Sinking and rising

Sometimes the changes we can deduce are simple. In geology, not always so. If you visit Jack London Square, you shouldn’t miss Heinold’s First and Last Chance Saloon:

heinolds

The building and its floor are canted, and there’s a step down as you enter. The tilt adds a certain funhouse spice to the smoke-dimmed fixtures and memorabilia. What happened here is that the bar was set on landfill, the kind of early landfill done by Oakland’s first developers using harbor dredgings and other waste. Horse and hands and probably some steam powered the work, and little of that hard effort could be wasted on tamping the muck down to be worthy of the ages. So, imperfectly compacted, the “made land” settled for many years. At the same time, layer after layer of new material was laid around the tipsy little landmark, and now it’s the sunken treasure we enjoy today.

Did the building sink or the land rise? Yes.

Parts of San Francisco have gone through the same history, well south of Market around 10th AvenueStreet. Old sinking marshland, topped with layer after layer of fill added to keep the streets draining properly, have left century-old homes almost half a story below street grade.

On the California coast, much of the land is gradually rising while, over geologic time, the sea rises and falls. The dance of land and sea sometimes enables the sea to cut deeply into the coast, creating wave-cut platforms that perch above the beaches today. In Oakland that sort of topography is either obscured or nonexistent, most likely because the bay shore has never been exposed to Pacific surf.

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6 Responses to “Sinking and rising”

  1. Naomi Schiff Says:

    South of Market: 10th Street, not avenue, I think?
    When I worked on Fifth Street, in the 1970s, there was a 3-story 19th century building at Folsom on the northeast corner, and in the ground floor was a little short-order lunch place. It was referred to by everyone as The Step Down because of the small safety sign painted on the door: “Step Down!” It was about three or four steep little steps below the sidewalk.

  2. Eric Fischer Says:

    Are these the buildings near 10th Street that you are talking about? http://www.flickr.com/photos/walkingsf/4767010516/

  3. Andrew Says:

    That’s one example. Read about more examples here.

  4. Eric Fischer Says:

    Thanks for the explanation! Page 12 of that book has a picture of that same building.

  5. Emma Lyons Says:

    Do you know how far the landfill goes into downtown Oakland? I am considering moving to an apartment right near there, however I am concerned about the stability during an earthquake. Anyone know a good source of spatial data? Thank you.

  6. Andrew Says:

    Emma, the Oakland geologic map on this site shows the artificial fill clearly. Another source, a bit more detailed and printed on paper, would be the Oakland Watershed Map, sold at the Oakland Museum gift shop.

    But any modern engineered building will be designed for the ground it sits upon. In that respect it should not matter where you are. Now if you’re looking at an older building, then you should ask about the retrofitting and maybe even ask if the owner has earthquake insurance. That wouldn’t help you directly, but it would show that the owner is taking earthquakes seriously.

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