Had the chance to survey Rialto Beach earlier this week, on the coast of Washington in Olympic National Park, as part of my shoreline morphology monitoring program (which is, by the way, looking for a better name...should you have any ideas). And I decided to post about it because...MAN, WHAT A BEACH! Rialto is so very cool...every time I go out there I am blown away by its morphology and the degree of variability it exhibits.
The first thing you notice at Rialto are logs. Does this beach ever have logs (see photos above)! And these aren't small logs either - these are massive old growth trunks grounded in the upper intertidal. These things are definitely influencing shoreline morphology and evolution...they must be...but exactly how isn't totally clear to me yet.
The next thing that always strikes me about Rialto is the evidence of erosion everywhere...mostly in the form of dead trees:
The odd thing, though, is that based on survey data from the last few years, it doesn't look like Rialto is eroding really at all over shorter, annual, timescales (though it is subject to seasonal variability). That suggests to me the likelihood that this shoreline is pretty subject to erosion related to relatively infrequent El Nino winters, or perhaps the once-or-twice-a-century extreme storms. I know that there have been big changes out there within recent living memory - I would love to hear any stories...
But the other thing I've started to really take note of at Rialto are exposures of what appears to be some base strata that the ocean is cutting into:
It would be interesting to date some of these exposures, and try to work out what they tell us about the evolution of the shoreline on the coast of Washington over longer time-scales.
Finally, I am always blown away by the ocean's power on display at Rialto:
Above, for example, is a photo of a sizeable small boulder wedged into the crook of a root wad, which is itself buried in the beach substrate. Now its entirely possible that this rock travelled with the root wad, but it sure looked like the thing had been forcibly jammed into place, and waves have been known to move bigger. The waves at Rialto always seem more powerful to me as compared to just across the river in La Push, which I've attributed to perhaps the off-shore bathymetry, or the beach orientation. Regardless, this was an indication to me of the forces at work on this beach.