Archive for the ‘other’ Category

New Lake Merritt

12 July 2013

I think it’s safe to say that everyone in town is thrilled with the improvements to Lake Merritt. After seeing the final configuration today, I’m feeling a deep satisfaction.

newlakemerritt

The new roadway and pedestrian bridge over the lake’s outlet serves vehicular traffic as well as ever, but residents and, most of all, the lake and the land get their due. The lake—actually it’s a tidal marsh—is noticeably healthier now that the tidal flow from the bay is no longer regulated with a dam. The range of the tide is greater now and the water is flushed more thoroughly. We have figured out how to trust nature with our lake. We’ll see in the future how the new lake deals with drought and flood, but I think that the city will not overreact to the occasional inundation as it might have in the past.

newlakemerritt2

The new lake is a triumph for the planners of Measure DD, where the money came from. The funds are still being spent on this and many other projects around Oakland, but I’m starting to wonder what the DD crew could do for an encore. Nature holds us in its hand with the Hayward fault, too. Can we envision better ways to live with it?

The gallery of Oakland geological science

31 May 2013

OMCAserp

The Oakland Museum of California has finished its three-years-plus shutdown of the Natural Science gallery; the new Gallery of California Natural Sciences had its grand opening today. I got a backstage look at it earlier this week and gave it a thumbs-up for KQED Science yesterday. For me the highlight is the gateway section of the gallery, all about Oakland. All except for Oakland (and California) geology. As far as geology goes, the museum’s great serpentinite boulder on the roof, shown here in 2000, is still as good as it gets.

You’ll see in the new gallery how Oakland looked 300 years ago: its forests and grasslands and marshes. But you won’t see how it looked 30,000 years ago, or 3 million, or why those times are still relevant today. You won’t get a clue to the underlying framework that explains this landscape, or the deep history encoded there. You won’t see a hint of the active faults that shaped, and continue to shape, our region, nor will you see how they link us to California—how all of California is united—in a tight tectonic embrace. You won’t learn where and why the first Oaklanders dug for stone and gravel and water, or why they stopped. You’ll be able to add your backyard oak to a biome database that maps the ghostly living traces of our original forest—a marvelous thing!—but not your backyard outcrop or neighborhood roadcut.

All those things would have been simple to weave into the plan. The geologic subtheme would have enriched the whole exhibit and made it more truly a natural sciences gallery. Instead the new gallery is stuck, geologically speaking, back in 1969 when the old gallery was built. I’ll keep doing what I can here to fill the gap.

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.


Follow

Get every new post delivered to your Inbox.

Join 4,096 other followers