Walking along Acacia Avenue, you may feast your eyes on the homes and grounds of the core street of the Upper Rockridge neighborhood, but one exception stands out at 6240 Acacia: this rock peeking over the scene. This is Cactus Rock, attested to in old postcards about the ongoing development of this streetcar suburb (still served by the improbable bus route 59A). I can’t get a good look at it, but it appears to be a standard Franciscan knocker that is much smaller than the mysterious Rockridge Rock. To judge from the prospect at Alpine Terrace, the next street uphill from here, the views from the rock are fantastic.
Oakland Geology 
21 July 2008 at 1:16 pm
Because the 1991 fire burned through the Upper Rockridge area, clearing all the structures, there may be photos somewhere of that devastation that may help you find these rocks and outcroppings.
31 July 2008 at 6:25 pm
I find the quest fascinating, so I couldn’t resist following your footsteps to Rockridge to look around.
There are some good views of Cactus Rock from further away than Acacia Avenue – the ground level foliage and houses on Acacia obscure the base of the rock. Interestingly, there is a good view from near the intersection of Glenbrook Drive and Bowling Drive. Another good view is available from the Mountain View Cemetery, looking across Broadway Terrace.
I’ve posted some photographs on Flickr.
31 July 2008 at 7:34 pm
Oh, that’s great! I hadn’t even considered looking from other places. Now I won’t be able to help myself. Thanks a bunch for taking those photos.
15 August 2008 at 3:32 pm
you can get a pretty good view of this rock using microsoft’s live search maps:
http://tinyurl.com/54tvc5
you can use the circular arrows to see the other 3 views of the rock.
its pretty much in their driveway!