The Earth Machine

The Earth Machine: The Science of a Dynamic Planet

Edmond A. Mathez
James D. Webster
Copyright Date: 2004
Pages: 378
https://www.jstor.org/stable/10.7312/math12578
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  • Book Info
    The Earth Machine
    Book Description:

    From the scorching center of Earth's core to the outer limits of its atmosphere, from the gradual process of erosion that carved the Grand Canyon to the earth-shaking fury of volcanoes and earthquakes, this fascinating book -- inspired by the award-winning Hall of Planet Earth at New York City's American Museum of Natural History -- tells the story of the evolution of our planet and of the science that makes it work. With the same exuberance and expertise they brought to the creation of the Hall of Planet Earth, co-curators Edmond A. Mathez and James D. Webster offer a guided tour of Earth's dynamic, 4.6-billion-year history.

    Including numerous full-color photographs of the innovative exhibit and helpful, easy-to-understand illustrations, the authors explore the major factors in our planet's evolution: how Earth emerged from the swirling dusts of a nascent solar system; how an oxygen-rich, life-sustaining atmosphere developed; how continents, mountain ranges, and oceans formed; and how earthquakes and volcanic eruptions alter Earth's surface. Traversing geologic time and delving into the depths of the planet- -- beginning with meteorites containing minuscule particles that are the solar system's oldest known objects, and concluding with the unusual microbial life that lives on the chemical and thermal energy produced by sulfide vents in the ocean floor -- The Earth Machine provides an up-to-date overview of the central theories and discoveries in earth science today. By incorporating stories of real-life fieldwork, Mathez and Webster explain how Earth is capable of supporting life, how even the smallest rocks can hold the key to explaining the formation of mountains, and how scientists have learned to read nature's subtle clues and interpret Earth's ever-evolving narrative.

    eISBN: 978-0-231-50087-6
    Subjects: General Science, Physics, Geology

Table of Contents

  1. Front Matter
    (pp. i-vi)
  2. Table of Contents
    (pp. vii-x)
  3. PREFACE
    (pp. xi-xv)
    Edmond A. Mathez and James D. Webster
  4. PART I HOW HAS EARTH EVOLVED?
    • [PART I Introduction]
      (pp. 1-2)

      On a desolate patch of rock scraped bare by countless advances of the Greenland ice cap, Minik Rosing, a geologist with the Geologisk Museum in Copenhagen, is on his knees, hand lens to his eye, intent on the details under his nose. To the casual observer, the outcrop is but a cold, grayish lump, almost hostile in its nondescript appearance and barren environment. Indeed, the rock had suffered long, having once been buried kilometers deep and cooked by the hot, caustic fluids that circulated through that region of Earth. To Rosing and the other geologists with him, however, it is...

    • 1 The Birth of Planet Earth
      (pp. 3-12)

      One late morning found Martin Prinz, one of the world’s foremost experts on meteorites and Curator of Meteoritics at the American Museum of Natural History, hunched over his desk, an assistant and a postdoc peering over his shoulder.¹ The three were staring intensely at a fist-size rock and talking excitedly to a slightly disheveled character who was sitting across from them. Actually, Prinz was bargaining—Prinz wanted what the dealer had. The object of their attention had fallen from the sky a year earlier, by chance landing in the mountains of Argentina. It had produced a sonic boom so loud...

    • 2 Learning the Age of Earth
      (pp. 13-22)

      Before about the middle of the eighteenth century, the question of the age of Earth was primarily the concern of theologians and philosophers, and the estimated ages varied as widely as the belief systems.¹ Aristotle, for example, regarded Earth as eternal, but Christian scholars, beginning in about the second century, used events recorded in religious and historical texts and astronomical observations to arrive at young ages. From these sources, the most frequently cited date for the beginning of Earth is 4004 B.C.—at “the entrance of the night preceding the twenty third day of Octob.,” to be exact.² This estimate...

    • 3 The Evolution of the Continents
      (pp. 23-35)

      The crust is like an eggshell enveloping Earth. It comprises a mere 0.5 percent of Earth’s mass but records nearly all of its history. There are two distinct types. The ocean basins are underlain by crust that is typically 5 to 8 kilometers (3 to 5 miles) thick and nowhere older than about 180 million years.¹ The oceanic crust is young (in geological terms) because it forms, slowly but steadily, at ocean ridges worldwide and then disappears back into the mantle at subduction zones, where one plate dives beneath another. The oceanic crust is composed almost entirely of basalt and...

    • 4 Life and Conditions on Early Earth
      (pp. 36-48)

      The first life probably inhabited Earth more than 3.8 billion years ago.¹ That life, and in fact all life for the following 3 billion years or so, was entirely microbial. The oldest fossils we know of are microscopic forms in rocks of the 3.3- to 3.5-billion-year-old Warrawoona Group, a sequence of metamorphosed sediments in Western Australia (figure 4.1).² These fossils were formed from microbes that may have grown in shallow seas near the surface. They represent a diverse group of microbes resembling cyanobacteria (blue-green algae), which are light sensitive. If the interpretation is correct, then photosynthesis (the process by which...

    • 5 Reading Rocks: The Story of the Grand Canyon
      (pp. 49-61)

      From its beautiful rim vistas, many of the rock layers in the Grand Canyon appear in startlingly bright shades of maroon and yellow. The bands of rock stretch across the distant panorama as far as the eye can see. Deeper into the canyon, the cliffs show sharp breaks in color, with earthen-tone layers interspersed among maroons and yellows. Some of these layers are horizontal, but the sharp eye sees that others are distinctly tilted. Deeper still, in the inner recesses, the rocks do not appear layered but are more massive, darker in the shadows, mysterious, some highly contorted, as if...

  5. PART II WHY ARE THERE OCEAN BASINS, CONTINENTS, AND MOUNTAINS?
    • [PART II Introduction]
      (pp. 63-64)

      Imagine yourself as a space traveler, and you happen upon the solar system and its Earth. What a strange planet, you might think, quite different from any other that you know. Among the first things to strike you would be the vast blue area that we know to be the oceans, and the regions of greens and browns that seem to be embedded in the blue: the continents. Your alien eyes would record swirling patterns of clouds and polar ice caps. Looking more closely at the continents, you would realize that they include belts of high, rugged terrain, or mountains....

    • 6 Internal Earth
      (pp. 65-83)

      Before seismology, or the study of earthquakes and related phenomena, almost nothing was known about the deep interior of Earth. The point was eloquently made by Richard Oldham (1858–1936), one of the pioneers in the nascent discipline: “Many theories of the earth have been propounded at different times: the central substance of the earth has been supposed to be fiery, fluid, solid, and gaseous in turn, till geologists have turned in despair from the subject, and become inclined to confine their attention to the outermost crust of the earth, leaving its centre as a playground for mathematicians.”¹

      Earthquakes and...

    • 7 Plate Tectonics
      (pp. 84-98)

      The central idea of plate tectonics is remarkably simple. The lithosphere, the rigid, strong outermost shell of Earth, is broken into 10 large plates that move independently, driven by convective currents in the mantle below.¹ Independent movement means that at some boundaries the plates diverge, at others they converge, and at others they move past each other. In this way, the plates grow and disappear, and their boundaries are sites of volcanism, earthquakes, and mountain building. These phenomena teach us about plate tectonics; in return, plate tectonics offers a grand explanation for why volcanoes and earthquakes occur where they do...

    • 8 Lavas from the Depths of Earth
      (pp. 99-115)

      There are about 540 active volcanoes in the world. Bearing in mind that the geologist’s view of active is different from that of most people, what we really mean is that there are about 540 volcanoes that have erupted within the past 10,000 years or so (figure 8.1). The geological view of active is somewhat arbitrary, however. It arises because the typical volcano has a life span on the order of 1 million years or more, and during that time it may not erupt for thousands of years. So, let’s just say that there are 540 volcanoes that would not...

    • 9 Great Explosive Volcanoes
      (pp. 116-136)

      By mid-March, thousands of people had congregated at the ancient temples of Pura Besakih on the lower slopes of Gunung Agung, the most venerated of the six active volcanoes on the Indonesian island of Bali. According to the Balinese, the volcano is “the focal point from which the world springs,” and hence it is called the Navel of the World. Every hundred years, the Balinese attend the Eka Dasa Rudra, the sacred festival of sacrificial ceremonies held at Besakih. But never before had there been a ceremony like the one in 1963. Gunung Agung had been shaking the local area,...

    • 10 Earthquakes
      (pp. 137-155)

      In 1906 an earthquake devastated San Francisco. The event announced to the world that an active fault zone runs along the coast of California. It made people wonder why earthquakes happen, and it ushered in the modern era of earthquake studies. Two years later, Andrew Lawson wrote this report:

      Extending thru the greater part of the Coast System of mountains from Humboldt County to the Colorado Desert, a distance of over 600 miles, is a line or narrow zone characterized by peculiar geomorphic features, referable either directly to the modern deformation of the surface of the ground or to erosion...

    • 11 Mountains
      (pp. 156-171)

      Mountains capture our imagination with their grand peaks, distant profiles, and deep valleys. By their mass and might, they remind us how small we are. From the earliest days of the science, they have also inspired numerous questions: Why are mountains so high? What are they made of? How do they form? Why do they even exist in the face of erosion?

      Mountain belts are features of the continental crust. They are zones of deformation hundreds to thousands of kilometers across; because they are so wide, their structure and evolution cannot be entirely understood in terms of simple plate tectonics...

    • 12 The Alps
      (pp. 172-181)

      Modern studies of mountain belts began in the Alps. The structure of this mountain chain, which probably better than anywhere else illustrates crustal shortening, had a profound influence on the evolution of geological thought. For example, it inspired Alfred Wegener in the development of his theory of continental drift, and it was in the Alps that the general theories of mountain building were first developed.

      The most outstanding feature of the Alps—and that which illustrates crustal shortening—is the exposure of structures called nappes.¹ Nappes are flat-lying folds, the lower limbs of which have been greatly thinned or are...

  6. PART III WHAT CAUSES EARTH’S CLIMATE AND CLIMATE CHANGE?
    • [PART III Introduction]
      (pp. 183-184)

      One thing is certain: anywhere one travels, weather is a very popular topic of conversation. We talk about whether it will snow or rain, and about the temperature, cloudiness, humidity, and wind. The same variables also describe climate. But what is climate, and how is it distinct from weather? Weather refers to the conditions at any one time in the atmosphere, whereas climate is the long-term state. In particular, climate is the weather condition of a given region averaged over some time, traditionally 30 years.

      The atmosphere, the subject of chapter 13, is not an isolated system. It is influenced...

    • 13 The Atmosphere
      (pp. 185-196)

      The atmosphere is a transparent, protective blanket that makes life possible.¹ It is the air we breathe; it protects surface life from the Sun’s deadly ultraviolet radiation; it regulates surface temperature such that liquid water is stable; and, in concert with the ocean, it transports heat from equatorial to polar regions (figure 13.1).

      We perceive air as weightless, but it has mass, and like everything else it is held to Earth by gravity. To be exact, a column of air 1 meter (3.3 feet) on a side at its base and extending from sea level to the outer limit of...

    • 14 The World Ocean
      (pp. 197-208)

      We tend to think of the oceans as separate bodies, but water flows from one to another. The oceans work together as a single, global system, and together they conspire with the atmosphere to control climate. For these reasons, it is useful to conceive of a single world ocean.¹ Being mostly beyond view and unfamiliar, the deep ocean is mysterious. Vast regions are more than 4000 meters (13,000 feet) deep—as deep as high mountains are high—and the ocean bottom is for the most part a vast, flat, featureless expanse known as the abyssal plain. The edges of the...

    • 15 The Geological Record of Climate Change
      (pp. 209-225)

      There is good reason to wonder how and why climate has changed. The geological record, which is fairly complete for the past 100,000 years, clearly shows times of rapid change. Some changes occurred over just several years and were far more extreme than any experienced in all of recorded human history. Others took hundreds to thousands of years. Over the past couple of million years, climate has fluctuated in approximately 100,000-year cycles of long glacial periods terminated by short interglacial periods. The changes are clear and in some cases dramatic; some of the causes are known, whereas others remain mysterious....

  7. PART IV WHY IS EARTH HABITABLE?
    • [PART IV Introduction]
      (pp. 227-228)

      Why is Earth habitable? In some sense, this is a rhetorical question. It is not one that we scientists ask one another, because it is not one we can answer in detail, and any answers that we can give are not short. The fact is, there are many reasons why Earth is habitable, and we do not know all of them. It is a valid question, nonetheless, so in part IV we shall explore it.

      One reason the answer is not simple is that it involves not just Earth but Earth’s place in the solar system and the nature of...

    • 16 Conditions for Life
      (pp. 229-241)

      Sherwood Chang, a scientist at NASA has observed, “The ability of a planet to produce and sustain a complex hierarchy of [self-organizing] systems over geologic time may be a prerequisite for the origin and sustenance of life.”¹ His statement implies what has become widely accepted: that life began as a consequence of a normal chemical evolution of organic compounds under favorable chemical and physical conditions.² Although we remain ignorant of some of the steps in the evolution, we now understand something of the conditions that enabled that evolution to proceed and allowed life to evolve. For one thing, Earth has...

    • 17 Black Smokers from the Deep
      (pp. 242-254)

      The spreading of the lithospheric plates and the production of new crust occur along a global system of ridges, a process accompanied by the intrusion of magma beneath the ridge axis and the eruption of lava on the overlying ocean floor. This magmatic system is a gigantic heat engine that drives the circulation of water through the extensive fracture system in the crust. Cold seawater percolates downward, heats up, and buoyantly rises to complete the convection cell. As it becomes hotter, the water reacts with the rocks, picking up hydrogen sulfide (H2S), iron, manganese, copper, zinc, lead, and other metals,...

    • 18 Some Natural Resources and How They Form
      (pp. 255-272)

      Civilizations use an abundance and a diversity of resources. Modern society demands metals—aluminum, iron, copper, zinc, lead, tin, and so on—to make buildings, pipes, wires, vehicles, and innumerable other products; it exploits clay to make bricks; it needs sulfur to manufacture fertilizer and refine petroleum; it uses oil, coal, and natural gas for energy; it even requires common sand and gravel to construct buildings and highways. The list seems endless. These various resources come from what are known as mineral deposits, and finding them is the business of many geologists.¹ Few outside the profession, however, have the faintest...

  8. NOTES
    (pp. 273-298)
  9. GLOSSARY
    (pp. 299-304)
  10. BIBLIOGRAPHY
    (pp. 305-326)
  11. INDEX
    (pp. 327-336)