Archive for the ‘Other topics’ Category

The human presence, benign to sanctified

28 May 2018

In my last post I described the spectrum of waste to be seen around the landscape. Piles of garbage are easy to see and judge as litter. Bones and downed trees are natural, but for citydwellers it takes an effort not to wish them removed.

Then there are all the things on the spectrum of art, like these amaryllis bulbs donated to undeveloped Knowland Park. Yeah, they’re an alien species, but neither is their presence a heedless desecration. People decorate things; it’s what we do. We make spaces where there were none before.

We make local habitations, some even with names, in wild Oakland.

I’ve come to enjoy the signs of artistic impulse out in the field. Many are harmless roadside attractions, too small to catch attention except at walking speed.

Others turn the nondescript into something . . . descript. I wish I knew more about this little assemblage that was up in Knowland Park a few years ago.


I think a solo artist made that.

I think a small group adopted this tumbledown shed on Grizzly Peak; their affection shows.

And then there’s the communal gallery up in Leona Heights Park; been going on for years; different every visit. Anyone can participate, but you can tell the standards are intimidatingly high. The first time I found it I went yeesh; now I take my cue from the Grateful Dead: “nothing left to do but smile, smile, smile.”

The best place for this kind of art is the Albany Bulb. I haven’t been in a few years. Wikipedia suggests that the art has been fading and is no longer what it was. With that in mind, here are some photos from about ten years ago.

The general scene is a former dump site for construction waste. Today, most material of this sort is recycled — old concrete can be used as aggregate in new concrete and rebar is easily melted into new steel. At the Bulb, this material was recycled into art.

Lots of the work was crude, but effective.

The setting, on the Bay shore, was a crucial part of the work.

This is one of my favorites, now long gone.

The landmark of Mad Mark’s Castle was once a sublime place.

litterart-13.jpg

Today I’m told it’s not really there any more. Sic transit gloria mundi.

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The litter spectrum, benign to unholy

14 May 2018

The litter on the land falls along a spectrum. This disembodied deer hoof does not qualify as litter because, as far as I know, a human didn’t leave it on this abandoned, overgrown fire road. I felt no obligation to do anything more than pause and contemplate it.

At the opposite end of the spectrum is this spectacle just off Pinehurst Road on well-posted watershed land. I felt ashamed on behalf of humanity, but could do no more than pause and contemplate it.

Fortunately, that same day East Bay MUD had a crew nearby with a backhoe and related equipment, cleaning up an even worse litter pile.

That leaves a wide space between the two ends of the spectrum with different judgments to make and responses to consider. This next photo of cannabis seedlings is a few years old, and maybe these days people are doing a little less surreptitious planting in our out-of-the-way places.

It’s possible to do this without making an unholy mess, but I’ve come upon several instances in Oakland’s hills and they were all unholy messes of degraded plastic, bags of spilled fertilizer and remnants of crude camping practices. And the plants didn’t look very good either. So these seedlings . . . I left alone with a sense of foreboding similar to what I’d feel upon seeing fresh bear scat.

Stuff like this dead mylar balloon, lost from some celebration and fallen to ground way off the trail in upper Grass Valley, makes me feel ashamed . . .

but I’ve learned to stop stewing and just pick it up. One by-product of my quest to reduce my collection of rocks (I no longer call it a rock collection) is a growing set of used baggies. I pack several and fill at least one each outing.

Turns out that while I’m not that much of a hiker — just a flâneur of the hills — I’m right up there with the hardcore wilderness walkers who carry trash bags as their eleventh essential. It’s a practice I urgently recommend you follow too. Maybe we can’t fix the unholy messes that way, but it beats shame.

And here and there, you come upon trash that is picturesque.

And occasionally you come upon a thoughtful act of self-expression, around some corner where it’s been waiting to meet you. That’s what my next post will be about.

In other news, I’ll be leading a walk for Oakland Urban Paths next month visiting some of our historic former rock quarries. That’s in addition to the Oakland Heritage Alliance walk I’m leading in July. Also in the works, a walk for the Friends of Sausal Creek.

How useful is the Orinda Formation?

30 April 2018

Walking along the paved trail north of Inspiration Point, I was brought up short by a splendid outcrop of conglomerate.

It’s strongly reminiscent of the Orinda Formation conglomerate exposed to the south in Claremont Canyon, in Sibley Volcanic Preserve and along Route 24 east of the Caldecott Tunnel.

Naturally I fired up the geologic map (I keep USGS map MF-2342 on my tablet) to see how the locality is mapped. It’s the little hill northwest of Inspiration Point, right above the word “Nimitz” where a power line runs.

But instead of Orinda Formation (the orange unit labeled “Tor”), which underlies Inspiration Point, it’s mapped as “Tus,” or “unnamed sedimentary and volcanic rocks (late Miocene).” Turns out there’s a major fault that separates two big blocks of young East Bay rocks — that thick black line with the teeth that represent the upthrown side — and even though the rocks look the same, we can’t say for sure they are.

The area of “Tus” rocks is rather large; in fact it’s the largest single rock unit on the geologic map.

I poked around the literature and found that the Orinda Formation has drastically shrunk over the years. As one example, here’s part of a 1973 map of the Lafayette area (Calif. Div. Mines & Geology Map Sheet 16) that classified a bunch of rock as Orinda Formation, drawn with the exquisite attention that emanates authority.

But the details are quicksand. First, the map is not about bedrock per se, but landslide hazards. Second, the author’s citations are generally very old, not that there’s anything wrong with that, but still. Third, the author’s idea of the Orinda is a unit that mixes lava beds (lumped today in the Moraga Formation) with the coarse sediment that defines the Orinda today. A long footnote explaining his thinking shows that he basically made an arbitrary choice of stratigraphic nomenclature to match the informal usage of local engineering geologists, who tend to talk about “Orinda-type” materials (like I was thinking at my outcrop) without making sure the stuff actually matches all the criteria for the Orinda Formation.

I’ve read my share of geologic engineering reports; any large construction project has to have one prepared. They’re good for their purpose — ensuring that the work is suited for the ground — but they don’t critically assess all the details of the science. And they probably shouldn’t. Instead, they line up the existing literature, outmoded and current alike, and discuss or dismiss it on the way to reaching their conclusions and advising their client.

Maps like Sheet 16 propagate obsolete or informal nomenclature, and thus stratigraphic concepts that are outmoded or discredited persist in the geotechnical literature like zombies long after research scientists have moved on. But I don’t blame people. The old idea of the Orinda Formation, widespread and simple, was very handy. The current idea of the Orinda, constricted and specific, is less handy because it leaves a large area of bedrock with the mumbly label “unnamed sedimentary and volcanic rocks (late Miocene).”

Geologic maps aren’t written in stone. Only stone is, and we’re still learning to read it.

A new kind of shoreline

5 March 2018

Rising sea level is a threat to the Bay area. Already, king tides are flooding the levees and seawalls built for the last century’s ocean. I touched upon this topic a few weeks ago with my proposed walk around Lake Merritt in 2100, assuming that the Bay will be a couple meters higher than today.

Yesterday, happenstance allowed me to witness a promising project that has built an experimental coastline modeled after a natural one — specifically, a living water filter meant to sit between the low tidal mudflats and the higher levees holding the Bay back. The Northern California Science Writers Association arranged for a group of members to visit the Horizontal Levee Project, on the grounds of the Oro Loma Sanitary District wastewater treatment plant in San Lorenzo.

Let me sketch the idea behind the project. To begin with, the natural coastal landscape has been totally messed up. It used to be a nice grassland plain, gradually sloping down to a series of wetlands that merged organically into the tidal marsh, mudflats and open Bay waters. Water from the hills percolated gently down the streams and through the ground, nourishing a lovely ecosystem full of species. American settlers cut off the top part of this landscape and covered it with buildings, dammed and diverted the streams, then filled in and walled off the lower part with levees. Today the coastal wetlands are cut off from the water and sediment from the hills, and meanwhile the sea is creeping up and washing them away.

The thinking behind the Horizontal Levee Project is to build a new slope on the uphill side of this truncated coast, then restore the groundwater flow that used to be there using treated wastewater. Even compressed to a fraction of its former width, the resulting slope should be a powerful water-scrubbing engine and a vibrant habitat. (Figure from here.)

The wastewater part is crucial because we have lots of it, we can control its flow, and the new slope — scientifically, an ecotone — cleanses the wastewater of nitrates and other hard-to-remove compounds better than treatments costing 10 times as much. All while feeding a splendid tidal marsh that resists storm waves better than concrete walls!

Our visit took place on a brisk, bright day by the bayshore. The Oro Loma Sanitary District treatment plant is mostly clean, stark and Brobdingnagian.

But the operators found space to put up this pilot project on their own land, where they didn’t need so many permits. They built a gently sloping earthwork, installed pipes at the top and drains at the bottom, then raised a mix of plants from local sources to seed it with, using these planter boxes.

Project staff noted that the alkali bulrush is particularly good at resisting storm waves with its tall, stiff stems.

Seeding and planting happened in the rainy season of 2015-16, so this lush jungle of native marsh plants on the ecotone was just two years old. It’s so dense that invasive weeds, even pampas grass, don’t stand a chance.

And the water coming out at the lower end is really clean. (Even so, the water was pumped out through the white pipes on the left and put back into the treatment stream.) Soil bacteria actually convert the nasty nitrate to nitrogen gas, so it isn’t just trapped in the dirt or building up within the plants.

Water treatment agencies all around the Bay have their eyes on this experiment. It looks like the design will be flexible enough to be adapted for as much as 5000 acres of wetlands, a significant fraction of the coastline that’s particularly vulnerable to sea rise.

Awareness of sea-level rise needs to happen faster than the rising sea itself. The speakers yesterday found that the hardest nut to crack in moving things forward is regulations: interpreting them creatively, coordinating the regulators, combating inertia. To envision, scope, design and plan improvements to the shoreline literally takes decades, meaning that we have to aim for a target in the year our children reach our age.