New Mexico’s landforms span four major regions: the Sangre de Cristo Mountains, the southernmost range of the Rockies, in the north; the Colorado Plateau of mesas and volcanic necks in the northwest; the Great Plains and the Llano Estacado tableland in the east; and the basins and ranges of the Chihuahuan Desert in the south, with the Rio Grande rift valley running down the middle. The highest point is Wheeler Peak at about 4,011 m (13,161 ft); the lowest is Red Bluff Reservoir on the Pecos River at the Texas border, about 868 m (2,845 ft). Over four-fifths of the state lies above 1,200 m (4,000 ft), and its 314,915 km² (121,591 sq mi) make it the fifth-largest state. Walking the state from its summit down to its lowest shoreline passes almost every one of its signature landforms.
Wheeler Peak and the Sangre de Cristo crest
The descent starts in Taos County, about 24 km (15 mi) northeast of the town of Taos and 3 km southeast of Taos Ski Valley. Wheeler Peak sits in the Sangre de Cristo Mountains, which run south from Poncha Pass in Colorado to Glorieta Pass near Santa Fe. Mount Walter, just north of Wheeler and the second-highest named summit in New Mexico, reaches 4,005 m (13,141 ft) but rises only about 16 m above the saddle between them, so it is not counted as a separate peak. The mountain was called Taos Peak until 1950, when it was renamed for Major George Montague Wheeler, who spent ten years leading survey parties across New Mexico and six other southwestern states. Published figures for its height vary by a few metres depending on the survey: the USGS figure is 13,161 ft (4,011 m), while other surveys give 13,167 ft (4,013 m).
The peak is the centre of the Wheeler Peak Wilderness in Carson National Forest, and much of the mountain country just south of it belongs to Taos Pueblo, which regained some 48,000 acres (190 km²) of former national forest in 1970. Snowmelt from these slopes feeds both sides of the range: the Rio Grande to the west and, from the eastern slopes further south, the headwaters of the Pecos, which begin above 3,700 m (12,000 ft) in Mora County.
West of the range, the land drops onto the Taos Plateau, a sheet of basalt lava flows. Here the Rio Grande has cut the Rio Grande Gorge, a chasm about 80 km (50 mi) long that reaches 240 m (800 ft) deep just south of the Rio Grande Gorge Bridge, 16 km (10 mi) northwest of Taos. In 1968 this stretch was among the first eight rivers in the National Wild and Scenic Rivers System, and since 2013 the gorge has been the heart of Rio Grande del Norte National Monument.
Redondo Peak inside the 22-kilometre Valles Caldera
Across the rift to the southwest, the Jemez Mountains hold the textbook example of a resurgent caldera. The Valles Caldera is 22 km (13.7 mi) wide and formed when a huge eruption about 1.23 to 1.25 million years ago emptied the magma chamber beneath and the ground collapsed into it. It swallowed an older crater, the Toledo Caldera, which had formed 1.61 million years ago. Both eruptions spread thick layers of ash, now the Bandelier Tuff, whose orange-tan cliffs form the mesas of the Pajarito Plateau around Los Alamos and Bandelier National Monument.
After the collapse, the caldera floor pushed back up. Redondo Peak, at 3,430 m (11,254 ft), is a resurgent lava dome standing entirely inside the caldera, and Valles was the site where geologists first worked out how such resurgent calderas form, a model later applied to Yellowstone. The youngest eruption, the Banco Bonito obsidian flow, came only about 68,900 years ago, and hot springs and fumaroles show the system is still warm. Grassy valleys such as Valle Grande fill the moat around the dome, and the area has been the Valles Caldera National Preserve since 2000. For the process itself, see our explainer on what a caldera is.
Sandia Crest over the Albuquerque Basin
Further south, the Rio Grande rift shows itself as a string of deep basins separated by uplifted blocks. The rift is a zone where the continent is being pulled apart; it runs from central Colorado to Chihuahua in Mexico and averages about 50 km (31 mi) wide. Its three main basins, from north to south, are the San Luis, Española and Albuquerque basins, and the Rio Grande follows them all the way to El Paso. Albuquerque, Santa Fe, Taos, Española and Las Cruces all sit inside the rift.
The Sandia Mountains are the clearest example of a rift shoulder. They form a single tilted block, about 27 km (17 mi) long, with a steep, rugged western face that rises straight out of the Albuquerque Basin to Sandia Crest at 3,255 m (10,678 ft). The Sandia Peak Tramway climbs that face from the northeast edge of the city, and it was the longest aerial tram in the world from 1966 until 2010. The city itself spreads across the basin floor between the mountains and the West Mesa, with the Rio Grande and its cottonwood bosque running through the middle.
Shiprock on the Colorado Plateau
West of the rift, the northwest quarter of New Mexico belongs to the Colorado Plateau, a high country of flat-lying rock layers, mesas, dry grassland and pinyon-juniper woodland. Its landmark is Shiprock, called Tsé Bitʼaʼí, "rock with wings", in Navajo, which rises about 482 m (1,583 ft) above the plain of the Navajo Nation in San Juan County to a peak of 2,188 m (7,177 ft).
Shiprock is a volcanic neck: the solidified throat of a volcano that formed perhaps 750 to 1,000 m underground about 27 million years ago and was exposed as the softer rock around it wore away. Wall-like dikes of dark minette radiate from it across the plain. It sits in the Four Corners region, where New Mexico meets Colorado, Arizona and Utah, and was designated a National Natural Landmark in 1975. The peak is governed by the Navajo Nation and holds a central place in Navajo religion and tradition: the name recalls the great bird that, in Navajo legend, carried the people to their present lands.
White Sands in the closed Tularosa Basin
South of Albuquerque the rift widens and the land drops into the Chihuahuan Desert, the largest desert in North America. East of the Rio Grande lies the Tularosa Basin, a graben of about 16,800 km² (6,500 sq mi) between the San Andres and Oscura mountains to the west and the Sacramento Mountains to the east. No water flows out of it. Rain and snowmelt dissolve gypsum from the surrounding ranges and carry it into the basin, where it collects in Lake Lucero, a playa that fills and dries. As the water evaporates, gypsum crystallises as selenite, and wind breaks the crystals into white sand and drives it northeast.
The result is a gypsum dune field of about 710 km² (275 sq mi), the largest of its kind on Earth, with dunes up to 18 m (60 ft) high and about 4.1 billion tonnes of sand. White Sands National Park protects the southern 41% of it; the rest lies inside White Sands Missile Range, which also contains the Trinity Site, where the first atomic bomb was tested in 1945. Our White Sands desert guide looks at the dunes in more detail.
The Llano Estacado and the Pecos valley
The eastern third of New Mexico is Great Plains country. Its most striking part is the Llano Estacado, or "Staked Plain", one of the largest tablelands in North America, shared with northwestern Texas. The surface slopes almost uniformly at about 2 m per km (10 ft per mile), from over 1,500 m (5,000 ft) in the northwest to about 900 m (3,000 ft) in the southeast. Its western boundary in New Mexico is the Mescalero Ridge, an escarpment that Spanish explorers compared to the palisades of a fort, which may be where the name comes from.
Between the escarpment and the mountains, the Pecos River runs south roughly parallel to the Rio Grande. It flows 1,490 km (926 mi) from the Sangre de Cristo to its meeting with the Rio Grande at Del Rio, Texas, and it later played a large role in the Spanish exploration of Texas. In the northeast corner of the state, the plains are broken by the Raton-Clayton volcanic field, where Capulin Volcano, an extinct cinder cone, has been a national monument since 1916.
Carlsbad Caverns and Red Bluff Reservoir, 868 metres
In the southeast corner, the Guadalupe Mountains rise from the Pecos valley. They are built of the Capitan Reef, formed about 250 million years ago along the shore of an inland sea in the Permian period and later buried under evaporites. Underneath the reef lie oil and gas reserves, and hydrogen sulphide rising from them mixed with oxygen-rich groundwater to make sulphuric acid, which dissolved the limestone from below. The gypsum left in the caves is evidence of that process.
The best known of these caves, Carlsbad Cavern, was explored in 1898 by a teenager named Jim White using a homemade wire ladder. Its Big Room is almost 1,220 m (4,000 ft) long, 191 m (625 ft) wide and up to 78 m (255 ft) high, the largest chamber in North America. Until 1932 visitors walked down a switchback trail to 230 m (750 ft) below the surface before elevators were installed. Carlsbad Caverns became a national park in 1930 and a World Heritage Site in 1995; our Carlsbad Caverns guide covers its rooms.
Downstream of Carlsbad the Pecos crosses into Texas at Red Bluff Reservoir, formed in 1936 by a dam built for irrigation and hydroelectric power. Its northern shoreline in Eddy County, about 868 m (2,845 ft) above sea level, is the lowest point in New Mexico, roughly 3,140 m below the summit of Wheeler Peak.