Certain places are prized by geologists, especially teachers, for their educational value. Out-of-towners make pilgrimages to them. Sure we all enjoy the Grand Canyon, but real geologists have Siccar Point, Darwin’s outcrop, the Carlin unconformity and other obscure sites on their life lists.
One of those places was right nearby in Hayward, until very recently. At the corner of Rose and Prospect Streets is a corner curb that happened to be built precisely across the Hayward fault, where the steady progress of aseismic creep slowly wrenched it apart.
The best time series of this corner was compiled by Sue Ellen Hirschfeld, a now-retired geology teacher at UC East Bay. It goes back to 1971, and even then there was a sizable offset. Probably the curb was first emplaced in the late 1950s.
It’s a popular site for folks in the know, and there’s at least one Flickr group with lots of photos. The neighbors are probably sick of us, though. I’ve visited it many times, and I sometimes took pictures. This photo is from 2006.
We’re looking east across the fault. This side is moving northward a few millimeters per year. I came back the next year and took this shot of the “echelon cracks” in the street, with the iconic curb in the corner.
In 2012 I brought a few enthusiasts to see it; they asked for anonymity but I can show you where they stood.
A closeup at the time shows that it had a total offset of about 7-1/2 inches, or 20 centimeters, since it was built. The painted arrow at the left shows the offset in the six years since 2006.
Last week I joined a party of visitors there, and to my dismay the corner has been dismantled. It looks like the plan is to put in a cutout for people with disabilities, which is a good thing and undoubtedly overdue. Still.
Anyway, I’m here to put the word out: Rose and Prospect is defunct. It is no more. Come back in 20 years. In the meantime, downtown Hayward is full of other examples of bent curbs.
There’s always the Old City Hall, too, which was built directly on the fault and has long been abandoned. The first time I visited there, maybe 25 years ago, I was looking at the street adjacent to it. As I watched, a little tongue of water emerged in the center of the street and started trickling downhill. Assuming that an old iron water main had just cracked, I found a phone booth and alerted the city. Cleaning up after a creeping fault never ends.