activity along the margins of the continent PTS: 1

REF: 20.2. Continental Architecture: Cratons and Mobile Belts

2. What were three major mobile belts in North America in the Paleozoic?

ANS: Appalacian, Cordilleran, Ouachita PTS: 1

REF: 20.2. Continental Architecture: Cratons and Mobile Belts

3. What were the six major Paleozoic continents?

ANS: Baltica, China, Gondwana, Kazakhstania, Laurentia, Siberia PTS: 1

REF: 20.3. Paleozoic Paleogeography

4. During the Cambrian, where were the major continents located?

ANS: They were dispersed around the globe at low tropical latitudes.

PTS: 1

REF: 20.3. Paleozoic Paleogeography

5. When and where did the Acadian orogeny occur?

ANS: Devonian, eastern margin of Laurasia PTS: 1

REF: 20.3. Paleozoic Paleogeography

6. When and where did the Antler orogeny occur?

ANS: Devonian, Cordillera of North America PTS: 1

REF: 20.3. Paleozoic Paleogeography

7. What worldwide effect was caused by Gondwana moving over the South Pole during the Carboniferous Period?

ANS: The extensive continental glaciation on Gondwana produced global changes in sea level.

PTS: 1

REF: 20.3. Paleozoic Paleogeography

8. What is a cratonic sequence?

ANS: A large-scale rock unit representing a major transgressive-regressive cycle bounded by cratonwide unconformities.

PTS: 1

REF: 20.4. Paleozoic Evolution of North America

9. What are believed to be the causes of global transgressive and regressive cycles?

ANS: Changes in sea level resulting from major tectonic and glacial events.

PTS: 1

REF: 20.4. Paleozoic Evolution of North America

10. What is the name of the first major transgression onto the North American craton, and when did it begin?

ANS: Sauk, Middle Cambrian PTS: 1

REF: 20.4. Paleozoic Evolution of North America

11. Name the four Paleozoic transgressive sequences in order from oldest to youngest.

ANS: Sauk, Tippecanoe, Kaskaskia, Absaroka PTS: 1

REF: 20.4. Paleozoic Evolution of North America

12. What is the Tippecanoe sequence?

ANS: The transgressive-regressive sequence that followed the Sauk sequence and preceded the Kaskaskia sequence) PTS: 1

REF: 20.4. Paleozoic Evolution of North America

13. How did the extensive layers of dolostones form?

ANS: by magnesium substituting for calcium in the mineral calcite PTS: 1

REF: 20.6. The Tippecanoe Sequence

14. The early transgressing seas of both the Tippecanoe and Kaskaskia sequences are marked by deposition of what sedimentary rock type?

ANS: clean quartz sandstone PTS: 1

REF: 20.6. The Tippecanoe Sequence

15. What are cyclothems?

ANS: rhythmically repeated alternating marine and nonmarine sedimentary strata

PTS: 1

REF: 20.8. The Absaroka Sequence

16. What is the sedimentary sequence, from base to top, of an idealized cyclothem?

ANS: fluvial-deltaic deposits, coals, detrital shallow water marine sediments, limestones PTS: 1

REF: 20.8. The Absaroka Sequence

17. What is the currently favored hypothesis for explaining cyclothems?

ANS: rise and fall of sea level that accompanied advance and retreat of Gondwana glaciers PTS: 1

REF: 20.8. The Absaroka Sequence

18. The Absaroka sequence spans which periods of geologic time?

ANS: Late Mississippian through lower Jurassic PTS: 1

REF: 20.8. The Absaroka Sequence

19. In what two areas are there major exposures of the rocks formed in the Ouachita mobile belt?

ANS: The Ouachita Mountains of Oklahoma and Arkansas, the Marathon Mountains of Texas PTS: 1 COMPLETION

REF: 20.9. History of the Paleozoic Mobile Belts

1. The presumed causes for transgressions and regressions of shallow seas during the Paleozoic were ____________________ and ____________________.

ANS: glaciation, plate movement PTS: 1

REF: 20.2. Continental Architecture: Cratons and Mobile Belts

2. During the Paleozoic, cratons were covered with large bodies of water called ____________________.

ANS: epeiric seas PTS: 1

REF: 20.2. Continental Architecture: Cratons and Mobile Belts

3. The Taconic orogeny occurred during the ____________________ of geologic time in the region of ____________________.

ANS: Late Ordovician, New England PTS: 1

REF: 20.3. Paleozoic Paleogeography

4. The three orogenies of the Devonian were the ____________________, ____________________, and ____________________.

ANS: Acadian, Antler, Ellesmere PTS: 1

REF: 20.3. Paleozoic Paleogeography

5. The supercontinent that formed near the end of the Paleozoic from an assembling of all the continents was called ____________________.

ANS: Pangaea

PTS: 1

REF: 20.3. Paleozoic Paleogeography

6. The assemblage of the Late Paleozoic supercontinent concluded during the ____________________ Period.

ANS: Permian PTS: 1

REF: 20.3. Paleozoic Paleogeography

7. The first major transgression onto the North American continent is recorded in rocks of the ____________________ sequence.

ANS: Sauk PTS: 1

REF: 20.4. Paleozoic Evolution of North America

8. Prior to the transgression of epeiric seas in the Middle Cambrian, the North American craton had been undergoing ____________________ and ____________________.

ANS: weathering, erosion erosion, weathering PTS: 1

REF: 20.5. The Sauk Sequence

9. By the (Early/Middle/Late) ____________________ Cambrian, most of North America was covered by epeiric seas with the exception of a highland known as the ____________________.

ANS: Late, Transcontinental Arch PTS: 1

REF: 20.5. The Sauk Sequence

10. The most abundant rock type deposited during the Kaskaskian sequence was ____________________.

ANS: carbonates PTS: 1

REF: 20.7. The Kaskaskia Sequence

11. The ____________________ mobile belt of southern Europe corresponds to the ____________________ and ____________________ mobile belts of North America.

Collectively, these mark the zone along which ____________________ collided with ____________________.

ANS: Hercynian, Appalachian, Ouachita, Europe, Gondwana PTS: 1

REF: 20.9. History of the Paleozoic Mobile Belts

12. The ____________________ orogeny that occurred in the Cordilleran mobile belt was caused by ____________________.

ANS: Antler, subduction PTS: 1

REF: 20.9. History of the Paleozoic Mobile Belts

13. Erosion of the Taconic Highlands resulted in the development of a(n) ____________________ called the ____________________.

ANS: clastic wedge, Queenston Delta PTS: 1

REF: 20.9. History of the Paleozoic Mobile Belts

14. The ____________________ orogeny in Europe is a mirror of the Taconic and Acadian orogenies in North America.

ANS: Caledonian PTS: 1

REF: 20.9. History of the Paleozoic Mobile Belts

15. Most of the productive coal beds of Paleozoic age are found in rocks formed during the ____________________ period.

ANS: Pennsylvanian PTS: 1

REF: 20.11. Paleozoic Mineral Resources

MULTIPLE CHOICE 1. How many of the six Paleozoic geological systems were described in William Smith’s first geological map of England? a. two b. four c. five d. six

ANS: C

PTS: 1

REF: 20.1. Introduction

2. Each of the major continents at the beginning of the Paleozoic had two major components.

These were a. a trough and a range b. a craton and a mobile belt c. an immobile belt and a rift margin d. a craton and a ocean basin e. a volcano and a desert

ANS: B

PTS: 1

REF: 20.2. Continental Architecture: Cratons and Mobile Belts 3. The shield portion of the craton is underlain by ____ age rocks and was tectonically ____. a. Archean, active b. Precambrian, active c. Precambrian, inactive d. Phanerozoic, inactive e. Phanerozoic, active

ANS: C

PTS: 1

REF: 20.2. Continental Architecture: Cratons and Mobile Belts 4. Rocks of the shield are primarily ____. a. igneous b. metamorphic c. sedimentary d. igneous and metamorphic e. igneous and sedimentary

ANS: D

PTS: 1

REF: 20.2. Continental Architecture: Cratons and Mobile Belts 5. The Precambrian igneous rocks of the shield areas record evidence for ____. a. continental growth by accretion b. extensive Precambrian orogenic activity c. extensive pre-Phanerozoic erosion d. continental growth by accretion AND extensive Precambrian orogenic activity e. all of these

ANS: E

PTS: 1

REF: 20.2. Continental Architecture: Cratons and Mobile Belts 6. Which of the following was not a mobile belt around the North American continent during the Paleozoic? a. Franklin b. Cordilleran c. Hercynian d. Ouachita e. Appalachian

ANS: C

PTS: 1

REF: 20.3. Paleozoic Paleogeography

7. What were the general climatic conditions on the Paleozoic supercontinent (Pangaea)? a. arid b. arid to semiarid c. semiarid to subtropical d. subtropical to humid e. humid

ANS: B

PTS: 1

REF: 20.3. Paleozoic Paleogeography

8. A cratonic sequence is recognized by ____. a. a transgressive phase followed by regressive phase b. a regressive phase followed by a transgressive phase c. a regressive phase only d. a transgressive phase only e. a lack of any sequence

ANS: A

PTS: 1

REF: 20.4. Paleozoic Evolution of North America

9. How long has the Colorado Plateau been uplifting? a. 1 billion years b. 300 million years c. 30 million years d. 3 million years e. 300,000

ANS: C

PTS: 1

REF: Geo-Insight. The Grand Canyon--A Geologist's Paradise 10. The Vishnu Schist in the Grand Canyon records a period of ____. a. deep ocean sedimentation at a passive margin b. nearshore sedimentation at a passive margin c. dune building on land d. carbonate precipitation at a passive margin e. mountain building

ANS: E

PTS: 1

REF: Geo-Insight. The Grand Canyon--A Geologist's Paradise 11. Why are organic reefs useful paleoecological indicators? a. Organisms only form limestone reefs in cold, tropic waters. b. Organisms only form limestone reefs where there is a great abundance of mineral matter in the water. c. Organisms only form limestone reefs in warm, clear, shallow water. d. Organisms in the modern world only form limestone reefs between 30 degrees north and south of the equator. e. Modern organisms only form limestone reefs in warm, clear, shallow water, between 30 degrees north and south of the equator.

ANS: E

PTS: 1

REF: 20.6. The Tippecanoe Sequence

12. The Michigan Basin is an important source for ____. a. rock salt b. gypsum c. oil d. gas e. all of these

ANS: E

PTS: 1

REF: 20.6. The Tippecanoe Sequence

13. What was the probable source for detrital sand in the basal Kaskaskia unit? a. Ozark domes b. the Appalachian mobile belt c. the Canadian Shield d. all of these e. Ozark domes and the Appalachian mobile belt

ANS: D

PTS: 1

REF: 20.7. The Kaskaskia Sequence

14. Devonian black shale units are all but which of the following? a. calcareous b. carbonaceous c. thinly bedded d. conodont bearing e. less than 10 meters in thickness

ANS: A

PTS: 1

REF: 20.7. The Kaskaskia Sequence

15. What characteristic feature of Pennsylvanian rocks distinguishes rocks of the Absaroka sequence from those of the Kaskaskia sequence as well as others of North America? a. cyclothems b. carbonates c. coal d. conodonts e. chordates

ANS: A

PTS: 1

REF: 20.8. The Absaroka Sequence

16. What do cyclothems represent? a. transgressive and regressive sequences b. transgression of marine sediments over nonmarine sediments c. transgression of nonmarine sediments over marine sediments d. regression of marine sediments e. regionally extensive erosional surfaces

ANS: A

PTS: 1

REF: 20.8. The Absaroka Sequence

17. An idealized cyclothem is characterized by which of the following sequences from bottom to top? a. coal beds, fluvial deltaic sediments, detrital shallow water marine, limestone b. limestone, detrital shallow water marine, fluvial deltaic sediments, coal beds c. limestone, detrital shallow water marine, coal beds, fluvial deltaic sediments d. fluvial deltaic sediments, coal beds, detrital shallow water marine, limestone e. detrital shallow water marine, fluvial deltaic sediments, limestone, coal beds

ANS: D

PTS: 1

REF: 20.8. The Absaroka Sequence

18. Uplift of the Ancestral Rockies occurred during ____.

a. the Late Kaskaskia b. the Early Absaroka c. the Late Absaroka d. the Early Kaskaskia e. the Middle Devonian

ANS: C

PTS: 1

REF: 20.8. The Absaroka Sequence

19. What did the Queenston Delta form in response to? a. uplift of the Taconic Highlands b. subduction of the Iapetus plate c. uplift of the Caledonides d. carbonate deposition e. the Mississippi River

ANS: A

PTS: 1

REF: 20.9. History of the Paleozoic Mobile Belts

20. During the entire Paleozoic, the western margin of North America could be described as ____. a. tectonically active with the development of numerous mobile belts b. a passive margin with only localized mountain building events c. a passive margin with no evidence of orogeny d. an active margin with thick carbonate platforms e. a zone of active volcanism

ANS: B

PTS: 1

REF: 20.9. History of the Paleozoic Mobile Belts

21. When did the Ouachita system change sedimentation styles from those typical of a passive margin to an active margin? a. Late Paleozoic b. Early Pennsylvanian

c. Late Permian d. late Devonian e. Early Mississippian

ANS: E

PTS: 1

REF: 20.9. History of the Paleozoic Mobile Belts

22. The clastic wedge that formed off of the uplifted Caledonian Highlands is known as what? a. Old Caledonian Sandstone b. Old Catskill Sandstone c. Oriskany Sandstone d. St. Peters Sandstone e. Old Red Sandstone

ANS: E

PTS: 1

REF: 20.9. History of the Paleozoic Mobile Belts

23. The orogeny, which affected the northern Appalachians during the Late Silurian to the end of the Devonian, is known as the ____. a. Acadian Orogeny b. Caledonian Orogeny c. Appalachian Orogeny d. Hercynian Orogeny e. Ouachita Orogeny

ANS: A

PTS: 1

REF: 20.9. History of the Paleozoic Mobile Belts

24. The Zechstein deposits of Europe form the caprock for large quantities of what? a. lime b. gas c. aluminum d. silica

e. iron

ANS: B

PTS: 1

REF: 20.11. Paleozoic Mineral Resources

25. The Silurian Clinton Formation is an important source for ____. a. rock salt b. oil and gas c. iron d. silica e. lime

ANS: C

PTS: 1

REF: 20.11. Paleozoic Mineral Resources

26. What desirable type of coal is mostly found in the Appalachian region? a. anthracite b. coke c. bituminous d. evaporite e. none of these

ANS: A

PTS: 1

REF: 20.11. Paleozoic Mineral Resources

TRUE/FALSE 1. Mobile belts form when convergent plate margins develop.

ANS: T

PTS: 1

REF: 20.2. Continental Architecture: Cratons and Mobile Belts

2. Rise and fall of sea level in epeiric seas can be partly explained by continental glaciation events.

ANS: T

PTS: 1

REF: 20.2. Continental Architecture: Cratons and Mobile Belts 3. The Appalachian and Ouachita mountains represent ancient mobile belts.

ANS: T

PTS: 1

REF: 20.2. Continental Architecture: Cratons and Mobile Belts 4. Platform sedimentary rocks are entirely carbonate rocks.

ANS: F

PTS: 1

REF: 20.2. Continental Architecture: Cratons and Mobile Belts 5. Polar ice caps existed through most of the Cambrian.

ANS: F

PTS: 1

REF: 20.3. Paleozoic Paleogeography

6. During the Sauk transgression, the Transcontinental Arch was a highland estimated to be tens of thousands of feet high.

ANS: F

PTS: 1

REF: 20.5. The Sauk Sequence

7. The Transcontinental Arch represents portions of the Canadian Shield not covered by seas in the Sauk transgression.

ANS: T

PTS: 1

REF: 20.5. The Sauk Sequence

8. After the Sauk Sea had regressed, the exposed surface of the North American continent was subjected to extensive glaciation.

ANS: F

PTS: 1

REF: 20.6. The Tippecanoe Sequence

9. The boundary between the Tippecanoe and Sauk sequences is a vast unconformity with deep erosional relief.

ANS: T

PTS: 1

REF: 20.6. The Tippecanoe Sequence

10. The basal unit of the Tippecanoe sequence is the St. Peter Sandstone.

ANS: T

PTS: 1

REF: 20.6. The Tippecanoe Sequence

11. In the Tippecanoe sequence, widespread carbonate deposition was related to the Taconic orogeny.

ANS: F

PTS: 1

REF: 20.6. The Tippecanoe Sequence

12. The Colorado River is no longer deepening the Grand Canyon.

ANS: F

PTS: 1

REF: Geo-Insight. The Grand Canyon--A Geologist's Paradise 13. The basal unit of the transgressive Kaskaskia sequence is marked by extensive black shale deposition.

ANS: F

PTS: 1

REF: 20.7. The Kaskaskia Sequence

14. Terranes and microplates were part of the formation of Pangaea.

ANS: T

PTS: 1

REF: 20.10. What Role Did Microplates and Terranes Play in the Formation of Pangaea?

Chapter 21—Paleozoic Life History

ESSAY

1. What is the age of the Burgess Shale? What is its significance, and why did this unique preservation occur?

ANS: The Burgess Shale dates from the Middle Cambrian. The animals and enclosing mud were transported by slumps to anaerobic conditions where bacterial activity could not destroy the buried animals. This allowed preservation of this unique assemblage of fossils of soft-bodied animals.

PTS: 1

REF: 21.1. Introduction

2. What hypotheses have been put forward to explain the rise of so many different types of organisms at the time of the Cambrian explosion?

ANS: The Cambrian explosion was probably due to a combination of factors. Global environmental changes, from glaciations to warmer periods, may have contributed. An increase in calcium in the oceans may have allowed calcium carbonate and calcium phosphate to precipitate and create the shells of organisms. Shells would have protected organisms from predators and so there would have been a strong evolutionary advantage for organisms to have shells. The evolution of Hox genes, which control the development of individual regions of the body, indicate that the basic body plans had evolved by the end of the Cambrian explosion.

PTS: 1

REF: 21.2. What Was the Cambrian Explosion?

3. Briefly state why the development of the amniote egg was so significant in the evolution of the reptiles.

ANS:

This type of egg allowed the developing organism to bypass a larval stage that needed to live in water. Therefore, organisms were able to inhabit many ecosystems on land without being dependent on water for part of their reproductive cycle. The organism that hatched was selfreliant and looked like a miniature of the adult.

PTS: 1

REF: 21.8. Evolution of the Reptiles--The Land is Conquered

4. Briefly state the problems that animals faced in their adaptation to the land.

ANS: Because animals evolved in a moist environment, they had to adapt to the drying effects of the atmosphere, so they had to develop an outer skin covering for protection. They also had to develop a means to extract oxygen from the atmosphere rather than from water. Because animals need mobility to find food, they also had to develop a means of locomotion and a skeletal structure for support. Finally their reproductive system had to combat the problems of desiccation of unprotected eggs.

PTS: 1

REF: various

5. What was the distribution of trilobites in time and space during the Paleozoic? What niches did trilobites fill? Most were bottom dwellers, crawling around on the seafloor eating detritus.

ANS: Trilobites lived from early Cambrian to the end of the Permian in all marine environments, from shallow to deep ocean settings, all around the world. Some were free swimming predators or filter feeders swimming throughout the water column.

PTS: 1

REF: Geo-Insight. Trilobites--Paleozoic Arthropods

SHORT ANSWER 1. What was the Cambrian Explosion?

ANS: At the beginning of the Paleozoic Era, animals with skeletons appeared abruptly in the fossil record. This explosive development of new types of animals is called the Cambrian explosion.

PTS: 1

REF: 21.2. What Was the Cambrian Explosion?

2. What selective advantages did an exoskeleton or shell provide?

ANS: Possibilities include (1) protection against ultraviolet radiation, (2) protection against desiccation, (3) support, and (4) protection against predators.

PTS: 1

REF: 21.3. The Emergence of a Shelly Fauna

3. What was the evolutionary advantage of having a mineralized skeleton?

ANS: It allowed organisms to successfully occupy a wider variety of marine habitats.

PTS: 1

REF: 21.3. The Emergence of a Shelly Fauna

4. Describe the characteristics of an excellent guide fossil and give one example.

ANS: The ammonoids are excellent guide fossils because of distinctive physical features, short life span, and wide geographic distribution.

PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

5. Describe the four feeding groups and how they get their nutrition.

ANS:

Suspension feeders are animals that remove microscopic organisms and nutrients from the water. Herbivores eat plants; carnivore-scavengers are meat eaters; and sediment-deposit feeders extract nutrients from the sediments they digest.

PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

6. Describe the difference in cell division between echinoderms and chordates versus other invertebrates.

ANS: The cells of chordates and echinoderms divide by radial cleavage so the cells are aligned directly above each other. Cells of other invertebrates undergo spiral cleavage so cells are nested between each other.

PTS: 1

REF: 21.5. Vertebrate Evolution

7. What is the significance of the different types of cell cleavage between echinoderms and chordates versus other invertebrates? What other evidence is there for this idea?

ANS: Since chordates have the same type of cell cleavage as echinoderms, it is thought that they have a shared common ancestor. The biochemistry of muscle activity and blood proteins, plus the larval stages, are similar between echinoderms and chordates.

PTS: 1

REF: 21.5. Vertebrate Evolution

8. Describe the evolutionary history and importance of crossopterygians.

ANS: Crossopterygians are one of the two groups of lobe-finned fish and are considered the most important because they are the evolutionary ancestors of the amphibians.

PTS: 1

REF: 21.6. Fish

9. Briefly discuss how the evolution of jawed fishes and other predatory creatures affected the marine ecosystem.

ANS: The development of predators had a major impact because organisms that had previously not needed defense mechanisms either developed defense systems or suffered great population losses.

PTS: 1

REF: 21.6. Fish

10. What were the factors that made it difficult for animals to adapt to land?

ANS: On land, animals had to worry about reproduction, desiccation, gravity, and the extraction of oxygen from atmosphere.

PTS: 1

REF: 21.7. Amphibians--Vertebrates Invade the Land

11. What was the name of the earliest known reptile, and when did it evolve?

ANS: Westlothiana had evolved by the Late Mississippian.

PTS: 1

REF: 21.8. Evolution of the Reptiles--The Land is Conquered

12. Briefly state some of the mammal-like features that therapsids developed.

ANS: The therapsids had differentiated teeth for various functions. They had larger lower jawbones than reptiles. They had a different leg structure which led to a more vertical posture.

PTS: 1

REF: 21.8. Evolution of the Reptiles--The Land is Conquered

13. What characterized the sphenopsid plant group?

ANS: jointed stem and horizontal underground stem-bearing roots PTS: 1

REF: 21.9. Plant Evolution

14. Name two examples of modern sphenopsids.

ANS: Equisetum (horsetail) and souring rushes PTS: 1

REF: 21.9. Plant Evolution

15. What is the importance of Glossopteris?

ANS: Glossopteris was a fern that lived in non-swampy areas and was widely distributed in the Late Paleozoic. The presence of fossils of this plant on many continents is one line of evidence for the plate tectonic theory.

PTS: 1

REF: 21.9. Plant Evolution

16. Briefly state some of the problems that plants had to overcome as they adapted to the land.

ANS: Plants had to solve some of the same problems that animals did by dealing with the effects of desiccation and gravity. They had to develop a support system, and they had to develop a reproductive system that would operate in this new environment.

PTS: 1

REF: 21.9. Plant Evolution

COMPLETION 1. The presence of an exoskeleton enables an organism to adapt to shallow water by providing protection from ____________________.

ANS: ultraviolet radiation PTS: 1

REF: 21.3. The Emergence of a Shelly Fauna

2. Organisms that live in the marine ecosystem above the seafloor are called ____________________.

ANS: pelagic PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

3. Pelagic organisms can be divided into the floaters, or ____________________, and the swimmers, or ____________________.

ANS: plankton, nekton PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

4. Three examples of phytoplankton are ____________________, ____________________, and ____________________.

ANS: diatoms, dinoflagellates, algae PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

5. Three examples of zooplankton are____________________, ____________________, and ____________________.

ANS: foraminifera, radiolaria, jellyfish PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

6. Organisms that live on the seafloor are called ____________________; those that move are ____________________, and those that remain stationary are ____________________.

ANS: benthos, mobile, sessile PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

7. Benthic plants are called __________ and benthic animals are called __________.

ANS: epiflora, epifauna PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

8. Benthos organisms that move through or live in the sediment are called ____________________.

ANS: infauna PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

9. Chordates are animals that have, during at least part of their life cycles, a dorsal hollow nerve chord, a(n) ____________________ and ____________________.

ANS: notochord, gill slits gill slits, notochord PTS: 1

REF: 21.5. Vertebrate Evolution

10. The trilobite body was divided into three parts: a(n) ____________________, a(n) ____________________, and a(n) ____________________.

ANS: cephalon (head), thorax (body), pygidium (tail) PTS: 1

REF: Geo-Insight. Trilobites--Paleozoic Arthropods

11. ____________________ in jawless fish eventually developed into jaws.

ANS: Gill arches PTS: 1

REF: 21.6. Fish

12. The development of ____________________ increased the diversity of foods that fish could consume, including ____________________.

ANS: jaws, other fish PTS: 1

REF: 21.6. Fish

13. By the end of the Permian, small mammal-like reptiles, called ____________________, evolved from the pelycosaur.

ANS: therapsids PTS: 1

REF: 21.8. Evolution of the Reptiles--The Land is Conquered

14. In an amniote egg, the embryo is surrounded by the ____________________ and provided with a(n) ____________________ and a(n) ____________________.

ANS: amnion, allantois, yolk PTS: 1

REF: 21.8. Evolution of the Reptiles--The Land is Conquered

15. The fin-back reptiles are called ____________________ and they went extinct in the ____________________.

ANS: pelycosaurs, Permian PTS: 1

REF: 21.8. Evolution of the Reptiles--The Land is Conquered

16. The development that set the stage for the evolution of animals that lived entirely on the land was the __________.

ANS: amniote egg PTS: 1

REF: 21.8. Evolution of the Reptiles--The Land is Conquered

17. ____________________ were warm-blooded, so they were able to adapt to a wide variety of latitudes.

ANS: Therapsids PTS: 1

REF: 21.8. Evolution of the Reptiles--The Land is Conquered

18. The oldest fossils of the first vascular land plants have been found in ____________________ age rocks.

ANS: Middle Silurian PTS: 1

REF: 21.9. Plant Evolution

19. The Carboniferous flora in coal-forming swamps was dominated by ____________________ plants.

ANS: seedless vascular

PTS: 1

REF: 21.9. Plant Evolution

20. The dominant type of flora in non-swampy areas of the Late Paleozoic was ____________________.

ANS: gymnosperms PTS: 1

REF: 21.9. Plant Evolution

21. The two most important seedless vascular plants of the coal-forming swamps were ____________________ and ____________________.

ANS: lycopsids, sphenopsids sphenopsids, lycopsids PTS: 1

REF: 21.9. Plant Evolution

22. The plant group that flourished during the Permian because it was well suited to a warmer drier climate was ____________________.

ANS: gymnosperms PTS: 1

REF: 21.9. Plant Evolution

MULTIPLE CHOICE 1. The Precambrian-Cambrian boundary represents the first appearance of ____. a. vertebrates b. amphibians c. reptiles d. animals with skeletons

e. animals with soft bodies

ANS: D

PTS: 1

REF: 21.1. Introduction

2. Hox genes a. control the formation of shells. b. control the development of individual body regions. c. mostly evolved after the Cambrian explosion. d. guide the formation of exoskeletons. e. all of these

ANS: B

PTS: 1

REF: 21.2. What Was the Cambrian Explosion?

3. Which of the following is not a function of an exoskeleton? a. protection against ultraviolet light b. protection against predators c. increased efficiency in reproduction d. protection from drying out e. support the organism to allow for increased size

ANS: C

PTS: 1

REF: 21.3. The Emergence of a Shelly Fauna

4. Which of the following is not one of the basic feeding groups? a. herbivores b. carnivore-scavengers c. sediment-deposit feeders d. suspension feeders e. inhalation feeders

ANS: E

PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

5. Which of the following is not an example of a pelagic organism? a. cephalopod b. fish c. algae d. worm e. foraminifera

ANS: D

PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

6. An organism classified as an autotroph ____. a. is a carnivore b. produces its own food c. is at the top of the food chain d. is a herbivore e. has eyes

ANS: B

PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

7. What is the correct order of trophic levels from bottom to top? a. primary consumer, secondary consumer, tertiary consumer, primary producer b. primary producer, secondary producer, tertiary producer, primary consumer c. tertiary consumer, secondary consumer, primary consumer, primary producer d. primary producer, primary consumer, secondary consumer, tertiary consumer e. primary consumer, secondary consumer, primary producer, tertiary consumer

ANS: D

PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

8. Which of the following does not apply to trilobites?

a. abundant in modern oceans b. excellent guide fossil c. benthos, mobile d. sediment-feeder e. invertebrate

ANS: A

PTS: 1

REF: Geo-Insight. Trilobites--Paleozoic Arthropods

9. Archaeocyathids can be characterized by all except which of the following? a. sessile b. benthos c. constructed reef-like structures d. suspension feeder e. sediment bottom feeder

ANS: E

PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

10. How did Ordovician reefs differ from those of the Cambrian? a. Cambrian reefs were generally small. b. Cambrian reefs were built primarily of Archeocyathids. c. Ordovician reefs represent a diverse community of organisms. d. Ordovician reefs were dominated by suspension feeders. e. all of these

ANS: E

PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

11. All but which of the following were important in the reef environment of the Ordovician? a. bryozoa b. stromatoporoids c. tabulate coral

d. crinoids e. rugose coral

ANS: D

PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

12. What did the mass extinction at the end of the Ordovician set the stage for? a. more species to go extinct b. groups of organisms to diversify c. groups of organisms to withdraw from previous habitats d. groups of organisms to repopulate abandoned niches e. diversification and repopulation of abandoned niches

ANS: E

PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

13. All except which of the following are important fossils groups from Silurian and Ordovician age rocks? a. crinoids b. brachiopods c. mollusks d. trilobites e. bryozoa

ANS: D

PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

14. Which of the following is not used as evidence to suggest an evolutionary link between chordates and echinoderms? a. blood proteins b. embyronic development c. larval stages d. biochemistry of muscle activity

e. none of these

ANS: E

PTS: 1

REF: 21.5. Vertebrate Evolution

15. What were the earliest fish? a. ray-finned b. boney-finned c. cartilaginous d. jawless e. jawed

ANS: D

PTS: 1

REF: 21.6. Fish

16. What did the earliest fish have? a. armored plated skin b. jaws c. spiny skin d. plated skin e. ray-fins

ANS: A

PTS: 1

17. What does the name Placoderm mean? a. plate-skinned b. bony skin c. scaly skin d. spiny skin e. fleshy skin

REF: 21.6. Fish

ANS: A

PTS: 1

REF: 21.6. Fish

18. The evolution of jaws played an important role in the evolution of fish because it allowed them to do what? a. diversify feeding styles b. increase oxygen consumption c. increase food consumption d. increase oxygen and food consumption e. all of these

ANS: E

PTS: 1

REF: 21.6. Fish

19. What feature distinguishes the two subclasses of bony fish? a. gill structure b. skeletal structure c. fin structure d. teeth structure e. scale structure

ANS: C

PTS: 1

REF: 21.6. Fish

20. The crossopterygians were well-adapted to move onto the land because they had this. a. lungs b. a means for locomotion c. cartilaginous skeletons d. lungs and a means of locomotion e. all of these

ANS: D

PTS: 1

REF: 21.6. Fish

21. The most critical barriers for animals in making the transition from sea to land were the development of ways to deal with what? a. desiccation b. reproduction c. the effects of gravity d. the extraction of oxygen from the atmosphere e. all of these

ANS: E

PTS: 1

REF: 21.7. Amphibians--Vertebrates Invade the

Land 22. The factors which lead to the success of the reptiles on land include all except which of the following? a. rapid locomotion b. advanced jaws and teeth c. method of reproduction d. herbivorous feeding e. none of these

ANS: D

PTS: 1

REF: 21.8. Evolution of the Reptiles--The Land is Conquered 23. The sail-like fin on the pelycosaur may have served as all except which of the following? a. sexual display b. a means of locomotion c. a means of protection d. a means of defense e. a thermoregulatory device

ANS: B

PTS: 1

REF: 21.8. Evolution of the Reptiles--The Land is Conquered 24. Plants are divided into which two major groups? a. coniferous and deciduous b. vascular and spore-bearing c. angiosperms and gymnosperms d. vascular and non-vascular e. seedless and non-seedless

ANS: D

PTS: 1

REF: 21.9. Plant Evolution

25. Non-vascular plants differ from vascular plants in that they ____. a. reproduce by seeds only b. live in dry arid climates c. are small and live in moist climates d. do not have specialized tissue to transport water and nutrients e. are small, live in moist climates and do not have specialized tissue for transporting water and nutrients

ANS: E

PTS: 1

REF: 21.9. Plant Evolution

26. The earliest vascular land plants were characterized by which of the following? a. seed-producing and rootless b. seedless and root-bearing c. seedless and rhizome-bearing d. seed-bearing and rhizome bearing e. none of these

ANS: C

PTS: 1

REF: 21.9. Plant Evolution

27. Seedless vascular plants evolved which of the following features of modern plants? a. seeds b. roots c. leaves d. secondary growth e. roots, leaves and secondary growth

ANS: E

PTS: 1

REF: 21.9. Plant Evolution

28. The development of the seed played what role in vascular plant evolution? a. Plants could grow taller. b. Plants could reproduce asexually. c. Plants could adapt to varied terrestrial habitats. d. none of these e. Plants could grow taller and reproduce asexually.

ANS: C

PTS: 1

REF: 21.9. Plant Evolution

TRUE/FALSE 1. Animals with rigid skeletons appeared abruptly in the fossil record at the beginning of the Paleozoic.

ANS: T

PTS: 1

REF: 21.1. Introduction

2. There is no evidence in the geologic record that multi-celled organisms of any kind existed prior to the Cambrian.

ANS: F

PTS: 1

REF: 21.2. What Was the Cambrian Explosion?

3. The first evidence of shelled organisms is in the early Cambrian in the Ediacaran fauna.

ANS: T

PTS: 1

REF: 21.2. What Was the Cambrian Explosion?

4. In the Early Cambrian, there was a great diversity of fauna which represented many phyla that exist today.

ANS: F

PTS: 1

REF: 21.2. What Was the Cambrian Explosion?

5. Life was more diverse in terms of phyla during the Cambrian than it is today.

ANS: F

PTS: 1

REF: 21.2. What Was the Cambrian Explosion?

6. One of the most significant roles of the exoskeleton is to provide protection from desiccation and predators.

ANS: T

PTS: 1

REF: 21.3. The Emergence of a Shelly Fauna

7. Organisms with endo- or exoskeletons usually have decreased locomotor functions because muscles are restricted.

ANS: F

PTS: 1

REF: 21.3. The Emergence of a Shelly Fauna

8. The presence of an exoskeleton gives an organism the protection to adapt to a much greater variety of habitats.

ANS: T

PTS: 1

REF: 21.3. The Emergence of a Shelly Fauna

9. Eurypterids are a subclass of the cephalopods that are excellent guide fossils.

ANS: F

PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

10. Devonian mass extinctions were caused by global cooling that made the environment unfavorable for the widespread reef organisms of the time period.

ANS: T

PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

11. Two groups that attained their greatest diversity during the Carboniferous were the stromatoporoids and tabulate corals.

ANS: F

PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

12. Carboniferous age reefs differed from those of the Devonian, in that they were much more massive than the older reef structures.

ANS: F

PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

13. Fusilinids, greatly diversified in the Pennsylvanian and Permian, are one of the most useful guide fossils for those periods.

ANS: T

PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

14. Organisms that comprised reef complexes remained virtually unchanged during the Paleozoic.

ANS: F

PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

15. Trilobites, an organism abundant in the Early Paleozoic and less abundant in the Late Paleozoic, greatly flourished after the Permian extinction.

ANS: F

PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

16. Trilobites are common organisms in aquaria today.

ANS: F

PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

17. The Permian extinction was unequivocally related to an extraterrestrial impact.

ANS: F

PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

18. The amalgamation of Pangaea may have played an important role in the Permian extinction because the shallow marine environment was greatly reduced.

ANS: T

PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

19. The Permian extinction may have been caused by the interrelated consequences of the amalgamation of Pangaea and global climate change.

ANS: T

PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

20. The critical factors in species survival of the Permian extinction are wide geographic distribution and tolerance of broad temperature ranges.

ANS: T

PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

21. At the end of the Permian, the marine invertebrates suffered the greatest extinction with about 90 percent loss of species.

ANS: F

PTS: 1

REF: 21.4. Paleozoic Invertebrate Marine Life

22. All chordates are vertebrates.

ANS: F

PTS: 1

REF: 21.5. Vertebrate Evolution

23. Based on embryo studies, blood proteins, and biochemistry of muscle activity, chordates may be more closely linked to echinoderms than to other phyla.

ANS: T

PTS: 1

REF: 21.5. Vertebrate Evolution

24. Because of the development of the jaw, fish changed their eating habits from being that of predators to filter feeders.

ANS: F

PTS: 1

REF: 21.6. Fish

25. Fish first evolved in a marine environment and later adapted to non-marine habitats.

ANS: T

PTS: 1

REF: 21.6. Fish

26. Lung-fish are important in the fossil record because amphibians evolved from them.

ANS: F

PTS: 1

REF: 21.6. Fish

27. All crossopterygians went extinct at the end of the Cretaceous.

ANS: F

PTS: 1

REF: 21.8. Evolution of the Reptiles--The Land is Conquered 28. Therapsids developed mammal-like features including hairy skins.

ANS: F

PTS: 1

REF: 21.8. Evolution of the Reptiles--The Land is Conquered Chapter 22—Mesozoic Earth and Life History

ESSAY 1. What is the name of the type of gold deposit found at Sutter's Mill, Coloma, California in 1848, and how are they formed? How did prospectors extract the gold from the deposit?

ANS: These placer deposits form by weathering of gold-bearing igneous rocks and mechanical separation of minerals by density during stream transport. The gold was collected by panning.

A shallow pan was dipped into a stream bed to capture sediment. The material was swirled around and the lighter material was poured off. Gold concentrated at the bottom of the pan.

PTS: 1

REF: 22.1. Introduction

2. Contrast saurischian and ornithischian dinosaurs. Describe the ancestor of both of these dinosaur groups.

ANS: Saurischian dinosaurs had a lizard-like pelvis. Ornithischians had a bird-like pelvis. Unlike saurischians, ornithischians had no teeth in the front of their mouth and they had bonelike tendons in the back region. The common ancestor of these dinosaurs was much like archosaurs. Archosaurs were small, long-legged carnivores that walked and ran on their hind limbs meaning that they were bipedal.

PTS: 1

REF: 22.6. Life of the Mesozoic Era

3. What are terranes? How are they recognized? What role did accretion of terranes play in the growth of western North America?

ANS: Small accreted lithoospheric blocks, called terranes, are found in many mountain systems.

They are composed of such different fossils, stratigraphy, structural trends, and paleomagnetic properties from the surrounding rocks and craton that geologists think that they were carried great distances as parts of other plates until they collided with other terranes and continents.

More than 100 different-sized terranes were added to the western margin of North America during the past 200 million years.

PTS: 1 REF: 22.4. What Role Did Accretion of Terranes Play in the Growth of Western North America?

SHORT ANSWER 1. How did the breakup of Pangaea influence geologic and biologic events during the Mesozoic?

ANS: Continental movements affected climatic and oceanic regimes. Populations of organisms became isolated from or were brought into contact with other populations, which led to evolutionary changes in the organisms.

PTS: 1

REF: 22.1. Introduction

2. What event was first in the breakup of Pangaea?

ANS: The first event was rifting between Laurasia and Gondwana.

PTS: 1

REF: 22.2. The Breakup of Pangaea

3. In what ways did the breakup of Pangaea affect geologic and biologic events on Earth?

ANS: The breakup affected global climates, oceanic regimes, individual continental climates, and distribution and future evolution of flora and fauna.

PTS: 1

REF: 22.2. The Breakup of Pangaea

4. What was the effect of the global rise in sea level during the Cretaceous?

ANS: Sea level rose causing transgressions onto the continents.

PTS: 1

REF: 22.2. The Breakup of Pangaea

5. What geologic evidence chronicles the separation of North America and Africa?

ANS: There are numerous rift basins that formed during the early part of the Mesozoic Era.

PTS: 1

REF: 22.2. The Breakup of Pangaea

6. Describe global climate on Pangaea during the Late Paleozoic and Early Mesozoic. How did the breakup of the supercontinent affect global climate?

ANS: Pangaea had relatively little coastline and a great deal of continental interior. This kept the supercontinent extremely arid. The breakup of Pangaea caused the global temperature gradient to decrease as continents moved northward in the Northern Hemisphere.

PTS: 1

REF: 22.2. The Breakup of Pangaea

7. Why did fault-block basins develop along the eastern margin of North America during the Triassic?

ANS: Upwelling magma caused Pangaea to begin to break apart.

PTS: 1

REF: 22.2. The Breakup of Pangaea

8. Describe the geologic deposits that filled the Triassic fault-block basins found in the Appalachian region.

ANS: The Triassic fault-block basins were the site of extensive basalt volcanism and intrusion concurrent with red, non-marine detrital sediments.

PTS: 1

REF: 22.3. Mesozoic History of North America

9. Based on the occurrence of dinosaur fossils in the Morrison Formation, what can you conclude about the depositional environment of the unit?

ANS: The depositional environment of this unit can be interpreted as marginal marine and fluvial.

PTS: 1

REF: 22.3. Mesozoic History of North America

10. Describe why there are such massive petroleum deposits in the Persian Gulf region.

ANS: The accumulation of petroleum in the region is related to the deposition of thick sections of sediment along the passive margin of Africa.

PTS: 1

REF: 22.5. Mesozoic Mineral Resources

11. What is the origin of the uranium in the Colorado Plateau?

ANS: The uranium is related to the presence of plant fossils in ancient stream channels.

PTS: 1

REF: 22.5. Mesozoic Mineral Resources

12. Where are most of the world's diamond resources found?

ANS: They are found in Cretaceous age kimberlite pipes in South Africa.

PTS: 1

REF: 22.5. Mesozoic Mineral Resources

13. What features do ammonites have that make them excellent guide fossils for the Mesozoic?

ANS: Ammonites developed a complex suture pattern that is distinctive enough for different species and ages.

PTS: 1

REF: 22.6. Life of the Mesozoic Era

14. Briefly state whether ectotherms or endotherms require more food and why.

ANS: Endotherms require more food because instead of obtaining heat from external sources, such as the sun, they generate heat internally, by burning food.

PTS: 1

REF: 22.6. Life of the Mesozoic Era

15. How distinct were Mesozoic mammals from their reptile neighbors?

ANS: Most Mesozoic mammals had both mammalian and reptilian features because some characteristics evolved more slowly than others.

PTS: 1

REF: 22.6. Life of the Mesozoic Era

COMPLETION 1. The three time periods of the Mesozoic, from oldest to youngest are ____________________, ____________________, and ____________________.

ANS: Triassic, Jurassic, Cretaceous PTS: 1

REF: various

2. The breakup of Pangaea began during the ____________________ Period and continued through the ____________________ Period.

ANS: Triassic, Cenozoic PTS: 1

REF: 22.2. The Breakup of Pangaea

3. Major mountain-building episodes during the Jurassic in the Cordilleran region resulted in the formation of the ____________________ and ____________________ Mountains.

ANS: Sierra Nevada, Rocky PTS: 1

REF: 22.3. Mesozoic History of North America

4. The Atlantic Ocean began to form in the ____________________ Period.

ANS: Late Triassic PTS: 1

REF: 22.3. Mesozoic History of North America

5. The Gulf of Mexico began to form in the ____________________ Period.

ANS: Late Triassic PTS: 1

REF: 22.3. Mesozoic History of North America

6. The distinctive sedimentary rocks that were deposited in the early-formed Gulf of Mexico were ____________________.

ANS: evaporites PTS: 1

REF: 22.3. Mesozoic History of North America

7. The Sonoma orogeny occurred at the ____________________-____________________ boundary.

ANS: Permian-Triassic PTS: 1

REF: 22.3. Mesozoic History of North America

8. The general term "Cordilleran orogeny" is applied collectively to a series of individual mountain building episodes known as the ____________________, ____________________, and ____________________ orogenies.

ANS: Nevadan, Sevier, Laramide PTS: 1

REF: 22.3. Mesozoic History of North America

9. Evaporite deposition ended and normal marine sedimentation began in the Gulf region by the ____________________ Period.

ANS: Late Jurassic PTS: 1

REF: 22.3. Mesozoic History of North America

10. The Early Cretaceous sedimentation in the Gulf Coastal region was related to a (transgressive/regressive) ____________________ seaway.

ANS: transgressive PTS: 1

REF: 22.3. Mesozoic History of North America

11. Cretaceous reefs of the Gulf Coastal region make excellent __________ __________ ANS: petroleum reservoirs PTS: 1

REF: 22.3. Mesozoic History of North America

12. The three phases of the Cordilleran orogeny in order from oldest to youngest were the ____________________, ____________________, and ____________________.

ANS: Nevadan, Sevier, Laramide

PTS: 1

REF: 22.3. Mesozoic History of North America

13. The main commodity associated with large batholithic intrusions in the western United States is ____________________.

ANS: gold PTS: 1

REF: 22.5. Mesozoic Mineral Resources

14. Low-grade copper deposits associated with large subduction related intrusions are called ____________________ deposits.

ANS: porphyry copper PTS: 1

REF: 22.5. Mesozoic Mineral Resources

15. The major reef builder of the Mesozoic was the ____________________.

ANS: rudists PTS: 1

REF: 22.6. Life of the Mesozoic Era

16. The ____________________ dinosaurs are also known as the bird-hipped dinosaurs.

ANS: ornithischia PTS: 1

REF: 22.6. Life of the Mesozoic Era

17. Many of the large dinosaurs such as Tyrannosaurus are known as the ____________________ dinosaurs.

ANS: saurischian

PTS: 1

REF: 22.6. Life of the Mesozoic Era

18. The ____________________ were characterized by a thickened dome-shaped skull.

ANS: pachycephalosaurs PTS: 1

REF: 22.6. Life of the Mesozoic Era

19. The duck-billed dinosaurs were in the ____________________ dinosaur group.

ANS: ornithischian PTS: 1

REF: 22.6. Life of the Mesozoic Era

20. A carnivorous dinosaur that used its heavily armored tail to kill for food was the ____________________.

ANS: stegosaurus PTS: 1

REF: 22.6. Life of the Mesozoic Era

21. The common ancestor of modern marsupials and placental mammals were the ____________________.

ANS: eupantotheres PTS: 1

REF: 22.6. Life of the Mesozoic Era

22. Scientists know that birds began to evolve prior to the Cretaceous due to the fossil ____________________.

ANS: Archaeopteryx

PTS: 1

REF: 22.6. Life of the Mesozoic Era

MULTIPLE CHOICE 1. The Gulf of Mexico began to form during the ____ ____ as North America separated from ____. a. Early Triassic, Africa b. Late Triassic, Africa c. Early Triassic, South America d. Late Triassic, South America e. Middle Triassic, Africa

ANS: D

PTS: 1

REF: 22.3. Mesozoic History of North America

2. The Permian/Triassic orogenic event that occurred with the collision of an island arc with the western margin of North America is called the ____ orogeny. a. Antler b. Cordilleran c. Sonoma d. Franciscan e. Western

ANS: C

PTS: 1

REF: 22.3. Mesozoic History of North America

3. The Franciscan Group rocks are a chaotic assemblage because they ____. a. represent ocean rift zone sediments b. represent deposition in an active deep ocean trench c. represent complex intrusion along a fault zone d. are high grade metamorphic rocks e. were deposited in a fault zone

ANS: B

PTS: 1

REF: 22.3. Mesozoic History of North America

4. The mountain building event that began in the Jurassic and continued into the Cenozoic is called the ____ orogeny. a. Sonoma b. Antler c. Cordilleran d. Rocky Mountain e. Alleghenian

ANS: C

PTS: 1

REF: 22.3. Mesozoic History of North America

5. The giant batholiths of the Sierra, Idaho, and Coast Range were emplaced during which orogeny? a. Sevier orogeny b. Nevadan orogeny c. Sonoma orogeny d. Laramide orogeny e. Allegheny orogeny

ANS: B

PTS: 1

REF: 22.3. Mesozoic History of North America

6. The interior of the North American continent was flooded during the Middle Jurassic by which Sea? a. Navajo Sea b. Moenkopi Sea c. Morrison Sea d. Sundance Sea e. Sevier Sea

ANS: D

PTS: 1

REF: 22.3. Mesozoic History of North America

7. Continental growth is a. faster at passive margins. b. faster along active margins. c. mostly by reworked older continental material. d. mostly by orogenesis. e. nonexistent

ANS: B

PTS: 1

REF: 22.4. What Role Did Accretion of Terranes Play in the Growth of Western North America?

8. Diamonds a. form at great depth where temperature and pressure are high. b. are brought to the surface by explosive volcanism. c. were formed intensely during the Cretaceous Period in South Africa. d. all of these.

ANS: D

PTS: 1

REF: 22.5. Mesozoic Mineral Resources

9. The Mesozoic Era is known as the age of a. reptiles b. dinosaurs c. Pangaea d. angiosperms e. flowering plants

ANS: A

PTS: 1

REF: 22.6. Life of the Mesozoic Era

10. In addition to expansion of reptile species during the Mesozoic, other life groups that showed an increase in diversity include which of the following? a. marine invertebrates b. plants c. mammals d. birds e. all of these

ANS: E

PTS: 1

REF: 22.6. Life of the Mesozoic Era

11. What are the major classes of Mesozoic mollusks? a. ammonites, brachiopods, and cephalopods b. gastropods, ammonites, and brachiopods c. bivalves, cephalopods, and ammonites d. trilobites, brachiopods, and ammonites e. gastropods, bivalves, and cephalopods

ANS: E

PTS: 1

REF: 22.6. Life of the Mesozoic Era

12. Ammonites of the Mesozoic were characterized by a very ____. a. restricted duration in time b. complex indenture pattern c. complex feeding mechanism d. complex growth suture pattern e. complex locomotor mechanism

ANS: D

PTS: 1

REF: 22.6. Life of the Mesozoic Era

13. All modern reptiles are ____. a. ectotherms b. endotherms c. echinotherms d. unitherms e. antitherms

ANS: A

PTS: 1

REF: 22.6. Life of the Mesozoic Era

14. What was the pterosaur adapted to flight with? a. a membrane-covered hand-like structure with an elongated fourth finger b. bird-like wings covered with hollow feathers c. bird-like wings with no covering d. bat-like wings covered with thick fur e. bat-like wings with no covering

ANS: A

PTS: 1

REF: 22.6. Life of the Mesozoic Era

15. What were the two groups of marine reptiles? a. plesiosaurs and pterosaurs b. pterosaurs and ichthyosaurs c. captorhinomorphs and plesiosaurs d. plesiosaurs and ichthyosaurs e. plesiosaurs and crocodiles

ANS: D

PTS: 1

REF: 22.6. Life of the Mesozoic Era

16. How did ichthyosaurs and plesiosaurs differ? a. Ichthyosaurs were able to travel onto the land. b. Ichthyosaur females probably gave birth to live young.

c. Plesiosaur females probably gave birth to live young. d. Plesiosaurs were adapted only to the aquatic environment. e. Ichthyosaurs ate fish and plesiosaurs did not.

ANS: B

PTS: 1

REF: 22.6. Life of the Mesozoic Era

17. What is the difference between a reptile's lower jaw and a mammal's lower jaw? a. Mammals have 16 teeth in the lower jaw. b. The lower jaw of a reptile is a single bone. c. The lower jaw of a reptile contains no teeth. d. The lower jaw of a mammal is a single bone. e. The lower jaw of a reptile contains 12 teeth.

ANS: D

PTS: 1

REF: 22.6. Life of the Mesozoic Era

18. During the Mesozoic, climatic variation on Earth could be described as ____. a. extreme in terms of precipitation b. extreme in terms of temperature c. lacking great north-south variation d. having great north-south variation e. similar to present day

ANS: C

PTS: 1

REF: Table 22.3. Mesozoic Biologic Events

19. Because of the nature of the world-wide climatic conditions in the Mesozoic, organisms ____. a. had few habitats to occupy b. could occupy extensive geographic regions c. could only occupy restricted geographic regions d. were not affected e. stayed where they were

ANS: B

PTS: 1

REF: 22.7. Mesozoic Climates and Paleogeography

20. What are greatly accelerated rates of extinction called? a. disasters b. punctuated equilibrium c. mass extinctions d. gradualisms e. normal

ANS: C

PTS: 1

REF: 22.8. Mass Extinctions--A Crisis in the History of Life 21. The effect of the meteorite impact at the end of the Cretaceous is thought to have been ____. a. great input of particulate matter into the atmosphere b. blocking of the incoming solar radiation c. cessation of photosynthesis d. collapse of the food chains e. all of these

ANS: E

PTS: 1

REF: 22.8. Mass Extinctions--A Crisis in the History of Life TRUE/FALSE 1. During the breakup of Pangaea, the eastern margin of North America went first through a passive margin stage and then through a rift margin stage.

ANS: F

PTS: 1

REF: 22.2. The Breakup of Pangaea

2. Mountain building in western North America did not begin until the Late Cretaceous Period.

ANS: F

PTS: 1

REF: 22.3. Mesozoic History of North America

3. One of the most productive dinosaur fossil stratigraphic horizons is the Triassic Newark Group.

ANS: F

PTS: 1

REF: 22.3. Mesozoic History of North America

4. The Palisades sill is a Cretaceous age basalt intrusion associated with compressional mountain building.

ANS: F

PTS: 1

REF: 22.3. Mesozoic History of North America

5. During the Jurassic and Cretaceous, the Appalachian range was eroded into a low-lying erosional surface.

ANS: T

PTS: 1

REF: 22.3. Mesozoic History of North America

6. As the Gulf of Mexico began to form, the shallow restricted basin was conducive for red bed formation.

ANS: F

PTS: 1

REF: 22.3. Mesozoic History of North America

7. Evaporite deposition continued in the Gulf of Mexico region throughout the entire Mesozoic.

ANS: F

PTS: 1

REF: 22.3. Mesozoic History of North America

8. Mesozoic age coal deposits in the United States are the primary source of coal in this country.

ANS: F

PTS: 1

REF: 22.5. Mesozoic Mineral Resources

9. Major copper deposits are associated with oolitic limonite and hematite in Jurassic rocks of Western Europe.

ANS: F

PTS: 1

REF: 22.5. Mesozoic Mineral Resources

10. More species went extinct at the end of the Permian than at the end of the Mesozoic.

ANS: T

PTS: 1

REF: 22.6. Life of the Mesozoic Era

11. Unlike the Paleozoic burrowing animals which were soft-bodied, burrowing animals of the Mesozoic were hard-shelled.

ANS: T

PTS: 1

REF: 22.6. Life of the Mesozoic Era

12. Ammonites were one of three major groups of Mesozoic marine fauna to go extinct at the end of the Cretaceous.

ANS: T

PTS: 1

REF: 22.6. Life of the Mesozoic Era

13. Most of the burrowing organisms of the Mesozoic marine community were soft-bodied animals.

ANS: T

PTS: 1

REF: 22.6. Life of the Mesozoic Era

14. Scleractinians were very different from the corals of the Paleozoic seas.

ANS: T

PTS: 1

REF: 22.6. Life of the Mesozoic Era

15. The marine fauna that repopulated the oceans after the Permian extinction was more diverse than the Paleozoic marine fauna.

ANS: F

PTS: 1

REF: 22.6. Life of the Mesozoic Era

16. Of the three major classes of mollusks, gastropods were the only significant group in the Mesozoic oceans.

ANS: F

PTS: 1

REF: 22.6. Life of the Mesozoic Era

17. The corals that proliferated in the Mesozoic oceans were scleractinians.

ANS: T

PTS: 1

REF: 22.6. Life of the Mesozoic Era

18. Rudists bivalves were an important component of the Mesozoic reef community.

ANS: T

PTS: 1

REF: 22.6. Life of the Mesozoic Era

19. Triassic land-plant communities were significantly different than Permian due to the evolution of angiosperms.

ANS: F

PTS: 1

REF: 22.6. Life of the Mesozoic Era

20. Cycads evolved during the Triassic.

ANS: T

PTS: 1

REF: 22.6. Life of the Mesozoic Era

21. The ancestry of the earliest angiosperm is hard to determine.

ANS: T

PTS: 1

REF: 22.6. Life of the Mesozoic Era

22. Mesozoic birds are similar to Cenozoic birds in that both have teeth.

ANS: F

PTS: 1

REF: 22.6. Life of the Mesozoic Era

23. The discovery of protoavis provides unequivocal evidence that birds evolved in the Triassic.

ANS: F

PTS: 1

REF: 22.6. Life of the Mesozoic Era

24. Mammals attained a high degree of diversity and abundance during the Mesozoic.

ANS: F

PTS: 1

REF: 22.6. Life of the Mesozoic Era

25. The first Mesozoic mammals were very distinctive from their ancestral reptiles.

ANS: F

PTS: 1

REF: 22.6. Life of the Mesozoic Era

26. The earliest mammals had a single line of descent into the monotremes, which are the ancestors for all modern mammals.

ANS: F

PTS: 1

REF: 22.6. Life of the Mesozoic Era

27. Based on fossil evidence, the distinct fauna of South America began evolving in isolation by the Late Cretaceous.

ANS: T

PTS: 1

REF: 22.7. Mesozoic Climates and Paleogeography

28. The Cretaceous extinction event was uniformly disastrous to all marine and nonmarine organisms.

ANS: F

PTS: 1

REF: 22.8. Mass Extinctions--A Crisis in the History of Life 29. There is evidence that some of the organisms that went extinct at the end of the Cretaceous were already beginning to decline in population strength.

ANS: T

PTS: 1

REF: 22.8. Mass Extinctions--A Crisis in the History of Life Chapter 23—Cenozoic Earth and Life History

ESSAY

1. In what two ways was the Laramide orogeny different from other orogenies?

ANS: The orogney took place much further inland from a convergent boundary, and volcanism and plutonism were not very common. Also, mountain building was mostly vertical, faultbounded uplift rather than compression-induced folding and thrust faulting.

PTS: 1

REF: 23.4. Paleogene and Neogene Evolution of North America

2. How were Neanderthals different from modern humans?

ANS: Neanderthal skulls were long and low with heavy brow ridges, a projecting mouth, and a receding chin. Their brain was slightly larger but differently shaped. The Neanderthal body was massive and more heavily muscled with rather short lower limbs.

PTS: 1

REF: 23.8. Pleistocene Faunas

3. Briefly state the arguments against the climate change hypothesis for the Pleistocene extinction.

ANS: The first argument is that there is evidence that other mammals migrated with changing conditions so the large mammals could have done the same to find food. The other argument is that there is no evidence for mass extinctions between other glacial epochs which would be expected if the large mammals were so sensitive to climate change.

PTS: 1

REF: 23.8. Pleistocene Faunas

4. What is the prehistoric overkill hypothesis, and what evidence supports overkill as the reason for the Pleistocene extinctions?

ANS: The hypothesis states that human hunters were responsible for the extinctions. The mass extinctions in North America, South America, and Australia followed closely after the arrival of humans on those continents. Perhaps hunting was easy because the animals had no previous experience with humans. No large extinctions occurred in Africa, perhaps because those animals were well acquainted with humans.

PTS: 1

REF: 23.8. Pleistocene Faunas

5. Briefly state the arguments against the human cause for extinction of large mammals at the end of the Pleistocene.

ANS: The first argument is that hunters generally focus on smaller and easier prey. The second argument is that the humans lived in small groups, and it is difficult to imagine how they would decimate an entire widely spread population. Finally, there is little fossil evidence to indicate that these animals were hunted.

PTS: 1

REF: 23.8. Pleistocene Faunas

6. Briefly describe the "out of Africa" view of human evolution.

ANS: Early modern humans evolved from a single woman in Africa, whose offspring then migrated from Africa, perhaps as recently as 100,000 years ago, and populated Europe and Asia, driving the earlier hominid populations to extinction.

PTS: 1

REF: 23.8. Pleistocene Faunas

7. Briefly describe the multi-regional view of human evolution.

ANS:

Early modern humans did not have an isolated origin in Africa but rather they established separate populations throughout Eurasia. Occasional contact and interbreeding between these populations enabled our species to maintain its overall cohesiveness while still preserving the regional differences in people that we see today.

PTS: 1

REF: 23.8. Pleistocene Faunas

SHORT ANSWER 1. How did the Cenozoic conditions of eastern and western North America differ?

ANS: The east was dominated by erosion, while in the west, tectonism yielded a number of basins that became the sites of sediment deposition.

PTS: 1

REF: 23.1. Introduction

2. Name, from oldest to youngest, the three groupings into which the Cenozoic is divided.

ANS: Tertiary, Quaternary/Paleogene, Neogene PTS: 1

REF: 23.1. Introduction

3. In what two major zones or belts has Cenozoic orogenic activity been mainly concentrated?

ANS: the Alpine-Himalayan belt, the circum-Pacific Belt PTS: 1

REF: 23.3. Cenozoic Orogenic Belts

4. What are the mountain ranges that have been produced by plate convergence associated with the Alpine orogeny?

ANS: the Pyrenees, Alps, Apennines, and Atlas PTS: 1

REF: 23.3. Cenozoic Orogenic Belts

5. What are some indications that the Alpine orogenic belt is still active?

ANS: ongoing deformation, active volcanoes, seismic activity PTS: 1

REF: 23.3. Cenozoic Orogenic Belts

6. What are the features of an orogeny?

ANS: deformation, metamorphism, emplacement of plutons, and crustal thickening PTS: 1

REF: 23.3. Cenozoic Orogenic Belts

7. What is the North American Cordillera?

ANS: This cordillera is a complex mountainous region in western North America extending from Alaska into central Mexico.

PTS: 1

REF: 23.3. Cenozoic Orogenic Belts

8. What was the name given to the most recent episode of large-scale deformation in the Cordillera, and when did it begin?

ANS: the Laramide orogeny, 85 to 90 million years ago

PTS: 1

REF: 23.4. Paleogene and Neogene Evolution of North America

9. How and when did the land that is the present state of Florida originate?

ANS: Florida is comprised of carbonates that were deposited on a platform that was established during the Cretaceous Period.

PTS: 1

REF: 23.4. Paleogene and Neogene Evolution of North America

10. Describe the geologic setting of the western margin of North America.

ANS: The western margin of North America is transform plate boundary known as the San Andreas Fault except for the zone west of the Cascade Mountain Range which is a subduction zone.

PTS: 1

REF: 23.4. Paleogene and Neogene Evolution of North America

11. What is the origin of the present topography of the Appalachian Mountains?

ANS: Although the Appalachian Mountains formed during the Paleozoic Era, the present topographic feature is a result of Cenozoic uplift and erosion.

PTS: 1

REF: 23.4. Paleogene and Neogene Evolution of North America

12. Describe the geologic setting of Cenozoic sedimentation along the Atlantic margin of North America.

ANS: Tectonically, this is a classic passive margin. There are a number of rift basins along the eastern side of the Appalachians that are filled with Appalachian sediments.

PTS: 1

REF: 23.4. Paleogene and Neogene Evolution of North America

13. What is the distinction between browsers and grazers? Why did this feature evolve?

ANS: Grazers have high crown teeth that evolved so the animal would have a tooth that is more resistant to abrasion when chewing grasses, which contain silicon dioxide.

PTS: 1

REF: 23.7. Paleogene and Neogene Life History

14. Briefly describe the lives of Cro-Magnon.

ANS: Cro-Magnons used specialized tools for hunting, lived in caves or rock shelters, and formed living groups. They were artistic, and the caves they inhabited are painted with hundreds of scenes.

PTS: 1

REF: 23.8. Pleistocene Faunas

15. Since the appearance of Cro-Magnon, what has been the major area of human evolution?

ANS: Human evolution since Cro-Magnon has been related to cultural changes rather than physical changes.

PTS: 1

REF: 23.8. Pleistocene Faunas

COMPLETION 1. The Cenozoic Era has been _______ years long. This is only _______ percent of all geologic time.

ANS: 66 million; 1.4% PTS: 1

REF: 23.1. Introduction

2. The ____________________ orogeny resulted in the formation of the Himalayan Mountains.

ANS: Himalayan PTS: 1

REF: 23.3. Cenozoic Orogenic Belts

3. The plate tectonic activity that gave rise to orogens around much of the circum-Pacific orogenic belt was ____________________.

ANS: subduction PTS: 1

REF: 23.3. Cenozoic Orogenic Belts

4. The sea that covered the Gulf Coastal Plain in the Early Tertiary was the ____________________ sea.

ANS: Tejas PTS: 1

REF: 23.4. Paleogene and Neogene Evolution of North America

5. The Cenozoic Atlantic margin of North America is an example of a(n) ____________________ tectonic margin.

ANS: passive PTS: 1

REF: 23.4. Paleogene and Neogene Evolution of North America

6. During the last two million years, there have been at least ______ warm-cold cycles.

ANS: 20 PTS: 1

REF: 23.5. The Pleistocene and Holocene Epochs

7. At their greatest extent during the Pleistocene, glaciers covered about ____________________ as much of Earth's surface as they do now.

ANS: three times PTS: 1

REF: 23.5. The Pleistocene and Holocene Epochs

8. During the Pleistocene of North America, there were at least ____________________ glacial stages. These stages, in order from oldest to youngest, are the ____________________, ____________________, ____________________, and ____________________.

ANS: four, Nebraskan, Kansan, Illinoian, Wisconsinan PTS: 1

REF: 23.5. The Pleistocene and Holocene Epochs

9. The sea level (decreased/increased) ____________________ (amount) ____________________ during the maximum glacial coverage of the Pleistocene.

ANS: decreased, 130 meters PTS: 1

REF: 23.5. The Pleistocene and Holocene Epochs

10. Less evaporation and more precipitation during the glacial stages led to the formation of ____________________ lakes.

ANS: pluvial PTS: 1

REF: 23.5. The Pleistocene and Holocene Epochs

11. Where the pluvial lakes once were, there are now thick sequences of ____________________.

ANS: evaporites PTS: 1

REF: 23.5. The Pleistocene and Holocene Epochs

12. Diatomaceous earth is a sedimentary rock composed of the ____________________ shells of micro-organisms.

ANS: siliceous PTS: 1

REF: 23.6. Cenozoic Mineral Resources

13. ____________________ gold deposits are formed by stream deposits.

ANS: Placer PTS: 1

REF: 23.6. Cenozoic Mineral Resources

14. Mammals that lay eggs are called ____________________ mammals.

ANS: monotreme PTS: 1

REF: 23.7. Paleogene and Neogene Life History

15. Mammals that produce an unprotected embryo that undergoes further development in a pouch are called ____________________.

ANS: marsupial PTS: 1

REF: 23.7. Paleogene and Neogene Life History

16. Mammals that give birth to live young that need little or no protection after birth are called ____________________.

ANS: placental PTS: 1

REF: 23.7. Paleogene and Neogene Life History

17. The group of hoofed mammals which are even-toed are the ____________________, while those which have an odd number of toes are the ____________________.

ANS: artiodactyls, perissodactyls PTS: 1

REF: 23.7. Paleogene and Neogene Life History

18. Ungulates that eat grasses are called ____________________.

ANS: grazers PTS: 1

REF: 23.7. Paleogene and Neogene Life History

19. The oldest hominids belong to the genus ____________________.

ANS: Australopithecus PTS: 1

REF: 23.8. Pleistocene Faunas

20. The oldest australopithecines were ____________________.

ANS: Australopithecus anamensis PTS: 1

REF: 23.8. Pleistocene Faunas

21. The first of the hominids to make major migrations was ____________________.

ANS: Homo erectus PTS: 1

REF: 23.8. Pleistocene Faunas

22. Homo sapiens clearly evolved from ____________________.

ANS: Homo erectus PTS: 1

REF: 23.8. Pleistocene Faunas

23. ____________________ was a robust creature with a developed social structure.

ANS: Neanderthal PTS: 1

REF: 23.8. Pleistocene Faunas

24. The major difference between modern humans and Neanderthals is ____________________.

ANS: skull structure PTS: 1

REF: 23.8. Pleistocene Faunas

25. The most recent ancestor of modern humans that evolved about 35,000 years ago is ____________________.

ANS: Cro-Magnon PTS: 1

REF: 23.8. Pleistocene Faunas

MULTIPLE CHOICE 1. The Cenozoic Era is divided into the

a. Tertiary and Quaternary periods. b. Paleogene and Tertiary periods. c. Tertiary and Neogene periods. d. Paleogene and Neogene periods. e. Quaternary and Paleogene periods.

ANS: D

PTS: 1

REF: 23.1. Introduction

2. The age of oceanic crust in the Pacific is asymmetric because a. much of the crust in the eastern Pacific has been subducted. b. spreading is faster on the east side of the ridge than on the west side. c. the eastern Pacific collided with the Americas to form mountain ranges. d. volcanism on the west side of the ridge has made the crust larger. e. all of these.

ANS: A

PTS: 1

REF: 23.2. Cenozoic Plate Tectonics

3. The Himalayas today are ____. a. volcanically active b. seismically active c. a place of mountain building d. no longer tectonically active e. seismically active with active mountain building

ANS: E

PTS: 1

REF: 23.3. Cenozoic Orogenic Belts

4. All but which of the following mountain ranges could be considered part of the Alpine chain? a. Urals b. Pyrenees c. Alps

d. Atlas e. Apennines

ANS: A

PTS: 1

REF: 23.3. Cenozoic Orogenic Belts

5. The orogenic event of the North American Cordillera that began in the Late Cretaceous and extended into the Cenozoic is the ____ orogeny. a. Laramide b. Sevier c. Nevadan d. Antler e. Appalachian

ANS: A

PTS: 1

REF: 23.4. Paleogene and Neogene Evolution of North America 6. The Mesozoic orogenies of the Cordillera ____. a. progressively affected areas from west to east b. progressively affected areas from east to west c. involved only deformation and no magmatism d. involved only magmatism and no deformation e. progressively affected areas from west to east AND involved only deformation and no magmatism

ANS: A

PTS: 1

REF: 23.4. Paleogene and Neogene Evolution of North America 7. The angle of the subducted slab during the Laramide orogeny was ____. a. very steep resulting in volcanism near the trench b. very shallow resulting in volcanism near the trench

c. very steep causing deformation far inland d. very shallow causing deformation far inland e. almost vertical

ANS: D

PTS: 1

REF: 23.4. Paleogene and Neogene Evolution of North America 8. The cause for cessation of Laramide deformation was a(n) ____. a. decrease in the angle of the subducted slab b. change from subduction to rift tectonics c. increase in the angle of the subducted slab d. change from subduction to transform tectonics e. cessation of subduction

ANS: C

PTS: 1

REF: 23.4. Paleogene and Neogene Evolution of North America 9. The Cascade Mountain Range includes a. shield volcanoes. b. composite volcanoes. c. plug domes. d. cinder cones. e. all of these.

ANS: E

PTS: 1

REF: Geo-Insight. Cascade Range Volcanoes

10. Formation of basin and range mountains is a result of ____. a. thrust faulting b. folding and faulting c. normal faulting

d. volcanism e. batholithic intrusions

ANS: C

PTS: 1

REF: 23.4. Paleogene and Neogene Evolution of North America 11. During the Early Tertiary, what were the interior lowlands of the continent the site of? a. local erosion b. deposition in marine and terrestrial environments c. minor volcanism d. local erosion and deposition in marine and terrestrial environments e. all of these

ANS: E

PTS: 1

REF: 23.4. Paleogene and Neogene Evolution of North America 12. The Early Tertiary sedimentary sequence of the Gulf Coastal Plain is ____. a. a generally transgressive sequence b. a generally regressive sequence c. completely nonmarine d. completely eroded away e. generally missing

ANS: B

PTS: 1

REF: 23.4. Paleogene and Neogene Evolution of North America 13. What can eastern North America during the Cenozoic be described as? a. an active orogenic belt b. an area of uplift and erosion c. an active volcanic region

d. a flat eroded plain e. a major marine basin

ANS: B

PTS: 1

REF: 23.4. Paleogene and Neogene Evolution of North America 14. What are streams that cut across ridges called? a. imposed drainages b. canyons c. superposed drainages d. erosional streams e. overposed canyons

ANS: C

PTS: 1

REF: 23.4. Paleogene and Neogene Evolution of North America 15. When did the last ice age begin? a. 150 years ago b. 500 years ago c. 10,000 years ago d. 1.5 million years ago e. 2.6 million years ago

ANS: E

PTS: 1

REF: 23.5. The Pleistocene and Holocene Epochs

16. Which of the following is not a direct or an indirect result of glaciation? a. uplift b. change in sea level c. proglacial lakes d. plate motion

e. pluvial lakes

ANS: D

PTS: 1

REF: 23.5. The Pleistocene and Holocene Epochs

17. Because of the large amount of weight in a glacial mass, the crust of Earth may ____. a. not be affected at all b. rebound or uplift c. subside d. collapse into the mantle e. melt

ANS: C

PTS: 1

REF: 23.5. The Pleistocene and Holocene Epochs

18. At the height of the Great Ice Age, the present desert regions of southwestern United States ____. a. were covered with continental ice sheets b. were drier than modern day conditions c. had large lakes form in intermontane basins d. were tropical rainforest environments e. were covered with valley glaciers

ANS: C

PTS: 1

REF: 23.5. The Pleistocene and Holocene Epochs

19. Why might the abundance of marine diatoms be related to increased volcanism? a. Volcanic activity resulted in decreased sunlight which affected the growth of all marine phytoplankton except diatoms. b. Volcanic activity may have resulted in the increase in silica in seawater. c. Increased volcanic activity warmed sea water, creating a favorable habitat for diatoms. d. Increased volcanism caused cooling of sea water which created optimal conditions

for diatom growth. e. Increased volcanism created new ecological habitats for diatoms.

ANS: B

PTS: 1

REF: 23.7. Paleogene and Neogene Life History

20. Which of the following cephalopods did not survive the Cretaceous extinction? a. nautiloids b. octopus c. squids d. ammonites e. pleisiosaurs

ANS: D

PTS: 1

REF: 23.7. Paleogene and Neogene Life History

21. During the Cenozoic, brachiopods ____. a. greatly expanded their numbers and diversity b. were greatly reduced in number of genera c. took over habitats previously occupied by mollusks, forcing those creatures to go extinct d. became the most important marine invertebrate phyla e. became extinct

ANS: B

PTS: 1

REF: 23.7. Paleogene and Neogene Life History

22. Ungulates include orders of mammals which are all ____. a. three-toed b. hoofed c. herbivores d. large e. hoofed herbivores

ANS: E

PTS: 1

REF: 23.7. Paleogene and Neogene Life History

23. The evolutionary trend in mammal size during the Pleistocene could have been in response to ____. a. global warming when there was more food available b. cooler temperatures because large animals retain heat more efficiently c. protection from predation of other organisms d. increased predatory ability e. decreased metabolic requirements

ANS: B

PTS: 1

REF: 23.8. Pleistocene Faunas

24. All of the following except which are features of primates? a. increased brain size b. stereoscopic vision c. opposable thumb d. less specialized teeth e. more specialized teeth

ANS: E

PTS: 1

REF: 23.8. Pleistocene Faunas

25. Prosimians are a. arboreal b. omnivorous c. the oldest primate lineage d. extinct e. arboreal, omnivorous, and the oldest primate lineage

ANS: E

PTS: 1

REF: 23.8. Pleistocene Faunas

26. All except which of the following distinguish hominids from other hominoids? a. bipedal manner of locomotion b. larger brain with internal segments c. reduced face and canine teeth d. are only carnivorous eaters e. use and construction of sophisticated tools

ANS: D

PTS: 1

REF: 23.8. Pleistocene Faunas

27. What did the extinction at the end of the Pleistocene affect? a. only marine organisms b. terrestrial mammals weighing more than 40 Kg c. terrestrial mammals weighing less than 40 Kg d. marine mammals weighing more than 40 Kg e. all mammal groups equally

ANS: B

PTS: 1

REF: 23.8. Pleistocene Faunas

28. During the Neanderthal era, what was climate characterized by? a. balmy pleasant weather year-round b. stifling hot summers and mild winters c. long, frigid winters and short summers d. temperatures extremes, frigid winters and hot summers e. the same types of temperatures in the same places seen today

ANS: C TRUE/FALSE

PTS: 1

REF: 23.8. Pleistocene Faunas

1. After the mass extinction at the end of the Mesozoic Era, marine invertebrates diversified.

ANS: T

PTS: 1

REF: 23.1. Introduction

2. Angiosperms constitute more than 90% of all land plants.

ANS: T

PTS: 1

REF: 23.1. Introduction

3. Geologists know more about Cenozoic Earth and life history than about any other era of geologic time.

ANS: T

PTS: 1

REF: 23.1. Introduction

4. New seafloor is being created in the East African rift.

ANS: F

PTS: 1

REF: 23.2. Cenozoic Plate Tectonics

5. The geologic province caused by the collision of India with Asia is known as the AlpineHimalayan Orogenic Belt.

ANS: T

PTS: 1

REF: 23.3. Cenozoic Orogenic Belts

6. The convergence of the Cocos and Nazca plates produced the Cascade volcanoes.

ANS: F

PTS: 1

REF: 23.4. Paleogene and Neogene Evolution of North America 7. The present day Appalachian Mountains are the product of Cenozoic subduction and orogeny.

ANS: T

PTS: 1

REF: 23.4. Paleogene and Neogene Evolution of North America

8. The North American Cordillera was only active in the Mesozoic and has a very simple deformational history.

ANS: F

PTS: 1

REF: 23.4. Paleogene and Neogene Evolution of North America 9. The Colorado Plateau has many deep canyons due to downcutting by rivers.

ANS: T

PTS: 1

REF: 23.4. Paleogene and Neogene Evolution of North America 10. The Colorado Plateau has been affected by Cordilleran orogenic events.

ANS: T

PTS: 1

REF: 23.4. Paleogene and Neogene Evolution of North America 11. The present topography of the Appalachians was formed by erosion during the Mesozoic.

ANS: F

PTS: 1

REF: 23.4. Paleogene and Neogene Evolution of North America 12. The Atlantic margin of North America has been a passive trailing margin since the early Mesozoic.

ANS: T

PTS: 1

REF: 23.4. Paleogene and Neogene Evolution of North America 13. There is evidence to suggest that the world's global cooling trend began in the Eocene and continued through the Pleistocene.

ANS: T

PTS: 1

REF: 23.5. The Pleistocene and Holocene Epochs

14. The Great Salt Lake in Utah is the only pluvial lake which remains at the size it was during the Wisconsin glacial stage.

ANS: F

PTS: 1

REF: 23.5. The Pleistocene and Holocene Epochs

15. Tertiary reservoirs of the Gulf Coastal Plain and southern California are important in U.S. petroleum production.

ANS: T

PTS: 1

REF: 23.6. Cenozoic Mineral Resources

16. The United States ranks first in global petroleum production.

ANS: F

PTS: 1

REF: 23.6. Cenozoic Mineral Resources

17. Late Cretaceous to early Tertiary age, coal deposits were higher grade coal than the Pennsylvanian age deposits found in the eastern United States.

ANS: F

PTS: 1

REF: 23.6. Cenozoic Mineral Resources

18. Evaporation of pluvial lakes formed thick sand and gravel deposits.

ANS: F

PTS: 1

REF: 23.6. Cenozoic Mineral Resources

19. Evaporite deposits formed as a result of the drying up of large pluvial lakes in the western United States.

ANS: T

PTS: 1

REF: 23.6. Cenozoic Mineral Resources

20. The adaptive radiation that led to evolution of diverse placental mammals began in the Late Cretaceous.

ANS: T

PTS: 1

REF: 23.7. Paleogene and Neogene Life History

21. Ungulates that eat leaves, shoots, and twigs are called browsers.

ANS: T

PTS: 1

REF: 23.7. Paleogene and Neogene Life History

22. The evolution of the horse involved major changes from Hyracotherium, including increase in size and development of one toe.

ANS: T

PTS: 1

REF: 23.7. Paleogene and Neogene Life History

23. A. africanus appeared about 3.0 million years ago and is very similar to A. afarensis except for a few minor details.

ANS: T

PTS: 1

REF: 23.8. Pleistocene Faunas

24. The oldest hominids belong to the genus Homo.

ANS: F

PTS: 1

REF: 23.8. Pleistocene Faunas

25. The oldest known fossil of the genus Homo is from rocks about 3.5 million years old.

ANS: F

PTS: 1

REF: 23.8. Pleistocene Faunas

Chapter 24—Geology in Perspective

ESSAY 1. What activities do humans engage in that make them geologic agents, and how effective are human activities at being geologic agents?

ANS: Human activities like agriculture, construction, deforestation, and resource extraction cause a great deal of erosion. Humans are more effective than any other geologic agent with erosions rates in some locations well over ten times the natural rate.

PTS: 1

REF: Chapter 24

2. What will the effects of an additional 3 billion people by the end of the 21st century be on environmental issues? How will these people secure the things that they need?

ANS: There are a variety of answers to this question and no one really knows what the right one is.

Some ideas are that people will be forced to live in even more marginal environments. Even more people will experience food insecurity and will be unable to obtain clean water for drinking and bathing. People will want and need more goods, including cars, and unless alternatives are developed, fossil fuel use will continue to increase. With that will be an increase in pollution and in the emission of greenhouse gases. That, of course, will increase global warming.

PTS: 1

REF: Chapter 24

3. Ask the students: Has learning the scientific basis of many issues caused you to change your mind or formulate an opinion on a topic? For example, do you now have a better sense about issues such as evolution, global warming, ozone depletion, etc.?

ANS: Answers will vary.

PTS: 1

REF: Chapter 24