This text takes a historical approach to the development of ideas about history. This is particularly evident in the first seven chapters, allowing the reader to recapture the development of major principles and concepts developed by past generations. The authors focus on "how do we know?" as much as "what do we know?", emphasizing concepts, not just information. Three maxims guide the writing: new concepts of time; the universality of irreversible evolutionary changes; and the importance throughout time of ecological interactions between life and the physical world. Most chapters feature a summary time-line that puts the entire sequence of events into a quick visual-reference frame. The text also contains end-of-chapter citations, case studies and chapter summaries. A key chapter suggests some conclusions following from a study of earth history. In this edition, the chapter on evolution and all sections dealing with the history of life have been rewritten, emphasizing the dynamic new ideas that have come out of paleobiology in the past decade. Chapters on Mesozoic and Cenozoic tectonics, particularly material covering the Cordilleran region, have been rewritten to reflect major changes in our understanding of those topics. Developments in paleoclimatology are also included.