Author: Doug Macdougall
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
"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.
