Book excerpt: This practical guidebook provides a basic grounding in the principles of geology and explains how to apply them. Using this book, readers will be able to figure out whether they are standing on an ancient seafloor, coal swamp, or sand dune. They will be able to determine the geologic hazards in their neighborhood, where to look for fossils and minerals, or where best to drill a water well. In plain English, The Geology Companion sheds light on the processes that shape the earth and how geology affects people in their daily lives.