West Potrillo Mountains


The West Potrillo Mountains are a mountain range in south central Doña Ana County, New Mexico, United States. They are located approximately northwest of El Paso, Texas, southwest of Las Cruces, New Mexico, and southeast of Deming, New Mexico Most of the mountains are located on land managed by the Bureau of Land Management as part of the Organ Mountains–Desert Peaks National Monument. Access to the vicinity is through Doña Ana County Road B-4 South from NM 549, which may be accessed from Interstate 10 Exit 116.

Geology

The West Potrillo mountains occupy the western part of the Potrillo volcanic field, an area of olivine basalts covering approximately. In addition to the West Potrillo Mountains, the Potrillo Volcanic Field includes Aden Crater and the Santo Tomas / Black Mountain basalts near La Mesa, New Mexico. The field includes hundreds of volcanic features, including maars, spatter cones, a shield volcano, and cinder cones. The most common peaks in the West Potrillos are cinder cones with a height of between. They are relatively undissected by erosion, and have estimated ages of 0.5 to 3 mya. Some features believed to be as young as twenty thousand years old.
The rocks in the area are extremely diverse, with exposed layers ranging in age from Paleozoic to Holocene. Marine deposits were deposited during repeated advances of late Paleozoic and early Mesozoic seas. Folding and faulting of Lower Cretaceous layers occurred during the Laramide disturbance in the nearby East Potrillo Mountains. The area has been above sea level since the Cretaceous period. In the early to middle Tertiary, the Riley Cox andesitic pluton was emplaced. This activity also seems to be associated with the intrusion of andesitic and quartz latite dikes in the East Potrillo range. During the middle Tertiary, high angle faulting and uplifting occurred in the East Potrillo range and began to form intermontane basins. In the middle to late Quaternary, alkali olivine basalt was extruded from fissures in the Fitzgerald, Robledo, and Aden faults. During the late Pleistocene to Holocene, movement occurred along the Fitzgerald and Robledo faults. Holocene deposits are mostly fine blown sand.

Climate

The West Potrillo Mountains lie within the Chihuahuan Desert. The climate is arid and continental. Weather records in nearby El Paso, Texas show that the average daily maximum temperature over the course of the year is 77.3 degrees Fahrenheit, with an average daily minimum of 50.1 degrees Fahrenheit. Average monthly maximum temperatures range from 96 degrees in June, to 58 degrees in January. Average monthly minimum temperatures range from 30 degrees in January to 70 degrees in July. Average annual precipitation in El Paso is 8.81 inches, with monthly averages ranging from 0.2 inches in April to 1.7 in September. Over half of the annual precipitation falls in the form of summer rains between June and September, although some snow can be expected in the winter.

Ecology

The plant communities found in the West Potrillos can be generally characterized as Chihuahuan desert scrublands, creosotebush desert, and desert grasslands. The dominant shrub species include creosote bush, honey mesquite, soaptree yucca, and fourwing saltbush. Common grasses include black grama, blue grama, sideoats grama, bush muhly, and alkali sacaton.
Common mammals include mule deer, coyotes, black-tailed jackrabbit, desert cottontail, white-throated woodrat, kangaroo rats, and cactus mouse.
Common birds include golden eagles, Swainson's hawk, northern harrier, burrowing owl, greater roadrunner, quail, horned lark, western meadowlark, doves, and black-throated sparrow.
Common reptiles include collared lizards, roundtail horned lizard, striped whipsnake, and western diamondback rattlesnake.
Common amphibians include New Mexico spadefoot toad, Great Plains toad, green toad, and red-spotted toad.

Human use

Archeological studies indicate that there have been at least three distinct periods of prehistoric human usage of the West Potrillos. The Paleo-Indian period began in about 9,500 BCE and ended in about 6,000 BCE. This period is itself divided into three traditions: Clovis, Folsom, and Plano. These people were thought to have been mobile big game hunters. Beginning in about 6000 BCE, members of the Desert Archaic cultures moved into the area and remained until about 100 ACE. These people were hunters and gatherers, who appear to have begun plant cultivation. From about 200 ACE to about 1450 ACE, the Mogollon culture became predominant. During this period, agriculture became predominant and pottery was introduced. People aggregated into villages and built above-ground residences. There was evidence of trade with other areas. In about 1540, it appears that the ancestors of the Apaches moved into the area and displaced the earlier residents. Apache resistance discouraged use of the area by Spanish Colonial or Mexican settlers. Occupation of the area by the Chiricahua Apache continued until about 1890.

Points of interest

Established in 2019 by the U.S. Congress, the Potrillo Mountains Wilderness, at 105,085 acres, is the 4th largest in New Mexico. High points in the range include Cox Peak, Mt. Riley, Potrillo Peak, and Guzman Lookout Mountain. The area is used for ranching, bird hunting, camping, hiking, and foot launched aviation. Many campers and hikers, however, look elsewhere because of the absence of trails and dependable water. This wilderness area is managed by the Bureau of Land Management.

In 1928, a fossilized ground sloth was found in a fumarole in Aden Crater. Its age was estimated to be 11,000 years. It was later acquired by the Peabody Museum of Natural History at Yale University.