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• Front Matter
  • Preface
    • PURPOSE OF THE BOOK
    • THE SYSTEMS APPROACH
    • THE BOOK’S ORGANIZATION
    • THE ILLUSTRATIONS
    • FEATURES
    • NEW TO THIS EDITION
    • ACKNOWLEDGMENTS
  • About the AUTHORS
    • Brian J. SKINNER
    • Barbara MURCK
• PART ONE: The Earth System: Our Place in SPACE
  • Our home in space The Sun, an average-size, middle-aged star, emerges over planet Earth in this digitally-generated image.
  • CHAPTER 1: The Earth SYSTEM
    • Earth and Moon The Moon rises over Earth in this photo, part of NASA’s famous Blue Marble series. The original Blue Marble photographs were taken in 1972. This particular version was taken by a Geostationary Operational Environmental Satellite (GOES) in 1997 and it is one of the most detailed images ever made of Earth. The prominent storm visible off the west coast of North America is Hurricane Linda.
    • OVERVIEW
    • WHAT IS EARTH SYSTEM SCIENCE?
      • A New Science and a New Tool
        • FIGURE 1.1: Earth’s interacting parts Earth system science is the study of the whole planet as a system of many interacting parts, with a particular focus on the changes within and among those parts, including the impacts of human activities.
      • Earth Observation
        • FIGURE 1.2: Studying Earth from space The exploration of space had an unexpected side-benefit: the opportunity to turn space-based instruments around and take a closer look at our own planet. Landsat, shown here in an artist’s rendition, was one of the first satellites used by NASA in the 1970s to begin collecting data about Earth by remote sensing.
        • Make the CONNECTION
        • A Closer LOOK: MONITORING EARTH FROM SPACE
          • FIGURE C1.1: Earth from space (A) Many different types of satellites are currently employed in the monitoring of Earth from space, including these from the American fleet. (B) This is a composite of two satellite images, showing dense smoke billowing from forest fires (red spots) in the Kalimantan region of Borneo, Indonesia, in September of 2009. The fires were set for the purpose of clearing land. (C) This Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) image of Mt. Vesuvius, Italy was acquired September 26, 2000. The image covers an area of 36 by 45 km. Warmer ground temperatures are shown in reds, and cooler temperatures in blue. In 79 CE, Vesuvius erupted cataclysmically, burying all of the surrounding cites with up to 30 m of ash. Vesuvius is intensively monitored for potential signs of unrest that could signal the beginning of another eruption.
          • FIGURE C1.2: Hurricane Katrina This satellite image of Hurricane Katrina in August, 2005 was taken by a high-altitude, geostationary satellite.
      • Systems
        • FIGURE 1.3: Geographic information systems Geographic information systems allow for the storage of large volumes of spatially referenced data points, along with their characteristics. The data can be used to produce maps showing the distribution of specific characteristics. The map layers can be combined and compared quantitatively, to yield derivative data and images.
        • FIGURE 1.4: A simple system The mountain–river–lake landscape shown here is an example of a system. Some of its component subsystems are outlined by boxes.
        • the BASICS: Types of Systems
          • FIGURE B1.1: Systems The three basic types of systems are: (A) An isolated system. (B) A closed system. (C) An open system.
      • Models
      • Fluxes, Reservoirs, and Residence Times
        • FIGURE 1.5: Models Models of Earth processes can be physical, like the fish-tank model of the water cycle, shown here (A), or graphical, like this artistic representation of the water cycle in an island system (B). Depicted in (C) is another type of graphical representation, a box model, showing the processes (arrows) and reservoirs (boxes) of the island water cycle in B.
        • FIGURE 1.6: Earth’s interacting parts This is a diagrammatic representation—essentially a simple box model—of Earth as a system of interacting parts. Each character represents one of the four major reservoirs (or subsystems), and each arrow represents a flow of materials or energy.
      • Living in a Closed System
        • FIGURE 1.7: Earth as a closed system Earth essentially operates as a closed system. Energy reaches Earth from an external source and eventually returns to space as long-wavelength radiation, but the matter within the system is basically fixed. The subsystems within Earth are open systems, freely exchanging matter and energy.
    • EARTH SYSTEM RESERVOIRS
      • FIGURE 1.8: The life zone All life on Earth lives within a zone no wider than 20 km. It is the zone where interactions between the geosphere, hydrosphere, and atmosphere create a habitable environment.
      • The Geosphere
      • The Hydrosphere
        • Make the CONNECTION
      • The Atmosphere
      • The Biosphere
      • The Anthroposphere
        • FIGURE 1.9: Earth’s subsystems The major subsystems of the Earth system are: (A) geosphere, (B) hydrosphere, (C) atmosphere, (D) biosphere, and (E) anthroposphere. Throughout the book we will be emphasizing the connections among these subsystems.
    • DYNAMIC INTERACTIONS AMONG RESERVOIRS
      • Feedbacks
        • FIGURE 1.10: Feedback cycles (A) Here is a familiar example of negative feedback. A change in temperature in one direction leads the thermostat to send a signal that makes the heating/cooling system change in the opposite direction. Hence, the feedback is negative. (B) Here is a familiar example of a positive feedback. A child who wants candy throws a temper tantrum in the store. In response, the parent gives the child some candy. This leads the child to have another temper tantrum the next time he wants candy. The response leads to a reinforcement or repetition of the initial condition; hence the feedback is positive. In a true positive feedback cycle, the child’s tantrums would get worse and worse each time.
      • Cycles
      • Important Earth Cycles
        • The Hydrologic Cycle
          • FIGURE 1.11: The global hydrologic cycle The hydrologic cycle is probably the most familiar of Earth’s important cycles. It traces the movement of water from one reservoir to another throughout the Earth system. Here the global hydrologic cycle is portrayed as a simple box model. Compare this to Fig. 1.5B, C.
          • Make the CONNECTION
        • The Energy Cycle
          • FIGURE 1.12: The energy cycle Energy from both internal and external sources cycles through the reservoirs of the Earth system, driving processes from wind and waves to photosynthesis.
        • The Rock Cycle
          • FIGURE 1.13: The rock cycle The rock cycle describes the processes by which competing internal and external forces meet at Earth’s surface, continually building up, breaking down, and transforming rocks. This simple version emphasizes the “cyclic” nature of these processes, but real Earth cycles are not this simple.
        • The Tectonic Cycle
        • Biogeochemical Cycles
          • FIGURE 1.14: Tectonic processes The geologic processes of the tectonic cycle link Earth’s surface with the interior of the planet. The tectonic cycle provides a unified context for processes like earthquakes (A) in Chile, 2010 and volcanic eruptions (B) Eyjafjallajökull erupting in Iceland, 2010, and explains their geographic distribution.
        • Human Impacts on Earth Cycles
    • HOW SCIENCE WORKS: HYPOTHESIS AND THEORY
      • FIGURE 1.15: Human activity and global change (A) The lights of human settlements—visible from outer space—give an idea of the extent of human impact on the Earth system. (B) Deserts expand and retreat as a result of natural processes, but human influences have greatly accelerated the rate of advance of deserts in some parts of the world. (C) Even the most remote parts of Earth have been affected by human activity. Polar bears accumulate pesticides in their fat, even though the nearest pesticide use is thousands of kilometers away, and the sea ice on which they depend may be melting as a result of global climate change.
      • FIGURE 1.16: The scientific method Science advances by way of the scientific method, the basic steps of which are shown here.
      • Formulating and Testing a Hypothesis
      • Developing and Refining a Theory
      • The Laws of Science
        • the BASICS: The Scientific Method in Practice
          • FIGURE B1.2: The scientific method The scientific method is used to test the various hypotheses that have been proposed to explain a phenomenon, as shown here.
      • The Role of Uncertainty
    • END OF CHAPTER 1
      • SUMMARY
      • IMPORTANT TERMS TO REMEMBER
      • QUESTIONS FOR REVIEW
      • QUESTIONS FOR RESEARCH AND DISCUSSION
      • QUESTIONS FOR THE BASICS
      • QUESTIONS FOR A CLOSER LOOK
  • CHAPTER 2: Energy
    • Energy drives the Earth system The Strokkur Geyser in Geysir, Iceland (the location from which geysers got their name) gushes skyward, propelled by heat energy from deep underground.
    • OVERVIEW
    • FIGURE 2.1: Energy in Earth’s subsystems Energy is present in every part of the Earth system and is required for the functioning of every Earth process, whether natural or human.
    • WHAT IS ENERGY?
      • Fundamental Laws of Thermodynamics
        • First Law: Conservation and Transformation
        • Second Law: Efficiency and Entropy
          • FIGURE 2.2: Energy transformations Energy can (and commonly does) change from one form to another as it moves through the Earth system. Some common examples of energy transformations are shown here. (Source: Adapted from U.S. Energy Information Administration).
        • Third Law: Absolute Zero
          • Make the CONNECTION
          • FIGURE 2.3: Temperature (A) The Kelvin and Celsius temperature scales are based on the same incremental scale, but their zero reference points are different. The Kelvin scale uses absolute zero, or zero entropy, as its zero reference point, whereas the Celsius scale uses the freezing point of water at surface atmospheric pressure as the zero reference point. (B) At temperatures close to absolute zero, some materials become “superconductors.” Superconductivity involves a lowering of electrical resistivity (in other words, the material conducts an electric current with extreme efficiency, without loss of heat), as well as the active exclusion of magnetic fields. The latter, called the Meissner effect, is responsible for the levitation of the small magnets shown floating near the superconductor in this photograph.
    • EXTERNAL ENERGY SOURCES
      • The Sun
        • Source of the Sun’s Energy
          • the BASICS: Heat Transfer: Conduction, Convection, and Radiation
            • FIGURE B2.1: Heat transfer There are three fundamental mechanisms of heat transfer. In this example, heat is transferred from the hot stove element directly to the bottom of the pot via conduction. As the water inside the pot warms, it rises; heat is thus transferred from the bottom of the pot to the top by convection. At the top surface, the warm water loses heat to the overlying air via conduction. The warmed air over the pot then rises, transferring heat upward into the atmosphere via convection. Warmth lost from all parts of the pot to the surrounding atmosphere also will travel through the air via the process of radiation.
        • From Sun to Earth
          • FIGURE 2.4: The Sun’s luminosity As discussed in the text, we can calculate the Sun’s luminosity by imagining a sphere centered on the Sun. The energy that falls on Earth’s surface, which we know to be 1370 W/m2, is a portion of the whole sphere and can be used to calculate the total energy reaching the sphere.
          • FIGURE 2.5: Solar energy flux Energy from the Sun passes through an imaginary disc that has a diameter equal to Earth’s diameter. The flux of energy through the disc is 1370 watts per square meter. The amount of energy that hits a square meter on Earth’s surface is a maximum at the point where the incoming radiation is perpendicular to Earth’s surface (that is, where the Sun is directly overhead at midday). This point changes daily because Earth’s axis is tilted at 23.5° to the ecliptic, the plane of the solar system.
        • Structure of the Sun
          • the BASICS: Electromagnetic Radiation
            • FIGURE B2.2: The electromagnetic spectrum All electromagnetic waves travel at the same speed (the speed of light, 3.0 x 108 m/s), which means that they can be discussed in terms of either frequency or wavelength.
        • The Solar Spectrum
          • FIGURE 2.6: The Sun’s interior The Sun consists of six concentric zones, as shown in (A). The chromosphere and the corona can only be clearly seen during a solar eclipse, when the Moon blocks the light coming from the photosphere. This photo (B) taken during an eclipse, shows faintly glowing gas streaming hundreds of thousands of kilometers out from the corona.
          • FIGURE 2.7: The Sun’s spectrum The black curves show the energy flux from blackbody radiators at different temperatures. Note how the radiation peak moves to shorter wavelengths and the total energy flux (the area under the curve) increases as the temperature of the radiating body increases. The Sun’s spectrum (the red curve) is nearly identical to that of a perfect blackbody radiator at 5800 K.
      • Gravity and Tides
        • FIGURE 2.8: Outer-space and sea-level spectra The outer-space spectral curve for the Sun is different from the sea-level spectral curve, because gases in Earth’s atmosphere selectively absorb some of the wavelengths of solar radiation. Notably, ozone (O3) in the stratospheric ozone layer absorbs radiation in the very short-wavelength (ultraviolet) portion of the Sun’s spectrum, thus preventing some of the highest energy and most biologically harmful solar energy from reaching the surface.
        • FIGURE 2.9: Earth tides Earth’s shape is distorted into an ellipsoid as a result of gravitational interaction with the Sun and (mainly) the Moon. In this example, the Moon is positioned over 30° N or 30° S. Red indicates material that has moved up relative to the reference sphere, and blue indicates material that has moved down relative to the reference sphere. One of the bulges points toward the Moon, the other points away. Much of the strain energy involved in tidal distortion of the planet’s interior is translated into heat energy; this is a significant source of Earth’s internal heat.
        • Make the CONNECTION
    • INTERNAL ENERGY SOURCES
      • The Distribution of Terrestrial Energy
        • FIGURE 2.10: Convection in Earth’s interior Hot rock rises slowly from deep inside Earth, cools, flows sideways, and sinks. The rising hot rocks and sideways flow are the source of plate tectonic motion, and have an enormous influence on the shapes and distribution of land masses and ocean basins on Earth’s surface.
        • FIGURE 2.11: Geothermal gradient Temperature increases with depth. (A). The dashed lines are isotherms, lines of equal temperature. Temperature increases more slowly under the continents than under the oceans. The lithosphere is thicker under the continents, so heat flows more slowly to the surface in those areas. (B). This is the same information as shown in (A) but in graph form. Earth’s surface is at the top, so depth (and corresponding pressure) increases downward. Temperature increases from left to right.
      • Sources of Terrestrial Energy
    • EARTH’S ENERGY CYCLE
      • Energy In
      • Energy Out
        • Make the CONNECTION
        • FIGURE 2.12: Solar and terrestrial spectra The spectra of the Sun and Earth are different because they are radiating at different temperatures. Shown are the smooth curves for perfect blackbody radiators at the relevant temperatures. The “actual” curves differ from the “ideal” curves (in black) principally because of absorption of radiation in certain wavelengths by Earth’s atmosphere.
      • Pathways and Reservoirs
        • FIGURE 2.13: Greenhouse effect Some of the short-wavelength solar radiation reaching Earth is absorbed by land, oceans, clouds, and atmospheric dust and gases, and some is reflected back into space by reflective surfaces that include snow, ice, clouds, and dust. Some of the shortest-wavelength (ultraviolet) radiation is absorbed by ozone (O3) in the ozone layer. Earth radiates longer-wavelength radiation back into space. Radiatively active greenhouse gases, including water vapor and carbon dioxide (CO2), absorb some of the outgoing long-wave (infrared) radiation, retaining it near the surface and causing the air temperature of the lower atmosphere to rise. This natural greenhouse effect makes it possible for life to exist, as we know it, on Earth’s surface.
    • ENERGY AND SOCIETY
      • Energy Sources and the Energy Cycle
        • FIGURE 2.14: Sources of energy for human use This is a simple diagram of the energy sources of modern society, from the perspective of Earth’s energy cycle. There are many different types and sources of energy, and many times more energy delivered to the surface than is required for human use. The challenge is to find energy sources that are sustainable and environmentally benign.
        • A Closer LOOK: MAKING USE OF THE SUN’S ENERGY
          • FIGURE C2.1: Energy from the Sun (A) Solar panels like these collect and concentrate energy from the Sun, making it available to power human technologies. (B) Biomass fuels, such as the wood being burned here, are indirect forms of solar energy. They make use of the matter generated by plants by photosynthesis, using energy from the Sun.
    • END OF CHAPTER 2
      • SUMMARY
      • IMPORTANT TERMS TO REMEMBER
      • QUESTIONS FOR REVIEW
      • QUESTIONS FOR RESEARCH AND DISCUSSION
      • QUESTIONS FOR THE BASICS
      • QUESTIONS FOR A CLOSER LOOK
  • CHAPTER 3: Matter
    • Earth from the inside out Lava—molten rock—from Hawaii’s Kilauea Volcano cascades over a cliff on its way to the ocean.
    • OVERVIEW
    • EARTH’S MATERIALS
      • Common States of Everyday Matter
        • Change of State
          • the BASICS: Solids, Liquids, and Gases
            • FIGURE B3.1: The common states of matter (A) Solids retain their shape and volume, and their constituent atoms have little mobility relative to one another. (B) Liquids take on the shape of their container, developing a free surface under the influence of gravity, and their constituent atoms move freely relative to one another. (C) Gases mix thoroughly and fill their containers completely (or escape into space if unconfined).
          • FIGURE 3.1: Two liquids Although lava (A) and rainwater (B) both occur in the liquid state at Earth’s surface, they are very different in chemical composition and physical properties.
          • FIGURE 3.2: States and phases Matter can coexist in various states and phases. In (A), matter of uniform composition (H2O) coexists in two different states (liquid and solid) and two different phases (water and ice), separated by physical boundaries. In (B), different phases coexist in the same state (oil and water, both liquids; different types of beans, all solids). In (C), there is only one phase and one state, as is always the case with gases.
        • Other States of Matter
      • Atoms, Elements, Ions, and Isotopes
        • FIGURE 3.3: Aerosols and colloids Many important materials, both natural and manufactured, occur as aerosols and colloids. (A) Aerogel or “frozen smoke” is an ultra-low-density manufactured colloidal gel that consists of solid nanoparticles in a vapor medium (instead of a liquid medium, as in most colloidal gels). (B) Mud is an example of a naturally occurring colloidal mixture of extremely fine clay particles in water.
        • FIGURE 3.4: Carbon atom This is a schematic diagram of an atom of the element carbon. The nucleus contains six protons and six neutrons. Electrons orbiting the nucleus are confined to specific orbits called energy-level shells. (A) This three-dimensional representation shows the first energy-level shells. The first shell can contain two electrons, the second eight. (B) This two-dimensional representation of the carbon atom shows the number of protons and neutrons in the nucleus and the number of electrons in the energy-level shells.
        • Isotopes
        • Ions
      • Compounds and Mixtures
        • Complex Ions
        • Mixtures and Solutions
          • FIGURE 3.5: A compound To form the compound lithium fluoride, an atom of the element lithium combines with an atom of the element fluorine. The lithium atom transfers its lone outer-shell electron to fill the fluorine atom’s outer shell, creating an Li+ cation and a F− anion in the process. The electrostatic force that keeps the lithium and fluorine ions together in the compound lithium fluoride is an ionic bond.
    • ORGANIC MATTER
      • Organic and Inorganic Compounds
      • Important Organic Molecules
        • FIGURE 3.6: Biopolymers Biopolymers such as proteins and nucleic acids are large organic molecules formed by polymerization—the stringing together of small molecules to make large chainlike or sheetlike molecules.
        • Proteins
        • Nucleic acids
        • Carbohydrates
        • Lipids
    • COMPOSITION AND INTERNAL STRUCTURE OF EARTH
      • Overall Composition and Internal Structure
        • Layers of Different Composition
          • FIGURE 3.7: Earth’s interior A sliced view of Earth reveals layers of different composition and zones of different rock strength. The compositional layers, starting from the inside, are the core, the mantle, and the crust. Note that the crust is thicker under the continents than under the oceans. Note, too, that boundaries between zones of different physical properties—lithosphere, asthenosphere, mesosphere—do not coincide with the compositional boundaries.
          • Make the CONNECTION
        • Layers of Different Rock Strength
        • Layers of Different Physical State
      • Abundant Elements
        • Make the CONNECTION
        • TABLE 3.1: The Most Abundant Chemical Elements in the Continental Crust
    • MINERALS
      • Mineral Compositions and Structures
        • FIGURE 3.8: Atomic structure of a mineral These figures show the arrangement of ions in the most common lead mineral, galena (PbS). Lead, Pb, is a cation with a charge of 2+, and sulfur, S, is an anion with a charge of 2−. To maintain a charge balance between the ions, there must be an equal number of Pb and S ions in the structure. Ions are so small that a cube of galena 1 cm on its edge contains 1022 ions each of lead and sulfur. (A) Ions at the surface of a galena crystal are revealed with a scanning-tunneling microscope. Sulfur ions are the larger lumps, and the smaller ones are lead. (B) The packing arrangement of ions is repeated continuously through a crystal. The ions are shown pulled apart along the black lines to demonstrate how they fit together.
      • The Common Minerals
        • Silicates
          • FIGURE 3.9: Silicate tetrahedron This is the tetrahedron-shaped silicate anion, SiO44−. (A) The anion has four oxygen atoms touching each other. A silicon atom (dashed circle) occupies the central space. (B) This exploded view shows the relatively large oxygen anions at the four corners of the tetrahedron, equidistant from the relatively small silicon cation.
          • FIGURE 3.10: Silicate polymerization Complex silicate anions form by polymerization. (A) This is a polymer chain in which each silicate anion shares two of its oxygen atoms with adjacent anions. A geometric representation of the chain is on the right. The formula of each basic unit in the chain is (SiO3)2−. (B) This is a double polymer chain for which the formula of the basic unit is (Si4O11)6−. Again, a simplified geometric representation is shown on the right.
          • FIGURE 3.11: Silicate polymerization to form minerals This table provides a summary of the way silicate anions polymerize to form the common silicate minerals. Typical examples of each type are shown in the photographs. The most important polymerizations are those that produce chains, sheets, and three-dimensional networks. Note the relationship between crystal structure and cleavage.
        • Nonsilicates
          • FIGURE 3.12: The most common minerals Crystals of feldspar (green) and quartz (gray) from Pikes Peak, Colorado represent the two most common minerals in Earth’s crust. This specimen is 20 cm across.
      • Identifying Minerals
        • Crystal Form and Growth Habit
          • FIGURE 3.13: Crystal form and habit Minerals have characteristic crystal structures, but these are not always manifested in the same way in the crystal form and habit of the mineral. (A) These two crystals are both quartz and have the same crystal form. Although the sizes of the individual faces differ markedly between the two crystals, each numbered face on one crystal is parallel to an equivalent face on the other crystal. (B) These quartz grains (colorless) grew in an environment where other grains prevented the development of well-formed crystal faces. The amber-colored grains are iron carbonate (FeCO3). (C) Pyrite (FeS2) characteristically forms crystals with faces at right angles and with pronounced striations. The largest crystals in this photograph are 3 cm across. The specimen is from Bingham Canyon, Utah. (D) Some minerals have distinctive growth habits, even though they do not develop well-formed crystal faces. The mineral chrysotile sometimes grows as fine, cottonlike threads that can be separated and woven into fireproof fabric. When used for this purpose, it is referred to by its industrial name, asbestos.
        • Cleavage
        • Luster, Color, and Streak
          • FIGURE 3.14: Cleavage (A) The relationship between crystal structure and cleavage is shown by this mineral, halite, NaCl, which has well-defined cleavage planes and always breaks into fragments bounded by perpendicular faces. (B) The perfect cleavage of mica (variety muscovite) is illustrated by the planar flakes into which this specimen is being split.
        • Hardness
          • FIGURE 3.15: Color and streak Hematite and its streak show different colors. Massive hematite is opaque, has a metallic luster, and appears black. On a porcelain plate, however, this mineral gives a red streak.
          • A Closer LOOK: STEPS TO FOLLOW IN IDENTIFYING MINERALS
            • TABLE C3.1: Mohs Scale of Relative Hardnessa
            • TABLE C3.2: Reference Chart for the Identification of Common Minerals and a Guide to the Rock Types in which the minerals might be found
        • Density and Specific Gravity
    • ROCKS
      • The Three Families of Rocks
        • FIGURE 3.16: Rock of the crust and surface These graphs show the relative amounts of sedimentary and igneous rock in Earth’s crust and at the surface. (A) Most of the crust consists of igneous rock (95%), with sedimentary rock (5%) forming a thin veneer at the surface. (B) Because the sedimentary rock veneer covers so much of Earth’s surface, it is mainly what we see. Thus, 75 percent of the surface is sedimentary rock. Igneous formations pushing through the sedimentary veneer account for the other 25 percent.
      • Features of Rocks
        • FIGURE 3.17: Thin sections of rock Polished surfaces and thin slices reveal rock textures and mineral assemblages to great advantage. The specimen here is an igneous rock containing quartz (Q), feldspar (F), amphibole (A), mica (M), and magnetite (Mg). (A) A thin slice of rock is mounted on glass. The slice is 0.03 mm thick, and light can pass through the minerals. (B) This is the polished surface of the hand sample of rock. The dashed rectangle indicates the area used to make the thin slice shown in part (A) (C) An area of the thin slice is viewed under a microscope at a magnification of 25x. (D) The same view as in part (C) is here seen through polarizing lenses in order to emphasize the shapes and orientations of individual grains.
      • Basic Rock Identification
        • TABLE 3.2: Minerals Most Commonly Found in the Three Rock Families
        • Identifying Igneous Rocks
          • FIGURE 3.18: The major rock families (A) Plutonic rocks, like the granodiorite shown here, are igneous rocks that form from the solidification of magma underground. They cool slowly and therefore have time to grow individual mineral grains that are coarse enough to be visible by eye. (B) Volcanic rocks are igneous rocks that tend to be fine-grained because they cool quickly and therefore do not have time to form large crystals. Shown here is volcanic glass that solidified so quickly that it didn’t grow any crystals at all, and has an amorphous (noncrystalline) structure. (C) Metamorphic rocks often show evidence of the mineralogical and textural features that result from exposure to high temperatures and pressures, as seen in the highly contorted banding of this sample of gneiss. (D) Sedimentary rocks are often identifiable by the individual accumulated grains of sediment, as shown in this sample of conglomerate. (E) Some rocks, like this limestone, contain fossils, which provide good evidence of sedimentary origin.
        • Identifying Metamorphic Rocks
        • Identifying Sedimentary Rocks
    • REGOLITH
      • The Surface Blanket
      • Sediment
        • FIGURE 3.19: Regolith Regolith consists of a variety of unconsolidated materials that blanket Earth’s surface. (A) Saprolite is rock that has been weathered and broken up but is still in place. The saprolite shown here resulted from deep weathering of rock in a tropical environment. (B) Sediment is loose, unconsolidated particulate matter, regardless of its location or origin. When sediment has been picked up by wind, water, or ice, transported to another location, and deposited, it is called alluvium. This satellite image shows the Betsiboka River in Madagascar carrying a substantial quantity of sediment—the reddish-brown material—to the ocean. (C) Soil is a special type of sediment that has been altered chemically and biologically, such that it can support rooted plant life.
      • Soil
        • Make the CONNECTION
    • HOW MATTER MOVES THROUGH THE EARTH SYSTEM
      • GEOLOGIC QUESTIONS
      • HYDROLOGIC QUESTIONS
      • ATMOSPHERIC QUESTIONS
      • BIOLOGIC QUESTIONS
    • END OF CHAPTER 3
      • SUMMARY
      • IMPORTANT TERMS TO REMEMBER
      • QUESTIONS FOR REVIEW
      • QUESTIONS FOR RESEARCH AND DISCUSSION
      • QUESTIONS FOR THE BASICS
      • QUESTIONS FOR A CLOSER LOOK
  • CHAPTER 4: Space and TIME
    • Earthlike planet? CoRoT-7b is a rocky planet about 480 light years from Earth, shown here in an artist’s rendition with its sun, the star CoRoT-7, rising in the background. Although there have now been many observations of exoplanets, or planets outside of our own solar system, CoRoT-7b is so far the most earthlike in its physical characteristics.
    • OVERVIEW
    • THE SUN: AN ORDINARY STAR
      • FIGURE 4.1: A galaxy like our own This photograph by the Hubble Space Telescope shows Spiral Galaxy NGC 3949, a galaxy that is quite similar to the Milky Way in both shape and structure, located in the constellation Ursa Major about 50 million light-years from Earth. Because our solar system is embedded in the Milky Way galaxy, it is impossible to get the right perspective to photograph the large-scale features of our own galaxy.
      • The Sun’s Vital Statistics
        • FIGURE 4.2: Earth’s Sun The Sun is almost unimaginably large compared to Earth. This photo shows a coronal mass ejection from the Sun, which took place in October, 2003.
      • The Life-Supporting Properties of the Sun
        • Make the CONNECTION
        • FIGURE 4.3: Solar system distances The average distance from Earth to the Sun is approximately 150 million km (defined as 1 AU). This distance varies because Earth’s orbit around the Sun is not exactly circular. As shown here, the inner planets are orbiting much closer to the Sun than the outer planets. On the scale of this diagram, the Moon’s orbit around Earth is so close that the two objects would not be distinguishable. The orbits of objects in the Asteroid Belt lie in the gap between the orbits of Mars and Jupiter.
      • Earth’s Warming Blanket
        • the BASICS: Seasons on Earth
          • FIGURE B4.1: Seasons Seasons occur on Earth because the tilt of Earth’s axis keeps a constant orientation as the planet revolves around the Sun, with the result that the northern hemisphere is pointed directly toward the Sun during June and the southern hemisphere is pointed toward the Sun during December.
    • THE SOLAR SYSTEM
      • Tour of the Solar System
      • Origin of the Solar System
        • Features to Be Explained
          • FIGURE 4.4: Earth from space The first photographs of Earth taken from space showed us a small, fragile, beautiful, and isolated planet full of color and life. This photo was taken in 1968 by astronauts on Apollo 8, the first human spaceflight to leave Earth’s orbit.
          • FIGURE 4.5: The solar system (A) The eight planets of our solar system are shown here in their correct relative sizes and order outward from the Sun (but not the correct distances from the Sun). The Sun is 13 times larger in diameter than Jupiter, the largest planet. (B) This table of data about the planets shows that the terrestrial planets are much smaller as well as much denser than the outer jovian planets.
          • FIGURE 4.6: Celestial spheres Aristotle pictured the Sun, the Moon, the five visible planets, and the stars as being suspended on concentric, hollow spheres that rotate about an imaginary axis extending outward from the two poles of Earth. Beyond the star sphere lay the realm of the gods.
        • The Solar Nebula
        • Condensation and Accretion
          • FIGURE 4.7: Supernovae and nebulae The cloud of interstellar gas from which our solar system eventually formed probably originated in the death of a very massive star through a supernova, such as the one shown here, SN 2004dj, in a distant galaxy called NGC 2403.
          • FIGURE 4.8: Nebular hypothesis A gas cloud slowly swirling in space marks the beginning of the nebular hypothesis (A). Slowly the thinly spread gas began to collapse inward under the force of gravity; eventually, the center became so compressed and hot that nuclear fusion began and a star (our Sun) was born. Gravitational forces caused the nebula around the young star to flatten into a rotating disk (B), as materials began to condense from the cloud. The temperature gradient in the nebular disk—from very hot near the center to very cold on the outer edges—controlled the nature of the materials that condensed in various parts of the cloud, thus influencing the final compositions of the inner and outer planets (C).
        • Subsequent Planetary Evolution
          • MELTING, IMPACTS, AND DIFFERENTIATION.
          • VOLCANISM.
            • Make the CONNECTION
          • PLANETARY MASS.
            • FIGURE 4.9: Scars of a violent past The heavily crated surface of Mercury, photographed by the Messenger spacecraft in 2008, displays the scars of violent impacts from early in the history of the solar system.
            • FIGURE 4.10: Key factors in planetary evolution The five key factors that influenced planetary evolution subsequent to the earliest formation of the solar system were (A) impact cratering and resultant partial melting, as seen here in an artist’s conception of a major impact event early in Earth history; (B) volcanism, as seen here in a photograph of the Martian volcano Olympus Mons—the largest known volcano in the solar system; (C) planetary mass, which determines the orbital characteristics of the planet as well as its ability to retain an atmosphere; Mercury (left), shown here in comparison to Earth, is too small and has insufficient gravitational pull to retain an atmosphere; (D) distance from the Sun, as seen here in an image of 55 Cancri, a star with a family of five known planets, one of which (depicted in blue) is the correct distance from the star to potentially support liquid water; and (E) the development of a biosphere and its subsequent influence on the chemical evolution of the atmosphere, hydrosphere, and regolith. Photosynthetic organisms like this filamentous alga (Cladophora) have greatly influenced the composition of the atmosphere over geologic time by contributing oxygen.
          • DISTANCE FROM THE SUN.
          • BIOSPHERE.
      • The Terrestrial Planets Today
        • Make the CONNECTION
      • The Jovian Planets Today
        • FIGURE 4.11: Impacts on Earth Although all of the planets experienced intense meteorite bombardment early in solar system history, the scars of these impacts on Earth have been hidden or erased by the subsequent action of weathering, erosion, and plate tectonics. Here, however, is a crater caused by an impact at Meteor Crater in Flagstaff, Arizona, just 50,000 years ago. The crater is 1.2 km in diameter and 200 m deep.
      • Other Solar System Objects
        • FIGURE 4.12: Jupiter, gas giant Jupiter is the largest of the gas giants. It is seen here (A) with a shadow (small dark spot) cast by Europa, one of its more than 60 moons. Like the other gas giants, the bulk composition of Jupiter is approximately the same as the composition of the solar nebula from which it formed. Jupiter is estimated to be 74 percent hydrogen, 24 percent helium, and 2 percent heavy elements. Storms are common in the turbulent atmospheres of the gas giants (B) Visible in this photograph is the famed Great Red Spot on Jupiter, twice as wide as Earth, an anticyclonic storm that is thought to have been active for over 300 years.
        • Moons
          • FIGURE 4.13: Europa, a moon of Jupiter Europa, the smallest of the four large moons of Jupiter, has a low density, indicating that it contains a substantial amount of ice. The surface is mantled by ice to a depth of 100 km.
        • Earth’s Moon
          • FIGURE 4.14: Jupiter’s interior Like the other gas giants, Jupiter probably has a relatively small core of rock that may be mantled by ice. Pressures in the interior of these massive planets are so intense that hydrogen may even exist in a solid state.
        • Asteroids and Meteorites
          • FIGURE 4.15: Formation of Earth’s Moon (A) Impact: Some 4550 million years ago, a still-forming Earth runs into another growing planet, which scientists have dubbed Theia. (B) Impact + 8 hours: Theia is obliterated, and its remnants—along with a good chunk of Earth’s mantle—are blasted into orbit around Earth. The off-center impact knocks Earth’s axis of rotation askew. (C) Impact + 24 hours: The debris spreads itself into a ring and begins to clump together. (D) Impact + 1 year: The largest clump starts to attract other fragments and is well on its way toward becoming the Moon.
          • FIGURE 4.16: Asteroids Asteroids are small, mostly rocky objects that orbit the Sun. Although there are no specific “rules” regarding the minimum or maximum size, asteroids tend to be smaller than dwarf planets, and they populate an orbital gap between Mars and Jupiter (A). The Trojan and Greek groups are asteroids whose orbits are perturbed by gravitational interaction with the massive planet Jupiter. (B) This small asteroid, named 243 Ida, is about 54 km in its longest dimension. Ida has a tiny moon named Dactyl (seen to the right of Ida and in the inset photo), only 1.4 km across, which may have originated as a fragment that broke off of Ida as a result of a collision.
        • Pluto and the Dwarf Planets
        • Comets, the Kuiper Belt, and the Oort Cloud
          • FIGURE 4.17: Pluto, dwarf planet Pluto, formerly the smallest of nine planets, was demoted to dwarf planet status in 2006. Pluto’s natural satellite, Charon (just below and right of Pluto), is almost 50 percent of Pluto’s size, making it more like a companion dwarf planet. Nix and Hydra, the two smaller moons of Pluto, are also seen here.
          • FIGURE 4.18: Comet Comets are small, loosely packed, icy bodies—like dirty snowballs. They travel periodically to the inner part of the solar system, following highly elongate, elliptical orbits. When they approach the Sun, the ices in their cores volatilize and incandesce, creating the glowing head long tail that we associate with comets, as seen here in Comet Hale-Bopp, 1997. The tail always points away from the Sun.
    • OTHER SUNS AND PLANETARY SYSTEMS
      • Classifying Stars
        • FIGURE 4.19: Classifying stars In the constellation Orion (the hunter), the reddish star at the upper left is Betelgeuse; the bright, bluish-white star at the lower right is Rigel. Because this photo is a time exposure, many faint stars not visible to the eye are shown.
      • Stellar Evolution
        • FIGURE 4.20: Star luminosity and temperature A Hertzsprung-Russell diagram is a plot of star luminosity versus surface temperature. The vertical axis is a comparative one based on the Sun having a luminosity of 1. The horizontal axis shows surface temperatures increasing to the left. The Sun is a middle-range, main-sequence star.
        • 1-S Stars
          • FIGURE 4.21: Shell fusion When a star that is roughly the mass of our Sun (1 S) uses up its hydrogen fuel and moves off of the main sequence on the H-R diagram, it commences a phase called shell fusion. The now helium-rich core contracts, generating a lot of heat and outward pressure. Hydrogen in the innermost part of the radiative layer begins to undergo fusion, contributing to the outward radiative pressure. The result is that the star increases greatly in size, becoming a red giant.
        • Small-Mass Stars
        • Massive Stars
      • Discovery of Other Planetary Systems
        • FIGURE 4.22: Exosolar planets This is an artist’s rendition of the exosolar family of five planets (only four are shown here) around the star 55 Cancri, the brightest dot. The blue planet that looms large in the foreground, which is about the size of Neptune, is thought to be orbiting within the habitable zone of the star and may thus be a candidate for an Earthlike exoplanet. This is the same planet as the one shown in Figure 4.10C.
        • A Closer LOOK: EXTRATERRESTRIAL LIFE
          • FIGURE C4.1: Seeking extraterrestrial life NASA’s twin robotic geologists, the Mars Exploration Rovers named Spirit and Opportunity, one of which is depicted here, carried a variety of scientific instruments to search for clues about the history of water (and therefore, possibly, life) on Mars.
    • TIME AND CHANGE
      • FIGURE 4.23: Time and space scales of Earth processes Earth processes happen on widely varying scales in time and space, from submicroscopic atomic and nuclear processes that happen almost instantaneously to the growth and evolution of planets and solar systems over billions of years.
      • Origins
      • Relative and Numerical Age
        • the BASICS: Measuring Numerical Age
          • FIGURE B4.2: Radioactive decay (A) At time zero, a sample consists of 100 percent radioactive parent atoms. During each time unit, half the atoms remaining decay to daughter atoms. (B) At time zero, no daughter atoms are present. After one time unit corresponding to a half-life of the parent atoms, 50 percent of the sample has been converted to daughter atoms. After two time units, 75 percent of the sample is daughter atoms, and 25 percent is parent atoms. After three time units, the percentages are 87.5 and 12.5, respectively. Note that at any given instant Np, the number of parent atoms remaining, plus Nd, the number of daughter atoms, equals No, the number of parent atoms at time zero.
        • FIGURE 4.24: Relative and numerical age A good analogy for relative age is a stack of papers placed one on top of the other, day by day. The paper on the bottom is older, in relative age, than any of the papers that overlie it. However, we cannot know the actual age of any of the papers, or the rocks in a geologic sequence unless we look at the date printed on the newspaper or determine the numerical age of the rock by some means such as radiometric dating.
        • FIGURE 4.25: Geologic time in perspective Through a combination of radiometric dating and other tools used to determine numerical ages, and geologic observations used to determine relative ages, geologists have established a geologic column that outlines the major periods and events of Earth history. Note that most of Earth history—88 percent of it—is “Precambrian” time, a period about which we still know relatively little.
      • Uniformitarianism and Catastrophism
        • FIGURE 4.26: Principle of uniformitarianism The internal structure of sand dunes, ancient and modern, demonstrates the power of uniformitarianism. (A) A distinctive pattern of wind-deposited sand grains can be seen in a hole dug in this dune near Yuma, Arizona. (B) The same distinctive pattern appears in ancient rocks in Zion National Park, Utah. We can infer that these rocks were once sand dunes.
    • END OF CHAPTER 4
      • SUMMARY
      • IMPORTANT TERMS TO REMEMBER
      • QUESTIONS FOR REVIEW
      • QUESTIONS FOR RESEARCH AND DISCUSSION
      • QUESTIONS FOR THE BASICS
      • QUESTIONS FOR A CLOSER LOOK
• PART TWO: The Geosphere: Earth Beneath Our Feet
  • Volcanic contributions
  • CHAPTER 5: The Tectonic CYCLE
    • The top of the world
    • OVERVIEW
    • FIGURE 5.1: Continental collision
    • FIGURE 5.2: Tectonics today
    • PLATE TECTONICS: A UNIFYING THEORY
      • The Development of an Idea
        • The Back Story of Plate Tectonics
          • FIGURE 5.3: Darwin’s inspiration
          • FIGURE 5.4: Evidence for continental drift
        • The Continental Drift Hypothesis
          • Make the CONNECTION
      • The Search for a Mechanism
        • Apparent Polar Wandering
          • FIGURE 5.5: Wandering poles?
          • the BASICS: Earth’s Magnetism
            • FIGURE B5.1: Earth’s magnetic field
            • ROCK MAGNETISM AND PALEOMAGNETISM
              • FIGURE B5.2: Magnetic magnetite
        • Magnetic Reversals and Seafloor Spreading
          • FIGURE 5.6: Magnetism in volcanic rocks
          • FIGURE 5.7: Magnetic reversals
          • FIGURE 5.8: Seafloor spreading
    • PLATE MOTION AND THE DRIVING FORCE
      • Heat Flow in the Mantle: Review
      • Convection as a Driving Force
        • FIGURE 5.9: Mechanisms of plate motion
        • FIGURE 5.10: Modeling mantle convection
        • A Closer LOOK: MEASURING THE ABSOLUTE SPEED OF PLATE MOTION
          • FIGURE C5.1: Movement of a curved plate
          • FIGURE C5.2: Absolute and relative speed
          • FIGURE C5.3: Measuring plate motion
          • FIGURE C5.4: Volcanic hotspots
      • Measuring Plate Motion
        • FIGURE 5.11: Plate speeds
      • Recycling the Lithosphere
    • PLATE INTERACTIONS AND EARTH’S LANDSCAPES
      • Plate Margins
        • FIGURE 5.12: Plates and plate boundaries
        • Divergent Plate Margins
          • FIGURE 5.13: The formation of an ocean
        • Convergent Plate Margins
          • FIGURE 5.14: Continental collision
        • Transform Fault Plate Margins
      • Earth’s Topographic Features
        • Topography of Ocean Basins
          • FIGURE 5.15: Transform fault margin
          • FIGURE 5.16: Topography of continents and oceans
        • Topography of Subduction Zones
          • FIGURE 5.17: The “true” edge of a continent
          • FIGURE 5.18: Subduction zone
          • FIGURE 5.19: Benioff zone
        • Topography of Continents and Collision Zones
          • FIGURE 5.20: Volcanic island arc
          • FIGURE 5.21: Continental volcanic arc
          • FIGURE 5.22: Transform topography
    • BUILDING THE CONTINENTS
      • FIGURE 5.23: North American cratons
      • Regional Structures of Continents: Cratons and Orogens
      • Stabilization of Continental Crust
      • Supercontinents
      • Isostasy, Gravity, and the Roots of Mountains
        • FIGURE 5.24: Supercontinents before Pangaea
        • FIGURE 5.25: Isostasy
        • Isostasy
          • FIGURE 5.26: Isostatic rebound
          • FIGURE 5.27: Mountain roots and isostatic adjustment
        • Gravity Anomalies
          • FIGURE 5.28: Gravimeter
          • Make the CONNECTION
      • Plate Tectonics And The Earth System Today
        • FIGURE 5.29: Gravity profile of North America
        • Climate and Ecosystems in Modern Orogens
        • Composition of Ocean Water
        • Composition of the Atmosphere
        • Sequestration of Carbon
    • END OF CHAPTER 5
      • SUMMARY
      • IMPORTANT TERMS TO REMEMBER
      • QUESTIONS FOR REVIEW
      • QUESTIONS FOR RESEARCH AND DISCUSSION
      • QUESTIONS FOR THE BASICS
      • QUESTIONS FOR A CLOSER LOOK
  • CHAPTER 6: Earthquakes and Volcanoes
    • Can you say “Eyjafjallajökull”?
    • OVERVIEW
    • EARTHQUAKES: WHEN ROCKS SHIFT
      • What Is an Earthquake?
        • FIGURE 6.1: Elastic energy
      • Origin of Earthquakes
        • FIGURE 6.2: Movement along a fault
      • Seismic Waves
        • the BASICS: Types of Seismic Waves
          • BODY WAVES
          • SURFACE WAVES
            • FIGURE B6.1: Seismic body waves
            • FIGURE B6.2: Seismogram of a typical earthquake
      • Determining Earthquake Locations
        • FIGURE 6.3: Seismograph
        • FIGURE 6.4: Earthquake focus and epicenter
      • Measuring Earthquake Magnitudes
        • FIGURE 6.5: Locating an earthquake
        • How Big Can Earthquakes Be?
          • TABLE 6.1: Earthquake Magnitudes, Frequencies, and Effects
        • Richter Magnitude
        • Seismic Moment Magnitude
        • Mercalli Intensity
    • EARTHQUAKE HAZARD AND RISK
      • Make the CONNECTION
      • FIGURE 6.6: Seismic hazard map
      • Earthquake Disasters
      • Earthquake Damage
        • Primary Effects
          • Ground Motion.
          • Surface Rupture.
            • FIGURE 6.7: Earthquake damage and building standards
            • TABLE 6.2: Earthquakes during the Past 800 Years That Have Caused 50,000 or More Deaths
        • Secondary Effects
          • Fires.
          • Landslides.
          • Liquefaction.
          • Tsunami.
            • FIGURE 6.8: Earthquake impacts
            • A Closer LOOK: THE SUMATRA-ANDAMAN EARTHQUAKE AND TSUNAMI
              • FIGURE C6.1: Progress of a killer tsunami
              • FIGURE C6.2: The Sumatra-Andaman Tsunami of 2004
      • Earthquake Prediction
        • Prediction and Early Warning
        • Forecasting
    • EARTHQUAKES AND EARTH’S INTERIOR
      • Earth’s Internal Layering
        • FIGURE 6.9: Seismic waves in Earth’s interior
        • Core-Mantle Boundary
        • Mantle-Crust Boundary
        • Seismic Discontinuities
      • Earthquakes and Plate Tectonics
        • FIGURE 6.10: Layering in Earth’s interior
        • FIGURE 6.11: Earthquakes and plate boundaries
        • Seismicity and Plate Margins
          • FIGURE 6.12: Earthquakes and tectonic environments
          • Spreading Ridges.
          • Transform Faults.
          • Continental Collisions.
          • Subduction Zones.
        • Focal Depths
    • VOLCANOES: WHEN ROCKS MELT
      • FIGURE 6.13: Flowing lava
      • Why Do Rocks Melt?
        • Pressure and Rock Melting
          • FIGURE 6.14: Magma and lava are hot
          • FIGURE 6.15: Geothermal gradient
          • FIGURE 6.16: Temperature, pressure, water, and rock melting
          • the BASICS: The Characteristics of Magma and Lava
            • RANGE OF COMPOSITIONS
              • FIGURE B6.3: Common magma compositions
            • ABILITY TO FLOW
              • FIGURE B6.4: Viscosity of lava
              • TABLE B6.1: Magmas and Associated Volcanic and Plutonic Rocks
            • HIGH TEMPERATURE
        • Water and Rock Melting
          • Make the CONNECTION
        • Fractional Melting
      • Volcanic Eruptions
        • Nonexplosive Eruptions
          • FIGURE 6.17: Rock melting and partial melting
        • Explosive Eruptions
          • FIGURE 6.18: Nonexplosive but gas-rich eruptions
          • Eruption Columns and Tephra Falls.
            • FIGURE 6.19: Pyroclasts and explosive eruptions
            • FIGURE 6.20: Eruption column
          • Pyroclastic Flows.
          • Lateral Blasts.
      • Types of Volcanoes
        • FIGURE 6.21: Lateral blast
        • FIGURE 6.22: Shield volcano
        • Shield Volcanoes
        • Tephra Cones and Stratovolcanoes
          • FIGURE 6.23: Tephra cones
          • FIGURE 6.24: Stratovolcanoes
        • Other Volcanic Landforms
          • FIGURE 6.25: Caldera
          • FIGURE 6.26: Fissure eruption
    • VOLCANIC DISASTERS
      • Volcanic Hazards
        • FIGURE 6.27: Deadly eruptions
      • Predicting Volcanic Eruptions
        • FIGURE 6.28: Victims of Mount Vesuvius
      • After an Eruption
        • Make the CONNECTION
        • FIGURE 6.29: Volcano monitoring from space
        • FIGURE 6.30: New volcanic soils
      • Volcanic Benefits
    • MAGMA UNDERGROUND
      • FIGURE 6.31: Volcanic neck
      • FIGURE 6.32: Plutons
    • THE TECTONIC CONNECTION: ORIGIN AND DISTRIBUTION OF MAGMAS AND VOLCANOES
      • Midocean Ridges, Hotspots, and Basaltic Magmas
        • FIGURE 6.33: Magmas, lavas, and plate tectonics
      • Continental Rifts and Rhyolitic Magmas
      • Subduction Zones and Andesitic Magmas
      • Now On to the Rock Cycle
    • END OF CHAPTER 6
      • SUMMARY
      • IMPORTANT TERMS TO REMEMBER
      • QUESTIONS FOR REVIEW
      • QUESTIONS FOR RESEARCH AND DISCUSSION
      • QUESTIONS FOR THE BASICS
      • QUESTIONS FOR A CLOSER LOOK
  • CHAPTER 7: The Rock CYCLE
    • Carbon storage
    • OVERVIEW
    • FIGURE 7.1: The rock cycle
    • FROM ROCK TO REGOLITH
      • Chemical Weathering
        • FIGURE 7.2: The zone of weathering
      • Physical Weathering
        • FIGURE 7.3: Impacts of weathering
        • FIGURE 7.4: Ion exchange in chemical weathering
        • FIGURE 7.5: Joint formation
        • FIGURE 7.6: Mechanical weathering
        • Make the CONNECTION
      • Sediment and Its Transport
        • FIGURE 7.7: Rock disintegration
        • Clastic Sediment
          • FIGURE 7.8: Clastic sediment and associated rocks
          • FIGURE 7.9: Transport of sediment by fluids
          • FIGURE 7.10: Sorting
        • Chemical and Biogenic Sediment
      • Mass Wasting
        • FIGURE 7.11: Landslides
        • FIGURE 7.12: Triggers for landslides
      • Tectonic Environments of Sedimentation
        • FIGURE 7.13: Tectonics and sedimentation
    • FROM REGOLITH TO ROCK
      • Diagenesis and Lithification
        • FIGURE 7.14: Sedimentary bedding
      • Sedimentary Rock
        • FIGURE 7.15: Lithification
        • Clastic Sedimentary Rock
          • FIGURE 7.16: Sedimentary clues
        • Chemical and Biogenic Sedimentary Rock
          • A Closer LOOK: BANDED IRON FORMATIONS
            • FIGURE C7.1: Record of a changing atmosphere
      • Sedimentary Strata
        • The Principles of Stratigraphy
          • FIGURE 7.17: Strata and the principle of original horizontality
        • Stratigraphic Correlation
        • Breaks in the Stratigraphic Record
          • FIGURE 7.18: Correlating sedimentary strata
          • the BASICS: Using Strata to Measure Geologic Time
            • FIGURE B7.1: Determining relative age
            • FIGURE B7.2: Geologic column
          • FIGURE 7.19: Unconformities
    • NEW ROCK FROM OLD
      • Metamorphism
        • FIGURE 7.20: Temperature and pressure conditions for metamorphism
        • The Role of Fluids
        • Temperature, Pressure, and Stress
          • FIGURE 7.21: Effects of uniform and differential stress
        • Metamorphic Mineral Assemblages
      • Metamorphic Processes
        • Contact Metamorphism
        • Burial Metamorphism
          • FIGURE 7.22: From shale to gneiss
          • FIGURE 7.23: Contact metamorphism
        • Regional Metamorphism
          • FIGURE 7.24: Tectonics and metamorphism
      • Metamorphic Rock
        • Metamorphism of Shale
        • Metamorphism of Basalt
        • Metamorphism of Limestone and Sandstone
          • FIGURE 7.25: Marble and quartzite
      • Metamorphic Facies and Plate Tectonics
    • FROM ROCK TO MAGMA AND BACK AGAIN
      • Melting and Magma: Review
      • Crystallization and Igneous Rock
        • FIGURE 7.26: Volcanic and plutonic rock
        • Rapid Cooling: Volcanic Rock
          • FIGURE 7.27: Volcanic glass
        • Slow Cooling: Plutonic Rock
        • Igneous Rock Diversification
          • FIGURE 7.28: Fractional crystallization
    • THE ROCK CYCLE, THE TECTONIC CYCLE, AND EARTH’S LANDSCAPES
      • Make the CONNECTION
      • Competing Geologic Forces
        • Uplift Rates
          • FIGURE 7.29: Steep slopes, rapid erosion
        • Denudation Rates
          • FIGURE 7.30: Sediment yield from continents
          • the BASICS: Factors Controlling Landscape Development
            • FIGURE B7.3: Differential erosion
      • Landscape Equilibrium
        • FIGURE 7.31: Computer simulation of environmental changes
    • END OF CHAPTER 7
      • SUMMARY
      • IMPORTANT TERMS TO REMEMBER
      • QUESTIONS FOR REVIEW
      • QUESTIONS FOR RESEARCH AND DISCUSSION
      • QUESTIONS FOR THE BASICS
      • QUESTIONS FOR A CLOSER LOOK
• PART THREE: The Hydrosphere: Earth’s Blanket of WATER and ICE
  • Where land, water, and ice meet
  • CHAPTER 8: The Hydrologic CYCLE
    • Water on Earth’s surface
    • OVERVIEW
    • WATER AND THE HYDROLOGIC CYCLE
      • FIGURE 8.1: The hydrologic cycle
      • Reservoirs in the Hydrologic Cycle
        • FIGURE 8.2: Reservoirs in the hydrologic cycle
      • Pathways in the Hydrologic Cycle
        • FIGURE 8.3: Pathways in the hydrologic cycle
        • the BASICS: Water, the Universal Solvent
          • FIGURE B8.1: Water in three states
          • FIGURE B8.2: Water, a dipolar molecule
          • FIGURE B8.3: Surface tension
    • WATER ON THE GROUND
      • The Stream as a Natural System
      • Stream Channels and Streamflow
        • FIGURE 8.4: Where precipitation goes
        • FIGURE 8.5: Drainage basins
        • Factors that Control Stream Behavior
        • Meandering Channels
          • Make the CONNECTION
          • FIGURE 8.6: Changes in stream behavior
          • FIGURE 8.7: Meanders
        • Braided Channels
      • A Stream’s Load
        • FIGURE 8.8: Oxbow lakes
        • FIGURE 8.9: Braided stream
        • Bed Load
          • FIGURE 8.10: Bed-load saltation
        • Suspended Load
          • FIGURE 8.11: Bed-load grain size
        • Dissolved Load
          • FIGURE 8.12: Suspended load
      • Running Water and Landscapes
        • Depositional Landforms
        • Tectonic and Climatic Controls on Divides
          • FIGURE 8.13: Streams and landforms
          • FIGURE 8.14: Continental divides
          • FIGURE 8.15: Climate divide
      • Surface Water Reservoirs
        • Lakes
          • FIGURE 8.16: Canadian lakes
          • Make the CONNECTION
        • Wetlands
          • FIGURE 8.17: Wetland
          • FIGURE 8.18: Mississippi River flood
      • Floods: When There’s Too Much Water
        • Impacts of Flooding
          • FIGURE 8.19: Hurricane Katrina coastal flooding
        • Flood Prediction
          • FIGURE 8.20: Flood hydrographs
        • Flood Prevention and Channelization
          • FIGURE 8.21: Predicting floods
    • WATER UNDER THE GROUND
      • Chemistry of Groundwater
        • FIGURE 8.22: Water under the ground
      • Movement of Groundwater
      • Recharge and Discharge
        • FIGURE 8.23: Groundwater flow paths
      • Aquifers, Wells, and Springs
        • Aquifers and Wells
          • the BASICS: Porosity and Permeability
            • FIGURE B8.4: Porosity
            • FIGURE B8.5: Clay
          • FIGURE 8.24: Aquifers
        • Springs
      • Groundwater and Landscapes
        • FIGURE 8.25: Springs
        • Caves and Sinkholes
        • Karst Terrains
          • FIGURE 8.26: Cave
          • FIGURE 8.27: Karst
    • WATER AND SOCIETY
      • Water Quantity
        • Water Shortages
          • Make the CONNECTION
          • FIGURE 8.28: Water stress
        • Diversions and Withdrawals
      • Water Quality
        • Surface Water Contamination
          • FIGURE 8.29: Eutrophication: A dying lake
          • A Closer LOOK: THE CASE OF THE ARAL SEA
            • FIGURE C8.1: The shrinking Aral Sea
            • FIGURE C8.2: Stranded boats
        • Groundwater Contamination
    • END OF CHAPTER 8
      • SUMMARY
      • IMPORTANT TERMS TO REMEMBER
      • QUESTIONS FOR REVIEW
      • QUESTIONS FOR RESEARCH AND DISCUSSION
      • QUESTIONS FOR THE BASICS
      • QUESTIONS FOR A CLOSER LOOK
  • CHAPTER 9: The Cryosphere
    • Ice from the land to the sea
    • OVERVIEW
    • EARTH’S COVER OF SNOW AND ICE
      • Snow
        • FIGURE 9.1: The cryosphere
        • FIGURE 9.2: Snow cover
        • Annual Snow Cycle
        • The Snowline
          • FIGURE 9.3: The snowline
          • FIGURE 9.4: Influence of climate on the snowline
    • GLACIERS
      • FIGURE 9.5: Glaciers
      • How Glaciers Form
        • FIGURE 9.6: Valley glaciers
        • FIGURE 9.7: Antarctic Ice Sheet
        • FIGURE 9.8: Recrystallization of glacial ice
      • Distribution of Glaciers
        • the BASICS: Snow and Ice
          • FIGURE B9.1: Snow crystals
          • FIGURE B9.2: From snow to ice
      • Warm and Cold Glaciers
        • FIGURE 9.9: Temperate and polar glaciers
      • Why Glaciers Change
        • FIGURE 9.10: Glacial features
      • How Glaciers Move
        • Internal Flow
          • FIGURE 9.11: Shifting equilibrium
          • FIGURE 9.12: Internal creep in a glacier
        • Basal Sliding
        • Ice Velocity
          • FIGURE 9.13: Crevasse
          • FIGURE 9.14: Movement in a temperate glacier
        • Response Lags
        • Calving
          • FIGURE 9.15: Debris flow on a glacier
          • FIGURE 9.16: Calving
          • FIGURE 9.17: Fjord glacier
          • Make the CONNECTION
        • Glacial Surges
          • FIGURE 9.18: Iceberg
          • FIGURE 9.19: Glacial surge
    • GLACIATION
      • Glaciated Landscapes
        • Glacial Sculpture
          • FIGURE 9.20: Glacial sculpting
        • Glacial Deposition
          • FIGURE 9.21: Drumlins
          • FIGURE 9.22: Glacial deposits
          • the BASICS: Glacial and Interglacial Periods
            • FIGURE B9.3: Pleistocene glaciation
      • Periglacial Landscapes and Permafrost
        • Permafrost
          • FIGURE 9.23: Kettles
        • Living with Permafrost
          • FIGURE 9.24: Living with permafrost
        • Periglacial Landforms
          • FIGURE 9.25: Periglacial landforms
      • Glaciers and People
      • Glaciers as Environmental Archives
        • FIGURE 9.26: Ice as an environmental archive
    • SEA ICE
      • FIGURE 9.27: Arctic sea ice
      • Make the CONNECTION
      • How Sea Ice Forms
        • FIGURE 9.28: Sea ice
      • Sea-Ice Distribution and Zonation
        • FIGURE 9.29: Changing sea-ice
      • Sea-Ice Motion
    • ICE IN THE EARTH SYSTEM
      • Influence on Ocean Salinity and Circulation
      • Influence on Atmospheric Circulation and Climate
      • Ice Cover and Environmental Change
        • A Closer LOOK: AN ICE-FREE NORTHWEST PASSAGE?
          • FIGURE C9.1: The Northwest Passage
          • FIGURE C9.2: Early exploration of the Northwest Passage
    • END OF CHAPTER 9
      • SUMMARY
      • IMPORTANT TERMS TO REMEMBER
      • QUESTIONS FOR REVIEW
      • QUESTIONS FOR RESEARCH AND DISCUSSION
      • QUESTIONS FOR THE BASICS
      • QUESTIONS FOR A CLOSER LOOK
  • CHAPTER 10: The World OCEAN
    • Moonset over the Pacific The Moon sets over the Pacific Ocean at sunrise on Northern California’s Sonoma Coast. The San Andreas Fault runs through this section of coast.
    • OVERVIEW
    • OCEAN BASINS AND OCEAN WATER
      • Ocean Geography
        • Make the CONNECTION
        • FIGURE 10.1: The world ocean This shaded relief map of the ocean is based on high-resolution marine gravity data obtained by satellite altimetry and on ship depth soundings, and shows the major and minor basins of the world ocean.
      • Depth and Volume of the Ocean
        • FIGURE 10.2: Ocean and land The unequal distribution of land and ocean can be seen if we view Earth from above Britain and above New Zealand. In the first view, land covers nearly half the hemisphere, whereas in the other nearly 90 percent of the hemisphere is water.
      • Age and Origin of the Ocean
      • The Salty Sea
        • FIGURE 10.3: Principal ions in seawater More than 99.9 percent of the salinity of seawater is due to eight ions, the two most important of which (Na+ and Cl−) are the constituents of common salt.
        • The Origins of Ocean Salinity
        • Controls on Ocean Salinity
          • FIGURE 10.4: Ocean salinity High salinity values are found in tropical and subtropical water where evaporation exceeds precipitation. The highest salinity has been measured in enclosed seas like the Persian Gulf, the Red Sea, and the Mediterranean Sea. Salinity values (shown here in per mil, or ‰) generally decrease poleward, but low values also are found off the mouths of large rivers.
      • Temperature and Heat Capacity of Ocean Water
        • FIGURE 10.5: Sea-surface temperatures This map shows typical sea-surface temperatures (in °C) in the world ocean during August. The warmest temperatures (≥28°C) are found in the tropical Indian and Pacific oceans. Temperatures decrease poleward from this zone, reaching values close to freezing in the north and south polar seas.
      • Vertical Stratification of the Ocean
        • FIGURE 10.6: Depth zones in the ocean Below the surface zone there is a zone in which the ocean-water properties experience a significant change with increasing depth. This zone is variously known as the pycnocline (A), a zone in which density increases with depth; the thermocline (B), a zone in which temperature decreases with depth; and the halocline (C), a zone in which salinity increases with depth. Still lower lays the deep zone, where water is dense as a result of low temperature and high salinity.
      • Biotic Zones
      • Oceanic Sediment
        • FIGURE 10.7: Marine single-celled organisms These skeletons of calcareous foraminifera (smooth globular objects), siliceous radiolarians (delicate meshed objects), and siliceous rod-shaped sponge spicules from deep-sea ooze were photographed using a scanning electron microscope. The fossils are from a sediment core collected in the western Indian Ocean during a Deep Sea Drilling Project cruise.
        • FIGURE 10.8: Ocean sediment This map of the world ocean shows the generalized distribution of the principal kinds of sediment on the ocean floor.
    • OCEAN CIRCULATION
      • Factors That Drive Currents
      • Factors That Influence Current Direction
        • The Coriolis Force
      • Ekman Transport
        • the BASICS: The Coriolis Force
          • FIGURE B10.1: Coriolis force The Coriolis force results from the influence of angular momentum on the movement of bodies on the surface of a rotating planet. (A) A body at the pole rotates completely around every 24 hours, whereas a body on the equator goes end-over-end but does not rotate. The face on the tower at the pole rotates with respect to an external observer, whereas a tower on the equator always faces the same direction. This demonstrates that angular momentum is highest at the poles, decreasing to zero for objects at the equator. (B) On the rotating Earth, an object freely moving in the northern hemisphere (a, b) is deflected by the Coriolis force to the right, whereas in the southern hemisphere (c, d) it is deflected to the left. A moving object at the equator (e, f) is not deflected.
        • FIGURE 10.9: Ekman transport Wind blowing across the ocean in the northern hemisphere affects the surface water, which drags on the water immediately beneath, setting it in motion, and so on down the water column. Internal friction steadily reduces the wind’s effect and the current’s velocity with depth, and the Coriolis force begins to take over with depth, shifting each successively deeper layer farther to the right. The net result is an Ekman spiral. The average flow over the full depth of the spiral is called the Ekman transport, and is directed at 90° to the wind direction.
        • Make the CONNECTION
      • Surface Current Systems
        • FIGURE 10.10: Upwelling and downwelling Winds blowing parallel to a coast exert a drag on the surface water, forcing it away from (A) or toward the land (B), depending on wind direction. If the net Ekman transport is away from the land, rising deeper water replaces the surface water moving offshore, which produces upwelling. If the net Ekman transport is toward the shore, the surface water thickens and sinks, which produces downwelling.
        • FIGURE 10.11: Surface ocean currents Surface ocean currents form a distinctive pattern, curving to the right (clockwise) in the northern hemisphere and to the left (counterclockwise) in the southern hemisphere. The westward flow of warm, tropical water (the Equatorial currents) in the Atlantic, Pacific, and Indian oceans is interrupted by continents, which deflect the water poleward. The flow then turns away from the poles to define the middle-latitude margins of the five great midocean gyres: two in the Atlantic, two in the Pacific, and one in the Indian Ocean. Blue arrows show cold currents, and red arrows show warm currents.
      • From Surface to Depth and Back Again: Major Water Masses
        • FIGURE 10.12: Water masses and ocean circulation This transect along the western Atlantic Ocean shows the major water masses and general circulation pattern. North Atlantic Deep Water (NADW) originates near the surface in the North Atlantic where northward-flowing surface water cools, becomes increasingly saline, and plunges to depths of several kilometers. As NADW moves into the South Atlantic, it rises over denser Antarctic Bottom Water (AABW), which forms adjacent to the Antarctic continent and flows into the North Atlantic as Antarctic Intermediate Water (AAIW) at a mean depth of about 1 km.
        • FIGURE 10.13: North Atlantic Deep Water North Atlantic Deep Water (NADW) forms when the warm, salty water of the Gulf Stream/North Atlantic Current cools, becomes increasingly saline due to evaporation, and plunges downward to the ocean floor. The densest water then spills over the Greenland–Scotland ridge and flows southward as Lower NADW. Less dense water forming between Greenland and North America moves southeastward as Upper NADW and overrides denser Lower NADW. Because both water masses are less dense than northward-flowing Antarctic Bottom Water (AABW), they pass over it on their southward journey (as shown in a side view in Fig. 10.12).
      • The Global Ocean Conveyor System
        • FIGURE 10.14: The thermohaline circulation The major thermohaline circulation cells that make up the global ocean conveyor system are driven by the density of ocean water, which is in turn driven by the exchange of heat and moisture between the atmosphere and ocean. Warm water brought in by the Gulf Stream (a) cools and sinks at a number of sites in the North Atlantic (b). The North Atlantic Deep Water (NADW) spreads slowly along the ocean floor to the South Atlantic (c), eventually to enter both the Indian (d) and Pacific (e) oceans before slowly upwelling (f) and entering shallower parts of the thermohaline circulation cells. Meanwhile, Antarctic Bottom Water (AABW) forms adjacent to Antarctica (near c) and flows northward in fresher, colder circulation cells beneath warmer, more saline water in the South Atlantic (see Fig. 10.12) and South Pacific. Surface water warmed by solar energy flows into the western Pacific and Atlantic basins (g) to close the loop of the great global thermohaline cells.
    • OCEAN WAVES
      • FIGURE 10.15: The Gulf Stream current The Gulf Stream is the shallow, warm current by which the thermohaline convection returns water to the North Atlantic. This is a satellite image showing sea-surface temperatures, with the reds and oranges representing warm temperatures and blues and greens representing cool temperatures. The warm Gulf Stream current can be seen swirling from the Caribbean past the eastern coast of North America (at the left) and into the cooler water of the North Atlantic.
      • Wave Motion and Wave Base
        • the BASICS: Wave Terminology
          • FIGURE B10.2: Wave terminology Although different kinds of waves vary considerably in their properties and how they are generated, wave terminology is fundamentally the same whether it is used in reference to water waves, light waves, sound waves, or seismic waves.
          • FIGURE B10.3: Wave fronts When a set of waves is being propagated in the same direction (A), a plane passing through the crests of all advancing waves is called the wavefront. See if you can identify the locations of the wavefronts in this photograph of water waves (B).
      • Breaking Waves
        • FIGURE 10.16: Waves Water in a wave in deep water makes a looplike motion as the crest of the wave passes by. The dots mark the position of a particle of water as a wave passes through. Beneath the surface, where the influence of the wind is less, parcels of water travel in smaller loops.
        • FIGURE 10.17: Waves moving ashore Waves change form as they travel from deep water through shallow water to shore. The circular motion of the water parcels found in deep-water waves changes to elliptical motion as the bottom becomes shallower than the wave base (at a depth of L/2), and the wave begins to encounter frictional resistance from the bottom. Vertical scale is exaggerated, as is the size of loops relative to the scale of the waves.
        • FIGURE 10.18: Catching a wave A surfer catches a breaking wave off the coast of Oahu, Hawaii.
      • Wave Refraction and Longshore Currents
      • Tsunami: A Different Type of Wave
        • FIGURE 10.19: Breaking waves Waves arriving obliquely along a coast near Oceanside, California, change orientation as they encounter the bottom and begin to slow down. As a result, each wavefront is refracted so that it more closely parallels the bottom contours. The arriving waves develop a longshore current that moves from right to left in this view.
        • FIGURE 10.20: Longshore current A longshore current develops parallel to the shore as waves approach a beach at a right angle and are refracted. A line drawn perpendicular to the front of each approaching wave (a) can be resolved into two components. The component oriented perpendicular to the shore (b) produces surf, whereas the component oriented parallel to the shore (c) is responsible for the longshore current. Such a current can transport considerable amounts of sediment along a coast.
        • FIGURE 10.21: Tsunami A tsunami can form any time the ocean floor undergoes a sudden movement that has a significant vertical component (A), causing the overlying water to be displaced upward. (Horizontal displacement will not cause the overlying water to be shoved upward and therefore will not generate a tsunami.) (B) When the displaced volume of water falls back down, it splits into two components that move away from the site of wave generation in opposite directions.
    • OCEAN TIDES
      • Tide-Raising Force
      • Tidal Bulges
        • FIGURE 10.22: Tide-raising forces Tide-raising forces are produced by the Moon’s gravitational attraction and by inertial force. On the side of Earth that faces toward the Moon, gravitational attraction distorts the water level from that of a sphere and raises a tidal bulge. On the opposite side of Earth, a tidal bulge is created by inertia.
    • WHERE LAND AND OCEAN MEET
      • FIGURE 10.23: Tidal bulges When Earth, Moon, and Sun are aligned (positions 1 and 3), tides of highest amplitude are observed. When the Moon and Sun are pulling at right angles to each other (positions 2 and 4), tides of lowest amplitude are experienced.
      • Beaches and Other Coastal Deposits
        • FIGURE 10.24: Tidal range The tidal range in the Bay of Fundy, eastern Canada, is one of the largest in the world. (A) Coastal harbor of Alma, New Brunswick, at high tide. (B) Same view at low tide.
      • Marine Deltas
        • FIGURE 10.25: Beach A sandy beach along the shore of Bora Bora, a volcanic island in French Polynesia, consists of coral and shell debris carried landward by wave action and mixed with lava fragments from the eroding volcano.
        • FIGURE 10.26: Coastal landforms (A) The long, curved spit of Cape Cod, Massachusetts has been built by longshore currents that rework glacial deposits forming the peninsula southeast of Cape Cod Bay. (B) These barrier islands off Corpus Christi, Texas (along the south side of a large bay) are seen from an orbiting satellite. To the right is the Gulf of Mexico. Padre Island National Seashore occupies the barrier island extending south from Corpus Christi Bay.
      • Estuaries
        • FIGURE 10.27: Deltas The Mississippi River has built a series of overlapping deltas (A) as it has continually dumped sediment into the Gulf of Mexico. The ages of deltas are given in years before the present, determined by radiocarbon dating. Swirling clouds of sediment can be seen in the water of the current Mississippi Delta (Balize), in this satellite image (B).
      • Reefs
      • Coastal Erosion
        • FIGURE 10.28: Estuary This is a satellite image of the shrinking San Francisco Bay estuary. Filling and diking of tidal marshes to create farmland, evaporation ponds, and residential and industrial developments has reduced 2200 km2 of wetland marshes that existed before 1850 to less than 130 km2 today.
        • FIGURE 10.29: Island to atoll Evolution of an atoll from a subsiding volcanic island. (A) Rapid extrusion of lava builds a volcano that begins to subside as the oceanic crust is loaded by the growing volcanic pile. A fringing reef grows upward, keeping pace with subsidence. (B) As the volcano becomes inactive, subsidence continues and the fringing reef becomes a barrier reef, separated from the eroded volcano by a lagoon. (C) With continuing subsidence and upward reef growth, the last remnants of volcanic rock are submerged, leaving an atoll reef surrounding a central lagoon.
    • CHANGING SEA LEVELS
      • Submergence and Emergence
      • Sea Ice, Land Ice, and Sea Level
        • A Closer LOOK: WHEN THE MEDITERRANEAN DRIED UP
          • FIGURE C10.1: The Mediterranean Sea and the Strait of Gibraltar Water from the Atlantic Ocean flows through the Strait of Gibraltar into the Mediterranean Sea, returning to the ocean as a deep, dense, saline countercurrent.
          • FIGURE 10.30: Coastal submergence Coastal submergence of eastern North America and western Europe resulted when meltwater from wasting ice sheets returned to the ocean basins at the close of the last glaciation. (A) This is the area of northeastern North America covered by glacier ice during the last glacial maximum, the approximate position of the shoreline at the glacial maximum (18,000 years ago), and coastal areas submerged by the postglacial rise of sea level. (B) This is the area covered by ice sheets in western Europe at the last glacial maximum and by land areas that have been submerged during the postglacial rise of sea level.
          • FIGURE C10.2: Mediterranean evaporite deposits Evaporite deposits formed in three small basins during the Miocene Period when the Mediterranean repeatedly dried up and refilled.
      • The Ocean and Society
        • FIGURE 10.31: Ocean abundance The abundant yield of fish—currently more than 80 million tons per year—is just one of the many services provided to humankind by the world ocean.
    • END OF CHAPTER 10
      • SUMMARY
      • IMPORTANT TERMS TO REMEMBER
      • QUESTIONS FOR REVIEW
      • QUESTIONS FOR RESEARCH AND DISCUSSION
      • QUESTIONS FOR A CLOSER LOOK
      • QUESTIONS FOR THE BASICS
• PART FOUR: The Atmosphere: Earth’s Gaseous ENVELOPE
  • Above the clouds Earth’s atmosphere provides a thin but vitally important protective blanket. Water, seen here in the form of clouds, is an important atmospheric constituent.
  • CHAPTER 11: The Atmosphere
    • Earth’s atmosphere In this spectacular photograph, taken from the International Space Station as it orbited over the Pacific Ocean on July 21, 2003, you can clearly see the troposphere (the lower layer of the atmosphere) as a thin blue band above the curved horizon. Anvil-shaped clouds in the foreground are thunderstorms. Their unique shape is caused by the fact that warm air in the clouds cannot rise past the upper boundary of the troposphere.
    • OVERVIEW
    • THE HABITABLE PLANET
      • Past Atmospheres of Earth
      • Chemical Evolution of the Atmosphere
        • Make the CONNECTION
        • FIGURE 11.1: Titan, or Hadean Earth? This painting is an artist’s version of the surface of Saturn’s largest moon, Titan, with pools of hydrocarbons, an icy and rocky landscape, and a dense atmosphere that may be similar to the Hadean atmosphere of Earth.
        • Addition of Oxygen
          • FIGURE 11.2: Composition of Earth’s atmosphere over time The composition of Earth’s atmosphere has changed over time. Changes in the oxygen and carbon dioxide contents, in particular, were driven by photosynthesis and other life processes.
        • Removal of Carbon Dioxide
          • FIGURE 11.3: The atmosphere of Venus The atmosphere of Venus is thick and cloudy (A), giving the planet a bright, white appearance when viewed through a telescope. The CO2-rich composition causes a runaway greenhouse effect, with the result that the surface temperature is hot enough to melt lead, with clouds composed not of water but of sulfuric acid (B).
    • COMPOSITION AND STRUCTURE OF OUR ATMOSPHERE
      • FIGURE 11.4: Earth and sky Earth’s atmosphere is the interface between our planet and outer space. Atmospheric processes are closely linked to processes in the geosphere and biosphere. Here trees in the Swiss Alps can be seen poking through a low-lying cloud layer.
      • Composition
        • FIGURE 11.5: What air is made of Air contains two substances whose concentration varies from place to place and day to day: water vapor and aerosols. The rest of the atmosphere consists primarily of nitrogen and oxygen, with small amounts of other gases.
        • A Closer LOOK: AEROSOLS IN THE ATMOSPHERE
          • FIGURE C11.1: Aerosols (A) Aerosol particles are extremely fine—less than 1 micrometer in diameter by definition—and are thus too small to be seen by the eye. (B) Although we can’t discern the individual particles, we can see the results when billions of aerosol particles gather together to form fog, clouds, haze, smog, or smoke, as seen here in a photo of smoke from a forest fire in California in 1991. (C) This is a false-color electron micrograph of fly ash, a common type of solid aerosol particle. Fly ash comes from power plants and other sources of combustion. Individual spheres range in size from about 0.5 to 100 micrometers.
      • Temperature
        • FIGURE 11.6: How a greenhouse works The glass in a real greenhouse (A) and certain “greenhouse gases” in the troposphere (B) work in approximately the same way.
        • FIGURE 11.7: A shield against harmful radiation Ultraviolet radiation coming from the Sun can be harmful or lethal; generally speaking, the shorter the wavelength, the more harmful the radiation. Fortunately, the atmosphere protects us from almost all these rays because they are absorbed by three kinds of oxygen—O, O2, and O3 (ozone).
        • Temperature Versus Heat
        • Insolation
      • Temperature Profile of the Atmosphere
        • Troposphere
          • FIGURE 11.8: Temperature profile of the atmosphere Temperature varies with altitude in the atmosphere. In the lowest level, the troposphere, temperature drops rapidly with increasing altitude. In the next layer, the stratosphere, the reverse is true. Two more reversals occur in the mesosphere and the thermosphere. Upwards in the thermosphere the atmosphere becomes more and more tenuous, until it eventually merges into outer space in the exosphere.
          • FIGURE 11.9: Altitude of the tropopause The altitude of the tropopause varies with latitude. It is high from the equator to about 40° latitude, where it drops precipitously, continuing at this lower level and declining gently toward the poles. The precipitous drop at 40° latitude facilitates the development of jet streams.
          • the BASICS: Sunlight and the Atmosphere
            • TRANSMISSION AND WINDOWS
            • REFLECTION, REFRACTION, AND SCATTERING
              • FIGURE B11.1: Atmospheric windows and blinds Some wavelengths of electromagnetic radiation are transmitted easily through the atmosphere; there is an atmospheric window for those wavelengths of light. For example, there is an atmospheric window for light in the visible portion of the spectrum. Other wavelengths of electromagnetic radiation do not pass through the atmosphere because they are absorbed by atmospheric gases; there is an atmospheric window for those wavelengths of light. For example, ozone (along with some other gases) absorbs electromagnetic radiation in the ultraviolet part of the spectrum, creating an atmospheric blind.
              • FIGURE B11.2: Scattering Light coming from the Sun is scattered. Air molecules are so small that they scatter shorter blue wavelengths more easily then longer red wavelengths of light. The scattered blue light makes the sky appear blue in all directions. If there were no scattering by air molecules, the sky would appear pitch black and the stars would be visible all day.
              • FIGURE B11.3: Rainbow Rainbows result from complex refraction and reflection of light by water droplets in the atmosphere.
            • ABSORPTION AND BLINDS
        • Stratosphere
        • Mesosphere
        • Thermosphere
          • FIGURE 11.10: Aurora When protons flowing from the Sun hit the ionosphere, they create the beautiful electrical phenomenon known as an aurora. This aurora was seen in a far-northern latitude, and at the moment it was photographed a meteor flashed across the sky.
      • Air Pressure
        • Measuring Air Pressure
          • FIGURE 11.11: Mercury barometer This is a sketch of a simple mercury barometer. Air pressure on the surface of the open bowl of liquid mercury holds up the column of mercury inside the glass tube. The downward pressure exerted by the air exactly balances the downward pressure exerted by the column of mercury on the bowl. When the air pressure changes, the height of the column adjusts in response.
          • FIGURE 11.12: Measuring air pressure (A) Puy-en-Velay in France is where Pascal showed that air pressure decreases with altitude. Mountaineers carried a barometer up the Puy, an ancient volcanic neck, making air pressure measurements along the way. (B) Today, scientists send up radiosondes to make such measurements. The helium-filled balloon will burst in the upper atmosphere, allowing the scientific instruments to parachute back to the surface with their measurements.
        • Air Pressure Variation with Altitude
          • FIGURE 11.13: Change in air pressure with altitude Air pressure decreases smoothly with altitude. If a helium balloon 1 m in diameter is released at sea level, it expands as it floats upward because of the pressure decrease. If the balloon did not burst, it would be 6.7 m in diameter at a height of 40 km.
          • FIGURE 11.14: Air compressibility Air is compressible and behaves like a pile of springs. (A) The springs near the base are compressed by the weight of the springs above. (B) Air, like the springs, is compressed by the weight of the air above. Molecules of the gases nearest the ground are squeezed closer together than molecules higher up. Compression is also the explanation for the shape of the curve in Figure 11.13.
    • MOISTURE IN THE ATMOSPHERE
      • Relative Humidity
        • the BASICS: Changes of State
          • FIGURE B11.4: Change of state and latent heat Heat is either added to or released from a gram of H2O when it changes state.
        • FIGURE 11.15: Saturation pressure of water vapor This graph shows the variation in the saturation pressure of water vapor with temperature. The water shown in the small measuring cylinders is equivalent to the amount of H2O present, if the vapor in a kg of saturated air at sea level were condensed at each temperature. This demonstrates that the water content in a kg of air increases with increasing temperature.
        • Make the CONNECTION
      • Adiabatic Lapse Rate
        • FIGURE 11.16: Evaporation and water vapor in the atmosphere This map shows the annual addition of water vapor to the atmosphere as a function of geography. The amount evaporated per year is measured in millimeters of water. Areas of highest evaporation (blue) are over the ocean in equatorial and midlatitudes. Evaporation is low in the deserts (gold) because deserts have little water available for evaporation.
        • FIGURE 11.17: Adiabatic lapse rate As an unsaturated mass of air rises, it expands and cools at the dry adiabatic lapse rate (10°C/km). When the dry air temperature falls to the point where the air is saturated, condensation commences and latent heat is released. With further altitude increase, the air temperature decreases at the moist adiabatic lapse rate (6°C/km). Also shown is the change in volume of a mass of rising air that starts as a cube 1 km on an edge.
      • Cloud Formation
        • Lifting Forces
          • FIGURE 11.18: Lifting forces These are the main lifting forces that lead to cloud formation. Under most circumstances two or more lifting forces operate at the same time. (A) Density lifting causes a convection cell as warm, low-density air rises and cold, higher-density air sinks. (B) Frontal lifting and a warm front occur when flowing warm air overrides cold air and is forced upward. (C) Frontal lifting and a cold front occur when a wedge of forward-moving cold air slides under a warm air mass and forces it upward. (D) Orographic lifting occurs when flowing air is forced upward by mountains or other sloping ground. (E) Convergence lifting occurs when masses of air collide and are forced upward.
        • Condensation, Nucleation, and Precipitation
          • FIGURE 11.19: Raindrops Raindrops grow by coalescence of tiny cloud droplets. When the raindrops fall, they combine with other droplets in their path.
      • Cloud Types
        • FIGURE 11.20: Bergeron process Ice crystals grow by the Bergeron process, in which supercooled water droplets in clouds evaporate and ice crystals grow by incorporating the newly formed water vapor.
        • FIGURE 11.21: Cloud types and altitudes This drawing shows the various types of clouds, their shapes, and the altitudes at which they characteristically occur.
        • FIGURE 11.22: Clouds These are several of the principal types of clouds: (A) cumulus; (B) stratocumulus; (C) cumulonimbus; (D) stratus; (E) nimbostratus; (F) cirrus.
    • THE ATMOSPHERE IN THE EARTH SYSTEM
      • The Atmosphere and the Life Zone
      • Recent Atmospheric Changes
    • END OF CHAPTER 11
      • SUMMARY
      • IMPORTANT TERMS TO REMEMBER
      • QUESTIONS FOR REVIEW
      • QUESTIONS FOR RESEARCH AND DISCUSSION
      • QUESTIONS FOR THE BASICS
      • QUESTIONS FOR A CLOSER LOOK
  • CHAPTER 12: Wind and Weather SYSTEMS
    • Quenching rain Severe weather affects our lives in a variety of ways. Here, an approaching thunderstorm offers hope for a parched landscape at Lake Thunderbird, Oklahoma, during a severe drought in 2006.
    • OVERVIEW
    • Make the CONNECTION
    • WHY AIR MOVES
      • Wind Speed
        • FIGURE 12.1: Wind High-speed winds can be devastating, as shown here in a photo of damage caused by Hurricane Andrew in Florida, 1992.
        • the BASICS: Windchill Factor
          • FIGURE B12.1: Windchill Adjacent to any solid body, such as a human arm, there is a thin layer of air that is held stationary by friction. Away from the body, wind speed, indicated by the length of the arrows, increases as the effect of frictions weakens with distance. Higher wind speeds cause the thickness of the boundary layer to decrease. This lessens its insulating effect and allows the body to lose heat to the atmosphere more easily.
      • Factors Affecting Wind Speed and Direction
        • Pressure-Gradient Force
          • FIGURE 12.2: Isobars This is a typical air pressure map of the United States and part of Canada. The blue lines are isobars, lines of equal air pressure, and the numbers are air pressure in kPa. (Weather maps often report air pressure in millibars; to convert kPa to mb, multiply by 10.)
          • FIGURE 12.3: Wind and pressure gradients (A) Widely spaced isobars indicate a slow pressure drop over a long distance and thus a low-pressure gradient; low-speed winds will result. Closely spaced isobars indicate a steep pressure gradient; high-speed winds will result. (B) Symbols like these are used to portray wind direction and speed on weather maps. The orientation of the stem indicates the direction, and the barbs indicate speed. If more than one barb is on the stem, add them together to get the wind speed.
        • Coriolis Force
        • Friction
      • Geostrophic Winds
        • FIGURE 12.4: Geostrophic wind (A) A parcel of air is subjected to a pressure-gradient force and a Coriolis force; the resultant vector determines the direction of movement of the air. (B) The parcel of air moves in response to a pressure gradient. At the same time, it is turned progressively sideways until the pressure-gradient force and the Coriolis force balance, producing a geostrophic wind, whose flow is parallel to the isobars.
        • FIGURE 12.5: High-altitude geostrophic winds This map of North America shows upper-atmosphere wind flow. The lines (shown here in millibars, mb) represent the air pressure contours at a height above sea level of 5.5 km. Note that the winds are nearly all parallel to the isobars and therefore are geostrophic. This is based on a map compiled by the National Weather Service.
      • Convergent and Divergent Flow
        • FIGURE 12.6: Convergence and divergence Air spirals into a low and out from a high. Lows are centers of convergence, while highs are centers of divergence. In both lows and highs the flow direction is oblique to the isobars because of friction.
        • FIGURE 12.7: Low-pressure convergence This low-pressure center (a cyclonic system) is centered over Ireland and moving eastward over Europe. The counterclockwise winds characteristic of a Northern Hemisphere low are clearly shown by the spiral cloud pattern.
    • GLOBAL AIR CIRCULATION
      • FIGURE 12.8: Cyclone and anticyclone (A) Convergence in a cyclone causes a rising updraft of air and with it clouds and probably precipitation. (B) Divergence in an anticyclone draws in dry, high-altitude air, creating a downdraft; clear skies and fair weather are the result.
      • FIGURE 12.9: Columbus and the trade winds This map shows the winds used by Columbus on his first voyage to America. Outward bound after visiting the Canary Islands from August 12 to September 8, 1492, he sailed west with the northeast trades behind him. On his return voyage, Columbus sailed north to pick up the prevailing westerlies that had prevented previous European mariners from sailing any further west than the Azores.
      • the BASICS: Air Masses
        • TABLE B12.1: Characteristics of Air Masses
        • FIGURE B12.2: Air masses This map shows the sources of the major air masses that typically control the weather in North America.
      • Hadley Cells and the ITCZ
        • FIGURE 12.10: Global circulation on a nonrotating Earth On a nonrotating Earth, huge convection cells would transfer heat from the equatorial regions, where the solar energy per unit area is greatest, to the poles, where the solar input is least. The equatorial region would be a zone of low pressure, and the poles would be high-pressure zones.
        • FIGURE 12.11: Global atmospheric circulation Earth rotates, with the result that the flow of air toward the poles and the return flow toward the equator are constantly deflected sideways. This results in three major sets of circulating air masses: Hadley cells, Ferrel cells, and polar cells. The cells shift somewhat in location, but they are permanent features of Earth’s atmosphere and therefore have a great influence on both day-to-day weather and long-term climate.
        • FIGURE 12.12: Trade winds and the ITCZ (A) The Intertropical Convergence Zone, where the trade winds of the northern and southern hemispheres merge, shows up very clearly in this satellite photograph. Warm, rising air near the equator causes ocean water to evaporate and form a nearly perpetual band of storm clouds. (B) The continual blowing of the east-to-west trade winds has caused this tree, near the southern tip of Hawaii, to lean far to one side.
      • Ferrel Cells
      • Polar Fronts and Jet Streams
        • FIGURE 12.13: Jet stream The jet stream is a high-speed westerly geostrophic wind that occurs at the top of the troposphere over the polar front, where a steep pressure gradient exists between cold polar air and warm subtropical air. At this location, the altitude of the tropopause declines precipitously.
    • REGIONAL WIND AND WEATHER SYSTEMS
      • Monsoons
        • FIGURE 12.14: Rossby waves Rossby waves distort the polar-front jet stream. (A) The axis of the jet stream starts out flowing to the east in a nearly straight line. Undulations grow into gigantic meanders that pull masses of cold polar air toward the south (B, C).
        • FIGURE 12.15: Monsoon A monsoon is a regional weather system characterized by seasonally reversing winds. (A) During the winter when the Sun is overhead in the southern hemisphere, winds flow offshore from the northeast toward the intertropical convergence zone. Note how the winds curve toward the east as they cross the equator. (B) During the summer, the land heats up and winds flow from the southwest across Asia. When the Sun is overhead on land, the intertropical convergence zone moves farther to the north; in Asia, it becomes less pronounced and is not a distinct band of low pressure.
        • Make the CONNECTION
      • El Niño and the Southern Oscillation
        • FIGURE 12.16: El Niño sea-surface temperatures These maps show sea-surface temperatures, as determined from satellite data, with the warmest water temperatures shown in red and the coolest shown in blue. During a normal year, cold water from Antarctica wells up alongside the western coast of equatorial South America. During an El Niño event (left), the easterly trade winds fail to push warm surface waters away from South America, with the result that a tongue of warm water builds up in the eastern equatorial Pacific Ocean. The opposite phase, called La Niña (right), is characterized by cold ocean temperatures across the equatorial Pacific.
        • A Coupled Atmosphere-Ocean Phenomenon
          • FIGURE 12.17: Walker circulation and El Niño In a normal year (A), the air pressure difference between the eastern and western Pacific causes the trade winds to blow to the west across the tropical Pacific, pushing the warm water away from the coast of South America. This allows cold water from Antarctica to well up in the eastern Pacific. In the western Pacific, the warm water causes the moist air to rise and cool, bringing abundant rainfall in Indonesia. The drier, cooler air returns at high altitude to the eastern Pacific, in the Walker circulation. (B) During an El Niño year, the trade winds slacken or even reverse, and warm water accumulates in the eastern and central Pacific. A strong El Niño is disruptive to weather over much of the planet.
          • FIGURE 12.18: Past El Niño events (A) This record of more than a half-century of El Niño events (1950–2010) shows the irregular frequency and magnitude of the events. Plotted on the vertical axis is the Multivariate ENSO Index, or MEI, which includes measures of sea-level pressure, surface winds, sea-surface temperature, surface air temperature, and total cloudiness. The zero line is a “normal” year, red represents El Niño, the warm phase of the cycle, and blue represents La Niña, the cold phase. The strongest El Niños on record were those of 1982–1983 and 1997–1998. (B) A slice through a coral from the Galápagos Islands shows annual layering (alternating light and dark bands). This layering preserves a record of changing surface water conditions, and therefore of sea-surface temperature and El Niño events.
        • Understanding ENSO
    • LOCAL WIND AND WEATHER SYSTEMS
      • Coupled Local Wind Systems
      • Katabatic and Chinook Winds
        • FIGURE 12.19: Land and sea breezes (A) During the day, the land heats up more rapidly than does the sea. Air rises over the land, creating a low-pressure area. Cooler air flows in to this area from the sea, creating a sea breeze. (B) During the night, the land cools more rapidly than the sea, and the reverse flow, a land breeze, occurs.
    • SEVERE WEATHER
      • Cyclones
        • FIGURE 12.20: Rotation in a northern hemisphere cyclone This is a map view showing how the Coriolis force and the pressure-gradient force combine to cause cyclonic wind systems to rotate in a counterclockwise direction in the northern hemisphere. The black arrows show the wind directions. The blue arrows are the pressure-gradient force, which tends to make the wind blow in toward the low-pressure center. The red arrows represent the Coriolis deflection, toward the right. The combination yields a counterclockwise-rotating wind—a cyclone.
        • Types of Cyclones
          • FIGURE 12.21: Midlatitude wave cyclone Wave cyclones are extratropical synoptic weather systems that form as a result of the interaction of cold, polar air and warm, tropical air along the polar front. In this infrared image, collected by instruments on the GOES-7 satellite, shows a developing midlatitude cyclone off the eastern coast of North America.
        • Tropical Cyclones
          • FIGURE 12.22: Tropical cyclones (A) Hurricane Katrina slammed into the Gulf coast of Louisiana in August of 2005. Unusually warm sea-surface temperatures in the Gulf of Mexico that summer may have contributed to the very active hurricane season. (B) Cyclones and hurricanes form in places where the right conditions of ocean-water temperature and the Coriolis effect occur. Arrows show the usual directions followed by hurricanes once they form. In the Atlantic Ocean, hurricanes typically originate as tropical depressions off the coast of Africa. The path followed by Hurricane Katrina is shown in blue.
      • Thunderstorms and Tornadoes
        • Thunderstorms
          • FIGURE 12.23: Thunderstorms (A) A thunderstorm over Tucson, Arizona shows the classic dark, anvil-shaped cumulonimbus clouds, dense, rain, and lightning. (B) Lightning strikes farm fields in Oklahoma during a severe thunderstorm.
        • Tornadoes
          • FIGURE 12.24: Tornado A classic funnel-shaped tornado crosses the plains of Nebraska in 2003.
      • Drought and Dust Storms
        • TABLE 12.1: Enhanced Fujita Scale for Tornado Intensity
        • Drylands and Atmospheric Circulation
          • FIGURE 12.25: Deserts and atmospheric circulation This map shows the distribution of arid and semiarid climates and the major deserts associated with them. Many of the world’s great deserts are located where belts of dry air descend near the 30° N and 30° S latitudes. Notice also that regions of cold, descending air also surround both of the poles. Despite being covered by ice, the polar regions receive little precipitation and are considered to be frozen deserts.
          • FIGURE 12.26: Deserts (A) The Sahara is the greatest of the world’s subtropical deserts. Here, a camel caravan crosses the desert in Libya. (B) Mongolian nomads transport their belongings through the Altai Mountains, which border on the Gobi desert. This is a typical inland continental desert, which receives little rain because it is so far from the ocean. (C) Rainshadow deserts form when a mountain range creates a barrier to the flow of moist air, causing a zone of low precipitation to form on the downwind side of the range. Death Valley, seen here, lies just east of the Sierra Nevada Mountains. (D) Baja, California, the long, narrow peninsula in Mexico just south of its border with the western United States, consists mostly of coastal desert. Coastal deserts occur locally along the western margins of continents, where cold, upwelling seawater cools and stabilizes maritime air flowing onshore, decreasing its ability to form precipitation. (E) Even cold regions like this landscape in Greenland are technically deserts, because annual precipitation is extremely low.
          • TABLE 12.2: Main Types of Deserts and Their Origins
        • Drought
        • Dust Storms
          • FIGURE 12.27: Desertification In the Sahel region of Niger, a herd of goats grazes on pasture at the edge of the desert. As the goats consume the remaining grass and bushes, the dunes of the desert will likely advance.
          • FIGURE 12.28: Dust storms (A) Particles of fine sand and silt at the ground lie within the boundary layer where wind speed is extremely low. As a result, it is difficult for the wind to dislodge and erode these grains. Turbulent air picks up the finest grains of sediment and carries it as a suspended load. (B) During major dust storms, like this one in Gao, Mali, visibility is greatly reduced.
    • WEATHER AND THE EARTH SYSTEM
      • FIGURE 12.29: Feedbacks in the climate system Earth’s weather and climate are affected by innumerable interconnected feedbacks, only a few of which are illustrated here. Human actions play a major role in these feedbacks. For example, as shown on the diagram, human laws, policies, institutions, technologies, and economic systems affect the composition of the atmosphere. This, in turn, affects weather and climate, which in turn affects ecological systems.
      • Feedbacks
      • Thresholds
        • A Closer LOOK: THE BUTTERFLY EFFECT: CHAOS THEORY AND WEATHER FORECASTING
          • FIGURE C12.1: Sensitivity to initial conditions The small squares indicate four different starting conditions for a complex process that is sensitively dependent on initial conditions. The starting conditions differ from one another by just a tiny bit, but because of the sensitivity this results in four very different outcomes (the black dots).
    • END OF CHAPTER 12
      • SUMMARY
      • IMPORTANT TERMS TO REMEMBER
      • QUESTIONS FOR REVIEW
      • QUESTIONS FOR RESEARCH AND DISCUSSION
      • QUESTIONS FOR THE BASICS
      • QUESTIONS FOR A CLOSER LOOK
  • CHAPTER 13: The Climate SYSTEM
    • Climate proxy Each ring in this cut section of a cedar trunk represents one growth season. The rings vary in thickness and density, depending on the conditions in which the tree grew during that season. Natural archives like tree rings can provide valuable “proxy” information about climates of long ago.
    • OVERVIEW
    • EARTH’S CLIMATE SYSTEM
      • FIGURE 13.1: Earth’s climate system Earth’s climate system has five major interacting components: the geosphere (including land relief); the atmosphere (including the role of gases and particulates); the hydrosphere (especially ocean basins and circulation); the cryosphere (including the reflectivity of the polar ice caps); and the biosphere (including vegetation, soils, and photosynthesis). The anthroposphere—human activities—has become a recent contributor to the climate system.
    • EVIDENCE OF CLIMATIC CHANGE
      • Historical Records of Climate
        • FIGURE 13.2: Variations of Earth’s surface temperature This graph, from the National Climatic Data Centre of NOAA’s National Environmental Satellite, Data, and Information Service, shows global mean surface temperature anomalies from 1880 to 2010. A temperature anomaly is a departure from a long-term average – in this case, the average surface temperature for the 20th century. A positive anomaly indicates that the observed temperature was warmer than the reference temperature, whereas a negative anomaly indicates that the observed temperature was cooler than the reference value.
        • the BASICS: Köppen System of Climate Classification
          • THE MAJOR CLIMATE CATEGORIES
            • FIGURE B13.1: Köppen climate classification This world map shows the locations of some of the major climatic zones as classified by the Köppen system.
            • A. EQUATORIAL CLIMATES
            • B. DRY CLIMATES
            • C. WARM TEMPERATE CLIMATES
            • D. CONTINENTAL CLIMATES
            • E. POLAR CLIMATES
            • H. HIGHLAND CLIMATES
          • TEMPERATURE, PRECIPITATION, AND SEASONALITY MODIFIERS
        • FIGURE 13.3: Retreating glacier Many alpine glaciers are currently in retreat as a result of a general warming of the climate. In the late nineteenth century, Findelen Glacier in the Swiss Alps covered all the bare, rocky terrain seen here. Since that time the glacier’s terminus has retreated far up the valley.
        • Make the CONNECTION
      • The Geologic Record of Climatic Change
        • FIGURE 13.4: Tropical fossils in the Arctic The discovery of tropical organisms in areas that are now subarctic is a strong indication that global climates have changed. This 125-million-year-old fossilized turtle shell was found in northern British Columbia, Canada.
      • Climate Proxy Records
        • Human Records of Climate Proxies
          • FIGURE 13.5: Human records of climate proxies Some human records of climate proxies span more than 1000 years. (A) The frequency of major dust-fall events in China is an indication of a cold, dusty atmosphere. (Source: After Zhang, 2982) (B) The severity of winters in England is based on the number of mild or severe months experienced. (Source: After Lamb, 1977) (C) The number of weeks per year during which sea ice reached the coast of Iceland is a record that has been kept by fishers for almost 1000 years. (Source: After Lamb, 1977) (D) The freezing date of Lake Suwa in Japan is represented here as being early or late relative to the long-term average date. (Source: After Lamb, 1966)
        • Ice Cores and Isotopic Studies
          • FIGURE 13.6: Reconstructing temperature records from climate proxies (A) Chemical analysis of ice cores taken from glaciers and ice caps can provide a record of temperature at the time the ice was formed. (B) Glacier ice forms from snow, which is deposited in annual layers, as seen here in glacier ice from Glacier Bay National Park, Alaska. (C) Direct measurements of the temperature in the northern hemisphere from the middle of the nineteenth century onward are shown by the black curve. The other curves are based on indirect reconstructions of temperature from tree rings (green), glacier lengths (dark blue), and ice cores (light blue). The remaining curves (yellow, red, and purple) were reconstructed using a combination of different proxy data sources. All curves show that temperatures during the last few decades of the twentieth century were higher than during any comparable period in the last thousand years.
          • FIGURE 13.7: Growth rings as climate proxies The growth of some corals produces structures similar to the annual rings of trees. Analyzing the chemical composition of the coral can provide a temperature record. Black lines drawn on the lower section mark years, and red and blue lines mark quarters.
        • Annual Growth Rings
        • Sedimentary Evidence
          • FIGURE 13.8: Varves: seasonal layering in lake sediment These varves are seasonal layers deposited in a glacial-age lake near Seattle, Washington. Each pair of layers in a sequence of varves represents an annual deposit.
        • Fossil Pollen Studies
          • FIGURE 13.9: Deep-sea microfossils as climate proxies Seafloor sediment obtained by drilling contains fossils of tiny sea creatures, foraminifera, which once lived in surface waters. These microfossils contain abundant information about the chemistry and temperature of the ocean. Foraminifera have calcium carbonate shells that contain oxygen. The ratio of oxygen-16 (the lighter isotope of oxygen) to oxygen-18 is a measure of the temperature of the seawater in which the microscopic creatures lived.
          • A Closer LOOK: USING ISOTOPES TO MEASURE PAST CLIMATES
            • ISOTOPIC FRACTIONATION
              • FIGURE C13.1: Temperature reconstruction from ice-core data (A) Ice-core data from Antarctica shows a reconstruction of temperature, in terms of the difference (Δ) from present-day temperature, going back 420,000 years. This temperature reconstruction is based on analysis of oxygen isotopes from the ice. (B) The temperature reconstruction shown here, also from Antarctica, is based on Deuterium isotopic analyses and extends to 740,000 years before the present.
            • ISOTOPES AND GLOBAL CLIMATE
              • FIGURE C13.2: Temperature reconstruction from deep-sea sediment data (A) This curve of average oxygen-isotope variations during the last 2 million years is based on analyses of deep-sea sediment cores. The curve illustrates changing global ice volume during successive glacial-interglacial cycles. (B) This record of surface ocean temperatures is based on oxygen-isotope ratios measured in a sediment core from the western Pacific Ocean. Relatively warm surface waters cooled abruptly about 35 million years ago, reflecting a dramatic change that led to the buildup of glaciers in Antarctica. With further cooling, an ice sheet developed over Antarctica, and by 2.5 million years ago, northern hemisphere ice sheets had formed.
          • FIGURE 13.10: Pollen grains as climate proxies Fossil pollen can be used to reconstruct past vegetation and climate. (A) This is a scanning electron microscope photograph of a grain of Drymis winterii pollen, diameter 42 micrometers. Its waxy coating protects it from degradation. (B) Windborne pollen grains from trees and shrubs fall into a nearby pond, where they are incorporated as part of the accumulating sediment. (C) This simplified diagram, based on data collected from Rogers Lake, Connecticut, shows variation in pollen counts as a function of time. A major change in forest composition occurred about 10,000 years ago at the end of the last glaciation, when the spruce/pine forest was replaced by a forest dominated by deciduous trees, mainly oak.
    • EARTH’S PAST CLIMATES
      • FIGURE 13.11: Past climatic change These graphs show an estimate of global temperatures, based on deep-ocean sediments, over (A) the last 60 million years ago to present. At the beginning of the Cenozoic Era, Earth’s surface was largely free of ice. Sea levels were higher and seawater could circulate freely, (B) As plate motions moved the major landmasses near their present locations, temperatures fell and glaciers appeared at the poles. In the last 800,000 years (the blue band in the temperature graph), the climate has fluctuated eight times between ice ages and warm interglacial periods. (C) At the peak of the last ice age, glaciers blanketed most of North America. Earth is now warmer than it has been at any time in the last 100,000 years, and roughly at the same temperature as it was in the last interglacial period 120,000 years ago.
      • Climate of the Last Millennium
      • The Last Glaciation
        • Temperature
          • FIGURE 13.12: Wheat price as a climate proxy Fluctuations in the price of wheat in western Europe from the thirteenth to the nineteenth century, expressed in Dutch guilders, track the course of climate change. Intervals of cool, wet climate were unfavorable for wheat production, causing the price to rise. The two largest peaks, in the early seventeenth and early nineteenth centuries, coincide with the greatest advances of glaciers in the Alps during the Little Ice Age.
        • Ice Extent
          • FIGURE 13.13: North America during the last glaciation This map shows some aspects of the geography of North America about 20,000 years ago, during the last glaciation. Coastlines lie farther seaward, owing to a fall in sea level of about 120 m. Sea-surface temperatures are based on analysis of microfossils in deep-sea cores. Circled numbers show the estimated temperature lowering, relative to present temperatures, at selected sites, based on climate-proxy evidence.
        • The Dusty Ice-Age Atmosphere
          • FIGURE 13.14: Snowline altitude A transect along the coastal mountains of western North America shows the relationship of the present snowline to existing glaciers (blue) and of the ice age snowline to expanded glaciers during the last glaciation (light blue). The difference between present and ice-age snowlines was about 900 to 1000 m along the southern part of the transect and about 600 m in northern Alaska. The depression in altitude of the snowline gives an indication of the lowering of temperature during the glacial period. The change in slope of the two snowlines at about 55° latitude occurs where the transect passes inland across the Alaska Range and then northward across the Brooks Range to the Arctic Ocean.
        • Water Levels and Precipitation
        • Vegetation
          • FIGURE 13.15: Glacial Lake Bonneville Horizontal beaches at several levels above the surface of Great Salt Lake, Utah, mark shorelines of Lake Bonneville, a vast Pleistocene lake. At its maximum extent and depth during the last glaciation, the surface of Lake Bonneville stood more than 300 m above that of the present lake.
          • FIGURE 13.16: Changing forests These maps, based on fossil pollen data, show the changing distribution of spruce, hemlock, and elm trees in North America at 6000-year intervals between 18,000 years ago and the present day. The color intensities indicate the relative abundance for each species, with the darkest shade of green being the highest and the lightest shade the lowest.
      • Pleistocene and Older Glacial Ages
        • The Glacial Epoch
          • FIGURE 13.17: Present and past ocean temperatures (A) This map shows the modern August sea-surface temperatures (in °C). (B) The other map is a reconstruction, showing the August sea-surface temperatures during the last glaciation, about 18,000 years ago. Cold polar water extended far south of its present limit in the North Atlantic, and plumes of cool water extended westward from South America in the equatorial Pacific and from Africa in the Atlantic.
        • Ancient Glaciations
        • The Warm Middle Cretaceous
          • FIGURE 13.18: The warm Middle Cretaceous (A) During the Middle Cretaceous Period, sea level was 100 to 200 m higher than now, and ocean waters flooded large areas of the continents, producing shallow seas. Warm-water animal assemblages (labeled “W”) and evaporite deposits (labeled “E”) were present at low to middle latitudes. Coal deposits (labeled “C”) developed from tropical swamps in northern latitudes, implying warm year-round temperatures. (B) This reconstruction shows changing atmospheric carbon dioxide levels and average global temperature over the past 100 million years. High CO2 values and high temperatures in the Middle Cretaceous contrast with much lower modern values. Other intervals of higher temature and CO2 occurred during the Eocene and Middle Pliocene Epochs.
    • WHY CLIMATES CHANGE
      • External Causes of Climatic Change
        • Solar Variation
        • Milankovitch Cycles
          • FIGURE 13.19: Milankovitch cycles The geometry of Earth’s orbit and axial tilt influence insolation, which in turn influences climate and glacial cycles. (A) Earth wobbles on its axis like a spinning top, making one revolution every 26,000 years; this is called precession. The axis of Earth’s elliptical orbit also rotates, though more slowly, in the opposite direction. These motions together cause a progressive shift, or precession, of the spring and autumn equinoxes, with each cycle lasting about 23,000 years. (B) The tilt of Earth’s axis, which now is about 23.5°, varies from 21.5° to 24.5°. Each cycle lasts about 41,000 years. Increasing the tilt means a greater difference, for each hemisphere, between the amount of solar radiation received in summer and that received in winter. (C) The shape of Earth’s orbit is an ellipse with the Sun at one focus. Over 100,000 years, the shape of the orbit changes from almost circular (low eccentricity) to more elliptical (high eccentricity). The higher the eccentricity, the greater the seasonal variation in radiation received at any point on Earth’s surface.
      • Internal Causes of Climatic Change
        • Atmospheric Filtering
          • FIGURE 13.20: Orbital influences on glacial cycles These curves show variations in eccentricity, tilt, and precession during the last 800,000 years. Summing these factors produces a combined signal that shows the amount of radiation received on Earth at a given latitude, through time (the curve labeled “Combined signal”). The magnitude and frequency of oscillations in the combined orbital signal closely matches those of the marine oxygen isotope curve, which is a temperature proxy (at right). This supports the idea that Earth’s orbital changes influence the timing of the glacial-interglacial cycles.
          • FIGURE 13.21: Atmospheric carbon dioxide and methane over time These curves show changes in atmospheric carbon dioxide and methane (based on chemical analysis of trapped air samples) compared to changes in temperature (based on oxygen–isotope values from ice) in samples from deep ice cores drilled at Vostok Station, Antarctica. Concentrations of the greenhouse gases were high during the early part of the last interglaciation, just as they are during the present interglaciation, but they were lower during glacial times. The curves are consistent with the hypothesis that the atmospheric concentration of these gases contributed to warm interglacial climates and cold glacial climates. This remarkable record goes back 420,000 years.
        • Changes in Albedo
        • Volcanic CO2
        • Shifting Continents
          • FIGURE 13.22: Volcanoes and climate Major volcanic eruptions can cause global cooling. (A) The fissure eruption of Laki, a volcano in Iceland, lasted from 1783 to 1784 and was the largest flow of lava in recorded history. (B) In the winter after Laki’s eruption, the average temperature in the northern hemisphere was about 1°C below normal. In the eastern United States, the decrease was closer to 2.5°C. At the same time, ice cores from Greenland record a dramatic spike in acidity, due to acid precipitation caused by the volcanic emissions reacting with water vapor in the atmosphere. (C) Mount Pinatubo, a stratovolcano in the Philippines, erupted violently in June, 1991, producing a sulfur-rich aerosol haze that encircled the globe. The color scale in this diagram shows atmospheric sulfur dioxide in ppb, as measured in the upper atmosphere by the Microwave Limb Sounder (MLS) in September, 1991. The warmer colors indicate higher levels of sulfur dioxide. (D) Sulfate aerosols from the eruption of Pinatubo caused a global decrease in temperature of about 0.4°C, and more in the northern hemisphere.
          • FIGURE 13.23: Pangaea and Panthalassa (A) Around 225 million years ago the continents were still gathered together in one supercontinent, Pangaea, with vast areas of land located far from the temperature-moderating influence and moisture source of the global ocean, Panthalassa. (B) Early in the Cretaceous Period, however, Pangaea began to split apart, which would have brought much more land in closer contact with the ocean, leading to warmer temperatures, higher precipitation, and lesser extremes in temperature.
        • Changes in Ocean Circulation
          • FIGURE 13.24: The Younger Dryas event (A) Under full-glacial conditions, plants that are currently limited to polar and high-altitude regions could move into forests in northwestern Europe. Among these plants is Dryas octopetala, shown here. A large amount of Dryas pollen was found in deposits dating to the cold period now known as the Younger Dryas event. (B) Measurements of oxygen isotopes in sediment taken from a Swiss lake (left) and an ice core from the Greenland Ice Sheet (right) show that both the onset and the end of the Younger Dryas event were rapid. At the end of the event, the climate over Greenland warmed by about 7°C in only 40 years.
          • FIGURE 13.25: The Younger Dryas and Heinrich events (1) As the ice sheet over eastern North America retreated, vast meltwater lakes holding icy water were created. At the same time, the ocean conveyor belt was at work in the North Atlantic. Wind-driven warm surface currents, such as the Gulf Stream, headed toward the poles, cooling and eventually sinking at high latitudes., having transferred energy around the globe. (2) As the ice shrank further, it uncovered a natural drainageway between the meltwater lakes and the North Atlantic. The meltwater flooded rapidly into the ocean, forming a freshwater lid over the denser salty seawater. The cold surface meltwater in turn reduced the salinity of the water and the rate of evaporation from the ocean surface, shutting down the normal pattern of ocean thermohaline circulation. (3) Without the thermohaline circulation system, air passing over the cold North Atlantic brought colder conditions to northwestern Europe that led to the growth of glaciers and a major change in vegetation.
          • Make the CONNECTION
    • FEEDBACKS AND COMPLEXITY IN EARTH’S CLIMATE SYSTEM
      • Feedbacks
      • Feedbacks in Carbon Cycling
        • Negative Feedbacks in the Carbon Cycle
        • Positive Feedbacks in the Carbon Cycle
      • Anthropogenic Causes of Climate Change
    • END OF CHAPTER 13
      • SUMMARY
      • IMPORTANT TERMS TO REMEMBER
      • QUESTIONS FOR REVIEW
      • QUESTIONS FOR RESEARCH AND DISCUSSION
      • QUESTIONS FOR THE BASICS
      • QUESTIONS FOR A CLOSER LOOK
• PART FIVE: The Biosphere: LIFE on EARTH
  • Insect world
  • CHAPTER 14: Life, Death, and EVOLUTION
    • Life is persistent
    • OVERVIEW
    • WHAT IS LIFE? AN OVERVIEW OF BASIC BIOLOGICAL PROCESSES
      • The Necessities of Life
        • Metabolism
          • FIGURE 14.1: Life on Mars?
          • Autotrophs.
          • Heterotrophs.
        • Reproduction
        • Growth
        • Evolution
          • FIGURE 14.2: Reproduction
          • the BASICS: DNA and RNA
            • FIGURE B14.1: DNA and RNA
          • FIGURE 14.3: Defining species
      • The Hierarchy of Life
        • The Cell as a Structural Unit of Life
          • Prokaryotes and Eukaryotes.
            • FIGURE 14.4: Cells: Building blocks of life
        • From the Cell to the Biosphere
          • FIGURE 14.5: Hierarchical structure of life
        • The Kingdoms of Life
          • FIGURE 14.6: Kingdoms of life
    • LIFE: A PLANETARY PERSPECTIVE
      • The Ecosphere and the Life Zone
        • the BASICS: The Linnaean System of Taxonomic Classification
          • FIGURE B14.2: Linnaean System
      • Early Earth and the Origin of Life
        • The Environment of Early Earth
          • FIGURE 14.7: History of life on Earth
          • FIGURE 14.8: Early Earth
        • The Origin of Life
          • FIGURE 14.9: Ancient fossils
          • A Closer LOOK: HYPOTHESES ON THE ORIGIN OF LIFE
            • “PRIMORDIAL SOUP” HYPOTHESIS
            • “BLACK SMOKER” HYPOTHESIS
            • “PANSPERMIA” HYPOTHESIS
              • FIGURE C14.1: Birthplace of life?
        • The Influence of Life on Earth Systems
          • Oxygen Buildup.
          • Carbon Sequestration and Other Effects.
            • Make the CONNECTION
            • FIGURE 14.10: The changing Earth
        • The Gaia Hypothesis
          • Make the CONNECTION
    • EVOLUTION: THE HISTORY OF LIFE
      • The Mechanisms of Evolution
        • FIGURE 14.11: Natural selection by adaptation
        • FIGURE 14.12: Genetic drift
      • Early Life Forms
        • FIGURE 14.13: Stromatolites
        • Prokaryote World
        • The Emergence of Eukaryotes
        • The Ediacaran Fauna
          • FIGURE 14.14: Ediacara fauna
      • Phanerozoic Life
        • The Cambrian Radiation
          • FIGURE 14.15: Phanerozoic life
          • FIGURE 14.16: Fossils from the Burgess Shale
        • Life on Land
          • Plants.
            • FIGURE 14.17: Earliest life on land?
            • FIGURE 14.18: Evolution of plant life
          • Insects.
          • Animals with Backbones.
            • FIGURE 14.19: Ancient insect
            • FIGURE 14.20: Pikaia, the first chordate
            • FIGURE 14.21: Pioneer fish?
            • FIGURE 14.22: Early birds and mammals
          • The Human Family.
            • FIGURE 14.23: The human family
      • Environmental Change and Biodiversity
    • EXTINCTION: THE HISTORY OF DEATH
      • Background Rate of Extinction
      • Mass Extinctions
        • FIGURE 14.24: Mass extinctions
        • FIGURE 14.25: The day the dinosaurs died?
      • The Sixth Great Extinction
    • END OF CHAPTER 14
      • SUMMARY
      • IMPORTANT TERMS TO REMEMBER
      • QUESTIONS FOR REVIEW
      • QUESTIONS FOR RESEARCH AND DISCUSSION
      • QUESTIONS FOR THE BASICS
      • QUESTIONS FOR A CLOSER LOOK
  • CHAPTER 15: Ecosystems, Biomes, and Cycles of LIFE
    • A marsh ecosystem This green frog (Rana clamitans) is intimately connected to both the biotic and abiotic components of its shallow-water marsh home by innumerable biogeochemical and ecological processes and pathways.
    • OVERVIEW
    • ENERGY AND MATTER IN ECOSYSTEMS
      • FIGURE 15.1: Biosphere-II Biosphere-II was an attempt to create a closed, life-sustaining system, like that of Earth. It failed because of an unanticipated depletion of oxygen, caused when bacteria digested the cement walls of the structure.
      • Energy Flow in Systems
        • Functions of Energy: Biological Productivity
          • BIOMASS AND PHOTOSYNTHESIS.
            • the BASICS: Thermodynamics Revisited
              • FIGURE B15.1: An impossible ecosystem The energy in this impossible ecosystem is being recycled again and again. In the real world, the energy would become degraded and would eventually be lost, and the system would run down.
          • NET PRIMARY PRODUCTION.
        • Pathways of Energy: Trophic Dynamics
          • FOOD CHAINS.
            • FIGURE 15.2: Mono Lake Mono Lake in California, east of the Sierra Nevada Mountains, is a salt lake that has few species and a relatively simple food-chain structure (see Figure 15.3), but high biological productivity. The rock structures (called tufa) were formed when volcanic gases bubbled through the salty, alkaline water of the lake.
          • TROPHIC PYRAMIDS.
            • FIGURE 15.3: Mono Lake food chains This diagram shows who feeds on whom in the Mono Lake ecosystem. Compared to most ecosystems, Mono Lake has few species and the food chains are relatively simple.
            • FIGURE 15.4: Trophic pyramid In this ecosystem, grasses (autotrophs; primary producers) capture and lock up energy from the Sun, as food molecules. These plants form the base of the trophic pyramid. Deer (heterotrophs; first-order consumers) eat the grass and form the second trophic level. Wolves (heterotrophs; second-order consumers) eat the deer and form the third trophic level. Various bacteria decompose waste products and dead organisms, recycling their material components. Energy flows one-way through the trophic levels of the ecosystem, whereas chemical elements are recycled (the wolf will eat the deer, and excrete waste products). Energy is lost, and stored biomass decreases in moving from one trophic pyramid to the next.
      • Material Cycling in Ecosystems
        • Decomposers
          • Make the CONNECTION
        • Food Webs
          • FIGURE 15.5: Food web This is the food web of the harp seal. The arrows show who feeds on whom, indicating the pathways taken by both energy and matter. The harp seal feeds on more than one trophic level.
        • Nutrients, Toxins, and Limiting Factors
          • FIGURE 15.6: Nutrients for life This version of the periodic table of the elements shows which elements are required for life and which are toxic to living things.
        • Biological Concentration of Elements
          • FIGURE 15.7: Biological concentration Marine algae like this example bioconcentrate chemicals by selectively taking them in from the environment.
          • MECHANISMS OF BIOCONCENTRATION.
            • FIGURE 15.8: Biomagnification and bioaccumulation Chemicals from the environment (including toxins) bioaccumulate in organisms over time, if they are taken in faster than they are excreted. Substances can also become concentrated through biomagnification, when consumers eat organisms from lower trophic levels that contain the material.
          • CONSEQUENCES FOR THE SURROUNDING ENVIRONMENT.
      • Minimum Requirements of a Life-Supporting System
    • GLOBAL CYCLES OF LIFE
      • Basic Principles of Biogeochemical Cycling
        • Modeling Biogeochemical Cycles
          • A Closer LOOK: THE HUMAN BODY AND ELEMENT CYCLING
            • FIGURE C15.1: Minamata disease This person suffers from a neurological syndrome called Minamata Disease, caused by extreme mercury poisoning incurred as a result of eating mercury-contaminated fish.
            • FIGURE C15.2: Mercury bioaccumulation (A) This graph shows the decrease of mercury in the body of an organism that eliminated half of a single-exposure dose each 100 days. (B) This graph shows the buildup of mercury in the body of an organism that receives a steady intake of mercury each day. As the amount in the body builds up, the rate of elimination is increased. A balance is reached when the intake equals the elimination rate.
            • TABLE C15.1: Increase in Mercury Concentration Up the Food Web
          • Make the CONNECTION
          • FIGURE 15.9: Biogeochemical box models (A) Box models are a convenient way to represent the transfer of materials from reservoir to reservoir in biogeochemical cycles. (B) These are the basic elements of a biogeochemical cycle, using water as an example. X, Y, and Z are reservoirs, and the arrows represent transfer processes and fluxes of material between the reservoirs.
        • Biogeochemical Cycles of a Metal and a Nonmetal
          • THE CALCIUM CYCLE.
            • FIGURE 15.10: Calcium cycle This diagram shows the annual calcium cycle in a forest ecosystem. In the circles are the amounts transferred per unit time (the flux rates, in kilograms per hectare per year). The other numbers are the amounts stored (kilograms per hectare). Unlike sulfur, calcium does not have a gaseous phase. The information in this diagram was obtained from Hubbard Brook Ecosystem. (Source: G. E. Likens, F. H. Bormann, R. S. Pierce, J. S. Eaton, and N. M. Johnson, 1977, The Biogeochemistry of a Forested Ecosystem, Springer-Verlag, New York.)
            • FIGURE 15.11: Sulfur cycle This diagram shows the annual sulfur cycle in a forest ecosystem. The circles show the amounts transferred per unit time (the flux rates) (kilograms per hectare per year). The uncircled numbers are the amounts stored (kilograms per hectare). Sulfur has a gaseous phase as H2S and SO2. The diagram is based on studies of the Hubbard Brook Ecosystem. (Source: G. E. Likens, F. H. Bormann, R. S. Pierce, J. S. Eaton, and N. M. Johnson, 1977, The Biogeochemistry of a Forested Ecosystem, Springer-Verlag, New York.)
          • THE SULFUR CYCLE.
        • The Carbon Cycle
          • FIGURE 15.12: Carbon cycle (A) This is a generalized version of the global carbon cycle. (B) Parts of the carbon cycle are simplified in a box model to illustrate the cyclic nature of the movement of carbon. (Source: Modified after G. Lambert, 1987, La Recherche, 18, pp. 782–783, with some data from R. Houghton, 1993, Bulletin of the Ecological Society of America, 74(4), pp. 355–356.)
        • The Nitrogen Cycle
          • FIGURE 15.13: Nitrogen cycle (A) This is a box model showing the basic processes in the global nitrogen cycle. (B) Some details of the global nitrogen cycle are shown here. Pools or reservoirs for nitrogen and their contents are shown in boxes; transfer processes are shown as arrows, with annual fluxes in 1012 g N2. Note that industrial fixation of nitrogen is nearly equal to global biological fixation. (Source: Data from R. Söderlund and T. Rosswall, 1982, in O. Hutzinger (ed.), The Handbook of Environmental Chemistry, Vol. 1, Pt. B, Springer-Verlag, New York.) (C) These root nodules on white clover are produced by colonies of nitrogen-fixing bacteria.
        • The Phosphorus Cycle
          • FIGURE 15.14: Phosphorus cycle Phosphorus is recycled to soil and land biota by geologic processes that uplift the land and erode rocks, by birds that produce guano, and by human beings. Although Earth’s crust contains a very large amount of phosphorus, only a small fraction of it can be mined by conventional techniques. Phosphorus is therefore one of our most precious resources. Values of the amount of phosphorus stored or in flux are compiled from various sources. Estimates are approximate to the order of magnitude. (Source: Based primarily on C. C Delwiche and G. E. Likens, 1977, “Biological Response to Fossil Fuel Combustion Products,” in W. Stumm, ed., Global Chemical Cycles and Their Alterations by Man, Abakon Verlagsgesellschaft, Berlin, pp. 73–88, and U. Pierrou, 1976, “The Global Phosphorus Cycle,” in B. H. Svensson and R. Soderlund (eds.), “Nitrogen, Phosphorus and Sulfur—Global Cycles,” Ecological Bulletin, Stockholm, pp. 75–88.)
      • Biogeochemical Links among the Spheres
        • The Atmosphere
        • The Hydrosphere
        • The Geosphere
        • Soil: A Biogeochemical Link
          • FIGURE 15.15: Soil: one of Earth’s unique features These microscopic views show Earth’s soil (A) compared to regolith from the Moon (B). Earth’s soil contains organic material and hydrous minerals such as clay, while lunar regolith contains neither.
          • SOIL PROPERTIES AND FORMATION.
            • FIGURE 15.16: Soil particle sizes Mineral particle sizes in soils are named sand, silt, and clay (which includes colloids). Gravel is typically not included when discussing soil texture. Size grades are defined using the metric system, and each unit on the scale represents a power of 10. English equivalents are also shown.
            • the BASICS: Soil Classification
              • FIGURE B15.2: World soils
          • SOIL FERTILITY.
            • TABLE B15.1: Soil orders*
            • FIGURE 15.17: Soil profile This is a typical sequence of soil horizons that would commonly develop in moist, temperate climates. The A horizon, which lies within reach of plant roots, is commonly called the topsoil.
            • FIGURE 15.18: Arable soil Fertile, farmable soil is crucial for global food security. Modern farmers use contour plowing, as shown here, to slow erosion and preserve topsoil.
            • FIGURE 15.19: Soil water Water that fills or partially fills the pore spaces between the mineral grains in the soil occurs as a film that adheres to the surfaces of mineral particles. Most of the components dissolved in the water are cations; they can include vital plant nutrients, as well as applied fertilizers and other agrochemicals, and some pollutants.
            • Make the CONNECTION
        • The Anthroposphere: Impacts on Biogeochemical Cycles
          • IMPACTS ON THE CARBON CYCLE.
          • IMPACTS ON THE SULFUR CYCLE.
          • IMPACTS ON THE NITROGEN AND PHOSPHORUS CYCLES.
            • FIGURE 15.20: Human impacts on biogeochemical cycles Modern human activities have significant impacts on global biogeochemical cycles. (A) This forest is suffering from acid mine drainage associated with coal mining in East Germany. (B) Here phosphate is being mined near Jasper, Florida. Human industrial activities such as mining change the fluxes of naturally occurring substances like phosphate.
    • BIOMES: EARTH’S MAJOR ECOSYSTEMS
      • Biogeography
        • Biomes and Ecozones
          • FIGURE 15.21: World terrestrial biomes The locations of biomes are influenced by temperature, precipitation, atmospheric circulation, and other factors.
        • Differences between Terrestrial and Aquatic Biomes
      • Terrestrial Biomes
        • The Major Terrestrial Biomes
          • TUNDRA.
          • BOREAL FOREST.
            • FIGURE 15.22: Alpine biomes With increasing altitude, biomes change in ways that are similar to changes observed from the equator to the poles.
            • FIGURE 15.23: Some important terrestrial biomes (A) Tundra (Yukon Territory, Canada) (B) Boreal forest (Minnesota, USA) (C) Temperate rain forest (Washington, USA) (D) Temperate deciduous forest (New England, USA) (E) Tropical rain forest (Georgia, USA) (F) Savanna (Kgaligadi, South Africa) (G) Grassland (Colorado, USA) (H) Desert (Utah, USA).
          • TEMPERATE RAIN FOREST.
          • TEMPERATE DECIDUOUS FOREST.
          • TROPICAL RAIN FOREST.
          • TROPICAL DECIDUOUS FOREST.
          • SAVANNA.
          • CHAPARRAL.
          • GRASSLAND.
          • DESERT.
            • FIGURE 15.24: Closed and open forests In a closed forest, the top layer of vegetation, called the canopy, provides essentially continuous cover. In an open forest, there are openings in the canopy where light can pass through to the forest floor.
      • Aquatic Biomes
        • Freshwater and Transitional Biomes
          • FLOWING-WATER ENVIRONMENTS.
          • STANDING-WATER ENVIRONMENTS.
            • FIGURE 15.25: Some important freshwater aquatic biomes (A) River (Newfoundland, Canada) (B) Lake (Southern Germany) (C) Wetland (Mantecal, Venezuela).
          • TRANSITIONAL ENVIRONMENTS.
        • Marine Biomes
          • NEAR-SHORE ENVIRONMENTS.
            • FIGURE 15.26: Oceanic zones The zones or biomes of the ocean can be divided on the basis of depth, distance from shore, and light levels.
          • OPEN-WATER ENVIRONMENTS.
          • BOTTOM ENVIRONMENTS.
            • FIGURE 15.27: Some important marine biomes (A) Intertidal zone (Monterey Bay, California) (B) Open ocean (Atlantic) (C) Benthic zone (Clayoquot Sound, British Columbia, Canada)
    • END OF CHAPTER 15
      • SUMMARY
      • IMPORTANT TERMS TO REMEMBER
      • QUESTIONS FOR REVIEW
      • QUESTIONS FOR RESEARCH AND DISCUSSION
      • QUESTIONS FOR THE BASICS
      • QUESTIONS FOR A CLOSER LOOK
  • CHAPTER 16: Populations, Communities, and CHANGE
    • Honeybee community Populations of honeybees in many parts of the world have undergone a dramatic collapse in the past few years, for reasons that are not thoroughly understood. Here, a community of bees (Apis mellifera) cooperates to repair its honeycomb. Humans depend on honeybees for the pollination of many food crops.
    • OVERVIEW
    • POPULATIONS
      • Factors That Cause Changes in Populations
        • FIGURE 16.1: Extrinsic factors can affect populations Here, fireweed (Epilobium angustifolium) is the first foliage to reemerge amid blackened spruce trees after a forest fire near Eagle Point, Yukon Territory.
      • Population Dynamics
      • Limits to Growth
        • Biotic Potential and Limiting Factors
          • FIGURE 16.2: History of the elephant seal population The Northern elephant seal (A, Mirounga angustirostris) was brought to near-extinction by 1890, primarily as a result of hunting. Estimates of the number of individuals alive at that time range from 20 to 200. Subsequently, as a result of protection afforded by its status as an endangered species, the population of elephant seals increased exponentially, at a rate of up to 9 percent per year (B). The current population of about 127,000 individuals is no longer considered to be endangered, but may be susceptible to disease because all extant individuals are descended from the same few survivors. This is an example of a genetic bottleneck.
          • FIGURE 16.3: Logistic growth curve The logistic curve is a model of population growth based on exponential growth that is limited by lack of resources and other factors. Growth rate is slow (A) when the population is small, even though resources and space are abundant, because few individuals are reproducing. Growth reaches a maximum at (B), because more individuals are reproducing but resources are still sufficient. Population growth slows at (C) in response to limiting factors such as lack of resources, overcrowding, or abundance of predators. The leveling-off point represents the carrying capacity (K).
          • Make the CONNECTION
        • Carrying Capacity
        • Population Stability
        • “Boom-and-Bust” Cycles
          • FIGURE 16.4: Growth in real populations (A) In 1911, reindeer (Rangifer tarandus) were imported to St. Paul Island in the Bering Sea, where there were no natural predators. The population grew extremely rapidly, reaching more than 2000 by 1938. This exceeded the carrying capacity of the island, which became severely overgrazed. The winter of 1940–1941 was particularly cold and many reindeer starved, leading to a large dieback. Other fluctuations have since occurred, but the present reindeer population has stabilized at about 450–500. (B) In the 1930s, Gause carried out classic experiments on populations of Paramecium, single-celled organisms that feed on bacteria. The graph shows P. caudatum in a laboratory experiment in which food and other environmental conditions were held constant and no competitors were present. The population increases, overshoots slightly, fluctuates, and then levels off.
          • FIGURE 16.5: Boom-and-bust cycles This graph, based on a classic study by MacLulich (1937), shows the abundance of the Canada lynx (Lynx canadensis) varying in response to the availability of the snowshoe hare (Lepus americanus), its main food source.
          • the BASICS: Population Growth
            • FIGURE B16.1: Exponential and linear growth Exponential growth is geometric growth, in which the rate of growth per unit of time is a constant. The J-curve is characteristic of exponential growth. Linear growth is arithmetic growth, in which the amount of growth per unit of time is a constant.
    • COMMUNITIES
      • Interactions among Organisms
        • Competitive Relationships
          • FIGURE 16.6: Competition Competition can be interspecific (between individuals of different species) or intraspecific (between individuals of the same species). Here, two American buffalo males (B. bison) compete over territory in Yellowstone National Park.
          • A Closer LOOK: K-STRATEGISTS AND R-STRATEGISTS
            • FIGURE C16.1: r-strategists and K-strategists Dandelions (A, Taraxacum officinale) and many other weeds are r-strategists. So are rabbits (B, Lepus arcticus). Gorillas (C, G. gorilla gorilla) and humans (D, H. sapiens sapiens) have few offspring but invest significant energy in ensuring their survival; they are K-strategists.
          • FIGURE 16.7: Parasitism and predation (A) A blood-sucking river lamprey (Lampetra fluviatilis, which does inhabit marine areas in spite of its name) parasitizes a rainbow trout (Oncorhynchus mykiss). (B) Ladybugs (family Coccinellidae) are beneficial to gardeners because they feed on aphids (superfamily Aphidoidea), as seen here. (C) Many species develop features that protect them from predators. Here, a crab spider (family Thomisidae) confronts a moth caterpillar (undetermined species). The long, stiff hairs on the caterpillar act as a defense against predators.
        • Exploitative Relationships
          • PARASITISM.
          • PREDATION.
        • Mutualistic Relationships
          • SYMBIOSIS AND MUTUALISM.
          • COMMENSALISM.
            • FIGURE 16.8: Symbiosis (A) An ant (genus Camponotus) herds aphids (Aphis nerii) on a seed pod of milkweed (Asclepias lanceolata). The ant guards the aphids against predators and, in return for this service, feeds on aphid honeydew; this is symbiosis and mutualism. (B) Red-billed oxpeckers (Buphagus erythrorhynchus) catch a ride on a Cape buffalo (Syncerus caffer) in South Africa; this is symbiosis and commensalism.
      • Keystone Species
        • FIGURE 16.9: Keystone species The sea otter (Enhydra lutris) is a keystone species because it controls the population of sea urchins (Strongylocentrotus purpuratus), which would otherwise inflict serious damage on kelp forest ecosystems in coastal marine environments. Here an otter eats a sea urchin in Monterey Bay, California.
      • Habitat and Niche
        • Fundamental and Realized Niche
          • FIGURE 16.10: Geometric representation of a niche This diagram illustrates the temperature-salinity-depth tolerances that bound the niche of a marine organism. The graph tells us that the water temperature reaches from 16° to 40°C, but the organism thrives only between 20° and 36°C. The water salinity ranges from 20 to 45 parts per thousand, but the organism lives only when the salinity is between 29 and 41 parts per thousand (per mil, or ‰). The fundamental niche is the complete range of environmental conditions favored by the organism. If there is competition for this niche, the organism may end up only occupying a portion of that range, shown here as the realized niche (the most restricted set of conditions).
          • FIGURE 16.11: Overlapping niches What happens when niches overlap? Experiments with flour beetles (Tribolium) demonstrate that one species will dominate if the environment is uniform, but they can split the niche if there are variations in environmental conditions.
        • Competitive Exclusion
          • FIGURE 16.12: Fundamental and realized niche Freshwater flatworms (Planaria) live in cold mountain streams in Great Britain. (A) Species A occupies a fairly restricted temperature range, even in streams where it occurs alone, preferring cold water. (B) Species B has a broader range of temperature in which it survives in streams where it occurs alone. (C) In streams where the two species occur together, both of their temperature ranges are limited; they have shared the niche according to the environmental gradient in the temperature. (A) and (B) represent the fundamental niches of the species, whereas (C) shows their more restricted realized niches.
          • FIGURE 16.13: Competitive exclusion The eastern gray squirrel (A, Sciurus carolinensis) was introduced into the British Isles and now outcompetes the red squirrel (B, Sciurus vulgaris) in Great Britain and Ireland, an example of the competitive exclusion principle in action. The British red squirrel is declining; its current range (C) is much smaller than its original range and is highly fragmented.
        • Specialists and Generalists
          • FIGURE 16.14: Niche differentiation MacArthur discovered that five species of warbler occupying the same tree could forage for the same resources if they differentiated their niche both temporally and spatially. The parts of the tree shown in black represent the areas where each of the different species spent at least 50 percent of their foraging time. He also found that the birds moved differently from one feeding area to another, some moving concentrically around the tree and others moving vertically, thus splitting the resource geographically.
        • Speciation
          • Make the CONNECTION
          • FIGURE 16.15: Speciation In allopatric speciation, a portion of the population becomes reproductively isolated as a result of a geographic barrier. In peripatric and parapatric speciation, part of the population colonizes an adjacent but slightly different habitat, causing natural selection to have a slightly different outcome. In sympatric speciation, variation occurs within the population, in the absence of any barriers, perhaps as a result of genetic variation or behavioral differentiation. The final result is that the new species is distinct from the original species; even if all barriers were removed, the two species would not be able to interbreed successfully.
      • Species Vulnerability
    • BIODIVERSITY
      • Defining and Measuring Biodiversity
        • FIGURE 16.16: Giant Panda: Specialist and K-strategist Many factors contribute to the vulnerability of the Giant Panda (Ailuropoda melanoleuca) from China. Its population is small and scattered. It is an extreme specialist, feeding only on certain types of bamboo, which are at risk because of habitat modification. It is also an extreme K-strategist, reaching sexual maturity late, bearing small litters, and investing significant energy in the rearing of offspring.
        • Genetic Diversity
          • TABLE 16.1: Kinds of Biological Diversity
          • FIGURE 16.17: Genetic bottleneck If a population undergoes a significant decline, it may rebound. However, a genetic bottleneck can cause the available genetic diversity in the new population to be significantly reduced.
        • Habitat Diversity
          • FIGURE 16.18: Biodiversity and latitude (A) The number of mosquito genera varies as a function of latitude, peaking in low-latitude regions. Comparable patterns are observed in clams, turtles, parrots, foraminifera, termites, snails, frogs, snakes, lizards, crocodiles, reef-forming corals, amphibians, butterflies, and palm trees. (B) Low-latitude environments, where the climate is stable and predictable year-round, tend to offer complex habitat and many narrow niches, contributing to high biodiversity. (C) High-latitude environments, like this northern boreal forest, have a wide variation in climatic and other environmental conditions. The niche is very broad, which tends to limit overall biodiversity.
          • FIGURE 16.19: Provinciality and biodiversity So-called anteaters (usually they eat termites) from different parts of the world are different species: They fill the same niches but are not competitive because they do not come in contact. The species shown here are (A) short-beaked echidna (Tachyglossus aculeatus) from Australia, (B) tamandua (Tamandua mexicana) from Central America, (C) giant anteater (Myrmecophaga tridactyla) from Venezuela, and (D) pangolin (Manis javanica) from Malaysia.
        • Species Diversity
          • SPECIES RICHNESS.
            • FIGURE 16.20: Species-area relationship In general, a larger area of habitat can support a larger number of species.
            • FIGURE 16.21: Richness, dominance, and evenness Habitats (A) and (B) have the same number of organisms and the same number of species (species richness). However, one species is overwhelmingly dominant in habitat (B), so it has lower species evenness than habitat (A).
          • SPECIES EVENNESS.
      • Threats to Biodiversity
        • Endangered Species
          • the BASICS: How Many Species?
            • FIGURE B16.2: Newly discovered species New species are being discovered all the time. This blackheaded dwarf marmoset (Callibella humilis) is the second-smallest primate species ever discovered; the adult is only 10 cm long. It was discovered in a Brazilian rainforest in 1998.
          • FIGURE 16.22: Endangered species The African black rhinoceros (Diceros bicornis), osprey (Pandion haliaetus), and Mauna Kau silversword (Argyroxiphium kauense) are among many species now listed as endangered on the IUCN Red List.
        • Habitat Loss and Fragmentation
          • FIGURE 16.23: Habitat fragmentation Loss of habitat, particularly through fragmentation, is the main threat to biodiversity today. Fragmentation not only decreases the size and connectivity of habitat, but changes it character by modifying the proportion of edge to core, as shown here.
          • FIGURE 16.24: Island biogeography The study of island biogeography can tell us some important things about the characteristics of habitat fragments, in terms of supporting species diversity. An island (or fragment of habitat) that is small and isolated will support the lowest number of species, whereas one that is large and not too far from the mainland (or connected to similar habitat) will support the largest number of species. The classic work on island biogeography was carried out by MacArthur and Wilson (1967), both referenced previously in this chapter.
      • Conserving Habitat and Biodiversity
        • FIGURE 16.25: World protected areas Only a small fraction (about 2 percent) of the world’s area is protected by international agreement. Luckily there are other national-level mechanisms that can also be used to protect habitat and biodiversity, as shown on this map from the United Nations Environment Program.
        • FIGURE 16.26: Ex situ conservation Using a puppet, keepers feed an endangered California condor (Gymnogyps californianus) at the San Diego Wild Animal Park. There are only 384 condors left in the world, including only 188 known in the wild.
        • Make the CONNECTION
      • Why Is Biodiversity Important?
        • Utilitarian Arguments
          • FIGURE 16.27: Value of biodiversity The berries of the acai palm (Euterpe oleracea), seen here in baskets waiting to be taken to a market in Abaetetuba, near the mouth of the Amazon River, are among many new products that can be harvested sustainably from Amazonian rain forests.
          • Make the CONNECTION
        • Intrinsic Value Arguments
    • END OF CHAPTER 16
      • SUMMARY
      • IMPORTANT TERMS TO REMEMBER
      • QUESTIONS FOR REVIEW
      • QUESTIONS FOR RESEARCH AND DISCUSSION
      • QUESTIONS FOR THE BASICS
      • QUESTIONS FOR A CLOSER LOOK
• PART SIX: The Anthroposphere: HUMANS and the EARTH SYSTEM
  • Desert palms This is Palm Jumeirah in Dubai, one of a series of artificial islands, peninsulas, and breakwaters constructed from sand dredged from the bottom of the Persian Gulf. The palm-tree-shaped island measures 5 km by 5 km. This is an infrared image, and the red color shows areas that are vegetated.
  • CHAPTER 17: The Resource CYCLE
    • Demolition derby A pile of junked cars awaits recycling and final disposal in Los Angeles, California.
    • OVERVIEW
    • RESOURCES FROM THE EARTH SYSTEM
      • History of Human Resource Use
        • FIGURE 17.1: People and the built environment The Three Gorges Dam on China’s Yangtze River, seen here under construction in 1999 and completed in 2006, is one of the biggest engineering projects ever undertaken, and the largest electricity-generating facility in the world.
        • FIGURE 17.2: Hunter-gatherers Some modern people, including this Mbuti hunter from the Ituri rain forest in Zaire, still follow the hunter-gatherer lifestyle of our distant ancestors which requires a large area of land to support a small population.
        • FIGURE 17.3: Stone tools Stones for tools, like this stone roller and metate used for grinding corn in the prehistoric Fremont culture of Utah, were among the first nonrenewable resources that were used and traded by our distant human ancestors.
        • FIGURE 17.4: Human population and environmental resistance Great technological advances, like the origin of agriculture and the Industrial Revolution, caused an easing of environmental resistance, effectively increasing Earth’s carrying capacity and allowing major, rapid increases in human population.
        • FIGURE 17.5: Discovery of smelting The discovery of how to extract metals from rocks by smelting was one of the great human technological advances. Lothal, in the Indus Valley civilization (dating from 2400 BCE), was an early center for trade in beads, pottery, shellwork, and copper artifacts made in furnaces like the ancient example being tended here.
      • Resources In, Wastes Out
        • FIGURE 17.6: The human economy as part of the Earth system (A) Traditionally, the human economy has been viewed as an open system in which resources like raw materials and energy flow in from an unlimited source, and products, waste, and pollution flow out into a reservoir with limitless absorptive capacity. (B) In fact, the open system of the human economy is surrounded and supported by the closed Earth system. The source for resources and the absorptive capacity of Earth system reservoirs are large, but ultimately limited.
      • Basic Concepts in Resource Use and Management
        • Managing Nonrenewable Resources
          • FIGURE 17.7: The resource cycle Waste can be generated at every stage in the resource and production cycle, from extraction of raw materials through production, packaging, transportation, use, and disposal of products. Closing this cycle means taking care to minimize waste and maximize reuse and recycling of materials at every stage.
          • FIGURE 17.8: Depletion and renewal of resource stocks (A) Renewable resources like trees, fish, and groundwater are, in principle, renewed or replenished by growth or addition to the stock on a seasonal or an ongoing basis. (B) Problems arise when renewable resources are harvested at a rate that is faster than the rate of renewal. This is a form of “mining,” and it renders the resource effectively nonrenewable because the stock is being depleted with each withdrawal.
        • Managing Renewable Resources
          • the BASICS: Types of Resources
            • FIGURE B17.1: Resources Resources exist on a continuum, from those that are perpetual or inexhaustible (left) through those that are renewable on humanly accessible timescales (middle) to those that are nonrenewable because the timescale for their replenishment is much longer than a human lifetime. On the far right is a resource that is truly nonrenewable because it can never be replenished—a split atom.
    • RENEWABLE RESOURCES: SEEKING BALANCE
      • Forest Resources
        • FIGURE 17.9: Plantations and old-growth forests Plantations (A) can replace harvested forest area, but their neat rows, lack of undergrowth, and single-aged trees demonstrate that they fall short of replacing the immense biodiversity and habitat diversity offered by old-growth forests (B).
        • The Value of Forests
          • Make the CONNECTION
        • Logging, Forest Management, and Agroforestry
          • FIGURE 17.10: Forest services Forests link the biosphere to the hydrosphere, atmosphere, and geosphere, and provide many valuable environmental services.
        • Deforestation
          • FIGURE 17.11: Forest changes Human settlement and subsequent land-use changes have had substantial impacts on forest cover worldwide. Remote sensing can be combined with on-site mapping to assess changes in the extent and health of forest cover from year to year, as shown here in this series of satellite images showing progressive deforestation in the Rondonia region of the Amazonian rain forest in Brazil.
          • FIGURE 17.12: Water and nutrient cycling by forests Temperate and tropical forests differ in the way they cycle water and nutrients between the atmosphere, hydrosphere, and soils. Temperate forests (A) typically have deep root systems that draw up water and nutrients from depth. Tropical forests (B) have shallow root systems, and most of their organic matter resides in the vegetation, not in the soil. The trees return a large proportion of precipitation directly back to the atmosphere.
        • Wilderness and Wildlife
          • Make the CONNECTION
      • Fisheries Resources
        • Status of the Resource
          • FIGURE 17.13: Global fisheries production Global capture fishery production has increased dramatically over the past few decades, but the rate of increase began to decline in the 1970s and 1980s, probably because many fisheries are nearing their productive limits. The proportion of global production provided by aquaculture has surged, especially in the past decade, to the point where it is now equal to about half of the production from capture fisheries.
        • Aquaculture
          • FIGURE 17.14: Lost abundance Fishermen in the 1950s off Canada’s New Brunswick coast haul in their catch of cod. Large cod and abundant hauls like this are no longer available since the collapse of the Atlantic cod fishery off the eastern coast of North America.
          • FIGURE 17.15: Aquaculture Aquaculture is increasing in importance as the world’s capture fisheries come under greater stress. Seen here are pens for fish farming on Lake Sebu in Mindanao, Philippines.
          • A Closer LOOK: THE TRAGEDY OF THE COMMONS
            • FIGURE C17.1: The Tragedy of the Commons (A) This pasture appears to have sufficient carrying capacity to support the number of goats grazing here. (B) It seems that too many goats have been pastured here, leading to degradation of the resource. The Tragedy of the Commons suggests that it is difficult to regulate commonly-held resources; individuals may benefit from over-using the resource, but the entire community shares the cost of the resource degradation.
          • Make the CONNECTION
      • Soil Resources
        • Soil as a Critical Resource
        • Traditional and Modern Agriculture
          • FIGURE 17.16: Monoculture One of the hallmarks of modern agriculture is monoculture, the sowing of large areas of a single crop type. This is a field of corn from Nebraska.
          • FIGURE 17.17: Salt-affected soil Salinization can occur when soils become waterlogged. Salts are drawn upward as the water evaporates and are deposited at the surface, as seen in this photo of a rangeland in Colorado.
        • Impacts of the Green Revolution
        • Erosion and Loss of Agricultural Soil
      • Water Resources
        • Consumption, Loss, and Supply
          • FIGURE 17.18: Irrigation and water loss Irrigation is the biggest consumer of water, as well as the main source of irretrievable water loss worldwide. (A) Here, a standard irrigation approach loses a large proportion of water to evaporation. (B) In modern drip irrigation approaches (seen here in Australia), exactly the right amount of water is delivered directly to the roots of the crops, minimizing water loss to evaporation.
        • Water Management
          • FIGURE 17.19: Water stress This map shows areas of the world that are experiencing water stresses as a result of demand outstripping the available supply of water.
    • LIMITS TO GROWTH
    • END OF CHAPTER 17
      • SUMMARY
      • IMPORTANT TERMS TO REMEMBER
      • QUESTIONS FOR REVIEW
      • QUESTIONS FOR RESEARCH AND DISCUSSION
      • QUESTIONS FOR THE BASICS
      • QUESTIONS FOR A CLOSER LOOK
  • CHAPTER 18: Mineral and ENERGY RESOURCES
    • Molten ore Molten gold is poured into containers at an ore refinery.
    • OVERVIEW
    • NONRENEWABLE RESOURCES: CLOSING THE CYCLE
      • FIGURE 18.1: Recycling Recycling of raw materials is one of the few ways to extend the lifetime of a nonrenewable resource. Seen here are bales of pop bottles waiting to be recycled; the plastic of which they are made is a petroleum product.
    • MINERAL RESOURCES
      • Make the CONNECTION
      • FIGURE 18.2: Minerals in everyday life Our modern society is fundamentally dependent on nonrenewable mineral resources, as shown by these everyday objects made or grown using minerals.
      • TABLE 18.1: Mineral Resources and Their Uses
      • Locating and Assessing Mineral Resources
      • How Mineral Deposits Are Formed
        • the BASICS: Deposits, Ores, and Reserves
          • FIGURE B18.1: Resources and reserves A reserve, as shown here, is that portion of a resource that has been identified and is economically extractable using current technologies. Portions of a resource that are less well known and/or not economically extractable are designated as hypothetical, speculative, or subeconomic resources.
        • 1. Hydrothermal Ore Deposits
          • FIGURE 18.3: Mineral deposits There are many ways that mineral deposits can form and processes by which ore minerals can be concentrated. The mechanisms of formation of these deposits are described in the text. (A) Hydrothermal: A miner in Potosi, Bolivia, points to a rich vein containing chalcopyrite (a copper mineral), sphalerite (a zinc mineral), and galena (a lead mineral). (B) Metamorphic: This rock is from a metamorphic mineral deposit at the Tempiute Mine in Arizona. The ore minerals are sphalerite (brown, lower left), pyrite (gold-colored), and scheelite (pale grayish brown, lower right). (C) Magmatic: In this unusually fine magmatic ore outcrop at Dwars River in South Africa, layers of pure chromite (black) are sandwiched by layers of plagioclase. (D) Sedimentary: Evaporite deposits, such as this salt pan in Death Valley, California, form when lake water or seawater evaporates and leaves its dissolved mineral behind. (E) Placer: The world’s richest known gold deposit, in Witwatersrand, South Africa, is an ancient placer deposit that was formed about 2.7 billion years ago. (F) Residual: In this bauxite sample from Queensland, Australia, rounded masses of aluminum hydroxide (gibbsite) are embedded in a matrix of iron and aluminum hydroxides.
          • FIGURE 18.4: Hydrothermal ore deposits (A) Hydrothermal ore deposits can form when groundwater or seawater is heated by nearby magma or when hot, aqueous solutions are expelled from a cooling plutonic body. (B) If a hydrothermal solution carries valuable metals, and if their precipitation is sufficiently sudden to concentrate them, an ore can result, like this gold ore hosted by a quartz vein at Burgin Hill Mine, California.
        • 2. Metamorphic and Magmatic Ore Deposits
          • FIGURE 18.5: Kimberlite: a magmatic ore deposit To reach the surface from their great depths, diamonds must be carried by an eruption of unusual ferocity. These eruptions leave behind a long, cone-shaped tube of solidified magma, called a kimberlite pipe. Although most people treasure diamonds for their beauty and luster, geologists treasure them also as “messengers”—samples from an otherwise inaccessible region of Earth’s interior.
        • 3. Sedimentary Ore Deposits
        • 4. Placer Ore Deposits
        • 5. Residual Ore Deposits
          • FIGURE 18.6: Placer deposits Dense ore minerals, such as gold, platinum, and diamond, tend to sink and accumulate at the bottom of sediment layers deposited by moving water, such as streams or longshore currents. Such concentrations are called placers. This diagram shows three typical geologic locations where placer concentrations can be found.
          • FIGURE 18.7: Residual ore deposits Residual ore deposits form in tropical climates, when soluble materials are picked up by slightly acidic rainwater and carried downward and deposited at a deeper level. The insoluble, residual material and the soluble, transported material can both become concentrated in this manner.
      • Mining
        • Steps in the Mining Process
          • FIGURE 18.8: Ore extraction Extraction is the second phase of the mining process, following exploration. In this photo a miner drills into gold ore at a mine in Gardiner, Montana, just outside Yellowstone National Park.
        • Impacts of Mining
          • Impacts on the Geosphere
          • Impacts on the Atmosphere.
          • Impacts on the Hydrosphere.
            • FIGURE 18.9: Environmental impacts of mining (A) Abandoned mine sites like this one in the San Juan Mountains of Colorado present significant management challenges; untended, they can continue to cause negative environmental impacts, and responsibility for them is often unclear. (B) Open-pit mines, even well-managed, are unavoidably disruptive to the natural environment. This is Bingham Canyon (Kennecott) Copper Mine in Utah, possibly the largest human excavation in the world. (C) Acid mine drainage, shown here at a mine site in Denali National Park, Alaska, can be extremely damaging to aquatic environments.
          • Impacts on the Biosphere and Human Health
    • ENERGY RESOURCES
      • Energy from the Earth System
        • FIGURE 18.10: Earth’s energy cycle All of the energy that we use to power the activities of modern society comes from some part of Earth’s energy cycle, shown here in a simple box model format.
        • FIGURE 18.11: Energy sources and uses In North America, fossil fuels (oil, natural gas, and coal) account for 85 percent of the energy used. The large amount of lost energy—nearly half, as shown in the upper-right arrow—arises both from inefficiencies in energy use and from the fundamental physical limits on the efficiency of any heat engine.
      • Fossil Fuels
        • FIGURE 18.12: Energy consumption An average American or Canadian uses energy, directly or indirectly, at a rate equivalent to burning more than 150 75-watt light bulbs every minute of the day, every day of the year. Here a highway sign admonishes Los Angeles commuters, “Don’t be fuelish—be carpoolish.”
        • FIGURE 18.13: World energy use The history of world energy consumption shows oil’s rise to prominence in the current energy mix. The brief decline in energy use in the late 1970s and early 1980s was a result of the “energy crises” of 1973 and 1979, when countries in the Middle East cut production and industrialized countries began to take conservation more seriously.
        • Coal
        • Petroleum: Oil and Natural Gas
          • FIGURE 18.14: Cutting peat A peat cutter harvests peat from a bog in Ireland. When dried, peat provides fuel for heat and cooking. It is higher in energy content than firewood but lower than coal because it is in the process of changing from plant matter to coal. If the peat cutter could wait a few million years, he might be able to harvest much higher-energy coal.
          • FIGURE 18.15: From peat to coal The conversion of plant matter to coal, or coalification, happens over a period of millions of years, as layers of peat are buried and compressed by overlying sediment.
          • FIGURE 18.16: Coal-forming environment Today’s major coal deposits formed millions of years ago, starting out in moist, heavily vegetated terrestrial environments like this one in the Great Dismal Swamp in North Carolina.
          • the BASICS: Trapping Petroleum
            • PETROLEUM MIGRATION
            • PETROLEUM TRAPS
          • FIGURE B18.2: Petroleum traps This figure illustrates six geologic circumstances in which oil can become trapped. Each kind of trap requires a source rock to provide organic material, a reservoir rock to store the oil or gas, and a cap rock to prevent its migration. Oil doesn’t usually form in an underground pool; it is trapped and accumulates in the pores of a reservoir rock. Oil is usually found with natural gas and salty water. The gas lies on top because it is the least dense, and the water lies underneath because it is densest.
          • FIGURE 18.17: Petroleum as a raw material Crude oil consists mostly of hydrocarbons—molecules containing carbon and hydrogen but no oxygen. The molecules come in many different sizes. At an oil refinery, the crude oil is distilled into heavier and lighter components. Each type of hydrocarbon has different uses. The ones with fewer carbon atoms generally have a lower boiling point and are more useful as fuels.
        • Unconventional Hydrocarbons
          • FIGURE 18.18: Unconventional hydrocarbons (A) The Athabasca Tar Sand covers about 7500 square kilometers in the province of Alberta, Canada. The tar is easily seen in the rock shown here. Nonetheless, extracting it from the rock is a complicated operation that involves cooking the stone with hot water and steam. (B) Another hydrocarbon-rich rock is oil shale, found in huge amounts in the Green River formation in Colorado, Wyoming, and Utah. The shale bookends held by this gem dealer contain about half a pint of oil.
      • Alternatives to Fossil Fuels
        • Make the CONNECTION
        • Solar, Hydrogen, Biomass, Wind, and Wave Energy
          • FIGURE 18.19: Energy from chemical reactions There are many types of fuel cells, but they all derive energy from chemical reactions, in a manner similar to regular batteries. Here, hydrogen fuel is introduced on one side of the fuel cell and diffuses through the core, reacting with oxygen to produce water and energy as by-products of the reaction.
          • FIGURE 18.20: Energy from biomass At Araras in São Paulo State, Brazil, sugar cane is crushed before being used to produce gasohol, a biomass fuel that is an alternative to gasoline.
          • FIGURE 18.21: Energy from wind Windmills at Tehachapi Pass, California, generate pollution-free electricity. Each fan’s rotary motion turns an electric generator. Wind farms can operate economically only where steady surface winds prevail year-round.
        • Hydroelectric, Tidal, and Geothermal Energy
          • FIGURE 18.22: Energy from ocean currents This is the Seaflow Marine Current Turbine off the coast of England, with its rotor raised for maintenance. These turbines work like submerged windmills, driven by flowing water rather than air. They can be installed at places with high tidal current velocities or swift, continuous ocean currents, to draw energy from these huge volumes of flowing water. This energy source is more predictable than wind or wave energy, which respond to the shorter-term variations of the weather system.
        • Nuclear Energy
          • FIGURE 18.23: Energy from nuclear fission In a chain reaction, a neutron strikes a uranium nucleus and causes it to split into smaller nuclei. The process releases more neutrons, which can go on to collide with more uranium nuclei. Each time a uranium nucleus splits it releases heat. A nuclear power plant uses that heat to generate steam, which turns turbines that generate electricity.
          • A Closer LOOK: NUCLEAR POWER AND RADWASTE
            • FIGURE C18.1: Radioactive waste management (A) Nuclear reactors produce radioactive waste that must be isolated from the hydrosphere and biosphere, including human contact, for thousands of years. Here, a technician uses a radiation detector at a waste storage site in France where reprocessed waste from 10 reactors is stored for five years before disposal. (B) In the United States, nuclear waste is currently stored at 125 temporary sites in 39 states. No permanent storage site has been built yet. In 2009 the U.S. government finally rejected the proposed permanent disposal facility site at Yucca Mountain, Nevada, shown here.
      • Energy and Society
        • The Impacts of Fossil Fuel Use
          • FIGURE 18.24: Impacts of oil use (A) Dark clouds of smoke and fire emerge as oil burns during a controlled fire in the Gulf of Mexico on May 6, 2010. The U.S. Coast Guard conducted the burn to aid in preventing the spread of oil following the April 20 explosion of BP’s offshore drilling unit, the Deepwater Horizon. (B) A brown pelican covered with oil is cleaned by a team hired to rescue animals affected by the Deepwater Horizon oil spill.
        • Will We Run Out?
          • FIGURE 18.25: How much oil is left? This map shows areas underlain by sedimentary rock and regions where large accumulations of oil and gas have been located. Where the ocean is deeper than 2000 m, sedimentary rock has yet to be tested for oil and gas potential.
    • END OF CHAPTER 18
      • SUMMARY
      • IMPORTANT TERMS TO REMEMBER
      • QUESTIONS FOR REVIEW
      • QUESTIONS FOR RESEARCH AND DISCUSSION
      • QUESTIONS FOR THE BASICS
      • QUESTIONS FOR A CLOSER LOOK
  • CHAPTER 19: The Changing Earth System
    • Antarctic ice shelf collapse A portion of the Larsen Ice Shelf off the coast of Antarctica, known as Larsen B, collapsed over a period of weeks during February and March, 2002, as shown in this series of satellite images. The collapse may have been accelerated by warm summer temperatures that caused meltwater to fill crevasses along the landward edge of the ice sheet, causing increased pressure. This portion of the shelf was more than 20 m thick and larger than the state of Rhode Island. This is one of a series of major Antarctic ice sheet collapses.
    • OVERVIEW
    • UNDERSTANDING ANTHROPOGENIC CHANGE
      • FIGURE 19.1: Early whalers By the 1800s, activities like whaling (shown near the coast of New England in this woodcut from the nineteenth century) had already begun to produce impacts on ocean ecosystems.
      • Make the CONNECTION
      • The IPAT Equation
        • the BASICS: Human Population Growth
          • FIGURE B19.1: Human population growth Extremely rapid increase of human population is a relatively recent phenomenon in the context of human history as a whole. Throughout history, there have been times when human population surged as a result of the development of new technologies, and times when population growth slowed as a result of environmental resistance.
      • Poverty and Affluence
      • Ecological Footprint
        • FIGURE 19.2: Ecological footprints The ecological footprint is a calculation of the resources required to support a person or community, rendered in terms of land area. The calculation translates into terms of land area the requirements for six categories of activities that support our material lifestyle: growing crops for food, feed, and fiber; grazing animals; fishing; harvesting timber; building infrastructure; and burning fossil fuels
        • Make the CONNECTION
        • A Closer LOOK: MALTHUS, POPULATION, AND RESOURCE SCARCITY
          • FIGURE C19.1: Malthus, population, and resource scarcity Thomas Malthus predicted that human population would grow exponentially, eventually exceeding the capacity of Earth to provide food and other resources.
      • Scientific Uncertainty
    • HUMAN IMPACTS ON THE EARTH SYSTEM
      • Geosphere: Impacts on Land
        • Desertification
          • FIGURE 19.3: Desertification Desertification is the advance of desert conditions into once-productive land. It can occur naturally, but it can be accelerated by human activity. Here, a grid of fencing has been set up to slow the advance of sand dunes into the ancient oasis of Tekenket, Mauritania.
          • FIGURE 19.4: Land degradation Overgrazing during years of drought killed much of the vegetation in this part of the Sahel in the Gao region of Mali. Without vegetation, topsoil is eroded and the land becomes infertile.
        • Soil Erosion
          • FIGURE 19.5: Deforestation and erosion Widespread deforestation in the Rio Branco area of the Amazon in Brazil has devastated a formerly luxuriant rain forest and led to accelerated runoff and deep gully erosion. Soils on the landscape quickly lose their natural fertility when forest is converted to crops or grazing land, leaving a degraded landscape with little value.
        • Waste Disposal and Toxins
          • FIGURE 19.6: Soil and groundwater contamination Toxic materials in improperly engineered disposal sites (1) or landfills (2) can percolate downward, contaminating both soil and groundwater. Also contaminated, in the scenario shown here, are a well downslope (3) and a stream (4) at the base of the hill. Alternative approaches to waste disposal that can be more secure include deep-well injection (5) and properly engineered secure landfills (6). Because neither of the latter approaches is foolproof, constant monitoring is required.
      • Hydrosphere: Impacts on Water
        • Dams and Diversions
          • FIGURE 19.7: Dams and their impacts Dams now exist on virtually every major waterway, and they have significant impacts on aquatic ecosystems. (A) The Aswan High Dam impounds the Nile River (top) to form Lake Nasser (behind the dam, at the bottom of photo). (B) Prior to construction of the Aswan Dam, the discharge of the Nile River varied seasonally, with peak discharge coming during the late summer and early fall interval of flooding. Controlled release of water after the dam was built greatly reduced the seasonal variability in discharge. Sediment formerly carried to the Mediterranean Sea is now settling in Lake Nasser; it will eventually fill the reservoir and make it unusable.
        • Mining Groundwater
        • Surface Water Contamination
          • FIGURE 19.8: Eutrophication: A dying lake This lake in Florida has turned green and mucky because of the growth of algae stimulated by excessive nutrients (possibly from sewage or fertilizer runoff). Eventually, the algae will use up all of the dissolved oxygen in the water, making it impossible for other aquatic life to survive. This process, called eutrophication, can occur naturally, but it can be accelerated by human activities.
        • Groundwater Contamination
        • Oil Spills and Other Marine Impacts
      • Atmosphere: Impacts on Air
        • Long-Range Transport of Pollutants
        • Stratospheric Ozone Depletion
          • FIGURE 19.9: Atmospheric transport of pollutants (A) In 1986 at the Chernobyl nuclear reactor in Ukraine, reactor number 4 (seen here from the roof of an adjacent reactor) experienced a core meltdown and explosion that caused a large release of radioactive material. (B) After the meltdown wind systems transported the emissions, leading to radioactive fallout throughout Europe within days. Radioactive emissions were eventually transported as far as North America.
          • FIGURE 19.10: Stratospheric ozone depletion The ozone “hole” is an area of depletion of stratospheric ozone. It is most severe during the springtime over the poles, especially Antarctic, as shown here (A) for the year 2006. The purple colors show the most strongly depleted areas. (B) Measurements from Antarctica show a steady depletion in ozone until the early 1990s. Regulations on ozone-depleting substances were implemented through the Montreal Protocol starting in 1987. (C) Chlorine atoms derived from chlorofluorocarbons can be recycled many times—perhaps tens of thousands of times—to cause depletion of ozone molecules in the stratosphere. (D) As a result of measures to cut back on emissions of ozone-depleting substances, stratospheric ozone levels are expected to return to 1980 levels (the date when significant ozone depletion began to be observed) by around 2045 in midlatitude regions and 2080 in Antarctica.
        • Smog
          • FIGURE 19.11: Photochemical smog Photochemical smog, which comes from the alteration of precursor pollutants in the atmosphere, has become a concern for human health throughout the industrialized and newly industrializing world. In Mexico City, shown here, the accumulation of smog is exacerbated by the location of the city in a geographic basin surrounded by mountains.
        • Acid Precipitation
          • FIGURE 19.12: Acid deposition Acid deposition in all forms (wet or dry) comes from the chemical interaction of natural chemicals and pollutants, especially nitrous oxides, sulfur dioxide, and carbon dioxide, with water vapor in the atmosphere. Both the precursor pollutants and the resulting acids can be transported far from their source by atmospheric processes.
      • Biosphere: Impacts on Life and Ecosystems
        • Loss of Forests
          • FIGURE 19.13: Changing forest cover The global forest cover has decreased over time, as shown in this map comparing original forest cover to 2005. Whereas recent forest cover can be accurately assessed using satellite imagery, “original” forest cover is necessarily only an estimate.
        • Empty Nets
          • FIGURE 19.14: Depleted stocks The United Nations Food and Agriculture Organization, which monitors the world’s fishery resources, estimates that 80 percent of fish stocks worldwide are now fully exploited to overexploited or depleted, as shown in (A). One cause of the depletion of marine stocks is harmful fishing techniques. Shown here (B) is dead by-catch from shrimp harvesting.
        • Coral Bleaching
          • FIGURE 19.15: Coral bleaching Coral reefs like this one from West Papua, Indonesia (A) are extremely productive and biologically diverse habitats. Corals are highly sensitive to environmental changes such as increasing water temperature, acidity, and cloudiness, and they may exhibit stress by undergoing bleaching, as shown here (B) in a sample from the South Male Atoll, Maldives. Coral bleaching is occurring in many locations throughout tropical and subtropical seas, as shown on this map (C).
        • Species at Risk
          • FIGURE 19.16: Biodiversity hotspots Biodiversity clusters in certain “hotspots” around the world, as shown here. Unfortunately, these important areas don’t always coincide with areas that are protected.
    • ANTHROPOGENIC ROLE IN GLOBAL CLIMATIC CHANGE
      • Human Activities and the Carbon Cycle
        • FIGURE 19.17: Human impacts on the carbon cycle Human activities affect the global carbon cycle (A) most dramatically through the burning of fossil fuels and clearing of forested land, shown in (B).
        • Changes in Atmospheric Chemistry
          • FIGURE 19.18: Changing atmospheric chemistry Atmospheric concentrations of carbon dioxide, methane, nitrous oxides, and several other key constituents have increased dramatically over the past 200 or so years, since the Industrial Revolution.
          • CARBON DIOXIDE.
            • FIGURE 19.19: Carbon dioxide varies seasonally This graph shows the concentration of carbon dioxide in dry air, measured since 1958 at the Mauna Loa Observatory in Hawaii (given in parts per million by volume, or ppmv). The “zig-zag” pattern is caused by annual fluctuations related to seasonal variations in biologic uptake of CO2. The long-term trend shows a persistent increase in this important greenhouse gas.
          • METHANE.
      • Assessing Climatic Change
        • Historical Temperature Trends
        • Future Climatic Change
          • FIGURE 19.20: Surface temperature anomalies since 1880 It is extremely challenging to reconstruct average surface temperatures, but most data suggest an increase of at least 0.6°C in the long-term trend. Here data showing average surface temperatures in the Northern and Southern Hemispheres are compared to a baseline (the 1951-1980 average). The Southern Hemisphere shows an overall increase of about 0.6°C; the Northern Hemisphere increase is slightly greater.
          • CLIMATE MODELS.
          • SCIENTIFIC CONSENSUS AND THE IPCC.
            • FIGURE 19.21: Predicting the present Scientists test climate models by entering climate data from past years and comparing the model predictions (blue areas) with actual observations (red lines). Models that incorporate only natural factors (A) or only anthropogenic factors (B) do not predict real climate trends as closely as models that incorporate both (C). (Source: IPCC 3rd Assessment Report, 2001).
            • TABLE 19.1: Projected impacts of global warming
        • Potential Impacts of Climatic Change
          • CHANGES IN THE HYDROSPHERE.
            • FIGURE 19.22: Projected temperature changes. This map shows projected surface temperature changes for the late twenty-first century (2090–2099), relative to the average temperature in the period 1980–1999. Note that the changes will not be uniform throughout the Earth system, and temperature increases are particularly high in the Arctic. (Source: IPCC Climate Change 2007).
            • FIGURE 19.23: Storms and climate change One projected impact of global climatic change is an increase in the frequency and intensity of storms. In the unusually intense hurricane season of 2005, water temperatures in the Gulf of Mexico were unusually warm; there was some speculation—still unconfirmed—that warming of the climate may have contributed to warmer sea-surface temperatures, and thus to the ferocity of storms like Hurricane Katrina, shown here in a satellite image just before making landfall in Louisiana. Unusually warm sea-surface temperatures in the Gulf of Mexico are shown in red and orange.
          • CHANGES IN THE BIOSPHERE.
          • CHANGES IN THE CRYOSPHERE.
          • CHANGES IN THE GEOSPHERE.
          • FEEDBACKS.
    • ANTHROPOSPHERE: HUMANS AND EARTH SYSTEM CHANGE
      • Mitigation, Adaptation, and Intervention
        • Mitigation: Minimizing Our Impacts
        • Adaptation: Preparing for Change
        • Intervention: Engineering the Earth System
          • BLOCKING INCOMING SOLAR RADIATION.
          • PREVENTING GREENHOUSE TRAPPING OF TERRESTRIAL HEAT.
      • Our Past, Our Future
        • FIGURE 19.24: Crossing planetary boundaries According to scientists from the International Geosphere-Biosphere Program, the inner (blue) circle of this diagram represents the safe operating space for the key planetary systems. The red wedges indicate the best estimate of the current situation. Three boundaries have already been crossed: climate change, the nitrogen cycle, and biodiversity loss.
      • To Our Readers
        • FIGURE 19.25: A delicate balance Humans and other organisms depend fundamentally on the continued functioning and integrity of interacting Earth systems. This composite, cloud-free satellite image gives a unique perspective on Earth’s land, ice caps, and vast oceans.
    • END OF CHAPTER 19
      • SUMMARY
      • IMPORTANT TERMS TO REMEMBER
      • QUESTIONS FOR REVIEW
      • QUESTIONS FOR RESEARCH AND DISCUSSION
      • QUESTIONS FOR THE BASICS
      • QUESTIONS FOR A CLOSER LOOK
• Back Matter
  • Appendices
    • APPENDIX A: Units and Their Conversions
      • ABOUT SI UNITS
      • COMMONLY USED UNITS OF MEASURE
        • Length
        • Area
        • Volume
        • Mass
        • Pressure
        • Energy and Power
        • Temperature
    • APPENDIX B: Tables of the Chemical Elements and Naturally Occurring Isotopes
      • TABLE B.1: Alphabetical List of the Elements
      • TABLE B.2: Naturally Occurring Elements Listed in Order of Atomic Numbers, Together with the Naturally Occurring Isotopes of Each Element, Listed in Order of Mass Numbers
    • APPENDIX C: Tables of the Properties of Selected Common Minerals
      • TABLE C.1: Properties of the Common Minerals with Metallic Luster
      • TABLE C.2: Properties of Rock-forming Minerals with Nonmetallic Luster
  • Glossary
  • Credits
    • Photo Credits
      • PART 1
      • CHAPTER 1
      • CHAPTER 2
      • CHAPTER 3
      • CHAPTER 4
      • PART 2
      • CHAPTER 5
      • CHAPTER 6
      • CHAPTER 7
      • PART 3
      • CHAPTER 8
      • CHAPTER 9
      • CHAPTER 10
      • PART 4
      • CHAPTER 11
      • CHAPTER 12
      • CHAPTER 13
      • PART 5
      • CHAPTER 14
      • CHAPTER 15
      • CHAPTER 16
      • PART 6
      • CHAPTER 17
      • CHAPTER 18
      • CHAPTER 19
    • Figure and Table Credits
  • Index

  UM RAFBÆKUR Á HEIMKAUP.IS

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  - Þú getur prentað síður úr bókinni (innan þeirra marka sem útgefandinn setur)
  - Möguleiki á tengingu við annað stafrænt og gagnvirkt efni, svo sem myndbönd eða spurningar úr efninu
  - Auðvelt að afrita og líma efni/texta fyrir t.d. heimaverkefni eða ritgerðir
  - Styður tækni sem hjálpar nemendum með sjón- eða heyrnarskerðingu