Nature's Clock: How Scientists Measure the Age of Almost Everything

285 Pages·2008·1.81 MB·English

by  Doug Mcadougall

Nature’s Clocks
The publisher gratefully acknowledges the generous contribution
to this book provided by the General Endowment Fund of the
University of California Press Foundation.
Nature’s Clocks
How Scientists Measure the
Age of Almost Everything
Doug Macdougall
UNIVERSITY OF CALIFORNIA PRESS
Berkeley Los Angeles London
University of California Press, one of the most distinguished uni-
versity presses in the United States, enriches lives around the
world by advancing scholarship in the humanities, social sciences,
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and institutions. For more information, visit www.ucpress.edu.
University of California Press
Berkeley and Los Angeles, California
University of California Press, Ltd.
London, England
© 2008 by The Regents of the University of California
Library of Congress Cataloging-in-Publication Data
Macdougall, J.D., 1944–
Nature’s clocks : how scientists measure the age of almost
everything / Doug Macdougall.
p. cm.
Includes bibliographical references and index.
isbn:978-0-520-24975-2 (cloth : alk. paper)
1. Geochronometry. 2. Geological time.
3. Radioisotopes in geology. I. Title.
qe508. m27 2008
551.7'01—dc22 2007046955
Manufactured in the United States of America
17 16 15 14 13 12 11 10 09 08
10 9 8 7 6 5 4 3 2 1
This book is printed on New Leaf EcoBook 50, a 100% recycled
fiber of which 50% is de-inked post-consumer waste, processed
chlorine-free. EcoBook 50 is acid-free and meets the minimum
requirements of ansi/astm d5634–01 (Permanence of Paper).
For Gustaf Arrhenius, Harmon Craig, Devendra Lal,
andHenry Schwarcz, great teachers all, who kindled
myinterest in isotopes and geochemistry

CONTENTS
List of Illustrations
ix
Acknowledgments
xi
Chapter 1. No Vestige of a Beginning...
1
Chapter 2. Mysterious Rays
21
Chapter 3. Wild Bill’s Quest
45
Chapter 4. Changing Perceptions
72
Chapter 5. Getting the Lead Out
101
Chapter 6. Dating the Boundaries
131
Chapter 7. Clocking Evolution
159
Chapter 8. Ghostly Forests and Mediterranean
Volcanoes
190
Chapter 9. More and More from Less and Less
219
Appendix A. The Geological Time Scale
239
Appendix B. Periodic Table of the Chemical Elements
241
Appendix C. Additional Notes
245
Glossary
251
Resources and Further Reading
257
Index
265
ILLUSTRATIONS
FIGURES
1. Oetzi, the Alpine Iceman 2
2. Sketch of a Rock Outcropping at Jedburgh, Scotland 10
3. The First X-ray Picture 26
4. Willard Libby and Ernie Anderson in Their
Laboratory 54
5. The Radioactive Decay of Carbon-14 56
6. Step Pyramid at Saqqara, Egypt 61
7. Arnold and Libby’s “Curve of Knowns” 66
8. The “Colossal Ghost,” a Dead Bristlecone Pine 83
9. Suess Wiggles in the Radiocarbon Calibration Curve 85
10. Cross-Section at Two Creeks, Wisconsin 93
11. Radiocarbon Dates for North American
Archaeological Sites 96
12. Patterson’s Age of the Earth Graph 114
13. A Fragment of the Allende Meteorite 120
14. Zircon Crystals 125
ix