Sunday, October 07, 2007

Normandy Park

Most of the southern shoreline of King County between Seattle and Federal Way is heavily developed and there is little natural shoreline left, but there are still some reaches that haven't been completely lost to bulkheads and lawns. Marine View Park, just north of Des Moines, is a nice beach at the bottom of a nice walk and a big stair tower.

I was impressed by the amount of wood on the beach. One argument is that logs tend to concentrate on those shorelines that aren't armored, since the wide high tide berm is conducive to the stranding of logs (and bulkheaded shorelines make this difficult). So maybe all the wood that normally would have been spread over the 30+ miles of beach between Seattle and Tacoma is right here!

Broad Spit

Dabob Bay is one of those few remaining places on Puget Sound where the forest still seems to dominate the landscape. There are homes and a few oyster operations, and the forest is certainly not original, but there's something special here that's been lost in other places.

We walked down to Broad Spit through fog, drizzle, ferns, and big trees (and bigger stumps). The recurved spit is fed from the bluffs to south and shelters a small lagoon.
The shore is littered with the remains of decaying timber oyster? rafts.

Both here and later, when out at North and South spits (farther north into Tarboo Bay), there were hints that maybe the spits had evolved over time. Spits form, but as sediment accumulates and the shape of the shoreline changes, new spits form. At Broad Spit, this may have allowed a small spit or spits to form on the north side, in the lee of the main spit. At the northern location, it looks like North Spit formed first and South Spit formed later, relegating the former to relic status.

We didn't get over to Long Spit, on the east side of the bay, nor to the spectacular bluffs and landslides that feed it. Maybe next trip - maybe from a boat on a sunny day?

Tuesday, September 18, 2007

Padilla Bay

Too many meetings; not enough beaches. Yesterday's meeting was at the Padilla Bay Reserve, however, so with sandwiches in hand a few of us walked down to the shore at lunch. Padilla Bay is an inactive portion of the much larger Skagit Delta - the Skagit River currently dumps all of its sediment into Skagit Bay between La Conner and Stanwood. Maybe because of the lack of fluvial sedimentation, the tidal flats of Padilla Bay are infested (maybe I should just say thick) with eelgrass (mainly zostera marina, some z. japonica). The bay is the largest single expanse of eelgrass in the Sound, although it is a bit unrepresentative of the narrow, fringing beds that characterize the steep, narrow platforms typical most everywhere else.

The gravel beaches along the edge of the bay are narrow and pretty low energy. As is typical of high-sediment areas around the margins of deltas, the transition from the steeper, gravelly foreshore to the fine-grained flats is pretty high - probably about mid-tide. On exposed beaches without big sediment loadings, the break is typically near MLLW.
I suspect the original gravel beach probably extends down below the fine grained sediment and the eelgrass, though I haven’t actually checked. Presumably as the delta moved into the neighborhood, it basically buried the existing low tide terrace and lower intertidal gravel beach. If the river had stayed, or if it were to come back, the edge of the bay might all eventually turn to salt marsh as the delta front marched north.

This time of year, eelgrass can wash up in thick windrows along the beach – two distinct deposits were evident today, both hopping with amphipods and small flies.

Monday, August 27, 2007

49th Parallel

There is a nice overlook and a trail down to the beach where the big gas-pressurized electric cables cross to Vancouver Island - or so I learned from the sign. Then I walked south to the minimally marked border. I guess anyone who tries to sneak in to the States via Point Roberts is sort of foolish anyway -- it's basically a dead end. I didn't want to do anything to alarm the guys at Homeland Security, so I didn't stray to far into the U.S. Maybe a little, but it was for the sake of photos and geological observations, right?

This is a nice gravel beach with a very broad sandy low-tide terrace (it's basically the outer part of the Fraser Delta). If the causeways have reversed long-term net drift directions, it sure isn't obvious here. There's some evidence of erosion, mainly at the foot of old slides, but for the most part the bluffs looked pretty stable. There's a broad backbeach and large firs growing on the face of the slope. There is a large drainage outfall structure just on the Canadian side of the line with a small stream dribbling out onto the beach.

The Canadian side of the border has big homes hanging over the top of the bluff, but Monument Park on the American side looks like a wonderful forested shoreline. I'll have to visit it some day - but I'll come in from the American side!


In general, I title my posts with place names, but I suppose historical artifacts are another option. If I can called one Bathtubs, I guess I can also call one Wheels. The tire doesn't appear to go with the hub, though they weren't too far away from one another. I wonder if they are Canadian, or they drifted north from the states? (I suspect the former).

English Bluff

English Bluff is the western side of the Point Roberts peninsula. The Canadian side is considerably more built up than the American side (it's basically suburban Vancouver). Homes line both the top and the bottom of the bluff. Amazing variety of bulkheads and foundations. It looks like they're on sewer at least, judging from the manhole covers in the beach.


Point Roberts began as an island in Georgia Strait, but thousands of years of sedimentation has subsequently attached it to North America as the Fraser Delta has engulfed its northern end. Now it's a Canadian peninsula that hangs down into the U.S. Last year I explored the American side (Lighthouse Park and Maple Beach). This year, I checked out the Canadian side.

Tsawwassen, which is an extension of aptly named Delta, B.C., is the site of two major causeways that extend out to the deep water at the edge of Roberts Bank. The first causeway connects to the Deltaport industrial complex, where coal and containers are loaded and unloaded. The second causeway serves the BC Ferry Terminal and extends southwest almost to the waterward extension of the U.S. border.

A gravel beach has formed on the south side of the ferry causeway, maybe from the fill material originally used to build the roadway? A pocket beach has built in the corner formed by the causeway and the original English Bluff shoreline, presumably as a result of northerly transport of material in the lee of this unintentional breakwater.

Monday, July 16, 2007

Lake Bonneville

Back when Puget Sound was covered with ice - the last time, at least - it was much wetter in Utah's Great Basin. The Great Basin was still a great basin, however, with no place for the water to get out. Lake Bonneville reached over 1000 feet in depth before spilling out it's north end into the Snake River valley. The Great Salt Lake is but a small remnant of this once much greater, and much fresher, body of water. The lake left several distinct shorelines and beaches at its margins - as seen in the benches on the hillslope in this picture (hazy due to brush fires).


Six weeks ago I was in New Orleans, not far from where the Mississippi enters the Gulf of Mexico. Almost 3900 miles upstream, in Yellowstone Park, the Firehole and Gibbon Rivers join to form the Madison River. The Madison joins the Jefferson and Gallatin Rivers in Three Forks, Montana, to form the Missouri River, which in turn joins the Mississippi at St. Louis. It's a long way from the hot springs of Yellowstone to the French Quarter.

Sunday, July 08, 2007

Yellowstone Lake

Some of my favorite gravel beaches are these barriers on Yellowstone Lake. I saw them first by accident about a dozen years ago - although my recollection is that the lake level was considerably higher. I believe on that trip, the beaches at the north end were almost submerged, whereas they seemed just the opposite this year. I'll have to see if I have some pictures from back then.

Although the lake is ultimately volcanic in origin - it fills a large part of the Yellowstone Caldera - these beaches are built of glacial sediments. The pictures include the north end near Sedge's Creek, a beach south of Bridge Bay, and a site on the western shore north of West Thumb. Maps and online aerial imagery show many more elegant barriers around the lake, each probably jealously guarded by its own grizzly bear.

Friday, June 29, 2007

Samish Beach

This stretch of spit on Samish Bay has a complicated history, as does the shoreline to the west from which this spit is fed (see May 2006 post). Beach erosion was rapid in the 1980s and early 1990s, leading to bulkhead failures in 1996-1997. A gravel beach was reconstructed in 1998 as an alternative to building more massive walls or placing riprap. The beach continues to look good. Sediment has continued to be lost to the east, as was expected, although at relatively low rates. This past winter's storms (maybe December 14-15th, in particular) reportedly caused significant erosion at the west end and has prompted residents to begin thinking about whether some minor renourishment may be in order.

Thursday, June 28, 2007


Different sizes and shapes of particles behave in different ways on beaches and there are folks (mainly British, I suspect) who have spent their careers looking at ridges of disc-shaped cobbles and bands of spherical pebbles found on shingle (gravel) beaches.

Based on this limited sample of an unusual sediment type, I have found that cast-iron bathtubs on southwest facing gravel-sand beaches in central Puget Sound tend to wind up upside down and are left projecting a few inches above the beach surface. I am not sure if this is generalizable to other types of bathtubs or other types of beaches, but I am absolutely sure this is pretty much irrelevant to just about anything.

Perkins Lane

A dynamic coastal city like Seattle deserves to have a big landslide within site of downtown. Perkins Lane is draped along the southern face of Magnolia Bluff, and has been for some time, although it has drooped with age. By the 1930s, the WPA was installing drain systems to stabilize the slope. It may have helped a little, although Perkins Lane remains possibly the best example of a large deep-seated landslide complex on the Sound - certainly the one most accessible to UW geology classes. Others include Ledgewood on Whidbey, Termination Point on Hood Canal, Sunrise Beach near Olympia, and some wonderful landslides north of Kingston (there are many more).

In 1996, six homes at the eastern end of Perkins Lane began their migration to the sea. It was slow, and even in 2000, the forms of houses were still fairly evident. Last Sunday, the homes were little more than piles of cement and rusty metal. And enough remnants of daily life to remind me that archaeology often begins as a sad story. The plastic high chair tray, for example. I was impressed by large sections of plumbing strewn across the beach and framing compressed between the hillslope and the concrete foundations slabs as if they were in a trash compactor.

Magnolia Bluff

I dropped the family off at SeaTac at 6AM last Sunday morning and then looked for ways to delay the inevitable return to a working weekend. Had coffee on Alki Beach, watched a cruise ship unload at Bell Street, wandered through the Sculpture Park, and then headed out to Magnolia.

There used to be more houses perched along this beach - evidenced by old piles and plumbing and photos. Only a few are left, though those seemed to be suffering from one storm too many. This large boulder still had dirt plastered on top, suggesting it came down fairly recently - probably this winter. Thump. I half expected to find a wicked witch pinned underneath. And I wondered what would have happened if it had come down the slope above one of those houses. I guess that's one reason people aren't allowed to build in places like this anymore.

Thursday, June 14, 2007

Bywater Bay

The Wolfe Property is one of Washington State Parks' best kept secrets. And a wonderful little study in barrier beaches and lagoons. The aerial photo (click on the title of the post) provides some context. A spit, a tombolo, a lagoon, and a forest.

The spit has multiple beach ridges, recent berms curving out from the old one, and an undulating shape. My instinct tells me this is a sign of instability, or at least of highly variable sediment supply. Even the beach south of the spit - at Seven Sisters Road - shows signs of both significant accretion and erosion. There may be both natural variability and a human history to this. Plus, like Shine Tidelands, this site is north of the bridge - so its sediment source has been impacted and the southerly fetch significantly reduced.

Today the beach had thousands of little crabs (maybe more) and dozens of herons (maybe less) - but it was the first day in the field in a long time that I don't recall seeing a bald eagle.

(Turn right at the west end of the bridge, go a mile to Seven Sisters Road, drive down to the parking area, and walk the beach north to the spit. But remember, it's a secret.)

Shine Tidelands

In an earlier post, I mentioned how the Hood Canal Bridge may have modified sediment transport at Salsbury Point at its eastern end. There's no question that the bridge mucked up the beaches at it's western end. The bridge is constructed on a fill that blocks northward drift and buried the southern end of a spit and its associated lagoon. Shine Tidelands is a beach with no sediment source and far less southerly wave action than prior to 1961. The southern end of the spit is riprapped and the beach is a cobble lag - starved of sand and gravel. The marsh is largely intact and remains a bit brackish near the northern end, where you can still see salicornia and the remains of the old drift logs.
We can't make the beach whole - at least not without the bridge sinking again - but we could make it a lot better. Pull the riprap out and get some small gravel and sand back onto the beach at the southern end, remove as much of the old fill as possible and plant native backshore vegetation, and maybe even restore tidal circulation with an inlet nearer the north end.
Today's meeting was exciting - maybe some of this stuff can really happen.

Thursday, June 07, 2007

Butterball Cove

I hadn't walked the beach east from Tolmie State Park in over a decade, so I was a bit apprehensive about doing it with a class. As it turned out, it not only went well, but provided me an opportunity to revisit a site that I had wondered about for years.

In the mid-1990s, a brand new bulkhead was built at the base of the near-vertical bluff just west of Butterball Cove. Shortly afterwards, the bluff collapsed on top of the new wall. I've used a picture of that partially buried seawall for years to show the limitations of a narrow-minded focus on the bluff toe. It turns out that more failures have occurred since then and folks had to take my word that there was indeed a concrete seawall buried deep beneath the dirt and broken trees.
The bluff itself has now been sprayed with gunnite (or shotcrete - are they the same?) and flowers neatly planted across the top. Someday, I suppose the bulkhead will be exhumed by waves - probably much to the surprise of the future owners of the property!

On very rare occasions on Puget Sound, we find Pleistocene sediments so resistant to erosion that they persist as headlands while the adjacent bluff recedes. This prow on the beach at Butterball Cove is one such example - the older iron-stained conglomerate is a natural bulkhead, extending out to a mid-tide. Interesting that on the beach to the west we saw what appeared to be this unit and possibly an underlying one outcropping in shore parallel bands on the beach. Again, not something we observe very often, since it probably requires resistant rock units, limited wave energy, and a minimal veneer of beach sediment.