Olympic-Wallowa Lineament - Structural Relationships With Other Features

Structural Relationships With Other Features

A problem in evaluating any hypothesis regarding the OWL is a dearth of evidence. Raisz suggested that the OWL might be a "transcurrent fault" (long strike-slip faults at what are now known to be plate boundaries), but lacked both data and competence to assess it. One of the first speculations that the OWL might be a major geological structure (Wise 1963) – written when the theory of plate tectonics was 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.