The Coyote Mountains are a small mountain range in San Diego and Imperial Counties in southern California. The Coyotes form a narrow ESE trending wide range with a length of about . The southeast end turns and forms a north trending "hook". The highest point is Carrizo Mountain on the northeast end with an elevation of . Mine Peak at the northwest end of the range has an elevation of . Coyote Wash along I-8 along the southeast margin of the range is 100 to 300 feet in elevation. Plaster City lies in the Yuha Desert about east of the east end of the range.
To the southeast lie the Jacumba Mountains and the Volcanic Hills. To the north and northeast lie the Carrizo Badlands, the Carrizo Valley and the Fish Creek Mountains. The west end of the range is within the Anza-Borrego Desert State Park and the east end is within the Carrizo Naval Gunnery Range. The international border lies approximately south of the southeast margin of the range.
The range consists of sand dunes left over from the ancient inland Sea of Cortez. Seismic activity has raised these. Much of the terrain is still loose dirt, interspersed with sandstone and occasional quartz veins. A dirt road leads towards the mountains, starting off State Highway 2 (S2), also known as the Imperial Highway, not far from the desert community of Ocotillo.
There are no marked trails and the footing is treacherous, made up of loose sand, dirt and crumbled shards of sandstone. Most slopes have no vegetation, but there is occasional mesquite and ocotillo, with coastal cholla at lower elevations. The local fauna includes jackrabbits and sparrows.
There are a few ancient sand dunes that have been fossilized and hollowed out by winds, producing wind caves. Marine fossils such as sand dollars and snails can be found, but it is illegal to remove any fossils. In 1994, the United States Congress designated 18,631 acres (75 km2) as a U.S. Bureau of Land Management managed U.S. Wilderness Area, the Coyote Mountains Wilderness.
Geology
The Coyote Mountains range consists of uplifted metamorphic basement rocks overlain by younger volcanic and sedimentary rocks. The peaks and mountain ranges are primarily Paleozoic and Jurassic basement rocks, which consist of marble, schist, and gneiss. This metamorphic basement rock and overlying volcanic and sedimentary rocks have been uplifted and exposed due to seismic activity along the Elsinore Fault Zone.
Volcanism
During the Miocene, around 22-14 million years ago, volcanic activity produced various volcanic rock features including basalt flows, an andesite plug, and various volcaniclastics including tuffs and breccias, known as the Alverson Formation. These volcanic rocks are primarily exposed along the east and southeastern portion of the range, and are best viewed and easily accessed in the Painted Gorge area of the range (where multiple volcanic rock types of varying colors are exhibited, giving the area a gorgeous 'painted' appearance).
Marine incursion
During the late Miocene, initiation of motion on the West Salton detachment fault caused rapid subsidence of the Salton Trough region, resulting in a marine incursion between 6.3 and 4.3 million years ago. This resulted in the Imperial Formation, composed of locally derived fossiliferous shallow marine sandstones and conglomerates that were deposited in a shallow inland sea across much of the Salton Trough. In the Coyote Mountains, these rocks were deposited directly on the older metamorphic and volcanic rocks. The Imperial Formation preserves many corals as well as shallow marine invertebrates and vertebrates.
Influence of the Colorado River Delta
The marine incursion of the ancestral Gulf of California also introduced a single, very large depositional system (the Colorado River delta) into the Salton Trough, which rapidly prograded to the south (Winker and Kidwell, 1986). During the early Pliocene, between 5 and 4.2 million years ago, this deltaic system facilitated the deposition of a thick marine deltaic sequence of mudstone and sandstone derived from the Colorado River, known as the Deguyños Formation of the Imperial Group (formerly the Imperial Formation). The Deguyños Formation represents the distal prodelta portion of the Colorado River delta, and is characterized by upward-coarsening cycles of claystone, siltstone, sandstone and/or coquina shell beds.