Tuesday, March 13, 2007

Cranberry Lake

This shoreline at the south end of Deception Pass State Park has the best developed dunes of any site on the Sound. The beach is at the northern end of the large littoral cell that extends from Point Partridge. It's a barrier beach that separates Cranberry Lake from the Strait of Juan de Fuca. The gravel continues north, falling off into the deep currents of Deception Pass, but some of the sand is blown inland to form these dunes. Coarse gravel can be found among the dunes, maybe evidence of past overwash by storms or the erosion of the dunes to expose earlier beach deposits. I don't think the wind bloew it there.

Offshore bars are common along West Beach, presumably in part due to the exposure to long-period waves coming down the Strait (muted Pacific swell?). The beach from the park south has experienced significant erosion recently - the logs have been cast up onto the eroding dunes. There is some suggestion that this erosional zone has been moving north over the past several years. West Beach appears susceptible to long periods of erosion and accretion which may be related to plugs of sand and gravel moving north.

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