Every neighborhood in Oakland with a “mont” in its name has bedrock exposed. Crestmont is a good example. Most of the Crestmont neighborhood, north of Redwood Road and east of Holy Names University, sits on serpentine rock—more precisely, serpentinite. This is the biggest exposure, at the intersection of Crestmont Drive and Westfield Way. Below is an exposure just to the north (click full size), which is somewhat bluer than the blue-green of the main patch. I’ve shown pieces of this rock to local geologists, asking them “Is this serpentinite or blueschist?” They usually say “Beats me” or, even better, “Yes.” These rocks are not easily assessed by just eyeballing them.
The open lot on the east side of Crestmont near Samaria Lane displays some splendid outcrops of this “lizard-skin” stone: