Abstract
Along the western edge of the Columbia River Plateau, next to the Cascade Mountains, a unique state park has been created. The Ginkgo Petrified Forest State Park, located in the State of Washington, is found in a panorama of hills and plains gashed by dry canyons and watercourses. The dark basalt that underlies the whole area shows up starkly in the cliffs along the many abandoned water channels. Although the water that rushed through long ago is mostly gone now, the story told by the remains is a fantastic one that speaks of major flooding and erosion by broken glacial dams and swollen rivers draining from the margins of the continental glacier.