Before the Clovis

Today's Peninsula Daily News (front page no less!) reported on an investigation that demonstrated that Carl Gustafson's conclusion in the 1970's, that a spear tip found lodged in a mastodon bone recovered in Sequim, WA, pre-dated the Clovis cultures that were previously thought to have populated North America. The investigation, published in Science, demonstrates once more that the stories we tell ourselves about how Homo sapiens populated North America are probably wrong.

The thing that it made me think of, though, is the phenomenal morphologic change that these pre-Clovis people must have been experiencing at the same time they were sending a spear into a mastodon 13,800 years ago near Sequim. Retreat of the continental glaciers happened just 1000 years previously, and the land was still actively rebounding after bring freed of the massive weight of ice. Between about 14,500 and 13,500 years ago, the sea level relative to the land in the Strait of Juan de Fuca dropped by ~150 m. In other words, EACH YEAR the sea was dropping by almost half a foot on average (see below a sea level curve for the Strait of Juan de Fuca, adapted from Mosher and Hewitt, 2004).

At the time that the mastodon was speared the sea was close to 200 feet lower than it is now, meaning that the shoreline would have extended far out beyond the modern-day Dungeness Spit, Ediz Hook and Protection Island, and that the mastodon's final resting spot would have been hundreds of feet in elevation and miles away from the coast. The Strait of Juan de Fuca would have been a much narrower water body, and Vancouver Island would have been almost within spitting distance of the Olympic Peninsula.

These observations may suggest something about the pre-Clovis people. Were the pre-Clovis people a coastal people in the same way that the Northwest natives are, reliant on marine resources? It is hard to imagine a very stable or productive intertidal ecosystem in an environment of such dramatic sea level change. Or were they inland hunters, relying on the big game that foraged on the post-glacial tundra? I would give a lot to go back and see that landscape...

Consumed by Wood

We have lots of wood around here, and some of it naturally makes it into the marine environment, delivered by flooding rivers and eroding banks. And then sometimes we help it along. Many harbors in the Puget Sound region are finding that they are "polluted" with wood waste. Decades of log rafting and storage in the quiet corners of the Salish Sea coated the bottom with logs, bark, twigs and wood fragments that can be meters thick.

Yesterday I had the opportunity to dive a site slated for a shoreline restoration by the Lower Elwha Klallam Tribe. Its an old log loading ramp - a place where trucks could drive over the water and dump their logs. Here is the site as it looked in 1990:



and here it is in 2009, after most of the over-water structure had been removed by the WA DNR:



Two things struck us as we descended to 60 feet under the surface that historically supported vasts rafts of logs. First, there wasn't a lot living in this environment. In particular, I was struck by the lack of shellfish. There were a few small Dungeness crab, a few monster Red Rock crab, and a Short-Spined sea stars (Pisaster brevispinus). Once we moved out of the major impact area I also spotted a large California cucumber (Parastichopus). In deeper water on some of the logs there were larger Metridium anenomes. But in the substrate itself - nothing that I could detect. No clams, no tube-worms, no amphipods.

Next, that there was an impressive amount of wood waste on the bottom. I could stick my entire arm into the bottom, up to my shoulder, and feel only bark and twigs. Even after being out of commission for 20+ years, there wasn't much sediment deposited on top of this waste. I suspect that the lack of shellfish and other life in the substrate is because there was no substrate - just wood.

We found many old log tags, some marked with the company name, "ITT Rayonier"



A giant Metridium. This one was almost almost a meter high.



One of those big Red Rocks, somehow getting big with nothing to eat? Look at the substrate - the pieces that look like big cornflakes? Those are big chunks of bark covering the bottom.



Big raft chain

Facebook as an oceanographic tool

Today my facebook page was full of accounts, from friends living on Puget Sound proper, of high winds. Here in Port Angeles though it was quite calm, in stark contrast to the apparent wind tunnel effect that turned Admiralty Inlet, just 30 miles away as the crow flies, into a froth of foam and waves. I wasn't there, but I saw the video.

So this told me that this particular wind storm was probably from the south, and while Port Angeles was protected by the mass of the Olympics behind us, Puget Sound was hammered. So, on to the oceanography. The real indicator that this was a region-wide south wind event comes from the tidal gauge in Port Angeles:



Note the little green line at the bottom of the plot - this is the "tidal residual", or the difference between the predicted water level and the actual water level. This is also called "storm surge" - piles of water that move in response to changing atmospheric pressure. Today's residual was almost 50 cm, or over a foot, of extra water - quite a bit when you consider that our normal tidal range is around 8-9 feet.

Now on to the cool part. Where is this extra water coming from? Those strong south winds in Puget Sound were even stronger on the outer coast:



This plot from iWindsurf.com plots wind observations from Destruction Island offshore of the Washington coast. We see high winds - exceeding 50 knots in some cases - blowing w/o pause from the south.

That strong wind pushes water in front of it but the rotation of the earth causes an apparent diversion (the Coriolis "force") of that water mass to the right - into and up the Strait of Juan de Fuca. So, despite the fact that we didn't feel any of today's strong winds, we certainly experienced them as an extra high-tide.

Tides at D-Day

The deeper I dig the more I find the history of my field (loosely defined as some mix of coastal oceanography, coastal geology and benthic ecology) fascinating. It turns out that a major turning point in our understanding of both waves and tides was motivated by World War II, and specifically the need to safely land a huge number of soldiers and equipment on the beach at Normandy.

Physics Today just published a really nice historical summary of tidal predictions, and their link to D-Day. It is a suggested read for the coast nerd. Find it here.

time lapse: accelearated learning

I've always been a believer in using photos to track change - in 2004, newly with the Surfrider Foundation, I kicked off a photo monitoring project focusing on the Elwha shoreline. I am also a natural cheap-skate and find that while I do love to play with expensive scientific equipment, I almost love it more when there are novel ways to measure natural systems with cheap, off-the-shelf kind of stuff. Time-lapse photography can be particularly valuable. Even if it doesn't yield quantitative data, it can help us to generate hypotheses or identify processes that are important over timescales that can be hard to observe directly. I experimented a bit with time lapse using CHDK on my Canon point and shoot, but realized that shooting long time-series would be problematic. Recently I was sent a few PlantCams to use to start collecting time-lapse at various points around the Elwha delta. At $80 each, these cameras are CHEAP and, because they are supposedly waterproof and built specifically for time-lapse outdoors, may be perfect for the sort of quick and dirty timelapse photography we have in mind to try to understand how the coast and delta changes over timescales of weeks to months to years. So just tonight I had the chance to pull the stored photos from the test camera that I put on our roof overlooking P.A. harbor:



Now I know what you may be thinking..."Nice timelapse of a tree". I will get better at aiming, I promise.

Lake Mills Delta

Jumped on an opportunity to visit the Lake Mills delta with Tim Randle of the Bureau of Reclamation and Gary Smillie and Brian Cluer of the National Park Service. Relative to the Lake Aldwell delta, the Lake Mills delta is huge - maybe 3-4 times the area, and seems to be composed of coarser sediment in general. Given that it is the primary trap for most of the sediment production in the watershed this makes sense. Overall it is an astonishing feature to visit. Tim, who had visited a month earlier, was shocked by the amount of change - a shifted river channel, new delta lobes, and a rapidly prograding delta front. It is a landscape in motion, with bigger changes coming over the next year...

A series of photos from the morning...

Drawndown

The latest in a long list of steps to be taken in preparation for dam removal on the elwha river was taken a few weeks ago. the power-houses for both dams were turned off, and the water diverted out of the penstocks feeding the turbines, and through the spillways in the dams themselves. The spillways were also fully opened, lowering the levels of both reservoirs by 10-20 feet. These actions exposed even more of the impressive deltas that have built up at the up-stream ends of Lakes Aldwell and Mills, and, seeing as the sediment of the deltas is the beach building sediment of the coming decade I've taken a few opportunities over the last week or two to view those deltas.




The Lake Aldwell delta, 25 June 2011









The Lake Mills delta 25 June 2011













fine sediments (mostly mud) compressed onto the bedrock side of the reservoir. and check out the logs!














shear scarp at the former water level.













cool stratigraphy exposed by the lowered water level, Lake Aldwell delta