A self-guided tour of the geology of the Columbia River Gorge–Portland Airport to Skamania Lodge, Stevenson, Washington (dnr.wa.gov) (PDF)Washington is uniquely positioned for the study of the geologic and structural setting of western North America. To the south in Oregon and Nevada, extensional features predominate as reflected by basin-and-range terrain. To the east, the Rocky Mountains influence the geology of Idaho. To the north, western British Columbia is characterized by a massive coastal crystalline belt and remnants of the geologic continent Wrangellia. All of these major crustal features of the adjacent regions terminate in or near Washington…