Panoche Hills

This area is one of the best preserved examples of the semi-desert communities that are found scattered along the eastern slopes of the South Coast Ranges.

Here, and in a few other localities farther south, the dominant plant species is mormon tea, Ephedra californica, which in the higher elevations forms a chaparral-like community. These sites are the only areas on the continent where a nonconiferous gymnosperm is the dominant woody species. The Ephedra occurs primarily on the south-facing slopes and is replaced on the north-facing slopes by Ericameria linearifolia and Stipa spp. The bunchgrasses are found in good numbers and are remnants of the once extensive grasslands that covered much of the floor of the valley. Among the semi-desert annuals found here are Plantago ovata, Pectocarya heterocarpa, and several endemic Eriogonum species. Hollisteria lanata is found here also.

A number of semi-xeric animals are found in the hills, including isolated populations of several reptiles, among them the desert night lizard, Xantusia vigilis. The desert spiny lizard, Sceloporus magister, and the endangered blunt-nosed leopard lizard, Crotaphytus silus, are present here, as are a number of other species of lizards, snakes and amphibians, several of which are becoming increasingly scarce.

Geologically, the rocks date from the Cretaceous and the Pliocene. This is the type locality of the Panoche group, an upper Cretaceous marine sedimentary formation that includes shale, sandstone, and conglomerate with shale predominating. The hills are capped by Pliocene non-marine sedimentary rocks. Deep canyons cut into the Cretaceous rock, permitting easy observation.

In the vicinity is a site unique in the State where a number of fossils of Cretaceous vertebrates have been found. The fossils include those of a number of reptiles such as the plesiosaurs Elasmosaurus and Morenosaurus, a duck-billed dinosaur, Prosaurolophus, the 7+ meter (23+ foot) long mosasaur, Plotosaurus, and a "flying dragon" pteranodon.

Integrity: A portion of the area is fenced and is used for sheep grazing. Some of the Ephedra and Ericameria have been disc-plowed to control the brush and enhance grazing. There are some motorcycle tracks. However, much of the area is relatively undisturbed, not having been overgrazed.

Use: Research, educational, observational, light recreation. Portions of the area are privately owned.

Ref: Payne, W. B. 1962. Type Panoche Group (Upper Cretaceous) and overlying Morene and Tertiary Strata on the West Side of the San Joaquin Valley. California Division of Mines and Geology Bulletin 181, pp. 165-175.

September 1975