Reef Ridge

This ridge forms the eastern escarpment of the Diablo Range and gives an excellent cross section of geological formations ranging from the Upper Cretaceous through the Pliocene. These beds have a uniformly northwesterly strike and dip northeast 40 to 80 degrees. Thus, hiking up the northeastern flank is essentially a walk through time, ranging from the Pliocene beds near the base to the Upper Cretaceous Panoche formation near the summit. The entire area is highly fossiliferous, predominantly marine. A few of the main classes present include Brachiopoda, Gastropoda, Pelecypoda and Echinoidea.

Vegetation is sparse throughout the area, though various grasses are found during the rainy season and there are stands of California juniper, Juniperus californica, scrub oak, Quercus berberidifolia, and gray pine, Pinus sabiniana.

The rare San Joaquin kit fox, Vulpes macrotis mutica, may be present.

Integrity: The area is in a relatively natural condition, though some tracks have been made.

Use: Private

Ref: Stewart, Ralph, 1946. Geology of the Reef Ridge Coalinga District, California. United States Geological Survey Prof. Paper, No. 205 C, p. 81-111.

March 1975