The geology of southern New Mexico and west Texas represents over a billion years of earth's history. Evidence of events such as explosive eruptions of great volcanoes, uplift and erosion of ancient mountains, and deposition of sediment in subtropical seas is available for those who know how to read the rocks. This guide for non-specialists not only provides the necessary background for comprehension but also a guide to local features. Part I explains the basic principles of geology, including the origin of rocks, geologic time, rock deformation, and plate tectonics. Part II divides the geologic history of the region into eight major events and illustrates both the rock strata produced by each event and the ancient geography of the era. Part III contains twenty-two field trips to view geologic history, mostly in easily accessible natural outcrops. Natives and visitors alike will find that this clearly written and well-illustrated book contributes to a greater appreciation of the unique landscape of the southwest.