Cape Mendocino

Cape Mendocino, the westernmost point in the State, has a coastline with rocky headlands, fringing rocks, reefs and sandy beaches. The heavy wave action and near-shore current patterns around the Cape are especially interesting to both oceanographers and biologists.

The biota is typical of the open rocky coast, with such invertebrates as the purple starfish, Pisaster ochraceus, mussel, Mytilus californianus, and a Pacific goose barnacle, Mitella polymerus. Postelsia palmaeformis is one of the more abundant algae found here.

Among the numerous offshore rocks, several of the larger are important rookeries (see Steamboat Rock and Sugarloaf Rock). The cliff and rocks are primarily Cretaceous marine sedimentaries, graywacke and shale. To the south of the Cape proper there is a Pleistocene marine terrace. The dominant vegetation on the cliffs and headlands is of the northern coastal scrub, with some grasslands.

Offshore, the area is of particular geological interest for within 10 kilometers (6 miles) is the head of the Mendocino submarine canyon, which leads to the north-facing Gorda escarpment. This escarpment, which is part of the Mendocino fracture zone, is nearly 2,000 meters (6,000 feet) high, less than 30 kilometers (20 miles) to sea, and is probably the offshore continuation of the San Andreas Fault. It has been proposed that there is a triple junction of continental and sea-floor plates in the general area.

Integrity: Virtually pristine.

Use: Research, educational, observational. There is a Coast Guard Reservation with navigational facilities. The remainder of the land area is private.

Ref: Silver, Eli, 1971. Transitional Tectonics and Late Cenozoic Structure of the Continental Margin of Northernmost California. Geo. Soc. Amer. Bul., Vol. 82, pp. 1-22.

March 1976