Geologic Tour of New Mexico — Physiographic Provinces

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.

The Prehistoric Trackways National Monument is located in the Robledo Mountains just northwest of Las Cruces in Dona Ana County, south-central New Mexico. It contains rocks of Permian age, from the Late Paleozoic Era. They are composed of sediments deposited about 280 million years ago, before the age of the dinosaurs. These rocks contain major deposits of fossilized footprints made by numerous amphibians, reptiles, insects, and crustaceans, as well as plants and petrified wood. Some scientists have called these features the most scientifically significant Permian tracksites in the world. These fossils provide important information about animal behavior in this ancient tropical environment on the edge of the supercontinent Pangea.

West of the flocks of birds and birdwatchers along the wetlands of the Rio Grande, a story of cataclysmic volcanic eruptions, ancient dune fields, and long-gone towering mountains lie quietly awaiting visitors to the Bosque del Apache National Wildlife Refuge. The Chupadera Wilderness Trail and the Canyon Trail traverse this geologic record in the contemplative solitude of a wilderness setting, affording “rockwatchers” a quick trip through millions of years of Earth history.

The Living Desert Zoo and Gardens State Park was established in 1971 to preserve and display the wide variety of animals, plants, and natural environments found in the Chihuahuan Desert. Located north of Carlsbad on US–285, Living Desert Zoo and Gardens State Park offers a variety of outdoor and indoor exhibits depicting the natural, geologic, archaeological, historical, and mineral wealth of the area.

Fenton Lake State Park is in the Jemez Mountains on the west side of the Valles and Toledo calderas, large collapse features that formed during voluminous volcanic eruptions 1.6 and 1.25 million years ago. The landscape around Fenton Lake is characterized by broad, grass-covered valley bottoms that lie between dissected orange-brown to white mesas that are bound by imposing cliffs. The cliffs are formed by the 1.6 to 1.25 million year old outflow sheets of Bandelier Tuff that erupted from the calderas. The south-flowing Rio Cebolla (Spanish word for onion), which feeds Fenton Lake, cut one of the broad valleys after 1.25 million years ago.

Lincoln State Monument encompasses most of the community of Lincoln, New Mexico and commemorates the lives of many of the key players in the Lincoln County War (1878-1881). Lincoln, which is located in south-central New Mexico, can be access via U.S. Highway 380. The community was originally named La Placita del Rio Bonito (village of the pretty river); the stream that runs along the north side of the village is called the Rio Bonito. The legislature of the territory of New Mexico, encouraged by local citizenry, renamed the village Lincoln in 1869, in honor of President Lincoln, who was assassinated 4 years earlier.

The main visitor’s center for the monument is located near the east end of town on the north side of the highway. The Lincoln County Courthouse Museum, which highlights the escapades and legal troubles of William H. Bonney (Billy the Kid), is the other main attraction associated with the monument. The courthouse is on the west end of town on the south side of the highway. Admission tickets ($5 for adults, children under 16 free) may be purchased at the visitor’s center or at the courthouse. Other buildings that can be visited as part of the tour include the Montaño store, the San Juan mission, the torreon, the post office and Turnstall Museum, and Dr. Wood’s home.

Cimarron is Spanish for wild and untamed and originally was used in New Mexico to refer to the wild bighorn sheep, and later to the wild horses and cattle that once roamed throughout the north-central mountains (Pearce, 1965). Today, the sparsely populated Cimarron country in western Colfax County can still be described as wild and untamed with its rugged, timbered mountains (the Cimarron Range), towering cliffs, and the previously unpredictable Cimarron River. The Cimarron River has been tamed somewhat by the Eagle Nest Dam, which controls flooding in the canyon.

The 64-mile stretch of narrow gauge railroad track between Antonito, Colorado and Chama, New Mexico was originally built in 1880 as part of the Denver and Rio Grande Western Railroad. This rail line provided much-needed transportation and freight service between Denver and mining camps in Silverton during the late nineteenth and early twentieth centuries. When the Federal Government discontinued the use of the silver and gold standard to back American currency, the "Silver Panic" in 1893 caused the closure of many of the mines in the Silverton area. The railroad continued to operate with revenues from transportation of livestock, timber, and farm produce. The oil and gas industry in the Four Corners region also utilized the railroad. Demand for rail transportation in this region waned by the mid-twentieth century. Passenger service on the Denver and Rio Grande Western Railroad ended in 1951 and freight service ended in 1968. Railroad enthusiasts and legislative bodies in New Mexico and Colorado recognized the scenic splendor of the train route between Chama and Antonito. Through a joint effort, the Cumbres and Toltec Scenic Railroad, complete with coal-powered steam engines carrying tourists in railcars on refurbished narrow gauge tracks, was created in 1970 to preserve this historic and picturesque section of railroad.

Cerro Pedernal, one of the most recognized landmarks in north-central New Mexico, is located in the northern Jemez Mountains . Cerro Pedernal lies in the transition zone between the Colorado Plateau and the Rio Grande rift. Typical, relatively flat-lying, Colorado Plateau Mesozoic stratigraphy is exposed at the base of the mountain, while younger Cenozoic basin fill sediments underlie the shoulders of the peak. The andesite and basalt flows capping Cerro Pedernal, which give the mountain its distinctive flat top, were erupted from the northern Jemez volcanic field about 8 million years ago. The lava flows and underlying rocks on Cerro Pedernal and on mesas to the southeast have since been faulted and down-dropped to the southeast by as much as 1870 feet (570 m) during Rio Grande rift extension in the last 8 million years.

America's newest national park (as of December 2019), White Sands is famous for its extensive sea of white gypsum dunes—indeed, it is the largest gypsum dune field in the world. Located in the southern Tularosa Basin, the park was established as a national monument in 1933 and encompasses nearly 176,000 acres (275 square miles, including 115 square miles of gypsum sand dunes). The park not only contains the large dune field but also a saline mudflat called Alkali Flat, a smaller ephemeral salt lake (or playa) named Lake Lucero, parts of the gypsum-dust plains east of the dune field, and alluvial fans from the surrounding mountains. The dune field and Alkali Flat extend more than 12 miles to the north of the park onto the White Sands Missile Range.

Also see the White Sands National Park sample chapter from our popular field guide: The Geology of Southern New Mexico's Parks Monuments and Public Lands.