Indio Hills Palm Oases

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Of the 24 oases distributed along the San Andreas or associated faults, these eleven in the Indio Hills are among the finest, and one, Thousand Palms, is considered the finest of all.

Over a quarter of the known California fan palm, Washingtonia filifera, are found in these oases. (Also see Dead Indian Creek Natural Area and Indio Hills Native Palms Natural Area.) This palm is a relict species dating back to the mid-Cenozoic when palms were distributed along the Pacific Coast as far north as present-day Oregon. In its present desert environment it is now restricted to localities with permanent water supplies, usually found in fault areas. The tree is comparatively uncommon, with perhaps 100 stands in the State, ranging from two or three specimens up to several thousand at Palm Canyon. There is one stand in Arizona and a number of large stands in Baja California.

The Indio Hills oases are of two types: one, the seep type, is found on the hillsides; the other, the wash type, on the floors of canyons. There is a distinct difference in vegetation, with the seep type marked by the rush, Juncus mexicanus, and the saltbush, Atriplex hymenelytra, and the wash type characterized by the smoke tree, Psorothamnus spinosus, which is dependent for seed dissemination and germination on flood waters and rock abrasion.

The soils of the oases are generally poor and have a high alkalinity. In the washes floods may reduce the alkalinity temporarily, with resultant benefits to vegetation, but on the hillsides the water may cause erosion which topples the palms.

For the desert, these oases support a high density of animal species typical of the Colorado Desert fauna. At most of the oases the desert toad, Bufo punctatus, and the tree frog, Hyla regilla, breed. Numerous resident and migratory birds are attracted to the water and vegetation.

The Indio Hills were tilted and thrust upward by the shearing and squeezing action between the Banning and Mission Creek faults. The two faults have dammed the water which supplies the oases.

There are a number of Indian trails observable in the area, with artifacts, sleeping circles, trail shrines, etc., found along the trailside. Thousand Palms was once a watering and rest stop on the Los Angeles to Colorado River stage route and later was a resting and watering stop for cattle being herded between the Santa Rosas and the wintering grounds in the San Joaquin Valley. In Pushawalla Canyon, gold from a nearby mine was processed in a mill driven by the water.

Integrity: Most of the oases have been grazed at one time or another and fire has damaged some of the trees, as have vandals. There are few roads in the area. Thousand Palms is the only oasis with permanent buildings.

Use: All are private save one, Nomad Oasis, which is on Bureau of Land Management land.

Ref: Vogl, R. J. and L. T. McHargue, 1966. Vegetation of California Fan Palm Oases on the San Andreas Fault. Ecology 47, pp. 532-540.

July 1975