Archive for the ‘other’ Category

Getting high in four dimensions

7 March 2016

Every now and then I like to climb parking structures. It feels like climbing trees felt when I was a kid. It’s also a lot like climbing hills to get an overview of the countryside. Parking structures are almost the only buildings in Oakland that the public can stand on top of. I like to climb them because adding that third dimension gives me a keener sense of where I am.

The Kaiser Permanente parking structure at 19th and Franklin Streets is almost unique in having a rooftop amenity — a little garden patio. It offers views of the bay and the hills, along with the buildings between. I was there the other day.


As it happens, I have photos from my last visit, in November 2005. The current drought must have prompted a redesign, because it used to be much more lush. The furniture was replaced, too.


Everything has changed, but it’s still the same place. That’s seeing the fourth dimension.

Toward the hills, you can see the Kaiser Center’s rooftop garden, a 3-acre cultivated wonderland on top of its parking structure. (Kaiser owns it, but public access to it was part of the bargain Kaiser made when the city allowed them to fill in part of Lake Merritt.)


You should pay it a visit. The plantings have been rejuvenated. And that’s the only other Oakland parking structure I know of with a rooftop amenity.

But back to the fourth dimension. It strikes me vividly as I view the Leamington Hotel building across the way, next to 1904 Franklin, both of them built in the 1920s.


What vast changes have come over us since that time!

The geologist carries this fourth-dimension awareness everywhere. The mere presence of a rock outcrop is a signal that once upon a time, that spot was a very different place — perhaps a deep sea basin far offshore, or a magma chamber miles underground. The configuration of a hillside may reflect environmental changes as drastic as the Ice Ages. All of this is there in plain sight, if you put in the work to understand the evidence.

So for me the natural Oakland primes me to see the built Oakland similarly. We have a fascinating four-dimensional cityscape that includes old things left old, old things turned new, and new things masquerading as old. It even has fossils. All deserve a closer look.

On the 1200 block of Harrison Street the King Building, in the back, looks old but has been refurbished while the structure in front looks like it needs a bit of rehab.


Elsewhere the way-new Oakland Hot Plate occupies the way-old Hotel Menlo/Empyrean Towers building, built in 1914. Note the ancient prism glass upper windows, designed to let in daylight without glare in the days before widespread electricity.


New (2000s) and old (1937) harmonize down in the warehouse district at 3rd Street near Jackson.


And a block of new apartments (2006) masquerades as an old manufacturing building at Jackson and 2nd Streets.


The past shines forth in the present everywhere you look. The present is a very thin veneer on a long history. This is the central concept of geology.

In other news, I’ll be speaking at the Oakland Museum of California on Friday the 18th.

Our native forest

8 February 2016

I spent Saturday in Napa Valley on a field trip with the Northern California Geological Society, visiting the ultrapremium Promontory vineyards west of Yountville and the merely superpremium vineyards of Harlan Estate west of Oakville.

High-end wine is a culture obsessed with the character of land, and Bill Harlan talked a lot about his land as we tasted the 2009 releases from both sites. What struck me most was his emphasis on the forest around the vineyards. Both properties are enclaves of vineyards in a forested setting. This view of woods-encircled vines is from the top of Promontory.


Harlan spoke of airs and influences while, given my recent reading, I thought of wild yeasts and soil microbiomes. I also thought of Oakland’s woods, which have been on my mind lately as I’ve explored the Leona hills.


To some Oaklanders, all trees are good trees. To me, the oak forest is what belongs here, and eucalypts should be exterminated from our wild lands. I’ll spell out several reasons, mostly familiar, plus a new one about living in Anthropocene time. But first, a clump of oaks in the Leona hills.


History: Once our oaks were the basis of a thriving native economy, and their acorns are still here in abundance for true locavores. Eucalypts were planted in our hills in a failed attempt to make a killing in timber. The poet Joaquin Miller, spellbound by a Victorian ideal of Arcadia, covered his grassy Hights with thousands more. Neither wave of tree-planting was done responsibly. We owe that legacy of heedlessness the same respect we owe pampas grass, French broom, foxtail grass and other pest species. Here’s a mono-stand near the Caldecott Tunnel.


Aesthetics: Our native oaks hug the hills in fleecy blankets; eucalypts hide them in scraggly tufts. Compare the two types of forest, side by side at Lake Chabot. The very air is different.


Accessibility: In my search for rocks, I go off trail and across country. Eucalyptus country is typically impassible, the footing noisy and slippery. Oak country is typically parklike and quiet, like this grove in the Leona hills — although it’s friendlier to poison oak, I’ll give you that.


Ecology: Oaks make food and mulch; eucalypts make trash.


The Anthropocene: The future’s climate is up to us. It’s vital that we pull CO2 out of the air. Trees are touted for doing that, but planting and managing forests is a sophisticated practice we’re just beginning to understand. Forests are more than just groves of fixed carbon. By far the majority of a forest’s carbon is in its soil, not above the ground.

A newly published study argues that more than two centuries of reforesting the European landscape hasn’t made a lick of difference to its CO2 balance. Because the new forests were managed for timber, the wrong kind of trees were subsidized.


Luckily, we don’t harvest timber in Oakland any more, so we can do things the right way. That means nurturing the biomes that suit the region: native oaks, redwood, chapparal and coastal wetland. Their intricate webs of underground organisms, tuned to our rocks and climate over thousands of years, soak up carbon better than any other strategy.

Well-chosen eucalypts are splendid specimen trees, but they should be phased out in the wild. If we feed our wildland soils correctly, Oakland can do its share to fight global warming. And it will be better in all the ways I’ve mentioned.


Restoring our land will take time, sustained funding and the same dedication that Bill Harlan gives his vineyards. If we take our ownership of Oakland’s land seriously, we can’t slack.

Two lessons about floods

19 October 2015

As we anticipate the strong possibility of heavy El Niño rains, my attention will be on Oakland’s streams this winter. Last week parts of southern California were hit by “thousand-year” rainfall events, cloudbursts that washed thick sheets of mud over roads and properties. We can expect such things here too, in any given thousand-year period.

Arroyo Viejo, the stream that crosses Knowland Park, offers two lessons about floods. The scene below is at the northern edge of the park, looking upstream: a streambed piled with boulders, some as large as sofas. (All photos 800 px)


Notice: these rocks have been tumbled by the stream. How much water would it take to do that? Let’s make a rough, arm-waving estimate.

The rainfall in last week’s cloudburst was almost 4 inches in one hour. Had it fallen on the watershed of Arroyo Viejo above this point — say, half a square kilometer — it would represent an input of roughly 30 cubic meters of rainwater every second.

Picture in your mind that volume of water — no, it would be mud and therefore that much greater — funnelled through this narrow valley. Do a little geometry and it’s easy to see the floodwater would be well above the tops of the boulders.

Hidden in plain sight in this photo, then, is a single hour of tumult that might have happened a thousand years ago or five hundered years ago — or perhaps during the dreadful winter of 1861-62, when it rained for 43 straight days and much of the Central Valley became a lake.

The lesson is that most of geology’s hard work gets done in rare spurts of extraordinary activity.

Okay, the second lesson is hidden in these rocks. All of them, like this boulder as tall as me, are made of conglomerate.


These rocks, assigned to the Knoxville Formation of Late Jurassic to Early Cretaceous age, were laid down by ancient floods in a nearshore or terrestrial setting. I’ll show you three different specimens. Notice the large clasts and the fine-grained matrix that surrounds them.


This boulder displays a wide range of clast sizes. It was probably laid down by what’s called a hyperpycnal flow, a slurry of sediment that carries everything along with it. We’ve watched them happen offshore in Monterey Canyon. Here’s another example.


Instead of an underwater landslide, as seen in the first specimen, this represents something gentler and more organized, like a mudflow, or like the mudslides we saw in the news. The clasts are aligned with the current that carried them here.

The key observation in both cases is that the large clasts are floating in the matrix. In geologist’s terms, they are matrix-supported conglomerates.

Then we have this.


Here’s a beautiful clast-supported conglomerate. It represents a clean bed of well-rounded cobbles, all touching each other, like you’d see in a rushing stream or a rocky beach, nicely infiltrated with clean silt or clay after it was laid down.

None of these stones were made by ordinary sediment wafting down streams during ordinary rainy seasons. They were assembled by floods of all sizes.