The Plains of San Agustin (sometimes listed as the Plains of San Augustin) is a region in the southwestern U.S. state of

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe, New Mexico, Santa Fe , LargestCity = Albuquerque, New Mexico, Albuquerque , LargestMetro = Albuquerque metropolitan area, Tiguex , Offi ...

in the San Agustin Basin, south of U.S. Highway 60. The area spans Catron and Socorro Counties, about 50 miles (80 km) west of the town of Socorro and about 25 miles north of

Reserve Reserve or reserves may refer to: Places * Reserve, Kansas, a US city * Reserve, Louisiana, a census-designated place in St. John the Baptist Parish * Reserve, Montana, a census-designated place in Sheridan County * Reserve, New Mexico, a US ...

. The plains extend roughly northeast-southwest, with a length of about 55 miles (88 km) and a width varying between 5–15 miles (8–24 km). The basin is bounded on the south by the Luera Mountains and Pelona Mountain (outliers of the

Black Range Black is a color which results from the absence or complete absorption of visible light. It is an achromatic color, without hue, like white and grey. It is often used symbolically or figuratively to represent darkness. Black and white have o ...

); on the west by the Tularosa Mountains; on the north by the Mangas, Crosby, Datil, and Gallinas Mountains; and on the east by the San Mateo Mountains. The

Continental Divide A continental divide is a drainage divide on a continent such that the drainage basin on one side of the divide feeds into one ocean or sea, and the basin on the other side either feeds into a different ocean or sea, or else is endorheic, not c ...

lies close to much of the southern and western boundaries of the plains.''New Mexico Atlas and Gazetteer'', Second Edition, DeLorme Mapping, 2000.

Geology

Geologically, the Plains of San Agustin lie within the Mogollon-Datil volcanic field, just south of the southeast edge of the Colorado Plateau, and west of the Rio Grande Rift Valley. The basin is a

graben In geology, a graben () is a depressed block of the crust of a planet or moon, bordered by parallel normal faults. Etymology ''Graben'' is a loan word from German, meaning 'ditch' or 'trench'. The word was first used in the geologic conte ...

(a downdropped block which subsided between parallel faults). The graben is younger than the Datil-Mogollon volcanic eruptions.Stearns, Charles E. (1962) ''Geology of the north half of the Pelona Quadrangle, Catron County, New Mexico'' Bulletin 78, New Mexico Bureau of Mines and Mineral Resources, Socorro, NM, The flat floor of the plains was created by a

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

lake ( Lake San Agustin).Halka Chronic, ''Roadside Geology of New Mexico'', Mountain Press Publishing, Missoula, 1987, . Although the graben has dropped an estimated 4,000 ft., the surface relief has been reduced to about 2,000 ft. by sedimentation. A great deal of the sediments entered the San Agustin basin prior to the formation of Lake San Agustin in the last glacial period. There is no evidence of tectonic activity in the area after Lake San Agustin became extinct. Ecologically, the plains lie near the northern end of the

Chihuahuan Desert The Chihuahuan Desert ( es, Desierto de Chihuahua, ) is a desert ecoregion designation covering parts of northern Mexico and the southwestern United States. It occupies much of far West Texas, the middle to lower Rio Grande Valley and the lo ...

(though the ranges surrounding the Gila River headwaters intervene), which is dominated by

shrubland Shrubland, scrubland, scrub, brush, or bush is a plant community characterized by vegetation dominated by shrubs, often also including grasses, herbs, and geophytes. Shrubland may either occur naturally or be the result of human activity. It ...

Climate

The Plains of San Agustin has a

cold semi-arid climate A semi-arid climate, semi-desert climate, or steppe climate is a dry climate sub-type. It is located on regions that receive precipitation below potential evapotranspiration, but not as low as a desert climate. There are different kinds of semi ...

( ''BSk'').

Landmarks

The plains are probably best known as the site of the Very Large Array, a

radio astronomy Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies. The first detection of radio waves from an astronomical object was in 1933, when Karl Jansky at Bell Telephone Laboratories reported radiation comin ...

observatory. The plains were chosen for the observatory because of their isolated location away from large population centers, and the partial shielding effect of the surrounding mountain ranges. The edges of the plains have sites of

archaeological Archaeology or archeology is the scientific study of human activity through the recovery and analysis of material culture. The archaeological record consists of artifacts, architecture, biofacts or ecofacts, sites, and cultural landscap ...

interest such as a prehistoric rockshelter known as

Bat Cave The Batcave is a subterranean location appearing in American comic books published by DC Comics. It is the headquarters of the superhero Batman, whose secret identity is Bruce Wayne and his partners, consisting of caves beneath his personal ...

. Other sites in the area include a ghost town called Old Horse Springs and the Ake Site, a prehistoric occupation site.

Notes

Sources

* Powers, William E. (1939) "Basin and Shore Features of the Extinct Lake, San Augustin, New Mexico" ''Journal of Geomorphology'' 2: pp. 345–356 * Weber, Robert H. (1994) "Pluvial Lakes of the Plains of San Augustin" ''In'' Chamberlin, R.M. ''et al.'' (1994) ''Mogollon Slope, West-Central New Mexico and East-Central Arizona'' pp. 9–11, New Mexico Geological Society, Forty-Fifth Annual Field Conference, Socorro, New Mexico.
Holliday, Vance T. 'et al.'' (2007) "Paleoindian Geoarchaeology and the Archaeological Potential on the Plains of San Augustin, New Mexico" Argonaut Archaeological Research Fund, Department of Anthropology and Department of Geosciences, University of Arizona, Tucson, Arizona, USA

External links

* {{coord, 33, 52, 31, N, 108, 15, 03, W, display=title Landforms of Catron County, New Mexico Great Divide of North America Landforms of New Mexico Landforms of Socorro County, New Mexico Plains of the United States