Fish Creek

This area, which is adjacent to the Anza-Borrego Desert State Park, includes the northern slope of the Fish Creek Mountains.

The vegetation is typical Sonoran creosote bush scrub, with Larrea tridentata, Aristida purpurea, Hoffmannseggia microphylla, Ambrosia dumosa, and Ferocactus cylindraceus.

Animals found here include the Scott's oriole, Icterus parisorum, verdin, Auriparus flaviceps, red diamond rattlesnake, Crotalus ruber, and the speckled rattlesnake, Crotalus mitchelli, among numerous others. In the rockslides at the north end of the mountains is the type locality of the rare snail, Micrarionta ora.

Geologically, the mountains are composed of Mesozoic granitics including hornblende-rich diorite, quartz diorite and gabbro, shattered and broken into numerous blocks. The Split Mountain formation is present irregularly on the older crystalline rocks and is composed of sandstones and conglomerates. Overlying this on the northern slopes is a playa deposit of white bedded gypsum and anhydrite that ranges up to 30 meters (100 feet) thick. This, in turn, is overlain by marine shales of the Imperial formation, all of which date to the Miocene.

Integrity: Undeveloped. The gypsum mine, the largest in California, is not included in the area.

Use: Research, educational. Part private.

March 1976