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There is something ominous about this place - huge soft flats, huge tide range. No wonder they post warnings about going out on the sand. The beaches are pretty minimal, at least as far as I could tell, in part because the railroad grade and the highway are built right along the edge and in part because the mud and silt are so thick, they pretty much come up to high tide. Maybe there was a beach once upon a time, but now it's buried under all that mud.
We passed along this shoreline four times, twice by car and twice by train, but never timed it right to see the tidal bore - though apparently it hasn't been the same since the bottom dropped out 44 years ago. Too bad, bores are limited to a very few places in the world where tides and topography conspire (Wikipedia).
Seward - another case study in geological hazards. Most of the town is built on the alluvial fan at the base of Lowell Creek. That's good because at least some of the town is out of reach of tsunamis. That's bad because there is no reason to think that the alluvial fan stopped growing when they built the town. As matter of fact, in 1917, Lowell Creek washed out pretty much everything in a big swath along Jefferson Street. But in the 1930s, the clever engineers solved the problem. They put the creek in a tunnel and diverted it to one end of town. I looked at the hole the creek goes down. It's not very big. A debris slide or a gully washer with a few big rocks and trees, and the hole is plugged. The overflow will go right down Jefferson Street, just like in 1917... (okay, so I'm being alarmist, I'm sure those clever engineers anticipated this back in 1930 and planned accordingly).
In 1964, most of Seward's shoreline slid into Resurrection Bay - carrying rail yards, fuel tanks, trains, you name it. The tsunami cleaned up some of the mess. Subsidence repositioned the shoreline. Now there's a strange beach with old piles and debris sticking out of it. The shoreline is now a two mile long RV park and a nice public trail and lots of tsunami warning signs. The Kenai Peninsula is one big study in how quickly beaches can re-establish after mother nature cleans the slate.
This beach is west of Anchorage, near where Cook Inlet splits to form Turnagain Arm and Knik Arm (this beach is on the latter). The tide range is large, the silt load is huge, and the beach was sort of weird. High sandy-gravel bluffs. Sand ripples on a gravel beach with a thin coating of silt on the sand. The ripples appeared to be around mid-tide and I suspect they reflect the role of fast tidal currents along the shore of the point. The silt seems inevitable given the muddy water.
This beach is particularly impressive when a 747 takes off to the north.
A gravel beach with a view across Cook Inlet of Mt. Iliamna. The backshore is wide - extending out in front of the base of the bluff (more place to park RVs). This is another place where I would love to know how the 1964 subsidence affected the shoreline and how the beach responded in the following years and decades.
I chose our lodgings in Homer before doing my pre-trip geology homework. It was only fitting, but highly ironic, that I found I had chosen the center of the local seawall controversy.
The wall is hideous, but as usual, the folks living above it don't have to look at it. And given Alaska's propensity to largesse, they may not have to pay for it either. A fairly small number of property owners get the views and the perception of being one with the environment, but the kharma is all wrong. There is nothing sustainable about this place. What is natural about this place is the eroding bluff, not the static view of the bay from the rampart of an engineered fortress.
The beach is eroding beneath the wall - the underlying till was exposed on the beach in front of the section of the wall that failed this past January. This wall will only get bigger. The wall encourages more investment in bluff top property, not less, so the likelihood of retreating becomes less. I'm all for property rights: the right to buy lemons and accept the consequences of investment choices. The issue of whether you can muck up a public resource or incur public expense to protect property value is not about property rights but something else.
In this case, I think the area of concern is sufficiently small that maybe the expedient solution may a government bailout -- not to build a bigger wall but to buy out the property owners and pull out the wall. Call it Munson Point Park. I can't believe doing this won't be cheaper (and better public policy) than even a decade or two of seawall maintenance and replacement.
There were some interesting twists. Each end of the wall is marked by barrier beaches - a small accretional feature at the updrift Munson Point end and the base of the much larger Homer spit at the downdrift end. The tide range is 20-30 feet, so there are wonderful sand and gravel bars and flats exposed at low tide, sprinkled with some big boulders. As we sometimes see on Puget Sound, high points on the gravel beach along the seawall correspond to the landward end of large tranverse sand bars that extend far offshore. And that may shift down shore fairly quickly - changing the locus of seawall damage from one year to the next.
What an elegant concept - a long, sinuous spit extending out across Kachemak Bay towards the snow covered peaks of the Kenai Range. From the hills above town the concept holds up well. Down on the spit, the elegance of the concept is blurred a little bit by the frontier-style development.
The beaches consist of sand and gravel transported from bluffs along Cook Inlet northeast of town (Bishop's Beach), but the foundation of the spit may be a moraine left by a glacier that once reached this far down Kachemak Bay.
In the 1964 earthquake, the spit, along with most of the Kenai Peninsula, dropped several feet. This pretty much neutralized any dry land on the spit's backshore, so most of the dry ground found today is the consequence of an enormous amount of fill added on top since then.
The spit is a five-mile long riprapped causeway with acres of parking lots, souvenir shops, and fish packing operations, plus a large marina and numerous port facilities. Some of the tourist places and restaurants are on piles hanging over the beach, as are some brand new condos near the tip. There were folks camping all along the beach - one of several scenes that contributed my image of Alaska beaches as gravel backshores lined with RVs.
I'd love to know more about how the shoreline has responded in the 44 years since the earthquake. Subsidence reduced the size of the spit and in the absence of human intervention, would have resulted in the shoreline shifting tens or hundreds of feet landward, but at the same time, subsidence might also have led to dramatic increases in updrift bluff erosion and the potential for a big pulse of new sediment to move towards the spit. I wonder if the multiple gravel berms on the outer face of the spit can be attributed in part to decades of earthquake-induced sediment supply?
The spit was equipped with tsunami sirens, but I doubt most of the folks on the spit would know what to do if they went off. At 3PM on a summer afternoon, as the halibut boats pull in and the gift shops are full and the ferry is unloading, the evacuation might be tricky. By the time people got the awning rolled up and the satellite dish folded away, the RV would already be floating upside down in the marina.
I picked up a copy of John Muir's Travels in Alaska at the lodge and started reading his accounts of visiting Glacier Bay in the 1800s. Everything in these photos was still under thousands of feet of ice at that time. The glacier named after him is now hidden, having retreat far up it's valley (Muir Inlet), and our boat didn't pursue it.
Two glaciers still emerge from the Fairweather Ice Field into the head of Tarr Inlet - the Margerie and the Grand Pacific. The former is the classic calving glacier, a face of blue ice several hundred feet high with relatively little rocky debris except at its margins. The Grand Pacific, at least from this perspective, is an enormous load of dirt being carried to the sea by the ice. It also appears to have retreated far enough so that it is barely qualifies as a tidewater glacier.
As you head up Tarr Inlet, you are following the retreat of the ice. 20 miles from the glacier, the landscape is many decades old, the geology has begun to settle down and the forest has moved in. As you approach the glacial front, the landscape gets younger - alder thickets on highly unstable rocky slopes. And in front of the ice, the land is only freshly exposed and there is no obvious vegetation.
In the photo up the alluvial fan into the mountain valley, you can see sloping lines (they are subtle) in the trees to the right of the stream showing a series of terraces developed as the stream has rapidly cut down into the ravine. The photo of the kayaks on the beach contains an intriguing feature. The beach, although it is a very young feature, is a fairly ordinary gravel beach (as far as I can tell from the boat), but it is backed by a higher terrace - something I did not see widely exposed elsewhere on the inlet. I'm guessing this is a remnant of a backbeach formed many decades ago, after the glacier retreated past this point, but before significant rebound had occurred. It has now been lifted beyond the reach of the waves and tides. In most places, this feature would be eliminated by subsequent erosion, but here it has been preserved - at least for another decade or so until the beach erodes back across it.
