still new and not entirely accepted – was called by the author "an outrageous hypothesis". Modern investigation is still largely balked by the immense span of geography involved and lack of continuous structures, the lack of clearly cross-cutting features, and a confusing expression in both rock millions of years old and glacial sediments only 16,000 years old. Geological investigation of a feature begins with determining its structure, composition, age, and relationship with other features. The OWL does not cooperate. It is expressed as an orientation in many elements of diverse structure and compositions, and even as a boundary between areas of differing structure and composition; there is yet no understanding of what kind of feature or process – the "ur-OWL" – could control this. Nor are there particular "OWL" rocks which can be examined and radiometrically dated. We are left with determining its age by looking at its relationship with other features, such as which features overlap or cross-cut other (presumably older) features. In the following sections we will look at several features which might be expected to have some kind of structural relationship with the OWL, and consider what they might tell us about the OWL. Cascade Range The most notable geological feature crossing the OWL is the Cascade Range, raised up in the Pliocene (two to five million years ago) as a result of the Cascadia subduction zone. These mountains are distinctly different on either side of the OWL, the material of the South Cascades being Cenozoic (<66 Ma) volcanic and sedimentary rock, and the North Cascades being much older Paleozoic (hundreds of millions of years) metamorphic and plutonic rocks. It is unknown whether this difference is in any way linked with the OWL, or is simply a coincidental regional difference. Raisz judged the Cascades on the north side of the OWL to be offset about six miles to the west, and similarly for the Blue Mountains, but this is questionable, and similar offsets are not apparent in the older – up to 17 Ma (millions of years) old – Columbia River basalt flows. In general, there are no clear indications of structures offset by the OWL, but neither are there any distinct features crossing the OWL (and older than 17 Ma) that positively demonstrate a lack of offsetting. Straight Creek Fault The Straight Creek Fault (SCF) – just east of Snoqualmie Pass and running nearly due north