page_title: Olympic-Wallowa Lineament
section_title: Puget Sound
hierarchical_section_title: Olympic-Wallowa Lineament / Structural relationships with other features / Puget Sound
context_page_description: The Olympic-Wallowa lineament – first reported by cartographer Erwin Raisz in 1945 on a relief map of the continental United States – is a physiographic feature of unknown origin in the state of Washington running approximately from the town of Port Angeles, on the Olympic Peninsula to the Wallowa Mountains of eastern Oregon.
context_section_description: Another notable feature that crosses the OWL is Puget Sound, and it is curious to consider the possible implications of a Puget Sound Fault.  (Such a fault was once proposed on the basis of certain marine seismic data, but the proposal was stiffly rejected, and now seems to have been abandoned.)  Combined terrestrial and bathymetric topography shows a distinct lineament along the west side of Puget Sound from Vashon Island (just north of Tacoma) north to the west side of Holmes Harbor and Saratoga Passage on Whidbey Island (see image).  But at Port Madison (at the red bar in the image) it is split by a distinct offset of several miles.
  Curiously, the southern section lies in the approximate zone of the OWL. (Note OWL–associated lineaments running parallel to the red line.) This suggests dextral offset along a strike-slip fault. But if that is the case then there should be a major fault in the vicinity of Port Madison and crossing to Seattle (perhaps at the Ship Canal, aligned with the red line) – but for this there is even less evidence than there was for the Puget Sound fault.
  The significance of this lineament and its offset is entirely unknown.  That it seems to be expressed in Ice Age (16 Ka) deposits implies a very recent but entirely unknown event; but perhaps these recent deposits are only draped over a much older topography. A recent offset might explain the apparent offsetting of north–south glacial drumlins bisected by the Ship Canal, but is not evident in more eastern segments.
  Alternately – and this would seem very pertinent in regard of the OWL – perhaps some mechanism other than strike-slip faulting creates these lineaments.
caption: The west side of central Puget Sound, Holmes Harbor, and Saratoga Passage forms a lineament (between blue bars) that is offset at Port Madison (red bar).
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