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 in the San Agustin Basin, south of

U.S. Highway 60 U.S. Route 60 is a major east–west United States highway, traveling from southwestern Arizona to the Atlantic Ocean coast in Virginia. The highway's eastern terminus is in Virginia Beach, Virginia, where it is known as Pacific Avenue, in the ...

. 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. 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 The Luera Mountains are a 15 mi (24 km) long, mountain range in southeast Catron County, New Mexico, USA in the central-southeast of the Plains of San Agustin. The range abuts the northwest end of the north-south extensive Black Range w ...

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 Tularosa is a villageFor census purposes it is called a village, but in New Mexico it is historically called a town. See, for example, Otero, Miguel A. (1903) ''Report of the Governor of New Mexico to the Secretary of the Interior - 1903'' Governme ...

; 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 ...

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 The Colorado Plateau, also known as the Colorado Plateau Province, is a physiographic and desert region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. This province covers an area of ...

, 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 contex ...

(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 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 (though the ranges surrounding the

Gila River The Gila River (; O'odham ima Keli Akimel or simply Akimel, Quechan: Haa Siʼil, Maricopa language: Xiil) is a tributary of the Colorado River flowing through New Mexico and Arizona in the United States. The river drains an arid watershed of n ...

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 m ...

Climate

The Plains of San Agustin has a cold semi-arid climate ( ''BSk'').

Landmarks

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

observatory An observatory is a location used for observing terrestrial, marine, or celestial events. Astronomy, climatology/meteorology, geophysical, oceanography and volcanology are examples of disciplines for which observatories have been constructed. His ...

. 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. 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