Earth Science: Understanding Environmental Systems
Edgar W. Spencer,
Washington and Lee University
ISBN: 0072341467 Copyright year: 2002
Preface
As we enter the twenty-first century, the need for a better understanding of Earth and the environment in which we live is increasingly apparent. In almost every community, some look to scientists for leadership in explaining the environmental issues society faces on a day-to-day basis. Ultimately, responsibility for making decisions about environmental issues rests with individual citizens and their representatives, few of whom are trained as scientists. Most of the students who enroll in earth science courses do so to satisfy a general education requirement. For many, this will be their only formal college-level science course. This course may be their only opportunity to learn what science is, how scientists go about examining issues, how scientific ideas evolve over time, and why science has been so successful as a way of looking at the world. In addition to providing broad perspectives on science and the environment, earth science courses also establish links between science, economics, politics, and history. For all these reasons, earth science courses are ideal general education courses.
This book is intended for introductory courses that place emphasis on the systems approach to earth science with special attention to the impact these systems have on the environment. It is appropriate for liberal-arts nonmajors with no previous college science or mathematics. By using a systems approach, students gain a better understanding of Earth as a whole, the relationships among processes acting on and inside Earth, and the connections between physical and biological sciences.
Overview
The primary goals of this book are to provide the background the general student needs to understand the way Earth works, how knowledge of Earth relates to the environmental issues confronting our society, and how scientists go about examining these issues. The unifying focus used to achieve these goals is the study of the processes that govern the evolution of Earth and control the operation of its environmental systems.
It is difficult for students to understand the present condition of Earth unless they are familiar with the processes that cause change. The time frame for these changes may vary from relatively short spans to those that take place slowly over thousands or even millions of years. Thus, the time frame in which natural processes bring about change is an important aspect of Earth systems. Slow processes such as those that cause the gradual shifting of continents, the rise of mountains, the formation of new sea floor, and the evolution of living organisms have set the stage for the present Earth. Although these barely perceptible processes continue, we are more acutely aware of changes produced over short time intervals. These include the development of atmospheric storms that can have great impact in a matter of days or even hours. Waves and currents can transform the coast by eroding some areas while depositing sediment in others, and earthquakes and volcanic eruptions can cause widespread changes in a day and can transform regions as the effects continue to accumulate over thousands of years.
Throughout human history, people have adjusted to natural conditions. Thousands of years ago, our ancestors moved south as glaciers gradually covered the northern latitudes. Subsequently, as the ice margin receded, some groups followed it north, eventually crossing from Siberia to North America where they began the settlement of the Americas. During most of the million of years that humans have inhabited Earth, their numbers were not great. They lacked the capability of modifying Earth's systems and surface significantly. But human population has grown exponentially in the last hundred years, and since the industrial revolution, humans have made significant changes to the environment. Both the size of the human population and our ability to alter Earth's environment have increased dramatically during the last few decades. We have constructed road systems that are long enough to reach the moon; extracted and used a large percentage of the total amount of oil and gas on Earth within a few decades; dug millions of miles of trenches for pipes; and connected oceans by canal works. We have stripped the soil from vast areas; modified drainage basins in ways that cause floods; and disposed of toxic waste using methods that endanger our drinking water. Many scientists think it is likely that humans are changing the climate of Earth, but at present, we do not know how fast those changes may take place or how extreme they may be. The last of the virgin forests are being cut down rapidly, causing thousands of animal and plant species to approach the edge of extinction. We do not know the extent to which our own survival is tied to that of other species or to the overall health of the ecosystem. These will be among the most challenging issues facing the current generation of students. How well they will be able to deal with these as scientists, business managers, teachers, politicians, and citizens will depend on how well they understand the nature of the problems, the interdependence and operation of natural systems.
Can we manage Earth's systems without damaging our own environment? Can we understand and live in harmony with the processes that govern the environment? Can we learn how the different parts of Earth systems are interrelated well enough to predict the consequences of our own actions? These are questions all informed individuals, especially scientists and engineers, must try to answer. These are the subjects this book explores and clarifies by examining the character of the solid earth, the oceans, the atmosphere, biological processes, and the ways they are interrelated.
This book provides a basis for understanding natural systems and identifies many of the problems we face as we try to avoid the difficulties caused by natural processes such as volcanic eruptions, earthquakes, and landslides, as well as those created by our own actions.
Features
1. Systems Emphasis. The systems approach emphasizes the relationships among the great variety of processes that affect Earth and its environment. Although the book provides coverage used in earth science courses, emphasis in the first three units is placed on Earth systems, the connections between geology, oceanography, meteorology, and ecology. The physical systems identified by NASA in a book entitled Earth System Science—A Closer View are used as a basis for organization of the systems approach. NASA recognizes three major physical systems, the core-mantle, plate tectonic, and physical climate systems. The close relationships between living organisms and the physical environment are treated through examination of biogeochemical cycles.
2. Major Ecosystems. Close connections exist between the study of the physical and biological aspects of Earth's environments. These connections are emphasized in this book. Chapter 14 provides an introduction to the land surface and the relationship between terrestrial geology and ecosystems. Similar emphasis is given to marine environments in chapter 8 and to coastal environments in chapter 10.
3. The Relationship Between Humans and Their Environment. Not only do natural processes shape the human environment, human activities have become a major influence on natural systems. This theme runs throughout this book, and special attention is given to the relevance of Earth systems for understanding environmental problems.
4. Flexible Organization. The interaction of Earth systems is like a web of interrelationships. Some instructors prefer to begin by looking at Earth as a planet and end by examining details of surface processes. Others prefer to cover topics more familiar to students at the start and end with a large-scale picture of Earth's interior. To accommodate various approaches, this book provides flexible organization. After completion of the Introduction in unit one, the instructor can proceed with other units of the book. However, the author thinks that most students will find later chapters easier to understand after they are more familiar with the recycling of Earth materials, the importance of time in the operation of Earth processes, and major features of Earth and its interior.
5. Chapter Guide. Each chapter begins with a brief introduction that relates the chapter to other parts of the text. The Chapter Guide summarizes the main objectives of the chapter and indicates how the subject matter of the chapter relates to Earth systems.
6. Key Words. Key words are identified in bold-faced print.
7. Case Histories. Where appropriate, case histories of events or localities are used to illustrate principles and demonstrate the relevance of the subject matter. Most students find the concepts presented with a case-history approach interesting and easy to understand and to remember because they can associate them with real situations.
8. Data Banks. Some tables contain files such as soil and climate types that students need to have readily available for reference as they read the text.
9. Summary Points. Summary Points provide a quick review of the most important concepts presented in the chapter.
10. Review Questions. Review questions are included to help students evaluate their mastery of basic materials presented in each chapter and to prepare for tests.
11. Thinking Critically. Thinking Critically questions encourage the student or a class to go beyond the text materials in exploring the relevance of the subject matter to environmental issues.
12. Units of Measure. Both English and SI units of measure are included in the text. Precise conversions are used for measurements that are exact, but approximate and rounded-off conversions are used if exact measurements are unknown.
13. Appendix. The appendixes provide supplementary information about several important subjects that some instructors may wish to include in their courses. Appendix A. Units and Conversions. This appendix contains basic information about units of measure and conversions between English and SI units. Appendix B. Minerals. This appendix explains how to identify minerals by using their physical properties. It contains a chart of physical properties and composition of common rock-forming minerals and common, economically important minerals. Appendix C. Rock Identification. This section contains additional details about common rocks. Appendix D. Topographic and Geologic Maps. This appendix contains a brief explanation of how to read topographic and geologic maps. Appendix E. Star Charts. Students who enjoy identifying stars will find these star charts and information about locating objects in the sky useful. Appendix F. The Periodic Table of Elements.
14. Glossary. The glossary provides brief definitions of the technical terms used throughout the text.
Organization
The organization of this book allows instructors to vary the sequence of coverage. It is organized into four units. Unit three, which covers surficial processes, is subdivided into parts that cover the oceans, the atmosphere, and the land surface.Unit 1 Major Elements of Earth Systems
The introduction defines science and Earth system science, explains how this field came into existence, and provides basic information that students without previous background in earth science will need in order to understand Earth systems. Unit one contains basic information about Earth, the materials that compose it, the time frame in which the processes cause change on Earth, modern ideas about the origin and place of Earth in the solar system, and the model scientists have developed of Earth's interior. This part encourages students to think of Earth as a planet, its place in time and space, and how processes operating deep inside Earth affect the surface and the human environment. Throughout the text, biogeochemical processes and ecology are emphasized in the discussion of Earth environments.Unit 2 The Plate Tectonic System
This unit explains the operation of the plate tectonic system and the way movements in the outer parts of Earth cause earthquakes and volcanic activity that have such profound impacts on the surface. The changes in the way Earth scientists think about Earth have been revolutionary. By examining the history of the development of plate tectonic theory, this unit gives students a better understanding of how hypotheses evolve to become widely accepted theories. Unit 3 Earth's Physical Climate System
This unit includes Earth's surface features and the processes that shape the surface.Part 1 Oceans and Coasts Chapters 8, 9, and 10 examine the oceans, which cover more than 70% of Earth's surface, the character of the ocean basins, the movement of water in the oceans, and the environments in the oceans. These are important components of systems that interact with the atmosphere and land surface. This part also includes the coastal transition zone between the open oceans and the land surface.Part 2 The Atmosphere Chapters 11, 12, and 13 begin with a chapter that defines the composition and structure of the atmosphere. This introductory chapter includes discussions of atmospheric pollution, greenhouse gases, global warming, and the ozone hole. It also provides modern coverage of El Niño and its effects on weather. Part 3 The Land Surface Chapters 14 through 20 examine the terrestrial environment. Terrestrial environments are covered in greater detail than transitional or marine environments because the processes that operate on land environments affect humans more directly. The chapter topics—soil, mass movement, streams, ground water, wind, and ice—resemble those found in conventional Earth Science texts. However, the treatment of these topics emphasizes systems and the relationships of these subjects to the environment. Special attention is given to the hydrologic cycle. Water-supply issues are so widespread and of such great importance that a separate chapter is devoted to this topic.Unit 4 The Solar System and Its Place in the Universe
Unit four examines the place of Earth in the solar system and as part of the universe. These topics, which are first introduced in chapter 4, are developed more fully in unit four for use in courses that have sufficient time for this coverage.
The Supplements Package
Online Learning Center
This website hosts instructor and student tools. The instructor center is password protected and offers topics for classroom discussions, test questions, an image bank, and PowerPoint lecture outlines. Students will find online quizzing, flashcards, additional readings, study tips, and Internet exercises that will enhance the text material and offer a thorough review of the content.PowerWeb
Included within the Online Learning Center, PowerWeb provides access to a course-specific website, developed with the help of instructors teaching the course, to provide instructors and students with curriculum-based materials, updated weekly assessments, informative and timely world news, refereed web links, and much more. You'll get daily news updates and have access to 5,900 research sources through the Internet's most thorough search tool, Northern Light. This differs from the Online Learning Center in that it extends the learning experience beyond the core textbook content into other subject areas. PowerWeb is designed to supplement the text content by offering more outside readings, research opportunities, and more. Digital Content Manager
Free to adopters, this CD-ROM contains illustrations, photos, and lecture outlines that can be imported into PowerPoint, as well as other presentation software, to create your own personalized presentation.Transparencies
One hundred acetate transparencies of key text illustrations are available to qualified adopters.Classroom Testing Software
Test questions are also available on McGraw-Hill testing software, for use with Macintosh and IBM PC computers.
Acknowledgments
It is difficult to emphasize how much this book represents the efforts of many people. I am deeply indebted to my students, colleagues, family, friends, reviewers, and the staff at McGraw-Hill who made the publication of this book possible. In addition to individuals, I am most grateful to the administrators of Washington and Lee University who have provided long-standing support and encouragement of the faculty to pursue their professional interests.
My wife has provided help and supported my work on this book for many years. She and our daughter Shawn prepared many of the illustrations. Our daughter Shannon and her husband Rich Wallace offered suggestions about ways to integrate recent work from fields of environmental studies in the text. Kary Smout, director of the Writing-Across-the-Curriculum program at Washington and Lee University, helped me improve the organization and presentation of ideas throughout the book. Cynthia Abelow, Katherine McAlpine, and Jennifer Strawbridge helped me improve the composition of the manuscript. Kate Metznik, Richard Kilby, Greg Bank, Betty Mitchell, Madelyn Miller, and Linda Davis assisted in editing the manuscript and preparing illustrations. I greatly appreciate the help of the people who assisted me in locating figures, as well as those who granted permission for the use of their illustrations. The reviewers provided constructive criticisms and detailed suggestions for content, organization, depth of treatment, presentation of ideas, and new information. The book has been greatly improved through their efforts. Thomas Arny was especially helpful in reviewing the chapters on astronomy. I appreciate the work of the developmental editor, Lisa Leibold, and the production team, including Rose Koos, Carrie Burger, and Stuart Paterson, who transformed the manuscript into a book.Reviewers
Miguel F. Acevedo University of North Texas
Ray Arvidson. Washington University
DeWayne Backhus Emporia State University
Ray Beiersdorfer Youngstown State University
Stephen K. Boss University of Arkansas
Lawrence W. Braile Purdue University
Walter J. Burke Wheelock College
Wayne F. Canis University of North Alabama
Lindgren L. Chyi University of Akron
James Collier Fort Lewis College
William C. Culver St. Petersburg Junior College
Paul K. Grogger University of Colorado, Colorado Springs
Jack C. Hall University of North Carolina at Wilmington
Darrell Kaufman Northern Arizona University
Michael J. Kirby Johnson State College
Robert Lawrence Oregon State University
Keenan Lee Colorado School of Mines
Michael B. Leite Chadron State College
Kathleen J. Lemke
Peter F. LeRose Mount St. Mary College
Judy Ann Lowman Chaffey College
Constantine Manos State University of New York at New Paltz
R. A. Mason Memorial University of Newfoundland
Barry R. Metz Delaware County Community College
Archie Moore Southern Louisiana University
Dr. Hallan C. Noltimier Ohio State University
Donald J. Perkey University of Alabama in Huntsville
Michael R. Rampino New York University
Max Reams Olivet Nazarene University
Godfrey A. Uzochukwu North Carolina AT&T State University
Anthony J. Vega Clarion University
Charles Todd Watson University of the Ozarks
Edgar Spencer Lexington, Virginia
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2002 McGraw-Hill Higher Education