Friday, March 13, 2009
Onamac is one of several similar landforms along the west shore of Camano Island - and such a common type on Puget Sound that I suppose we really need a better name for them. Or a name at all. I might call it an assymetric looped barrier (in private) (title of post links to an aerial view). It's hard to call it a cuspate foreland, or a recurved spit, because those don't quite fit (though they are close) and the more generic names like accretion beach, depositional shoreform, constructional landform, or low point are too broad. We were visiting this private site last week because it's a dead ringer for Kayak Point, a few miles east on the eastern shore of Port Susan. And we needed an analog to explain to the Parks folks the rationale for proposed improvements at Kayak Point.
The high bluff north of Onamac is an impressive perch for a bunch of big homes with outstanding views and an abrupt edge to their lawn. This is also the only place I am aware of on the Sound where we have good evidence for a large landslide that involved both the bluff and the submarine slope. This huge headscarp is matched by an enormous slide block on the bottom of Saratoga Passage (see Whitaker's UW senior thesis). Must have been an exciting ride - and maybe a big splash, too. With better coastal bathymetry, maybe we could identify more of these things.