'Radioactivity is like a clock that never needs adjusting,' writes Doug Macdougall. 'It would be hard to design a more reliable timekeeper.' In "Nature's Clocks", Macdougall tells how scientists who were seeking to understand the past arrived at the ingenious techniques they now use to determine the age of objects and organisms. By examining radiocarbon (C-14) dating - the best known of these methods - and several other techniques that geologists use to decode the distant past, Macdougall unwraps the last century's advances, explaining how they reveal the age of our fossil ancestors such as 'Lucy,' the timing of the dinosaurs' extinction, and the precise ages of tiny mineral grains that date from the beginning of the earth's history. In lively and accessible prose, he describes how the science of geochronology has developed and flourished. Relating these advances through the stories of the scientists themselves - James Hutton, William Smith, Arthur Holmes, Ernest Rutherford, Willard Libby, and Clair Patterson - Macdougall shows how they used ingenuity and inspiration to construct one of modern science's most significant accomplishments: a timescale for the earth's evolution and human prehistory.

About the Author

Doug Macdougall is Professor Emeritus of Earth Sciences at Scripps Institution of Oceanography, University of California, San Diego, and currently resides in Edinburgh, Scotland. He is the author of Frozen Earth: The Once and Future Story of Ice Ages (UC Press, 2004) and A Short History of Planet Earth.

Table of 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

Reviews

When most people read about dating an ancient artifact, we think of carbon-14 dating. But as earth scientist Macdougall (Frozen Earth) tells readers, carbon dating works only if the object contains carbon, and then it can't be more than about 50,000 years old. Many other elements are radioactive, allowing, for example, for a potassium-argon dating system of volcanic and Precambrian rocks, and other applications in studying archeology and human evolution. Macdougall says that scientists have used these various radiometric dating systems for research as far-flung as dating the age of the solar system, figuring out when humans immigrated to the North America and when the Neanderthals died out, determining that a huge tsunami was created by a massive earthquake off the Northwest Pacific Coast in 1700 and nailing down the age of the Shroud of Turin (it dates to the Middle Ages, though controversy persists). Science buffs from all fields along with general readers will find this a helpful handbook on how we are now able to travel to the distant past. B&w photos, line drawings, map. (June) Copyright 2008 Reed Business Information.

"A helpful handbook on how we are now able to travel to the distant past."--Publishers Weekly "The heart of the book reveals ingenious science."--Library Journal "For time-conscious readers, Nature's Clocks provides satisfaction beyond measure."--Washington Post Book World

Since the late 1800s, scientists have used "nature's clocks" to measure Earth's age, human beginnings, evolution, and extinctions. In one of the few overviews of geochronology, Macdougall (earth sciences, Univ. of California's Scripps Inst. of Oceanography) looks at fixed dating via decay rates of radioactive isotopes of carbon, uranium, and potassium. He examines relational dating via dendrochronology, ice cores, and stratigraphy. And he tells the stories of the scientists who teased out these techniques with excruciating patience. Although the prose is serviceable rather than soaring, and the opening and closing chapters are slightly unfocused, the heart of the book reveals ingenious science. From assessing zircon crystals in a clean room to measuring greenhouse gases in the ocean, scientists use nature's clocks to clarify the formation and composition of our world. Giving a sense of the scope of early discovery, Macdougall writes, "...in little more than a decade, the prevailing view about the Earth's age had shifted from Lord Kelvin's 20 million years to more than 1.5 billion years." Recommended for public and undergraduate libraries.--Michal Strutin, Santa Clara Univ. Lib., CA Copyright 2008 Reed Business Information.