The geologic history of the Pacific Northwest is as unique as the region itself. Completely reorganized and revised, the Third Edition of Geology of the Pacific Northwest brings the area’s volcanism, earthquakes, tsunamis, and geologic environmental issues into sharp focus. William and Elizabeth Orr provide a singular perspective and explore the Pacific Northwest writ large, including Southeast Alaska, British Columbia, Washington, Oregon, Idaho, and northern California. Descriptive and detailed photographs of the formations and terranes of each subregion are included, along with color plates that illuminate and expose the fundamental processes that shaped Pacific Northwest geology. The text reveals the geological origins, geographic features, phenomena, and natural resources of areas throughout the region. As urban development continues to expand in the tectonically active Pacific Northwest, environmental concerns and geologic hazards will grow more and more important. The authors’ central theme that continental plate tectonics are the fundamental processes of Northwest geologic history leads to deeper understanding of the region’s geology and new insights in volcanic eruption prediction, disaster preparedness, and the environmental effects of mining.