Archive for the ‘other’ Category

Oakland ochre

24 May 2013

oaklandochre

Here’s the story behind this photo. I just got back from five days in Fresno at the annual meeting of my regional section of the Geological Society of America, the Cordilleran Section. The first order of business was a field trip to see the Pleistocene fossils of the Fairmead Landfill, near Chowchilla. The guy whose hand this is is Blake Bufford, director of the Fossil Discovery Center just across the road from the site. His job is to follow around the giant scrapers at the landfill when they dig new pits and watch for fossils, so he’s the most important pair of eyes in the entire project. Blake showed our group the latest pit and then accompanied us to the Center for a tour and a reception by the FDC’s owners, the San Joaquin Valley Paleontology Foundation. Some nice Madera County wine, local cheese, “mammoth” meat balls and so on.

Blake and I got to talking, and the topic of Oakland came up. He asked if I knew anything about the traditional ochre diggings he had visited there. I told him about the Holy Names site, but that’s not the one he meant. No, he said, this was another place that was in the process of being wiped out to build a supermarket, where both red and yellow ochre were produced. “Let me show it to you.”

The Center is full of fossils, but it also has a little display cabinet dedicated to the people who once had the area to themselves, the Chowchilla tribe. There was an antique woven reed basket, of course, but everything else was a modern replica made with traditional techniques: arrows with interchangeable arrowheads, various kinds of twine, deerbone trowels and scrapers, a tiny wooden flute, necklaces, a soapstone bowl and trade beads, and balls of red and yellow ochre. Blake made all of it. He unlocked the case and showed me everything in it. He made the ochre balls, the size of a small egg, by grinding the stone to powder, then mixing it with boiled soaproot to hold it together. “We don’t know exactly what they used, but this worked.” There were a couple of raw ochre specimens lying next to them. “I collected this one from Oakland,” he said, and I said, “Please let me photograph that.”

MapView: Not ready for Oakland (updated)

11 March 2013

The U.S. Geological Survey’s programmers have made a nifty nationwide map server called MapView that lets you play with geologic maps from most of the country. Naturally I zoomed in on Oakland. I expected to see something like this when I looked at the Toler Heights area.

graymerbit

It’s kinda garish, but it’s from the USGS and as authoritative as these things can be. Instead, MapView shows me this:

dibbleebit

It’s crisp, it’s suitable for colorblind readers, but it’s wildly different. It shows simpler divisions and more limited areas of bedrock. It shows the active trace of the Hayward fault running on the opposite side of the hill from where it actually moves. Then there are things I notice: the names of the rock units have an antique feel and very few faults are mapped. And what’s with the ludicrously small landslide (“Qls”) and serpentinite pod (“sp”) in the middle? Why such a mixture of vagueness and precision?

In fact, this is not a USGS map at all, but a map issued by the Dibblee Foundation. Dibblee is the late and distinguished Tom Dibblee (1911–2004), popularly considered “the greatest geologic mapper who ever lived.” I consider him one of the greatest reconnaissance geologic mappers ever because that was his M.O.: to take his Jeep out to various high spots in poorly mapped territory and sketch out the bedrocks in the landscape onto a map base, then do field-checking until it was ready to publish. His skills were more than just fieldwork; he knew the literature and the community too, both scientific and industrial. I don’t have the talent to question his talent.

But. If you download the map and look at its sources, you’ll see that it’s based on Dibblee’s fieldwork in 1963 and a short return visit in 1977, plus three “preliminary maps” issued by the USGS, one of them in 1967 and all of them superseded by the map I use, Russ Graymer’s USGS Map MF-2342 published in 2000. I can only infer that this map was based on Dibblee’s old field notes as edited, posthumously, by John Minch in his role as official map editor for the Dibblee Foundation. I don’t question his talent, either, but it would be a major undertaking to update this map, one that has not been done.

What’s a few years, you might ask; the rocks never change. Well, consider that this map misplaces the Hayward fault. How do I know? It ignores the experience of Jim Lienkaemper’s meticulous mapping, which checks out in the field wherever I’ve looked. This is from his 1992 compilation of the fault trace and the supporting evidence.

lienkaemperbit

The Dibblee Foundation map is beautiful, but in this respect it is simply wrong. It didn’t go through the rigorous USGS review process; in fact I am confident that if it were submitted it would be rejected.

I’m going to ask the MapView people to reconsider using these maps in preference to USGS maps. For now I have to say that MapView is not curated to my standards.

UPDATE: The MapView administrator responded to me promptly and politely; I’ll excerpt his reply: “the point you raise has been a real concern . . . but [we] didn’t know the entire story nor had we been presented with a clear example of the problem, as you did in your blog. . . Our starting assumption is that newer maps supersede older mapping, and so unless there’s a compelling reason to not do so, we show the newer map. . . . The most effective way to improve upon what’s shown in MapView is for local and regional experts to weigh in with their opinion and experience, as you have done. I sincerely thank you for contacting us, and assure you that we’ll remove the Dibblee Foundation maps in all cases where there isn’t an older map of that scale that is ‘better’.” Translation: We pick maps by their release date and we won’t adjust that until someone squawks.

The other attractive feature of the Dibblee maps is that they’re standard 7.5-minute quadrangles, which makes things much easier for the MapView programmers. But ease of programming is not the same as usefulness.

Oakland powerlines

7 January 2013

Oakland’s infrastructure includes two major powerlines across the hills. One starts from the 1922-vintage substation on Landvale Road (the Claremont Substation) and runs parallel to route 24. The other starts from the vintage substation at Park Boulevard and Grosvenor Place (Substation X) and runs up Indian Gulch, Dimond Canyon and Shepard Canyon. Both of them offer little islands of open land, secret parks, around the support structures.

This idyllic spot, photographed in November, overlooks Indian Gulch between Hollywood Avenue and Glendome Circle.

trestlepowerline

And here’s a view of the Claremont Substation and powerline just east of Lake Temescal, taken in October 2008. This bit of empty land can be reached from the top of Pali Court or by a scramble up from Broadway or another scramble down from the fire road past Swainland Reservoir.

claremontsubstation

Like geologists, powerline operators have a totally different view of the city than most people. I’m a little surprised there aren’t more powerlines here, but two is plenty. (A third, smaller one runs through Oakland lands up Strawberry Canyon from the Cal campus past Grizzly Peak.)

The five-year mark

25 September 2012

thanks

On this day in 2007, I launched Oakland Geology with a photo of what happens when Oaklanders build without geological awareness. Since then I’ve made plenty of posts along the same lines, but geology is not a one-note subject. Most of the time I’ve celebrated what intrigues and tantalizes me about this remarkable city’s natural underpinnings, always with a photo to share.

In 2010 Oakland Geology was named Best Blog about East Bay Rocks. (I really should get myself over there and pick up my plaque.) This week I learned that one of our celebrated local authors, Michael Chabon, cited Oakland Geology in the acknowledgments of his newest book Telegraph Avenue. These are signs of what I always hoped to achieve with the blog: to extend popular awareness of this city’s place in deep time and its deep present, to include our rocks and soils and landforms and geologic forces in the everyday conversation that is constantly weaving our future.

This blog, more than all my other writing, has brought me face to face with interested Oaklanders, who appear to be roused enough by these snippets and snaps to come see me wave my arms, with Powerpoints or vistas behind me, and dump more data on their heads in person. I appreciate your audience and your readership. Long may we continue to wave.

North point

23 August 2011

north point

This is Oakland’s northernmost point, a little wedge of land between Summit Road and Tilden Park. It’s mainly occupied by a large EBMUD water tank and is supposedly underlain by Moraga Formation basalt, though I didn’t see any.

Oakland’s southernmost point is a runway at the airport, a place I expect never to visit, although I’ve certainly flown over it enough times. But that’s artificial fill. The southernmost bit of real land seems to be just north of the San Leandro water treatment plant between the end of Eden Road and Davis Street.

Joseph Le Conte’s grave

17 July 2011

Joseph Le Conte (1823–1901) is probably the most eminent geologist in Mountain View Cemetery. Born in Georgia to a wealthy family, he graduated from the University of Georgia in 1841 and earned an M.D. in New York in 1845. Five years later he gave up his practice in Macon to study geology and zoology at Harvard under Louis Agassiz, earning a B.S. in 1851. He then taught geology at three different universities, then endured the Civil War on the losing side, before riding the transcontinental railroad to Oakland in 1869, where he became the first professor of geology at UC Berkeley and his brother John the acting president, later a professor of physics. He spent the rest of his life here. The Cal paleo museum has a page about his role during this time. A much longer memoir, by Cal botanist Eugene Hilgard, was published by the National Academy of Sciences in 1907 and is fascinating reading.

In 1870 he first visited the Sierra Nevada, a six-week excursion on horseback, and traveled the West extensively thereafter. He moved with his family to Berkeley in 1874; “He always greatly admired and enjoyed the site of the university and town,” Hilgard says. The next year he was elected to the National Academy of Sciences. Le Conte’s textbook Elements of Geology was published in 1878 and went through four editions before his death. He was a dedicated and brilliant teacher who once said, “We never know any subject perfectly until we teach it.” As a writer, I can relate to that.

He died of heart failure in his beloved Yosemite Valley, which he was showing to his eldest daughter, on 6 July 1901. The funeral was a week later. “Many came from long distances to pay this last tribute of respect to Joseph Le Conte; the regents, faculties, and students of the university, where all activities had been suspended for the day, and a long line of carriages formed an imposing procession, accompanying the body to Mountain View Cemetery, near Oakland, where it was interred alongside of his brother John. A few months later the grave was marked with a large granite boulder procured by the Sierra Club from the vicinity of the camp where he died, in the Yosemite Valley.” So the “Yosemite” engraved on the stone must refer to the place where he died. Among his achievements, Le Conte was a founder of the Sierra Club.

Hilgard wrote of him, “It was Le Conte who through whom the University of California first became known to the outside world as a school and center of science on the western border of the continent; and for a number of years he almost alone kept it in view of the world of science. His presence and connection with the University was largely instrumental in attracting to it other men who otherwise would have hesitated to emigrate from their eastern homes to what was then the outskirts of civilization; and his ceaseless scientific activity acted as a strong stimulus both to his colleagues and to the students coming under his instruction, whose affection and esteem remained with him through life. . . . His modesty and simplicity survived, unscathed, the applause and laudations bestowed upon him, and his strong will and cheerful disposition carried him up to a mature age in undiminished mental vigor, despite an apparently frail body.”

Suiseki 2011

19 June 2011

This weekend was the 16th annual show by the California Suiseki Society, held at the Lakeside Garden Center. This is what it looked like.

suiseki

In my amateur opinion, it was a strong show with a lot of variety in its 35–40 stones. Nearly all the entries were from California with a heavy emphasis on the northern Coast Range. The photos below are a few of the stones that impressed me—but there were many more that were too hard to photograph well. Unlike last year, the exhibitors picked a background paper with a color that seemed a little too intrusive to me. But you’ll see how my camera did. I’m not going to comment on the styles of the suiseki because I’d surely botch them. But the rocks themselves are generally familiar stuff, like this dark slate.

suiseki

I’m always taken with the serpentinite conglomerate of which there are several excellent examples each year.

serpentinite

This blue-green Klamath serpentinite is by Tony Saraceno. I have a nice streamworn boulder of it at About.com. That’s not a suiseki, just a specimen.

peridotite

This one is by Tom Colby. Not everyone filled out their cards, but I like to acknowledge the collectors when I can.

suiseki

Felix Rivera collected this nice serpentinite. He’s the founder of the society; see his site at felixrivera-suiseki.com where the society’s home page lives.

suiseki

And Bob & Polly Gould exhibited this exquisitely weathered marble from Southern California. At least, I think it’s marble. Doesn’t matter.

suiseki

Look for the next show in mid-June 2012, right here in Oakland.


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