Archive for November, 2010

High-grade wall

27 November 2010

As you walk up Broadway Terrace from Broadway, you pass the Claremont Country Club and its golf course, then reenter the residential area of Upper Rockridge. At the corner of Country Club Drive and Broadway Terrace is a bus stop and this marvelous stone wall.

broadway terrace stone wall

The entire wall is faced with local rocks from the Franciscan mélange that underlies Piedmont and its surroundings: high-grade altered chert like this stone, greenstone, sandstone, serpentinite, radiolarian chert, basalt. It slows me down every time I pass. I don’t know where such an assortment was ever quarried. It seems more likely that the stone came from around the neighborhood, maybe even the lot itself. That is exceptional. The next lot also has a wall, but it’s a pale and homogeneous thing made of quarry rock, conventional and boring.


More Rockridge Rocks

21 November 2010

Lately I’ve returned to Upper Rockridge in search of the elusive Rockridge Rock. On Bowling Drive I captured this view of Cactus Rock, which perches high above Acacia Avenue. (A reader took the same photo in July 2008.)

cactus rock

Cactus Rock is impressive, but I still have trouble believing that picnic parties would come up there regularly; it’s 1000 feet and almost a 200-foot climb from Broadway Terrace. The climb to “Mount Ararat” would have been shorter; but I still lack evidence that a large rock sits up there.

That leads me to 5920 Broadway Terrace, where the owners have recently finished a major upgrade to the grounds revealing some very impressive rocks. (A commenter mentioned it last year.)

broadway terrace rock

Click the photo for a larger view. You can’t quite see it, but the rock beneath the porch now has a fountain installed that spills in a waterfall over it into a pool. Could this house be sitting on the original Rockridge Rock?

And now: Oakland in stereo

9 November 2010

I’ve been away in Denver, at the Geological Society of America annual meeting, plus a few days in the Rockies, so haven’t posted lately. And naturally I caught someone’s cold germs along the way, so I’m feeling pretty lousy. Let’s try a trick that geologists are trained to do: viewing stereophotos without a viewer. This is a pair of shots I took showing “Mount Ararat” in upper Broadway Terrace. It’s my personal candidate for the original Rockridge Rock. Click on the image for a much larger pair.

mount ararat

You get the stereo effect by crossing your eyes until the images fuse, then directing your focus onto the fused image. This example is a little strong. All I do to make them is take two shots, first leaning left, then leaning right. I give more detailed instructions for viewing stereopairs and some examples on my site. If the effort makes your eyes ache, now you know how I’m feeling at the moment.