Sunday, August 02, 2015

Mission Creek


Mission Creek is another small stream mouth with a long history. The old road cut across the mouth of the estuary on a small causeway but in the last couple of years, local groups have worked together to remove the armor and the fill and the creek now flows freely.

AERIAL VIEW

This site is at the south end of Olympia's Priest Point Park and within sight of the Capitol Building and the city's Port Peninsula. There's not much wave energy here on Budd Inlet. The shoreline in the park north of this site consists of a small promontory of Pleistocene gravel that would probably be long gone if the waves were bigger and a salt marsh that has formed without the need for a protective spit.

One the challenges of restoring these small stream mouths - besides the occasional railroad (see previous post) - is their cultural history. These places were probably always important Native American sites. They were low-lying areas with fresh water and easy access to the Sound. And later they were the obvious places for settlers to homestead or to build fishing camps and shingle mills. That means that although restoration may sound good to everyone, it is very difficult to do it without disturbing something of importance to someone.






Lund's Gulch


Meadowdale is one of the several small parks that sit on stream mouths along the railroad between Seattle and Everett. I like to call this stretch the Great Northern Beach, after the railroad that shaped this coastline for so much of the 20th century and which continues today as the BNSF.


Spits are common at the mouths of coastal streams and the one here has been growing the last few years, extending north and then pushing the stream outlet into a narrow channel. These spits tend to grow for a few years, get cut off by the erosion associated with a big stream flood or a big coastal storm, and then do it all over again.

AERIAL VIEW

The creek that flows through Lund's Gulch is one of thousands of small streams that empty into Puget Sound. Very few remain in their natural condition and even in remote parts of the Sound we find that their lower sections have been rechanneled, their estuaries filled, and their mouths funneled through culverts beneath roads and railroads.

This stream drains a small watershed surrounded by dense residential development. The valley itself seems to be in pretty good shape, but generates a lot of sediment, all of which must find its way to the mouth. Unfortunately, the stream's last leg is through a small concrete box culvert that must pass high flows, sediment, fish, and pedestrians - and it can't do these all at the same time.

There is no simple way to enlarge the opening beneath the rails. This problem is shared with many other stream mouths around the Sound and I've always wished their was some strategic approach that could be applied to a suite of these sites - an approach that would fix the stream mouths, improve conditions for fish, and also help improve safe public access to the beach along this dense urban corridor.

Some other stream mouths along the Great Northern Beach:
Carkeek Park (2009)
Boeing Creek (2013)
Picnic Point (2007)
Merrill and Ring (2009)
Howarth Park (2011)

And elsewhere:
Sequalitchew Creek (2010) (on another section of the railroad)
Nellita Creek (2010, 2011)
Seahurst (2009)
Glendale (2009)
Eglon (2007)

Brand new sand bar right at the stream mouth













Monday, July 13, 2015

Baker Beach




Whereas Crissy Field lies just inside the Golden Gate, Baker Beach lies just outside. And as a result, it was about 20 degrees colder! Whereas Crissy Field is an estuarine barrier beach, Baker Beach is more of a pocket beach, tucked in below steep bluffs of serpentinite.

The upscale Sea Cliff neighborhood is perched on the rocky cliffs above the southwest end of the beach - the closest homes isolated from the public by walls and chainlink fence.

AERIAL VIEW


The USGS has produced some beautiful sonar maps of the sea bottom off the Golden Gate, including an amazing field of sand waves in the deeper water offshore of this beach.

Under the Golden Gate Bridge, Dartnell and others, 2006.


This is the last post from my June road trip, which also means I've finally caught up. I've also caught up on my other blog. The road trip generated almost 30 entries on hshipman ("roadtrip2015") - and while there is a little bit of overlap with this one, most of the entries over there aren't beaches.

Crissy Field



Crissy Field is located in San Francisco, just inside the Golden Gate. It's seen major restoration work in the last couple of decades (mainly around 1999-2000, I believe) and has now become an amazing recreational destination. It offers great views of both the bay and the city (and of course, the Golden Gate Bridge) and on a Saturday afternoon in June it was crawling, rolling, jogging, and just plain crowded with visitors, both local and from far away.

AERIAL VIEW

The restoration work included not just the tidal lagoon and marsh, but also the beach and the dunes. For more on the history and restoration of Crissy Field, see this description at the Golden Gate National Recreation Area website.



Saturday, July 11, 2015

Bonneville Salt Flats


Here's yet another post from a place where the notion of beaches is a little fuzzy. The Bonneville Salt Flats are the floor of prehistoric Lake Bonneville. They are higher than the current extent of Great Salt Lake, but much lower than the prehistoric levels of Lake Bonneville. This is a pretty typical dry season view, but in wet periods the flats can flood with a very shallow layer of water, which may qualify the edge of the highway shoulder as a shoreline of some sort. Maybe with wave action, the gravelly shoulder of the road is actually a beach.

AERIAL VIEW

If you look carefully at this photo, you can find a distinct Lake Bonneville shoreline on the mountain slope in the background.

For another shot of Lake Bonneville's shorelines, you might check this post on Gravel Beach:
Lake Bonneville: July 2007

And for more about Lake Bonneville's history and geography, look at this one over on hshipman:
Bear Lake: June 2012

Medano Creek


Shorelines and geomorphology, but instead of coastal processes, the story here is the interaction of fluvial and aeolian processes. The broad San Luis Valley gathers sediment eroded off the surrounding mountain ranges, particularly the San Juan range to the west. Like so many western valleys, this one was once (probably more than once?) filled with a large lake and sand and silt accumulated on its bottom. When the lake dried up, southwesterly winds remobilized the sandy material and blew it across the valley, piling it up against the base of the Sangre de Christo Mountains and creating this large dune field. Storm winds coming down the hill from the east further shapes the dunes, creating the landscape we see today.

AERIAL VIEW

Medano Creek flows out of the Sangre de Christosand is deflected southward when it encounters the dune field. In spring, when it is flowing, it erodes the forward edge of the dunes and carries sand southward into the valley, where it is probably picked up again by the wind when the creek dries up.

The braided nature of the broad shallow creek is a result of its being maxed out with sandy sediment. It was fun to see the channels and riffles shifting around, even over short periods of time, and to watch the rapids surge as the flow fluctuated.


Thursday, July 09, 2015

Grimes Point



It's a little difficult to make out the old shorelines of Lake Lahontan in this photo. I'm sure it would have been better earlier or later in the day when the sun was lower and the shadows more distinct.


Lahontan was a large lake formed during the cooler period that followed the last glaciation and it filled much of the area between the mountains in western Nevada 10,000 years ago.  It lingered at lower levels much later than that and the petroglyphs at Grimes Point are carved into boulders that would have been scattered around the edges of of a shallower lake several thousand years later. Or at least that's how I understand the story.


Gilbert did some classic work on the spits and other landforms that formed on the shores of Lake Bonneville, but I haven't done my homework and don't know how much has been done on the shorelines of Lake Lahontan (although I'm pretty sure shorelines features and beach ridges have been described).


Nevada Beach


Nevada Beach is a long strand of coarse red sand, very different than the landscape at Sand Harbor. It's located at the southeast corner of the lake and appears to be the result of sand moved eastward, possibly from stream sources along the south shore shore of the lake. The backshore is wide and suggests a very long period of sand accumulation (or a lot of human intervention that I'm missing). From the shape of the beach, I assume the dominant wind and waves impacting this stretch are westerlies - it just seems like this shoreline would look very different if northerly wave action was a significant factor.

AERIAL VIEW

As usual, my observations are based on awfully limited experience and virtually no research, so I apologize if I've got the story wrong. All my searches for information on Lake Tahoe beaches went to tourist sites and vacation rentals, not shoreline geomorphology, although I can't imagine that some geologist hasn't found an excuse to spend a summer or two studying these beaches.


Sand Harbor



100 years ago, Sand Harbor was a place to load logs onto boats headed for the mill. Now it's the primary beach access for Nevada's Lake Tahoe State Park. The small bay is actually a pocket beach tucked into the north side of a bouldery point. There is a much broader beach on the south side of the point.  The orientation of the beaches at this northeast corner of the lake - here and just north in Incline Village - matches the large fetch across the 22-mile long lake.


AERIAL VIEW
I love the juxtaposition of the rounded boulders with the deep blue water. The beaches on the lake seem to range from white to pink - which I suppose reflects the variation in the granitic rocks from which they were eroded.


I made a mental note to come back sometime and spend a lot more time exploring the beaches around the rest of the lake. On this trip, I had to stick to a fairly tight schedule and to the east side.





Wednesday, July 08, 2015

Lake Almanor



Lake Almanor is a broad, shallow reservoir south of Mount Lassen, located on the north fork of the Feather River. Lake levels rise and fall through 10-20 feet seasonally depending on the year. The shoreline includes a diversity of landforms, including marshes, low bluffs, and beaches.  On my fairly quick drive down the eastern shore, I caught a few of these.




This post, along with the next several, are from a very nonlinear road trip in June. No route between Seattle and Madison, no matter how contrived, contains all that many beaches (although on some previous trips I've looked pretty hard), so some of the following sites are a little bit of a stretch. But I've noted before that this blog, despite it's title (and subtitle), allows for some flexibility. The common theme is that posts should be based on a relatively specific place and have some relevance to shorelines and/or geology. Which I think these all will.

While this trip only generated a small number of posts here, it did (or soon will) result in two dozen posts on my other blog. For readers of Gravel Beach that are also interested in extended road trips, obscure (and not so obscure) National Parks, state high points, geographic trivia, roadside geology, and glimpses into the peculiar things that float my boat (besides beaches), you might check out hshipman: Road Trip 2015 (in progress - it will be a few days before I catch up over there, too).