The impact event that led to the extinction of the dinosaurs was not an isolated occurrence, for, as the foreword writer reminds us, a near-miss with an asteroid occurred in 1996. Erickson, an independent Colorado-based geologist, provides students beginning to study the Earth sciences and general readers with a lucid introduction to the bearers of such planetary impacts and their ongoing role in shaping our solar system. The book features numerous b&w illustrations, including recent photos taken from spacecraft, and a glossary with a pronunciation guide. Annotation c. Book News, Inc., Portland, OR