Exotic rocks

At the 40th Street Cut exhibit, I was speaking with one of the artists, either Keith Evans or Dylan Bolles, and I pointed to these stones and blurted a dumb geologist question that was totally irrelevant to the artwork: “Those aren’t local rocks. Where are they from?”

They are a fairly high-grade schist, something you won’t see anywhere closer than the Sierra foothills, and maybe not even there. But that isn’t important to the art, dammit. Obviously the rocks were picked for their shape and color, to arrange in the symbolic pad under the rising and falling key evoking the Key System and contrasting the mute ground of all life with the mechanical motions of civilization and the metal rails whose relation to the rugged road metal beneath them recapitulates the pounding of hammer on rock that epitomizes Man’s Attitude To Earth——

But Keith (or Dylan) lit up instead. “I got those rocks in Maine,” he said. “They’re musical rocks. You strike them and they ring, like xylophone keys.” So these specific stones allude to the sound dimension of this work, and now you know about it too. You don’t particularly notice at first, but there are soundmaking elements that fill the room with humming tones rather like the lost electric whine of the old streetcar motors.

These guys are on their game.

The 40th Street cut

Apparently there are people besides me wandering my neighborhood and seeing the vanished past. This image comes from the 40th Street Cut blog, the record of an effort to put together an art show inspired by the Piedmont Avenue neighborhood. I have to say these guys know what grabs me.

The Key Route used to cut through the ridge running east of Broadway between Macarthur and CCA (which I’ve called Montgomery ridge, but on an old map it’s called Thermal Hill). This photo shows that cut before the tracks were pulled up and the cut filled in again. If I only had an hour to examine its walls!

The walls of the cut are steep, but there was no bedrock in it—that’s why the cut was made, because the work was easy. The material of the hill is stiff, well-compacted alluvium from a large, ancient fan that has had gulches cut into it by modern streams. Here the ridge was flanked by the two branches of Glen Echo Creek, one running along Broadway from the Claremont golf course and the other coming down from the cemetery grounds. (They join along Richmond Boulevard just north of 30th Street.) There was no danger of landsliding or rockfalls.

Geologists love roadcuts. In this part of Oakland they’re quite rare.

Oh—the 40th Street Cut people are having an opening reception Thursday the 18th, downtown. Details on the blog.

Oakmartre

I’ve kept this photo around for a long time, but I still can’t say exactly why. It reminds me of shots of Montmartre in Paris. It’s looking southeast toward the intersection of Park Boulevard and Chatham Road, which becomes a freeway onramp at this point. The road in the front is a nameless alley that branches off Excelsior Avenue, serving a tiny block of just nine houses.

I guess the shot exemplifies the hidden treasures of Oakland, hundreds of them, visible only to those who go about on foot with their eyes open. Not all of them are about geology. On top of the geologic palimpsest, the land bears another whole layer of human history: streets and lots laid out and partially erased leaving remnants and traces, not all of which can be deciphered. The people who witnessed the changes pass on, and details vanish. It is something like geology, whose story is likened to a newspaper with most of the pages torn out and the rest burned.

The Oakland geologic map

Time to share my geologic map of Oakland, adapted from USGS Miscellaneous Field Studies Map MF-2342. That map covers a much larger area, but I’ve cropped it to Oakland and faded out the neighboring cities. You’ll note the slash of the Hayward fault. Also note how much of the bay shore is fill. Click the photo to access the 2400×2400 version.

I know you’ll enjoy staring at this. To save traffic on my personal site, it would be best for youFeel free to copy the file to your own machine and view it at your leisure.

Happy holidays! By the way, I have a challenging Christmas geo-quiz up on About.com today; answers tomorrow in a separate post, so as not to spoil the experience for latecomers.

Human geomorphology

This clandestine bicycle track in the woods overlooking Montclair seems to be abandoned; there are fallen trees lying across it. I’m assuming that it was used by pedal-pumping kids, because dirt bikes would have been heard for miles around.

It represents a huge amount of work. But that’s our specialty: digging up the ground for purposes far beyond our biological needs. Researchers calculate that human activity, from dam-building to mining and beyond, now surpasses every other single geologic agent in moving stuff around.

Leave the stone alone

Oakland is in an unusual situation. Right now, nobody is exploring Oakland geology, yet the city has a great variety of features worth attention and even celebration. I’d like to see that change, which is one reason I began this blog just over a year ago. Right now, Oaklanders are spreading their attention on fresh culture, the creeks, the government, business, the lake and their houses and families and neighborhoods. People are outdoors—I see them almost everywhere I go—but nearly all of them are either construction crews, joggers or bicyclists. They aren’t there just to BE there. (Maybe I’m not either, strictly speaking, but let’s let that go.) Even if they set out to enjoy some of Oakland’s geology, there are no trails and almost no interpretive exhibits. And even if there were trails, I’m not sure I would favor that because development brings degradation. Let me give an example or two.

Mount Tamalpais, in Marin County, gave rise to mountain biking, starting in the seventies with a close fraternity of obsessive amateurs. Today the sport is an industry that benefits many thousands of people, some of whom—just a relative few—are poor citizens that blaze unsupervised trails and abuse existing ones where they are prohibited. The rocks of north Berkeley, most notably Indian Rock, spawned a lively school of rock climbing starting with the David Brower crowd in the 1930s, and today Berkeley’s public crags are so overrun with exercisers of all ages that visiting for any other purpose is difficult.

All this is just to say that if the geologizers of Oakland are ever to increase in number and sophistication, we have to build in righteous field manners, responsible enthusiasm, at the foundation. For the Oakland amateur, the city’s landscape is as good as a wilderness, and my own practice is evolving toward the wilderness ethic of the Sierra Club: take only pictures, leave only footprints. For some time to come, Oakland geologizing will be, not exactly underground, but unsupervised. And because “to live outside the law you must be honest,” I want to set a personal example of self-restraint.

And so one of my watchwords as I traipse about our streets and slopes is “leave the stone alone.” We aren’t real geologists, with a job to do that requires us to sample and hammer and drill the outcrops. We’re just out there to enjoy and learn, and I believe we should treat Oakland, for the most part, like a park. Everything I show you here in this blog is something I’ve left behind unblemished, so that you can enjoy it just as much.

Suiseki and gongshi—in Oakland?

Sunday I visited the Garden Center in Lakeside Park, including the bonsai garden, an attraction not to be missed. This large gongshi stone ushers you toward the entrance. The photo is from 2005 (click full size), because at the moment the stone has a wire around its waist holding up a small tree. It reminded me too much of a leashed animal, and I hope they remove it soon. Gongshi stones generally come from China, where the art form arose many centuries ago. This one is a white, deformed crystalline limestone that weathered and eroded into its arresting shape. Inside the bonsai garden there are several interesting California stones in various places. They are not quite suiseki, merely decorative rocks. This is a suiseki:

It was collected in California and mounted in its wooden daiza by Lance Plaza for the 2006 suiseki show, in the Garden Center. I’ve enjoyed several of these annual events, but for some reason missed this year’s. Had I gone to San Francisco instead, that very afternoon I could have seen the annual show of the San Francisco suiseki society. But Oakland has a goodly share of suiseki artists, including the bloggers Mas Nakajima and Janet Roth.

These art forms are a braintwister for geologists. We tend to dwell on what the stone says rather than what it is—or is that the other way around?