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

275 Pages·2008·3.22 MB·English

by  Douglas Macdougall

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, one of the most distinguished university
presses in the United States, enriches lives around the world by
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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.
qe 508. 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, and Henry Schwarcz,
great teachers all, who kindled my interest in isotopes and geochemistry
CONTENTS
List of Illustrations
Acknowledgments
Chapter 1. No Vestige of a Beginning …
Chapter 2. Mysterious Rays
Chapter 3. Wild Bill’s Quest
Chapter 4. Changing Perceptions
Chapter 5. Getting the Lead Out
Chapter 6. Dating the Boundaries
Chapter 7. Clocking Evolution
Chapter 8. Ghostly Forests and Mediterranean Volcanoes
Chapter 9. More and More from Less and Less
Appendix A. The Geological Time Scale
Appendix B. Periodic Table of the Chemical Elements
Appendix C. Additional Notes
Glossary
Resources and Further Reading
Index
ILLUSTRATIONS
FIGURES
1. Oetzi, the Alpine Iceman
2. Sketch of a Rock Outcropping at Jedburgh, Scotland
3. The First X-ray Picture
4. Willard Libby and Ernie Anderson in Their Laboratory
5. The Radioactive Decay of Carbon-14
6. Step Pyramid at Saqqara, Egypt
7. Arnold and Libby’s “Curve of Knowns”
8. The “Colossal Ghost,” a Dead Bristlecone Pine
9. Suess Wiggles in the Radiocarbon Calibration Curve
10. Cross-Section at Two Creeks, Wisconsin
11. Radiocarbon Dates for North American Archaeological Sites
12. Patterson’s Age of the Earth Graph
13. A Fragment of the Allende Meteorite
14. Zircon Crystals
15. The Acasta Gneiss
16. William Smith’s Fossils
17. An Ediacaran Fossil
18. Preparing Samples in a Clean Lab
19. The Magnetic Reversal Time Scale
20. An Evolution Time Line
21. A Time Line for Human Evolution
22. A Ghost Forest in Washington State
23. Occurrence Intervals of Large Pacific Northwest Earthquakes
24. Modern Human Migration into Europe
25. Radiocarbon Dating of the Santorini Volcanic Eruption
26. A Mass Spectrometer for Radiometric Dating
27. Bomb-Produced Radiocarbon in the Atmosphere
TABLES
1. A Comparison of Early and Modern Geological Time Scales
2. Principle Dating Methods for the Distant Past