Rosario Beach

Rosario Beach lies just north of Bowman Bay.  It's a smaller pocket beach, the southern portion of which lies in the State Park.  I've posted from here before (September 2009), but the purpose of this entry is mainly to provide a counterpoint to the previous post from Bowman Bay.


The Walla Walla University marine research station lies immediately north of the park.  As at Bowman, they have had recent erosion problems, but the setting and the history are a little different.  At the far end there is an eroding bank and there are also facilities vulnerable to storm damage.  The closer end is a low lawn, perhaps fill across the historical backshore.  High tide storms likely throw both water and logs up and over the berm and back toward the buildings -- erosion in itself may not have been a problem, but overtopping certainly was.


The solution that emerged is an interesting example of the kind of hybrid structure we are increasingly seeing on the Sound.  There's some large rock, a row of logs, and an artificial berm or dune. I suspect the latter is actually the most useful element of this project, since it adds elevation and will likely reduce overtopping. I'm a little more skeptical about the purpose or the utility of the rock and the logs (they provide a sense of security, if nothing else), but regardless, the result is a naturalistic approach that provides benefits during storms while maintaining the basic character of the beach.  It will look great when the dune grass grows in and the natural logs begin to obscure boulders.


AERIAL VIEW

Bowman Bay

The landslide at Cama Beach, combined with the realities of work and home, meant that that this post and the next have been stuck in my drafts folder for over two weeks. These two posts are from two pocket beaches on Fidalgo Island, just northwest of Deception Pass. Although both beaches tell many stories, these entries focus on recent efforts to deal with erosion control.


At the north end of Bowman Bay, the beach lies at the base of a gradual slope, but at the south end, it forms a barrier with a wetland behind it.  The wetland used to be larger, but historic development led to filling of the central portion of this area.  It appears that this fill was placed out across the backshore, which maximized upland real estate (for the state fish hatchery that used to occupy the site), but created a shoreline subject to erosion where a stable beach may have existed before.


For decades, the resulting bank had eroded, despite efforts to armor it with riprap and old concrete.  This erosion was a very real problem, but one likely attributable to the placement of the historic fill.  If there were homes or a railroad or a nuclear power plant built on edge, perhaps the only viable option would be to further armor the bank.  But here, what is threatened is a narrow strip of a large poorly drained lawn.  Not to trivialize the task, but pulling back the waterward edge of the fill might simply eliminate the erosion problem while creating a natural and much more enjoyable beach.


This recent effort to address the erosion focused on improving the ragged armor that was previously on the site.  It's an engineering fix focused on the integrity of the rock structure, not the underlying cause of the erosion nor, unfortunately, the recreational potential of the beach.  Technically, the solution may be fine.  It was probably less expensive and bureaucratically simpler than other options.  But it's also a missed opportunity (but not a lost one).


The north end of the beach, up near the old CCC shelters and the campground, offers a wonderful template for the eventual future of this central segment. 

AERIAL VIEW


Just to show that blogging naturalists can visit the same site, yet find completely different things to marvel at, you might check out Wild Fidalgo:  The Robins of Bowman Bay (also posted today).  Check out Dave's other blog,  Fidalgo Island Crossings, too.

Cama Beach

I went back to Cama Beach Saturday morning to see how the landslide was evolving.  It's hard to tell how much new material is being added from the headwall, although small chunks kept falling during my visit.  The debris in the gully has continued moving on down to the beach, with new trees and large blocks of till perched on top.


AERIAL VIEW

The landslide itself is interesting enough - but I think I am most curious about how the beach responds to the slide.  The debris cone at the base projects out onto the beach, acting like a groin, and has resulted in the accumulation of a small wedge of beach up against the southern side of the landslide debris.  Some of this new material may be beach sediment from the south, while some is derived directly from the eroding toe of the slide.  Most wave action here comes from the south.  While I was on site today, a gentle northerly breeze gradually gave rise to stronger southerly waves over a period of several hours.



Fine grained sediment is being winnowed from the toe of the slide during high tides and moved way in suspension - there is turbid water along the water's edge and extending in a plume offshore.  What is less clear is how the coarser fraction - sand and gravel - is moving.  We'll watch this, qualitatively at least, over the next weeks and months to see if it leads any noticeable change in beach profiles or sediment texture in the vicinity.


The headwall of the slide remains scary, with the loud thump of falling blocks of till reminding me to stay back from the edge.  Too much is still moving and there are some significant overhangs.


I've posted more photos of the landslide at:
Photos:  March 7th
Photos:  March 17th


It was raining when I left Seattle shortly after 7:00.  It was slushing in Marysville.  But it stopped by the time I got to Cama.  And then the sun gradually worked its way out from behind the clouds. I posted some less geologic pictures at hshipman, for those less interested in landslides and dirt and more interested in new places to enjoy coffee and scones while overlooking the beach.

Cama Beach

Along the high bluffs north of Cama Beach, there is a deep box canyon cut back into the till.  The upper end was pretty spooky when I first visited it in the 1990s, with vertical till cliffs on three sides, but a small window in the till at the base of the head wall offered a glimpse of the underlying fluvial sands.  At the beach at the base of the ravine, there was a block of hardened debris that suggested some sort of big slide in the past.


There was a slide in the canyon last year - you can actually see the toe on the beach in the 2011 Google image linked at the bottom of this post.  And then during the past couple of weeks, more material began sliding out of the canyon and onto the beach.  


I estimated close to 1000 cubic yards of debris on the beach and an awful lot still in the ravine.  Water flowing across the edges of the debris cone were depositing soft fans of sand, but the bulk of the slide was remarkably firm and dry and appeared to have arrived in an avalanche of fairly dry material.  Most of the surface of the slide consisted of sandy material, but there were also large angular blocks (some 1-2 meters across) of till.





The source of the slide was massive failures in the high cliffs at the head of the canyon.  Water was cascading from the forested surface (perhaps 140-150' above the beach?) down the face of the till - as I recall, the canyon coincides with a low point in the upland topography and may be drainage related.  I couldn't get close enough to see if there was seepage from within the fluvial sediments themselves.  Given the most recent failure last night, despite the lack of rain, and the current character of the steep cliffs at the head of the slope, I suspect additional large failures are likely.


The geology along these bluffs consists of till draped down over the seaward edge of the older flat-lying fluvial beds.  In places the till comes all the way to to the beach, yet at the head of the slide, the till appears to be just 10-15' thick on top of the very thick sandy unit.  You can sort of see this if you blow up the photo looking up the slope.


This is a fairly quick account - I'm sure I'll check back on this one -- and maybe the story will become a little clearer.


ADDENDUM:  Here's a link to a cool video taken last week (not by me) - before the big stuff came down.
Landslide @ Cama


AERIAL VIEW

Wolf Bauer

West Point 2004

Golden Gardens 2011

Seacrest 2011

Brackett's Landing 2009

Ambleside 2011

Tolmie 2009

West Point 2010

Birch Bay 2010 

24 February 2012

Wolf,

As you begin your second century, I wanted to remind you of what an amazing difference you have made for Puget Sound shorelines and for the people who visit them.

You were instrumental in raising awareness of shorelines and in creating a demand for shoreline protection.  Today, it’s easy to take our beautiful beaches for granted, but without the amazing efforts of you and others in the early 1970s, this place would be a very unattractive place.  Your language and your ideas have remained lasting elements of Shoreline Master Programs across the state.

You described accretion beaches as an endangered species.  At the time, you may have doubted our progress, and it’s true that we have lost some special places.  But thanks to your work, many remain intact and more are becoming public.  Lily Point on Point Roberts is now a county park.

In the 1980s you spoke adamantly of the need to restore our urban beaches and to enhance the public’s shoreline experience.  But you did not just talk about it, you gave us examples.  Today, we have examples everywhere: in Seattle, Tacoma, Bremerton, and elsewhere.  And there are a new generation of projects such as the Sculpture Park Beach in Seattle and Marine Park in Fairhaven that were inspired by your example and carried out by impassioned individuals who had learned from you.

People enjoy our most spectacular urban beaches, yet many do not realize that these places were once buried in riprap and would be still were it not for your efforts.  People love the beaches at Discovery Park, Golden Gardens, Birch Bay, West Vancouver, and Tolmie State Park.  They think these places have always been this nice!

This year, we are mapping feeder bluffs throughout the Sound – the feeder bluffs that you taught us were such a critical element of the shore-process corridor.  Also this year, I was approached about what to do about salt marshes choked with cut logs from decades of sloppy log-rafting practices.  I jumped at the chance to share your presentation on this subject from almost two decades ago.

Increasingly, parks managers and and government regulators and fish biologists are looking for opportunities to restore beaches and to put sediment back into the system, not lock it away behind walls of rock.  People still build bulkheads, but doing so is widely discouraged and is increasingly difficult. In some places we are actually pulling seawalls off the beach and removing riprap from our spits.

Your legacy runs deep on Puget Sound and our shorelines are far, far better places today than they ever would have been without your incredible passion and your tireless commitment.

Thank you,

Hugh

NOTE:  Wolf turned 100 on February 24th. These photos, most taken recently, are all nourished beaches designed by Wolf in the 1970s and 1980s. Their captions link (in most cases) to previous posts on those places. Previous Gravel Beach posts mentioning Wolf can be found at:  Bauer Posts.

West Point

On Saturday afternoon, the north and south shores of West Point were very different places.  A strong south wind was hammering South Beach.  The waves wrapped tightly around the riprap at the lighthouse, rapidly transforming into much more gentle westerly waves breaking along the sandy North Beach.  Well, sandy at least until it vanishes below the enormous rock revetment that cuts off the beach in the vicinity of the old tidal inlet.

The south bluffs in Discovery Park have been active this winter - there was dirt sliding over the Olympia beds from above even as I watched - and it wasn't even raining.  It's interesting to contrast the photo with ones taken two winters ago  (November 2009; February 2010).  There's also been fresh sliding on the north side where the riprapped spit merges with the bluff, toppling trees and spilling mud onto the beach.

Last year I chose West Point for a photo essay that was posted on the Coastal Care website:
      Coastal Care - Beach of the Month - November 2010

By the way, this is a fantastic website for people interested in understanding and protecting shorelines. The organization has an international scope, highlights a wide range of coastal issues, and hosts hundreds of great photos.


AERIAL VIEW (Google Maps)
Another AERIAL VIEW (Department of Ecology 2006 Aerial Photo)
(I'm not sure yet whether this second link will always work as predicted)

West Beach

The Hastie Lake boat launch is built on a depositional beach - in this case, a small spit that interrupts a long stretch of high bluffs.  Of course, it's hard to tell it's a spit beneath the asphalt, the riprap, and the houses.  There are more photos of the area in the preceding post and at:  Hastie Lake: Nov 2011.


The spit terminates about a quarter mile north of the boat ramp and the bluff begins to rise again.  The till gradually emerges above beach level and the bluffs continue to get higher.  Continuing north, the bottom of the till finally appears and the underlying stratified sediments emerge.  A few hundred feet farther north and the entire lower bluff consists of Whidbey Formation and the till, if it remains at all, is much thinner and much higher in the sequence.


Gerry Thorsen first called my attention to the distinct dogleg in the bluffs at the point where the till rises above the beach.  The till resists erosion south of the point much better than the Whidbey Formation to the north.  This is a nice example of how lithology at beach level can influence erosion rates.  It is not the only factor - wave exposure and beach character are both important, too.


The Whidbey Formation - imagine rivers flowing north across a broad floodplain towards a long-gone delta somewhere in the Strait of Juan de Fuca about 100,000 years ago - makes up a bulk of the bluffs to the north all the way to Swan Lake.  The bluffs rise to upwards of 250', higher if you include the perched dunes along the top edge of these bluffs (most now bulldozed for home sites).  Perched dunes, in case you weren't paying attention two years ago in Michigan (Grand Sable Dunes:  June 2010), are dunes formed by sand blown up and over the top of sandy bluffs.


AERIAL VIEW


Air Photo Note.  The Department of Ecology has just upgraded it's online coastal Atlas and air photo site.  You can find it at:
Washington State Coastal Atlas


It takes a little learning to navigate, but it is an incredibly powerful site, with a number of useful tools.  One feature, that I have long wanted, is the ability to link to individual photos.  I'll be looking for new ways to link between the blog and the Atlas in coming months.


Here's a link to a photo of the dogleg north of Hastie Lake:  2006 PHOTO

Hastie Lake

It's not unusual on Puget Sound beaches, particularly on the west side of Whidbey Island, to find maroon and black streaked sands on the uppermost beach face.  They are often just an extremely thin layer and appear to be left by the highest reaches of the swash in sandy areas. These are basically small placer deposits, where wave action (and sometimes wind?) has separated out slightly heavier minerals from lighter ones.  I believe the red grains are probably garnet.  I'm not sure what the black ones are - hornblende, magnetite (I didn't have a hand lens and even if I had, it's been a long time since I took mineralogy).

Most of this southern portion of West Beach - the general name for this northwestern shore of Whidbey Island, - consists of high bluffs, but here the upland surface drops toward sea level.  The county boat launch and the small development immediately north (Whitecap Lane) are actually on a small spit that extends another quarter mile to the north.  At low tide, and in years when beach sediment is thin, there is a well displayed peat bed on the beach containing lots of intact wood.  It is probably the remnant marsh from when the barrier lay farther offshore.  A little farther north at Swan Lake, similar peat has been dated to about 2000 years ago.

AERIAL VIEW


I was last here on Veteran's Day (Hastie Lake: November 2011), listening to the wind howl and watching the waves. Today is very different.

Lagoon Point

I lingered at Sound Waters through lunch time, but then headed out to enjoy an amazing February afternoon.


Lagoon Point is a relatively large barrier beach on the west side of Whidbey Island.  Old maps show a tidal inlet near the south end and a large salt marsh.  In 1970, the bulldozers were hard at work dredging channels in the marsh and using the resulting dirt to build finger peninsulas.  A mini-Venice, where everyone gets waterfront and their own moorage.  In 1971 folks started writing laws to prevent this kind of thing.

The water was calm and their were several fishermen and a bald eagle fishing from the beach.  The beach on the southern limb of Lagoon Point looked like it had been planed off (it was almost flat), perhaps in one of the season's early storms, and now there was a swash berm trying to rebuild the profile.

I walked south for a mile or so to the northern end of the smaller barrier south of Lagoon Point.  I had recently run into an old Wolf Bauer photograph of a log-choked lagoon and thought it was probably this one -- it was.  This photo is an attempt to recreate Bauer's shot from 40 years earlier.  Things don't look much different.  The logs are all still there - they rot slowly and there's no mechanism to release them once they become trapped in the lagoon.

The short stretch of beach between the two barriers is backed by a 60-80' high bluff of Vashon Till.  Till is a poorly sorted mixture of sediment sizes that has been compacted by the ice into something that often resembles concrete.  As a result, it tends to stand in vertical faces and often erodes through the failures of large slabs.  Boulders from the eroding till were scattered over the beach.  And more boulders, some very large, could be seen jutting out from the bluff face, waiting to join the others.





Unlike the gravelly sand beaches of the barriers themselves, this stretch of beach was all coarse gravel and cobble.  The source of the coarse material is no mystery, given the till bluff.  But why no sand?  It is possible that it is simply buried under the coarser armor layer - as is often the case.  Or is it related to the fact that this is a cove between two points and nature for some reason prefers to stack the finer material on either side.  Conventional coastal geomorphology suggests that just the opposite should occur, but in these mixed sediment systems with highly oblique wave action, conventional often doesn't work.

AERIAL VIEW

Possession

Boat ramps are nice meters of changing beach profiles.  Presumably, this ramp was originally built at beach grade - or at least at something close to typical summertime grade.  But the beach has continued to accrete and now the ramp is a foot or more below grade.  Which means that left alone, there would be a foot of gravelly sand on top of the ramp.  Which sort of negates the purpose of the ramp.  To keep the ramp clear probably requires near constant excavation and re-excavation with a loader.  Here, and at other ramps in similar predicaments, the result is often growing piles of gravel on both sides of the ramp, portions of which gradually erode back onto the beach, sometimes to simply rebury the ramp.




This morning there were two large piles of gravel down the beach - downdrift that is.  This boat ramp maintenance project has become a bypass operation, much like dredging sediment from a shoaling inlet and placing it on the downdrift beach. The concept is good but the level of disturbance (and effort) it creates for a small boat ramp seems awfully high.




There are probably dozens of these high maintenance ramps on the Sound, but a few that come to mind are Lighthouse Park on Point Roberts, Camano Island State Park, Port Hadlock, Kayak Point, and Phil Simon Park in Langley.


The best solution might be to raise the ramp to match the new beach grade, but that would be expensive.  And of course, the flip side of this problem is that when groins are built too high, or when they are built on eroding beaches, they increasingly begin to act like small groins.

AERIAL VIEW