Geologic Tour of New Mexico — Physiographic Provinces

The Bitter Lake National Wildlife Refuge covers about 38 square miles in central Chaves County, east and northeast of Roswell. Situated on the Pecos River where the Chihuahuan Desert meets the Great Plains, the refuge supports an amazing diversity of flora and fauna, including numerous migratory waterfowl in the winter months. Established in 1937, the refuge includes the new Joseph R. Skeen Visitor Center, which sits on the Orchard Park terrace overlooking floodplain wetlands and the redbed escarpment on the eastern skyline.

Beginning at the Visitor Center are a bike trail, a short walking trail, and an 8-mile auto-tour loop. The loop traverses a Pecos Valley terrace overlooking the floodplain for the first 4 miles. The remainder explores floodplain environments, from an abandoned Pecos River meander oxbow lake to the low-lying wetlands. The more adventuresome visitors can explore the refuge’s north tract, which includes the Salt Creek Wilderness. Here, one can hike to the mouth of Salt Creek at the Pecos River and continue onto some of the refuge’s many sinkholes, including the scenic Ink Pot.

The Tyrone mining district, the second largest porphyry copper deposit in New Mexico, is located 10 miles southwest of Silver City in the Burro Mountains of southwestern New Mexico. Native Americans initially mined turquoise from the area around 600 AD. Underground mining was established in the early 1860s and the current mode of mining, open-pit stripping, began in 1968. The mine became part of Freeport-McMoRan in 2007. Parts of the pit are currently being reclaimed.

Fort Selden State Monument is adjacent to Leasburg Dam State Park on NM–157 (Fort Selden Road) at the Radium Springs exit on I–25, north of Las Cruces. It is an area rich in both geologic and human history. The location was an ancient Indian campground and a crossing point for Spanish caravans headed across the Jornada del Muerto. Living-history demonstrations of 19th century military life at Fort Selden highlight many weekends during the summer. Wildlife viewing, especially bird watching, is popular at the state park. A bird list is available from the park office. In the winter months many species of ducks, teals, snow geese, cranes, herons, egrets, swans, and pelicans migrate through the southern Rio Grande valley and can be seen at the state park. Numerous raptors, including owls, turkey vultures, eagles, and hawks, can be seen hunting in the area. Small mammals common to the park include rabbits, squirrels, chipmunks, rodents, coyotes, and foxes.

Clayton Lake State Park is approximately 12 mi northwest of Clayton on NM–370 in northeastern New Mexico. Unlike most lakes in New Mexico, Clayton Lake was established in 1955 specifically as a recreational site by the State Game and Fish Commission after construction of the dam. In 1967 the site became Clayton Lake State Park. The lake offers excellent fishing and is stocked with rainbow trout, walleye pike, crappie, bluegills, bullheads, large-mouth bass, and channel catfish by the State Game and Fish Department. Boating is prohibited after the fishing season ends, so from October through April the park is a refuge for waterfowl.

The most exciting geological feature at Clayton Lake State Park is the dinosaur footprints found in sandstone at the dam spillway about 1982. Approximately 500 tracks of at least three species are found at the spillway; most of them pertain to ornithopod dinosaurs (ichnogenus Caririchnium) and theropods. The dinosaurs ranged in size from a baby Iguanodont that was approximately 1 ft long to adults that were 30 ft long. Most of the tracks are of bipedal herbivores or planteaters (Iguanodonts or Hadrosaurs). The kite-shaped tracks were made by Iguanodonts walking in wet mud. Worm borrows, fossilized impressions of plants, ripple marks from waves, and mudcracks are also common.

Cabezon Peak is one of the best-known and most visible landmarks in northwest New Mexico. This giant volcanic plug is visible for tens of miles in all directions, and as far away as Placitas. Cabezon means “big head” in Spanish, and it is aptly named. It is the largest of several dozen widely scattered rocky monoliths, called the Rio Puerco necks. Rising above the Rio Puerco valley floor, they are some of the best-preserved examples of volcanic necks in the world. The craggy black peaks stand in sharp contrast to the sparsely vegetated, buff-colored lowlands from which they emerge. Mt. Taylor looms majestically to the southwest, Mesa Prieta borders the valley to the east, and the Jemez Mountains are visible to the north. This starkly beautiful landscape is unique in New Mexico. At an elevation of 7,786 ft, Cabezon Peak towers more than 1,100 ft above its base, and 2,000 ft above the Rio Puerco nearby.

El Morro, which means "bluff" or "headland" in Spanish, is an imposing cliff made of Middle to Late Jurassic (155 to 165 million years old) Zuni Sandstone capped by Late Cretaceous Dakota (~95 to 96 million years old) sandstone and shale. Travelers, including Native Americans, Spaniards, and citizens of the United States, have carved their symbols, names, messages, and dates of their passage into the soft cross-bedded Zuni Sandstone for centuries.

The Zuni-Bandera volcanic field, in northwest New Mexico, has had many episodes of basaltic eruptions over the last million years. The youngest lava flow in the field is the McCartys flow, which is only 3000 years old, one of the youngest volcanic features in the 48 contiguous United States! The Zuni-Bandera volcanic field has produced many basaltic lava flows, some with a-a characteristics, and some that are paheohoe. There are also a number of well-preserved cinder cones that can be visited, as well as many lava tubes, some of which contain perennial ice. The Zuni-Bandera volcanic field is an excellent site for studying physical volcanology of basaltic magmatic systems.

Petroglyph National Monument is located on Ceja Mesa on the west side of Albuquerque. The monument is best known for the estimated 25,000 rock art images carved into basalt erupted from the approximately 200,000-year-old Albuquerque volcanic field. Using stone chisels and hammer stones, the ancestors of the Puebloan Indians cut most of the petroglyphs into the desert varnish coating the basalt between 1300 and 1680 A.D. A few of the markings are much older, dating back to perhaps 2000 B.C. Spaniards and later generations of Albuquerque inhabitants have produced younger petroglyphs with more modern themes. The monument, created in 1990, includes about 17 miles of petroglyph-covered basalt cliffs and five extinct volcanoes.

This recreation area in the Lincoln National Forest has spectacular cliffs and features a year-round spring-fed stream, waterfalls (the largest of which has a 150-foot drop), and many refreshing clear-water wading pools. There are picnic areas and several hiking trails, including T–68 and T–68A that lead to the spring source of the waterfalls. The Apache name for the area was “gostahanagunti,” which means hidden gulch, and the presence of flakes of worked chert, grinding holes (bedrock mortars), and nearby pictographs testify to long-standing Native American use of this wildlife-rich oasis in the desert.

Santa Rosa, "the city of natural lakes", lies in the semiarid, upper Pecos River valley in Guadalupe County where numerous natural artesian-spring lakes abound. Blue Hole, one of these lakes located within the city limits, is well known for its crystal-clear water and attracts scuba divers. However, the largest lake in the area is man made—Santa Rosa Lake, located about seven miles north of the city on the Pecos River. The dam was completed in 1981 at a cost of $43 million for conservation of irrigation water and flood and sedimentation control. The name of the dam was changed from Los Esteros (Spanish for pond or estuary) in 1980 when the state park was authorized.