Book excerpt: The introductory section of the book has an overview of the geology of the Pacific Northwest to give the necessary background and context for understanding the origin and evolution of large-scale landscapes. The Theory of Plate Tectonics revolutionized every aspect of earth science when it was formulated in the 1960s. This great unifying theory gave us a conceptual understanding of the origin and evolution of the major features of the continents and ocean basins. Throughout most of geological time archipelagos and microcontinents (the building blocks) have accreted to continents and continents have broken apart by rifting. Few continental margins of the Earth have been as affected by these processes as the American West. The Introduction also includes a timeline for the important events through geologic time and an overview of the common rocks and minerals of Idaho. Part two features geologic provinces and major rock types occurring in Idaho, and in many cases, extending over other States in the American West. Geologically significant landforms and features are scattered throughout Idaho and adjacent states. Many of these features are scientifically significant because they are among the best examples of their kind regionally, nationally, and in a few cases, globally. Part three describes water resources and features formed by water. Part four covers lode, placer, and gemstone deposits, using many Idaho examples.Idaho has outstanding examples of almost every type of landform, scientifically significant feature, rock type and mineral deposit. The oldest rocks are more than 2500 million years old and contain a record of many the events that transpired during that vast span of geologic time, including accretion of a significant portion of the Pacific Northwest terranes. During the last 20,000 years, Idaho has experienced major earthquakes, catastrophic floods, huge glacial ice sheets and volcanic eruptions. By visiting these diverse geologic environments, it is possible to develop a broad background in field geology applicable to understanding geology almost anyplace on earth.