What I marched for

24 April 2017

Saturday was Earth Day, an occasion that usually leaves me lukewarm at best. But this year it was also the day of the worldwide March for Science. A few news stories have quoted environmentalists who resented that the march happened on “their” day. But from my viewpoint, that’s the best day of the year for a science march. The Earth Day community needs the help, and the organizers are upping their game.

We should have a science march, or at least a rally, every year. This year’s inaugural march had a militant edge. So did the original Earth Day. And for centuries before that, scientific advances have shaken up establishments of all kinds. This sign, quoting Galileo’s legendary comment after the Church forced him to renounce his discoveries, was a shout-out to that long history.

The authorities can threaten people for their beliefs, but they can’t force facts to be untrue. And when Galileo muttered “Nevertheless it moves,” he was talking about the Earth.

Other signs were more contemporary, more pointed . . .

. . . and funnier.

One of my favorite geeky jokes was on Twitter: “The numbers for the Science March seem high but we won’t know until we compare it to the numbers at the placebo march that’s also happening.”

I could have marched with the group from the American Geophysical Union, which endorsed the event. I’ve been an AGU member and rabid fan since the mid-1980s. But I chose to walk with the Northern California Science Writers Association, because they represent my practice. Our little group took a side route to the march along Drumm Street, and when we got there Market Street was packed.

It took us an hour to stroll to the Civic Center. People lined the route, holding their signs and admiring ours. There was a learning fair at the other end, what we used to call a teach-in.

As I prepared to return to Oakland, incoming marchers still filled Market Street to the limits of my sight. This was not a small occasion.

There were thousands of signs. This one reminded me of an important truth.

It means that the scientific method is simply a more rigorous version of something we all do. When we face a question of any size, whether it’s choosing fruit at the market or investing our life’s savings, we make our best estimate of what to do, check the results against our expectation, and then make adjustments in how to proceed. Science is common sense weaponized, and the better we are at common sense the more we are like scientists.

One thing that stood out to me at the San Francisco March for Science was that science has more than practitioners — it has fans. When the speakers at the rally made shout-outs to NASA, they drew widespread cheers. The same for stem-cell researchers at the California Institute for Regenerative Medicine or NIH — cheers. These things deserve their applause, and I cheered them as a fan.

Although there were geologists and geology fans in the crowd, we didn’t get a chance to make or hear a cheer of our own on Earth Day. I know, we’re grownups and don’t need the adulation, but what about the kids who are into minerals and fossils? Do they sense there’s a pivotal role for them in extrasolar planetology? In evolution studies? In global sustainability, in climate studies, in remediation of polluted places, in ecology? Are geology’s strengths in earthquakes, volcanoes, floods and landslides unworthy of comment in a march for science? Does plate tectonics, with its elegance and grandeur and promise, have no fans among the rally planners?

Geologists do tend to keep their heads down. Because Earth science is too wonderful to neglect, I plan to push ahead. You are fans, and I have hundreds more stories for you.

The Hayward fault at Warm Springs

17 April 2017

Every extension of BART opens up a new region accessible to geologizers using public transit. So the other week I paid a visit to the far end of the Hayward fault, less than a mile from the new Warm Springs station in south Fremont. The station has nice views of the San Mateo Peninsula mountains to the west and Mission Peak to the east.

It appears, too, that the Irvington Gravels site to the north is accessible for determined walkers who bring provisions — that is, hikers.

To get to the fault just walk east on South Grimmer Boulevard toward the place marked “Weibel” on Google Maps.

Here’s the same area in Jim Lienkaemper’s detailed 1992 map of the fault. The map has a key to all the annotations. Note that both images are tilted to make the fault vertical; north is at about 1:30.

The fault runs through the “D” in “Blvd.”

Look back at the Google Maps image. See the line of green along the fault trace? That’s because of the 1972 Alquist-Priolo Act, which forbids new construction within 50 feet of an active fault. The area in the middle must have been built up before the act took effect. That’s where I went.

South Grimmer reveals the offset from fault creep well. This view is looking east toward Mission Peak. On the fault map, the locality (just below the horizontal dashed line) is circled and labeled “C1,rc,rf” signifying “strongly pronounced” evidence of creep in the form of right-offset curbs and a right-offset fence line.

And this is the other side of the road, looking west. Notice that the sidewalk is offset as well as the curb.

There’s another, much smaller offset higher up the slope that I didn’t get a good picture of. Repeated measurements show that together these offsets add up to about 6 millimeters per year. The slope itself is a sign of the fault, too.

To the north across little Arroyo Agua Caliente Park on Gardenia Way, this nice set of echelon cracks marks the fault trace. That’s what the “ec” in the circle labeled “C1,ec,rc,cc” stands for.

The fault nips the corner of Gardenia and Ivy Way, bending this curb (the “rc” in the label).

The city or the homeowner copes with the sidewalk by patching it as needed. You’ll see stuff like this everywhere on the Hayward fault.

Walking north through the park to Parkmeadow Drive on its north edge, you can look west down the street and see both an offset curb and the change in slope that marks the fault.

You can do this yourself all along the fault. The map has all the evidence (and the USGS has an updated version as of 2008).

A week later I hosted two French journalists — a writer and a photographer — for an afternoon, showing them fault offset features like these up in Hayward and Oakland. The writer went and spoke to a resident whose home was on the fault, and his fatalistic response took her aback a bit. She said “we don’t have attitudes like this in France.” I told her we Californians have been this way since the Gold Rush.

Shepherd Canyon landslides

10 April 2017

Last week I went to visit a landslide that had been in the news. As it happened, I saw three.

Shepherd Canyon always gets a lot of landslides, like its neighboring canyons in the high hills. The main reason is that Shephard Creek has a lot of cutting power, thanks to its relatively large watershed and the low base level provided by Dimond Canyon. That creates steep slopes and V-shaped valley profiles. A secondary reason is the relatively soft mudstone underlying those slopes.

My destination was the landslide that came down on the south side of Banning Drive. But along the way my path was blocked by two more mass movements. They’re marked by white asterisks on the geologic map below.

The Montclair Railroad Trail, my usual route, offers walkers good access to the canyon. On the inner side of the sharp curve and cut leading into the canyon, this slope failure exposed the rears of two houses. I classify it as a debris fall.

The majority of the material is broken rock, hence the term debris, and it tumbled in a heap rather than traveling any distance, hence the term fall. Only a little mud was present.

The area is mapped as the Oakland Conglomerate (Ko), although the debris appeared to consist mostly of fine sandstone and a little shale, like this. The rainwashed stone is well displayed.

Picking my way past that was no problem. Farther up the trail, though, was a complete blockage.

Like the lower slope failure, this one involved debris, but unlike it the material slid, so I classify it as a debris slide. Several large trees that came down with the rock didn’t appear to be to blame. However, this time of year is the most dangerous for trees because the ground is sopping wet and the limbs are heavy with young leaves, making them prone to catch the wind. Maybe they triggered the slide. Maybe the other way around.

Fortunately no houses appeared to be threatened above the headscarp, but now the slope is highly vulnerable.

A sewer line runs beneath the trail, so the city may have to clear the slide once the ground is no longer saturated. Meanwhile this is too dangerous to approach. It could fall with no warning.

The debris is made of fine-grained sandstone of the Redwood Canyon Formation (Kr).

Finally I got up to Banning Drive. It’s situated in one of the major side valleys in Shepherd Canyon, and the walls are exceptionally steep.

I classify this slope failure as a debris flow, what the news media often calls a mudslide. It traveled downhill a good hundred meters in a thick semifluid mass. The mud content was greater than the other two slides, and muck spilled into and around several homes on Banning. There’s plenty of footage of the scene online, so I don’t need to show you that. It was hard to watch the residents clearing out their red-tagged homes while the news vans gathered round.

I didn’t need to be there once I’d seen it. Presently I went uphill to Aitken Drive, where the slide originated.

Note a couple of things. Right beyond the gap in the road, a telephone pole was snapped off and the wires were hanging low. (The power was off.) The extra load caused the pole at the left edge of the photo to lean inward. The scar in the road reveals a wall of sandbags (I assume they were filled with concrete) that must have been put there after a previous slide.

Landslides occur where previous slides did. And sure enough, looking uphill I could see the young scar of a small rockslide, nestled in turn within a concavity in the hillside that looked like the scar of a much older slide.

There is another street higher up, Chelton Drive, but no houses up there appeared to be endangered. Meanwhile East Bay MUD had the road blocked while they were making sure the water lines underneath wouldn’t break and make more trouble.

Who’s responsible? Perhaps no one. The problem is above my pay grade, as I’m not a licensed geologist. But I can see the signs and warnings of landslides, and so can you if you pay attention to the landscape. The U.S. Geological Survey has resources, and so does the California Geological Survey.