Washington and Oregon, like most of the continent, is nearly all pre-Cenozoic rock, older than 66 million years. The exception is southwestern Washington and Oregon, which has virtually no pre-Cenozoic strata. This is the Columbia Embayment, a large indentation into the North American continent characterized by oceanic crust covered by thick sedimentary deposits. ("Embayment" is perhaps a misleading term, in that it suggests a bowing of a coast line, which only seems so in the context of the modern coast. In the geological past, the coast of North America was in Idaho and Nevada, as will be described later.) The Columbia Embayment is of interest here because its northern margin is approximately delineated by the OWL. The variations are mainly in the region of the CLEW, where sediments are buried under the basalts of the Columbia Basin, and in Puget Sound, where the Cenozoic geology extends as far north as Vancouver Island. Whether the OWL might reflect a deeper crustal boundary has been questioned by geophysical studies which may – or may not – see the characteristics expected of such a boundary. The southern edge of the Columbia Embayment is along a line from the Klamath Mountains on the Oregon coast to a point in the Blue Mountains just east of the Wallula Gap. Unlike the OWL, this line has little topographical expression, and aside from the Hite Fault System is not associated with any major fault systems. But mapping of gravitational anomalies shows a definite lineament, some 700 km (about 400 miles) long, called the Klamath-Blue Mountain Lineament (KBML). This lineament is of interest here because of the possibility it was formerly conjugate with OWL, discussed in the next section. Oregon rotation Rotation of the Earth's crust around the U.S. state of Oregon has been inferred from geodesy, paleomagnetism and other measurements. The Oregon Coast Range fault block rotates around a point in Washington State. The rotational geologic pole for right-lateral faults and seismicity lineations in western Washington and Oregon is Measurements of paleomagnetism (the record of the direction the rock was pointed when it cooled) from a variety of sites in the Coast Range – from the Klamath Mountains to the Olympic Peninsula – consistently measure clockwise rotations of 50 to 70 degrees. (See map, below.) One interpretation of this is that western Oregon and southwestern Washington have swung as a rigid block about a pivot point at