Palisades - Swartz Canyon and Vicinity

Much of this area is covered by the Pliocene Sonoma volcanics, though to the north there are extensive exposures of the earlier Franciscan formation, including serpentine. The most spectacular feature of this generally rugged area is The Palisades, a bluff several hundred meters high extending for several kilometers, which was probably formed through a combination of faulting and erosion. Bands of tuff, breccias, andesite flows and agglomerates are exposed. Hexagonal basaltic columns similar to those of the Devils Postpile are found here.

Vegetation in the area is quite mixed and runs from barrens on certain of the volcanics and serpentine to a mixed evergreen forest with Douglas fir, Pseudotsuga menziesii, and sugar pine, Pinus lambertiana. The pine is near its southern limit in the northern Coast Range here; there are, however, several disjunct populations some 320 kilometers (200 miles) south in Monterey County (see Cone Peak). Much of the area is covered by chaparral, with the pines, both knobcone and digger, Pinus attenuata and Pinus sabiniana, and cypresses, Sargent and MacNab, Cupressus sargentii and Cupressus macnabiana, occurring locally. In portions of the area the MacNab cypress, an Arctostaphylos sp., and a Pedicularis sp. form a very sparse cover. Blue oak, Quercus douglasii, is found at several sites within the area.

Three uncommon Fritillaria are present here, Fritillaria eastwoodiae, Fritillaria pluriflora, and the rare Fritillaria purdyi. Other rare plants include Erythronium helenae, which is locally abundant but restricted to the serpentine areas, Streptanthus morrisonii ssp. elatus, and Lupinus sericatus. The latter occurs on volcanic mudflows in the eastern section of the area.

As the country is rugged in parts, there is an abundance of animal life including such species as black bear, Ursus americanus, mountain lion, Felis concolor, the endangered peregrine falcon, Falco peregrinus anatum, canyon wren, Catherpes mexicanus, and white-throated swift, Aeronautes saxatalis, among others.

In Swartz Canyon there is a permanent stream with numerous pools, many 2 meters (7 feet) deep, which supports a variety of native fishes.

In the volcanic materials in the canyon are a number of caves formed by differential erosion.

Integrity: There are various mines in the area as well as roads and buildings. A portion of the area is grazed.

Use: Research, educational, observational. Portion private.

Ref: Kruckeberg, A. R. 1951. Intraspecific Variability in the Response of Certain Native Plant Species to Serpentine Soil. Amer. J. Bot. 38, pp. 408-419.

February 1977