The San Andres Mountains are a

mountain range A mountain range or hill range is a series of mountains or hills arranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form, structure, and alignment that have ari ...

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

counties A county is a geographic region of a country used for administrative or other purposesChambers Dictionary, L. Brookes (ed.), 2005, Chambers Harrap Publishers Ltd, Edinburgh in certain modern nations. The term is derived from the Old French ...

of Socorro, Sierra, and Doña Ana. The range extends about 75 miles (120 km) north to south, but are only about 12 miles (19 km) wide at their widest. The highest peak in the San Andres Mountains is

Salinas Peak Salinas Peak is the highest point in the San Andres Mountains of south-central New Mexico, in the United States. It lies near the northern end of the range, about northwest of Alamogordo and southeast of Socorro. To the east lies the Tularosa ...

, at 8,965 feet (2,733 m).

Geography

Though nearly contiguous with the Organ Mountains to the south, separated by St. Augustine Pass (elevation and U.S. Highway 70, the two are very distinct geologically and botanically. The

Oscura Mountains Oscura Mountains, originally known to the Spanish as the ''Sierra Oscura'', are a ridge of mountains, trending north and south, east of the Jornada del Muerto and west of the Tularosa Valley. It is located in Socorro County and Lincoln County, Ne ...

to the north are separated from the San Andres Mountains by Mockingbird Gap (elevation ) and the much lower Little Burro Mountains. The San Andres Mountains are comparatively dry and do not support extensive woodlands. They are mostly closed to the public, lying almost entirely within the restricted

White Sands Missile Range White Sands Missile Range (WSMR) is a United States Army military testing area and firing range located in the US state of New Mexico. The range was originally established as the White Sands Proving Ground on 9July 1945. White Sands National P ...

Geology

The San Andres Mountains form part of the eastern edge of the

rift valley A rift valley is a linear shaped lowland between several highlands or mountain ranges created by the action of a geologic rift. Rifts are formed as a result of the pulling apart of the lithosphere due to extensional tectonics. The linear d ...

of the

Rio Grande The Rio Grande ( and ), known in Mexico as the Río Bravo del Norte or simply the Río Bravo, is one of the principal rivers (along with the Colorado River) in the southwestern United States and in northern Mexico. The length of the Rio G ...

, and are made up of west-dipping fault blocks made primarily of San Andres Formation

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms w ...

, but also with extensive exposures of reddish Abo Formation

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicat ...

on the western side, and

quartz monzonite Quartz monzonite is an intrusive, felsic, igneous rock that has an approximately equal proportion of orthoclase and plagioclase feldspars. It is typically a light colored phaneritic (coarse-grained) to porphyritic granitic rock. The plagio ...

on the eastern side.Butterfield, Mike, and Greene, Peter, ''Mike Butterfield's Guide to the Mountains of New Mexico'', New Mexico Magazine Press, 2006,

Gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard or sidewalk chalk, and drywa ...

deposits washed from these mountains are the main source of the dunes in

White Sands National Park White Sands National Park is an American national park located in the state of New Mexico and completely surrounded by the White Sands Missile Range. The park covers in the Tularosa Basin, including the southern 41% of a field of white sand d ...

. Significant summits include:NM peaks on Lists of John

Desert bighorn sheep

The biggest and best

desert bighorn sheep The desert bighorn sheep (''Ovis canadensis nelsoni'') is a subspecies of bighorn sheep (''Ovis canadensis'') that is native to the deserts of the United States' intermountain west and southwestern regions, as well as northwestern Mexico. The ...

habitat in New Mexico is in the San Andres Mountains, which can host up to 400 bighorn.New Mexico Game & Fish (2002) "Desert bighorn sheep" ''Wildlife Notes''
An area of in the southern portion of the San Andres Mountain range was set aside in 1941 as the

San Andres National Wildlife Refuge The San Andres National Wildlife Refuge is located in the southern San Andres Mountains of southcentral New Mexico, USA. The refuge, which lies within the northernmost extension of the Chihuahuan Desert, has elevations ranging from to feet. Refu ...

to help preserve the desert bighorn sheep, which at the time numbered 33. In the mid 1970s there were around 200 sheep in the refuge; however, in 1979, a scabies mite epizootic reduced the population from 200 to 75. Subsequent years brought further declines from scabies and other causes until the population consisted of one ewe in 1997. Reintroduction of desert bighorn sheep occurred in 2002 and the herd has now about 80 members."Desert Bighorn Sheep" San Andres National Wildlife Refuge, March 2007
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References

"San Andres Mountains"
Peakbagger.com. Retrieved June 3, 2005.

New Mexico Tourism Department, as of December 9, 2006, via

Internet Archive The Internet Archive is an American digital library with the stated mission of "universal access to all knowledge". It provides free public access to collections of digitized materials, including websites, software applications/games, music, ...

"San Andres Mountains"

Encyclopædia Britannica The (Latin for "British Encyclopædia") is a general knowledge English-language encyclopaedia. It is published by Encyclopædia Britannica, Inc.; the company has existed since the 18th century, although it has changed ownership various t ...

, online edition. Retrieved June 3, 2005. {{Authority control Mountain ranges of Doña Ana County, New Mexico Tularosa Basin Mountain ranges of Sierra County, New Mexico Mountain ranges of Socorro County, New Mexico