Sunday, May 16, 2010
Des Moines' South 239th Street ends at a narrow set of public stairs that drop to the beach between waterfront homes and a terraced bluff. There is little sign of the original slope and the shoreline is lined with high seawalls of various histories. This is one of those old communities where I suspect the structures we see today are the 4th or 5th version of something (maybe a timber pile bulkhead) built early in the 20th century.
There isn't much beach left. Maybe it was buried beneath the walls. Maybe the last sources of sediment have long been shut off. Or maybe the beach has just continued to erode, despite the fortresses on the bluff, and 80 years has left little of the original sand and gravel beach. The sediment that used to be here has had ample time to move north and is now trapped half a mile north against the south side of the Des Moines breakwater. At least someone got a nice beach out of all of this.
Wednesday, May 12, 2010
Another freshwater shoreline, although one still influenced by the tides. This spot is really a point bar, not a gravel beach, after all it was formed by the flowing river, not by waves. Today, it was a little hard to believe that this river drains the entire western side of the North Cascades, but given a big fall or spring flood this place might get pretty exciting.
The river here (just upstream of the I-5 bridge north of Mount Vernon) is carefully confined between high levees and riprap. Overbank flooding and channel migration may be the river's natural inclination, but would be messy and inconvenient for the floodplain towns and their rapidly developing subdivisions and commercial strips. I guess we should hope that future floods stick to the script we have provided for them.
Saturday, May 01, 2010
This isn't the first time I've featured the railroad and it won't be the last. Trains only run on a few tens of miles of Puget Sound's beaches, a small fraction of the total, but the railroad grade and its accompanying seawall stand out in a way that a thousand miles of smaller, residential-scale bulkheads do not. The seawall, which is about 100 years old, is elegant - most of it a rock wall with a slight batter that rises 5 feet or so above the highest tides ever recorded around here. Occasional streams emerge through culverts built into the structure. Occasional landslides flow over the tracks and eventually end up on the beach (although the amount of sediment reaching this beach must be far, far lower than historical levels). Of course, there isn't much beach anymore. What there once was is now buried beneath the double track mainline. The only upper beach remaining along the 26 miles stretch from Seattle to Everett is at the occasional stream deltas and cuspate spits that extend seaward of the tracks.
I probably get glimpses of the Duwamish pretty much every week, usually at 55 mph on the way to or from a meeting south of Seattle, but I rarely get a chance to explore. On the other hand, doing so isn't too difficult, since all these shots are taken within a stone's throw of either 99 or I-5. They include the river flowing under the interstate, the river in front of the Tukwila Community Center, and several shots from North Winds Wier, where a large restoration project has recently been done (but where some more work clearly still needs to happen).
The Duwamish is an interesting river with a complex geologic history, especially if you include its major replumbing in the early 20th century.
Last March, I posted some photos from South Park, a little farther down the river:
Duwamish River (March, 2009)