Apparently there are people besides me wandering my neighborhood and seeing the vanished past. This image comes from the 40th Street Cut blog, the record of an effort to put together an art show inspired by the Piedmont Avenue neighborhood. I have to say these guys know what grabs me.
The Key Route used to cut through the ridge running east of Broadway between Macarthur and CCA (which I’ve called Montgomery ridge, but on an old map it’s called Thermal Hill). This photo shows that cut before the tracks were pulled up and the cut filled in again. If I only had an hour to examine its walls!
The walls of the cut are steep, but there was no bedrock in it—that’s why the cut was made, because the work was easy. The material of the hill is stiff, well-compacted alluvium from a large, ancient fan that has had gulches cut into it by modern streams. Here the ridge was flanked by the two branches of Glen Echo Creek, one running along Broadway from the Claremont golf course and the other coming down from the cemetery grounds. (They join along Richmond Boulevard just north of 30th Street.) There was no danger of landsliding or rockfalls.
Geologists love roadcuts. In this part of Oakland they’re quite rare.
Oh—the 40th Street Cut people are having an opening reception Thursday the 18th, downtown. Details on the blog.
Oakland Geology 
18 February 2009 at 10:44 pm
Thanks for the local history! But it seems like a bit of an exaggeration to say that the cut was filled… it isn’t what it once was, but today’s 40th Street runs through it (40th Way is the old 40th Street). Somewhere I have a copy of an Oakland Tribune article from when the tracks were being torn up, with a mention of the Cerrito Ave crossing being closed to avoid having to rebuild the bridge.
19 February 2009 at 8:47 pm
It would be fun to see that article, Eric.
The 40th Street Cut show is charming, especially if you’re from the Piedmont neighborhood but worth seeing even if you’re not. The gallery is only open Wednesday, Thursday and Friday from 11 to 5, so unless you have a day off it’s a lunch-hour outing, except for First Friday, March 6, when it’s open until 8 pm, and on March 19 when the artists give a talk from 5 to 7 pm. These artists and I are in the same business: opening people’s eyes to what’s around them.
20 February 2009 at 8:00 pm
That sounds like an art show made for me. I love watching how areas change over time by both natural and human processes.
I always just assumed Thermal Hill was a bedrock hill, it never occurred to me it was a fan.
21 February 2009 at 11:48 am
The upper half is indeed on bedrock, a golden-colored sandstone. You’ll see it on both sides of Pleasant Valley Road at the top of the hill. It extends down to about John Street, at least I picked up pieces in an excavation there.
22 February 2009 at 3:20 pm
Thanks for mentioning the show in Oakland Geology. I appreciate your writing and am especially inspired by your active, creative relationship with our local geography. In our exhibit we did not attempt to present a historical dissertation about the Key System or Glen Echo Creek but rather an interpretation of our experience in this place and with these systems. It was great chatting with you at the gallery.
22 February 2009 at 5:45 pm
Thanks, Michael, and congratulations on getting into today’s Oakland Tribune too.
I liked your project because it WASN’T a historical dissertation; it was an invitation to wonder, and it was rewarding to people of all levels of intimacy with Oakland’s landscape.