Oakland Geology

Way down in the Sheffield Village neighborhood is a big hill and a little hill, but most of the place is in a flat little basin. The geologic map shows it as a patch of old alluvial sediment of the same vintage as the Fan:

The big hill is on the east side, across the Hayward fault (the black line from the lower right corner). The little hill is on the west side, butting against I-580. The road on its west side is Middleton Street, so I give the hill that name. I didn’t realize it when I poked around there earlier this month, but the hill is mapped as San Leandro Gabbro, of Jurassic age. The rock doesn’t show itself very much, but here’s a small exposure. Next time I’ll bring a hammer.

The highlight of the hill is the little private park inside the ring of houses there, just a microscopic piece of the original oak meadow (although this is actually a cork oak).

From there you get a nice view of the big hill. The fault runs along the foot of the hills, behind the homes in the center and in front of the lower set of homes on the right.

Click the photo for a big version.

This entry was posted on 26 July 2013 at 10:00 pm and is filed under Hayward fault, Oakland gabbro, Oakland geology views, Oakland peaks. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.