DATING DINOSAURS AND OTHER OLD THINGS

Humankind has kept records for only a few thousand of its two million years; scientists (archaeologists, paleontologists, anthropologists) and historians are still finding new ways to read our history and that of the eons that preceded us. The remains include rocks, fossils, and artifacts; there's a variety of dating methods and tools—rock layering, potassium/argon migration, radioactive carbon decay, tree rings—each with its own strengths and limitations. Those in current use, plus some that are still experimental, are described here with examples of their uses. The result is a wide-ranging overview of methods and tools. Objects, time frames, and some of the people involved are also depicted in drawings and photos. Liptak's prose is a little leaden, but serviceable, though her explanations can be skimpy: ``trillion'' is explained, but ``half-life'' is deferred to the glossary, and although potassium/argon dating is described as the major dating clock for dinosaurs, neither word appears in the index. Uneven, then, but since there's little on the subject, it'll make a useful addition to science collections. Glossary; further reading; index. (Nonfiction. 12+)