Olympic–Wallowa lineament

The Olympic–Wallowa lineament (OWL) is a series of geologic structures oriented from northwest to southeast for 650 km (400 mi) across Washington and northeast Oregon in the United States, passing through the Seattle area and including notable features east of the Cascade Range such as the Yakima Fold Belt and Wallowa Mountains. It was first reported by cartographer Erwin Raisz in 1945 on a relief map of the continental United States. The origin of this feature in its entirety is not well understood. The Olympic–Wallowa lineament likely predates the Columbia River Basalt Group.