Area Description

Over 2 million years ago, the Cerro de la Olla shield volcano rose through and covered the thick Serviellta basalt lava flows of the Taos Volcanic Field, the largest volcanic field in the Rio Grande Rift system. These lava flows occurred approximately 5 million to 1.5 million years ago and blanketed the entire Rio Grande Trough. The Rio Grande and Rio San Antonio have carved beautiful gorges into these basalt lava flows. Landforms in the complex also include the forested volcanic intrusion of Cerro Chiflo and vast shrub and grass-covered, rolling mesas, which extend outward from the edge of the river gorges.

Elevations in the area range from 7,000 feet on the mesa scrublands to 9,464 feet atop Cerro de la Olla, the highest point on BLM public lands in New Mexico. Pinyon-juniper woodlands cover this mountain, and aspen stands grow on its peak. Most drainages within the complex lead to the Rio Grande. On the high mesa are also numerous natural depressions that have no natural outlet and therefore feed the aquifers of the Rio Grande Watershed.

Ecological Values

The Greater Rio Grande Gorge complex has extraordinarily high ecological value. The Rio Grande and Rio San Antonio are important water sources in an otherwise generally arid environment. Riparian areas along the river corridors, cliffs along the gorges, forested uplands, and grasslands and scrublands of the high mesa provide an incredibly diverse array of habitats.

The river corridors contain the highest biodiversity in the area. Riparian vegetation that lines the banks of the Rio San Antonio and Rio Grande include cottonwood, willow, boxelder, snowberry, mountain mahogany, golden currant, and gooseberry, as well as a variety of grasses including side-oats and blue grama, pinyon and Indian ricegrass, and bottlebrush squirreltail. The canyon walls and mountainous uplands consist primarily of conifer woodlands, which include blue spruce, white fir, and ponderosa pine mixed with the more dominant pinyon pine, Rocky Mountain juniper and Douglas fir. These upland forests and canyon corridors provide hunting grounds for mountain lion, bobcat, and gray fox. Black bear, elk, mule deer, beaver, porcupine chipmunk, and squirrel can also be found here. In addition, a reintroduction of the river otter is planned for the Rio Grande.

The river gorges also support a great diversity of passerine birds, including the southwestern willow flycatcher. Canyon walls provide habitat for endangered raptors such as the bald eagle, osprey, and the peregrine falcon, all of which have reportedly been sighted in this area. The rocky cliffs also offer prime nesting habitat for red-tailed, Cooper's, Swainson's, and rough-legged hawks; golden eagles; great-horned owls; and prairie falcons. Other birds present here include ducks, geese, blue heron, turkey, American kestrel, and a great number of smaller species such as quail.

The Rio Grande in the area of this complex is considered to be one of the best trout fisheries in New Mexico and supports both rainbow and brown trout. Other fish here include northern pike, catfish, white sucker, carp, long nose dace, and the endangered flathead chub.

Up above the rim of the river gorges, the open country of the rolling mesas is covered in grassland and scrubland. Plant species here include big sagebrush, broom snakeweed, and several varieties of grasses such as blue grama and western wheatgrass. Wildlife supported in these areas includes Nuttall's cottontail, white-tailed jackrabbit, prairie dog, badger, and coyote. In addition, habitat for sage grouse is excellent and reintroduction of this species is planned.

The nearly 2,000- foot rise of Cerro de la Olla gives it a diverse array of habitats from shrub-grasslands to pinyon-juniper forests to stands of aspen trees. This habitat diversity increases overall biodiversity in the unit, especially in the transition zones between habitat types. The most significant ecological value of the Cerro de la Olla unit is the critical winter habitat it provides for Rocky Mountain elk, mule deer, and pronghorn. These ungulates use the area year-round and form winter congregations at lower elevations. Elk from a large region of northern New Mexico and southern Colorado can gather into a herd of up to 1,500 animals, especially in severe winters.

Scenic and Recreational Qualities

The scenic wonder of the Rio Grande Gorge is a nationally recognized icon of northern New Mexico. The Rio San Antonio and other canyons have carved spectacular gorges as well. Volcanic cliffs of the river canyons have periodically released large boulders into the canyon bottoms, where they stand as evidence of the natural forces at work in the area. The deep canyons in the complex allow for a rugged wilderness experience of exploration. Recreational activities include hiking, rock climbing, river rafting, kayaking, and canoeing. Other more passive activities include bird watching and photography.

The relatively flat and open terrain of the high mesa contrasts sharply with the complex and rugged canyons of the area. These areas offer stunning views of the canyon gorges backed by the precipitous rise of the Sangre de Cristo Mountains. These uplands are excellent for hunting, wildlife viewing, horseback riding, and, when enough snow falls, cross-country skiing. The terrain of the high mesa is also easy to traverse and offers unlimited possibilities for remote campsites, making backpacking one of the primitive recreational activities possible in this area. In addition, light pollution is minimal at the relatively high elevation of the complex, making star gazing here particularly spectacular and enjoyable.

Special Management Areas

The Rio Grande Gorge unit includes approximately 25 miles of the Rio Grande Wild and Scenic River and a portion of the Wild Rivers Recreation Area. It is also contiguous with the Rio Grande Corridor ACEC to the north in Colorado. The complex also includes much of the San Antonio/Pot Mountain Winter Range Special Management Area (SMA), designated to protect critical winter habitat for elk, mule deer, and pronghorn.

Cultural Values

Archaeological sites in the Rio Grande Gorge area show that human use and occupation of the area date back 7,000 years. Most sites date to the Archaic period and indicate that the area was used most intensively from 5,500 B.C. to 500 A.D. Sites include hunting and butchering areas, campsites, quarries, and petraglyphs.

Access Information

The easiest access to the Rio Grand Gorge is from Hwy 378 which goes west from Hwy 522 about 4 miles north of Questa. This takes you to the Wild Rivers National Recreation Area, which is adjacent to the unit.

To get the Cerro de la Olla unit or the more remote western portion of the Rio Grande Gorge, take Hwy 285 north from Tres Piedras. At mile marker 401, head east on the maintained dirt road. You will soon see a BLM sign regarding travel restrictions in the area. Continue past this sign for a mile or so until the road forks in front of a couple of hills. Go right and stay on this main road. It will approach the north side of Cerro de la Olla. To the east of Cerro de la Olla is a ridge called Cerro Chiflo. Routes on its north and south sides come off this same main road and lead to the Rio Grande Gorge.

About 2 to 3 miles north of the route to Cerro de la Olla is a maintained road going west from Hwy 285. This road wraps around San Antonio Mountain and is the southern boundary of the Rio San Antonio unit. As this road heads to the west side of San Antonio Mountain and joins another main road, it comes within ½ mile of the Rio San Antonio itself.

The USGS 7.5 minute maps that cover this complex are: Rio Grande Gorge and Cerro de la Olla - Segita Peaks NE, Cerro de la Olla, Tres Piedras NE, Guadalupe Mountain, Ute Mountain, Sunshine. Rio San Antonio - Pinabeteso Peaks and Los Pinos.