Area Description

The Greater Potrillo Mountains Complex is located approximately 30 miles southwest of Las Cruces adjacent to the border with Mexico. The West Potrillo Mountains are the focal point of this area, which is one of the largest relatively undisturbed stretches of Chihuahuan Desert landscape in New Mexico. The area also includes the Aden Lava Flow, Mount Riley, Cox Peak, Eagle Nest, Indian Basin, and the East Potrillo Mountains. This landscape is a broad volcanic field encompassing hundreds of cinder cones, large craters, and the shield volcano of Aden Crater that produced extensive lava flows over 10,000 years ago. Mount Riley is the highest point in the region, rising abruptly over 1,700 feet above the surrounding desert plain to an elevation of nearly 6,000 feet. Ephemeral lakes are found in Indian Basin. In addition, the area is made up of isolated intrusive peaks like Eagle Nest, steep sedimentary mountains like the East Potrillo Mountains, sand dunes, and expansive, relatively level plains.

Ecological Values

Chihuahuan Desert grassland and yucca, in association with a mosaic of other desert shrubs such as creosote, acacia, and mesquite, make up the majority of the plant cover in the area. Isolated clumps of netleaf hackberry and other desert trees are found in the lava flow where depressions or deeper pockets of soil hold extra water after rainfall. Occasional juniper trees are also found on mountain slopes and in larger drainages. The limestone substrate of the East Potrillo Mountains provides habitat for a wide diversity of cacti, including Sheer's pincushion cactus. The late summer rains bring extensive stands of wildflowers in this area including white and yellow desert zinnias, desert marigolds, blackfoot daisies, globe mallow, pepperweed, desert sunflowers, Chihuahuan flax, and summer poppy. In one of the large basins in the center of the West Potrillo Mountains, there is a unique 'cholla savannah' vegetation type with large 8 to 10 foot tall cholla trees evenly spaced amongst the grasses. Unusually large specimens of barrel cactus are also found in this area.

Protection of large natural areas is particularly important for long-term preservation of biological diversity. Each unit is an important component in the larger complex of wildlands in the greater Potrillo Mountains area. This area's proximity to northern Mexico adds to its ecological significance. Like the Peloncillo and Big Hatchet Mountains to the west, the Greater Potrillo Mountains Complex forms a biotic link between species in northern Mexico and those in the southwestern United States.

The area's naturalness and large size also contributes to its significance for wildlife. Raptors are common, especially during the winter. Golden eagles, great-horned owls, and Swainson's hawks nest here, and peregrine falcons have been reported. Extensive grasslands in the area provide important habitat for grassland birds that have declined in recent years. This includes potential habitat for Aplomado falcons. Other species that forage and live in the area include pronghorn, mule deer, quail, jackrabbits, and occasional migrating ducks on ephemeral ponds. A high diversity of bats are found in the complex, and melanistic forms of mammals and reptiles occur on the lava flows. The Great Plains narrow-mouth toad has been reported immediately to the south of the West Potrillos and can be expected to occur here. A rare mollusk is also found in the area.

Scenic and Recreational Qualities

Although this complex is located near a bi-national metro-plex of more than 2.5 million residents, the Greater Potrillo Mountains area appears very natural, maintaining its wild beauty. Due to the rugged terrain and lack of water, many areas are inaccessible to cattle and largely ungrazed, adding to the scenic quality. Lava flows, craters, and cinder cones evoke a primeval, "moonscape" image for visitors. The shapes and forms of the lava rock are interesting, especially when juxtaposed to the varied forms of the desert vegetation found here. The Aden Lava Flow contains pressure ridges, lava tubes, and crevices up to 5 feet wide and 20-30 feet deep. In contrast, rounded, grass-covered hills in the complex add a hint of softness to the rugged landscape. These features provide excellent opportunities for photography and geological sightseeing.

Although less than an hour's drive from either Las Cruces or El Paso, most of the area receives little visitor use. This is an excellent area to explore if one desires to avoid contact with others. The area does not have any maintained trails, making cross-country travel for horseback riders, hikers, backpackers a very primitive experience. Isolated mountains, like Mount Riley and Cox Peak's, rise abruptly from the desert floor and make excellent day hikes. Peaks like these in the area, seldom traveled, remind the visitor of the true remoteness and isolation of the area. As one gains elevation, range after range appears on the horizon, jutting up out of vast valleys in the distance. This gives not only a sense of immense space, but also a visual connection between the region's of southwest New Mexico and northern Mexico, which lies only a few short miles to the south. Additional recreational opportunities include botanical study in the East Potrillo Mountains and excellent quail hunting throughout the area.

As nearby urban populations rapidly expand, nearby wild areas assume an even greater importance. The Greater Potrillo Mountains Complex provides these urban dwellers with primitive recreational opportunities that, in many places in the southwest, no longer exist due to urban sprawl into once wild areas. The primeval nature of the complex provides visitors with a wilderness experience and primitive recreational opportunities of the highest order.

Special Management Areas

Three Wilderness Study Areas (WSAs) are located in this complex: Aden Lava Flow, Mount Riley, and West Potrillo Mountains. The West Potrillo Mountains is the largest BLM WSA in New Mexico. The Aden Lava Flow Research Natural Area (RNA) is also located here. The RNA was designated in 1978 to preserve the unique geological and biological phenomena associated with the Aden Lava Flow and to provide research and educational opportunities. A portion of the area also falls within the West Potrillos Habitat Management Plan Area managed to improve habitat for deer and upland game.

Cultural Values

Evidence of pre-Columbian Indian habitation exists in caves in the East Potrillo Mountains. A Classic Mimbres Pueblo located in the region has the highest concentration of bird bones of any known Mimbres site. Several undisturbed El Paso Phase structures have also been found in the West Potrillo Mountains.

Access Information

The south part of the Greater Potrillo Mountains complex is easily reached by Highway 9 that goes from Santa Teresa to Columbus along the border with Mexico. From I-10 exit #8 in Texas, head west toward the border crossing on Highway 136. Just north of the border, about 9½ miles southwest of the interstate exit, turn west on Highway 9. In 16½ miles, CR A008 comes in on the north. This road forms the eastern boundary of the East Potrillo Mountains unit.

About 8 miles further west on Highway 9 from the intersection of CR A008, CR A005 comes in on the north side of the road. Approximately 4½ miles north of Highway 9, CR A007 intersects CR A005 from the east. This road heads to the northeast and forms the eastern boundary of Mount Riley and eventually accesses the southern end of the Aden Lava Flow unit (consult a detailed map before attempting to drive this route). From the intersection of CR A007 and CR A005, CR A005 continues north in between the Mount Riley unit on the east and the West Potrillo Mountains on the west. The southwest part of the West Potrillo Mountains is reached by continuing west on Highway 9 from the intersection of CR A005.

To get to the northeast part of the West Potrillo Mountains and the northwest part of Aden Lava Flow, take the Corralitos Ranch exit #127 off of I-10, about 15 miles west of Las Cruces. From the south side of the interstate, head west on CR B005, which also parallels the interstate. After about 2 miles, follow the gravel road as it curves away from the interstate. Continue on CR B005 from this point for about 8½ miles to the intersection of CR B004 at the railroad tracks. Cross over the railroad tracks here and turn left. Follow CR Boo4 and the RR tracks to the southeast for about 7 miles to the intersection of a road on the south. This route forms the western boundary of the Aden Lava Flow unit. The northeast part of the West Potrillo Mountains can be reach by following this side route southwest for about 7½ miles. The northern part of Aden Lava Flow can be explored by continuing southeast along the RR tracks and CR B004.

The USGS 7.5 minute maps that cover this complex are: Akela, Cambray, Mount Aden, Sibley Hole, X-7 Ranch, Mount Aden SW, Aden Crater, Afton, Mesquite Lake, POL Ranch, Potrillo Peak, Mount Riley, Kilbourne Hole, Coyote Hill, Camel Mountain, Guzmans Lookout Mountain, Mount Riley SE, and Potrillo.