Serpentine Prairie is a segment of Redwood Regional Park right across Skyline Boulevard from the Crestmont neighborhood (where my very first post came from). It’s a small remnant of a serpentine barren, most of which is occupied by hilltop homes. This is the entrance from the parking lot at 11500 Skyline Blvd. Some large boulders of serpentinite and its predecessor, peridotite, are here to keep out vehicles, but they’re handy for studying these rock types. The lush greenery is foxtail grass, an alien invader that benefits from the nitrogen of dog urine near the path and the absence of fire.
This view shows how serpentine ground differs from sandstone slopes in the distance.
Serpentinite yields a soil that is very high in iron and very low in calcium, phosphorus and nitrogen; it may also include high levels of chromium, nickel and cobalt that are toxic to most plants. The stony slope in the left distance is an old quarry scar that’s now a true serpentine barren, with almost nothing growing on it. The near ground has many endemic grasses and flowers but also a lot of foreign plants. Now is the time to see it. I visited on May 15 and caught the endangered Presidio clarkia in bloom.
The serpentinite itself presents a variety of colors from brown to grass-green, but the bulk of it here is close to bluejean color, hard to capture on camera but quite striking in person. Here it is: California’s state rock with Eschscholtzia californica, the state flower.
This fall (2009) the park plans to fence off 3 acres of the land and start protecting it from degradation. Of course, there is no picking the plants or collecting the rocks. There’s plenty of serpentinite that’s just as good along the roadside on Skyline and down in the Crestmont neighborhood.
Oakland Geology 
20 April 2010 at 4:20 pm
I was at the prairie a couple weeks ago, and the goldfields are dazzling. The fence is in place and the inappropriately introduced trees are being removed.