Tuesday, December 25, 2012

Stories in the bluffs

To understand the coast, at least in this part of the world, is to understand the soft, easily eroded bluffs that back much of the shoreline. I had the chance to stop by Port williams in Sequim Bay the day before Christmas Eve and, as is often the case while wandering beaches around here, i found myself awestruck by the bluffs. Two things in particular struck me about this site...first, the incredibly complex stratigraphy that given the interpretation of a better observer would have told stories that, I suspect, would go back at least a few million years. Second, this was one of the few places that I've actually seen "erosion notches" recorded in the base of the bluff...these notches are produced by high water and wave action eating away at the base of the bluff and are one of the hypothesized mechanisms of bluff failure...but I haven't really seen them anywhere else. So here are a few pictures from the walk:

A view looking along the bluff back (south) towards the Port Williams boat ramp

Look at that stratigraphy! McHenry for scale.

Notches cut into the base of the bluff...likely a product of the persistent high water of winter combined with wave action generated by the east wind we've been seeing a a bit of lately.

Okay, someone help me with this one. In places where there were pockets of well-sorted sand in the bluffs there were these things...clearly organic, parchment consistency...what are they?

Here they are in situ

a view seaward towards Protection Island from the site.

Tuesday, December 11, 2012

The latest sand deluge hits the beach

While the sand that hit the beach of the Elwha delta this summer was exciting, things really slowed down during the fall, and by October most of it had transported away (for more on this check out our poster from AGU 2012). The autumn beach, at least at my monitoring sites, was almost as cobbly as it had been at the beginning of the year. But perhaps due to the higher flows over the past few weeks (noting, though, that there still hasn't been a flow over 10,000 cfs this winter) and perhaps due in some way to the release of sand and gravel from the lowering of the Glines Canyon dam, the spigot has turned back on. Starting in mid-November a new pulse of sand arrived at the river mouth, this one easily larger, in both area and volumetric extent, than the one associated with Aldwell that flowed to the mouth of the river between April and July of this year. More to come on this, but here are a few panoramic views of the shoreline taken on the east side of the river.

This first shot was taken yesterday, 10 December 2012 at 4:40pm, looking shoreward from a point on my Line 164, about 300 meters east of the river mouth. This is a site I monitor routinely. The photo was taken from just above Mean Lower Low Water.

There was very little sand retained at this site just two weeks ago.

This next shot was taken from atop the berm on the east shore of the river, just upstream from the mouth, at about 4:30 pm.

Its not stunningly obvious given the perspective, but if you look close in the far field of this pano, to the right, you can see the two long shore-perpindicular bars that have built out from the river mouth. Both extend ~100+ meters or more at this point. Both weren't there a month ago, at least anywhere near that length or extent.

And finally, here is a view of the bar built on the west side of the mouth...couldn't pano this one, but this shot was taken at sunset on 10 December, at a water level of about -0.25 m MLLW. I walked out about 100m on to this brand new sand bar and shot this view back towards Place Road