Preface

Planet Planet Earth was first photographed from space more than 30 years ago by the
astronauts of the Apollo mission. Since then a variety of satellites have given us supernatural eyes in space. With sophisticated sensors we can “see” through clouds,
observe the surface features on the ocean floor, and selectively image temperature,
water vapor, ocean currents, and even patterns of ancient river systems now buried
beneath the sand of the Sahara Desert. New technology has permitted us to penetrate
deep into the interior of our planet and X-ray its internal structure. We can
now “see” hot material in the interior moving in huge convection cells, creating
ocean basins, volcanic islands, and mountain systems.
    With this era of enlightenment comes an increased awareness of how our planet
is continually changing and a fresh awareness of how fragile it is. Earth is a finite
sphere with limited resources, so it is impossible for the population to grow indefinitely.
We may find more oil, gas, and coal by improved detection methods, yet
nature requires more than a million years to concentrate the oil now consumed in
only one year. We have created nuclear waste, yet are unsure how to dispose of it
safely. What can we do about the fact that rivers today transport more agricultural
and industrial waste than natural sediment? Is greenhouse heating real? The answers
to these questions can be found only if we understand Earth’s dynamic systems
with their many interdependent and interconnected components.
    There are two major pathways for the flow of energy and matter on the planet:
(1) the hydrologic system—the circulation of water over Earth’s surface and through
its atmosphere powered by energy from the Sun, and (2) the tectonic system—the
movement of material powered by heat from Earth’s interior. Everything discussed
in this book is related to these unifying themes.
    This web edition of Earth’s Dynamic Systems introduces these systems and will
help students to understand and participate in the solutions to some of these problems.
It is written for students taking their first college course in physical geology
at both two- and four-year schools.

This Edition

This book was rewritten to make it a more effective learning tool.
  • We have reinforced the themes of the book by dividing it into four parts. In Part I, we discuss Earth’s materials and how they are created by geologic systems. In Part II, we discuss the hydrologic system by examining subsystems chapter by chapter. Plate tectonics is the theme of Part III, with separate chapters on divergent, transform, and convergent boundaries, as well as mantle plumes—the subsystems of the tectonic system. In Part IV, we look back and apply the principles learned to see how Earth’s resources formed and just how different our home in space is when compared with other planets. The focus on the hydrologic and tectonic systems is captured in the cover illustrations, which symbolize the energy sources—heat from the Sun and heat from Earth’s interior—that drive our dynamic planet.
  • We have included a series of essays that illustrate the scientific method. We call these summary messages GeoLogic, as we attempt to show the logic behind using simple observations to come to important conclusions about the way Earth works. We have designed illustrations to take students from “seeing” to “understanding.” Another series of highlights are called The State of the Art. In them, we have attempted to distill the important techniques used in modern geology into a few words and couple the them with some of the most spectacular and informative images available today. In these short essays, we show how geologists come to understand the world around us, emphasizing not just “what we know” but “how we know” it as well.
  • We strive to present a new perspective in visualizing geology by using panoramic photographs of the landscape. Panoramic photographs begin each chapter and provide the student with a visual summary of the theme of the chapter.
  • All chapters were checked for accuracy. Special attention was focused on the illustrations so that the student can more fully experience the excitement and satisfaction of visualizing and understanding geology. We have traveled over much of North America and many other parts of the world—including Brazil, Antarctica, Iceland, Mexico, China, Tibet, Australia, Europe, Oman—to take photographs specifically for this book. Photographs not otherwise credited were taken by W. Kenneth Hamblin or Eric H Christiansen.
  • An important element in this edition is the use of new digital topographic maps. The recent release of new data on seafloor and continental topography by defense and other governmental agencies has opened a new window through which we can see the continents and seafloor in a more accurate and detailed fashion than ever before. These colored, shaded relief maps are a visual and intellectual feast for those who carefully study them.
  • The real test of any textbook is how well it helps the student learn. We welcome opinions from students and instructors who have used this book. Please address your comments, criticisms, and suggestions to:

    Eric H Christiansen (eric_christiansen@byu.edu)

    Department of Geological Sciences

    Brigham Young University

    Provo, Utah 84602



    • Web Edition 10.0

    Donate: If you think this book has been useful, please consider donating some funds so that we can continue to offer this open access textbook. We have to pay for web hosting and development as well as for illustrations, page design, photographs, etc. Thanks for any support you can give us!