East Potrillo Mountains
Encyclopedia
The East Potrillo Mountains are a mountain range
in south central Doña Ana County, New Mexico
. They are located approximately 25 miles (40 km) west of El Paso
, Texas
, 30 miles (50 km) southwest of Las Cruces
, New Mexico
, and 30 miles east of Columbus
, New Mexico. The southern tip of the range is less than 5 miles (8 km) from the Mexican border. The mountains and most of the surrounding acreage are located on land owned by the Bureau of Land Management
. Access to the general vicinity is through New Mexico State Road 9
, and several unpaved county roads.
, a major structure that stretches from the vicinity of Leadville, Colorado
, through central New Mexico, and into the Mexican state of Chihuahua. In southern New Mexico, several large basins are associated with the rift, including the Mimbres
basin to the west of the Potrillos, and the Mesilla basin to the east. A large intra-rift horst lies between those two basins, and the range is situated on the horst. The uplifting of the Potrillos, together with the subsidence of nearby grabens, occurred in the late Tertiary
. The eastern boundary of the horst is the active Robledo fault, which has created a scarp
on the eastern side of the range.
The basal rocks in the range are sedimentary, and consist of limestone
, dolomites
, and silty beds of Middle Permian
age. The thickness of these beds is approximately 950 feet (300 m). Disconformably above these beds are layers of Lower Cretaceous
limestone, siltstone
, sandstone
, and conglomerate
. These rocks are about 1,800 feet (570 m) in thickness on the northern part of the range, but thin to the south. These Cretaceous rocks are correlative with the Hell-to-Finish Formation (Aptian
age) and the U-Bar Formation (late Aptian to middle Albian
) found in other parts of southwestern New Mexico. Quaternary
deposits include alluvial fans and wind-blown sands.
. The climate is arid and continental. Weather records in nearby El Paso, Texas show that the average daily maximum temperature over the course of the year is 77.3 degrees Fahrenheit, with an average daily minimum of 50.1 degrees Fahrenheit. Average monthly maximum temperatures range from 96 degrees in June, to 58 degrees in January. Average monthly minimum temperatures range from 30 degrees in January to 70 degrees in July. Average annual precipitation in El Paso is 8.81 inches, with monthly averages ranging from .2 inches in April to 1.7 in September. Over half of the annual precipitation falls in the form of summer rains between June and September, although some snow can be expected in the winter.
Soils on the mountains are generally rocky and thin. On the flats below, soils are somewhat deeper, and frequently consist of windblown dunes.
Plant communities can be generally characterized as Chihuahuan desert scrublands, creosotebush desert, and desert grasslands. Dominant shrub species include creosote bush
(Larrea tridentata), honey mesquite
(Prosopis glandulosa), soaptree yucca
(Yucca elata), and four winged saltbush (Atriplex canescens
). Common grasses include black grama
(Bouteloua eriopoda), blue grama
(Bouteloua gracilis), sideoats grama
(Bouteloua curtipendula), and alkali sacaton (Sporobolus airoides
).
Common animals/ mammals include mule deer
(Odocoileus hemionus), coyotes (Canis latrans), Black-tailed jackrabbit
(Lepus californicus), desert cottontail
, (Sylvilagus auduboni) and kangaroo rats (Dipodomys merriami and Dipodomys spectabilis). Common birds include golden eagles (Aquila chrysaetos), Swainson's hawk
(Buteo swainsoni), Northern harrier (Circus cyaneus), burrowing owl
(Athene cunicularia), roadrunner
(Geococcyx californianus), quail
(Callipepla gambelii and Callipepla squamata), doves
(Zenaida macroura and Zenaida asiatica). Common reptiles include Collared lizards (Crotaphytus collaris), Roundtail Horned Lizard
(Phrynosoma modestum), Striped whipsnake
(Masticophis taeniatus), and Western diamondback rattlesnake (Crotalus atrox
). Common amphibians include New Mexico Spadefoot Toad (Spea multiplicata
), Great Plains Toad (Bufo cognatus
), Green Toad (Bufo debilis
), and Red-spotted Toad (Bufo punctatus
)
. Although these peaks are located very close to the main spine of the East Potrillo Mountains, they are igneous, and more closely related geologically to the West Potrillo Mountains.
Of particular interest to visitors are a series of nearby maar
, or phreatomagmatic craters, which are located approximately 5–10 miles to the north and east of the main spine of the range. The craters include Kilbourne Hole
, Hunt's Hole, and Phillips Hole. These formations are estimated to have an age of between 24,000 and 50,000 mya. They are associated with the Potrillo volcanic field
. That field includes the West Potrillo Mountains
and the Aden
lava flows to the north and west.
The name Potrillo means "colt" in Spanish. The Bureau of Land management considered, but rejected Wilderness Study Area
status for a 26,300 acre unit that includes the range. A larger area (159, 972 acres) that includes the nearby West Potrillo Mountains has been designated as a Wilderness Study Area. Full wilderness status for this area was proposed, but defeated in the lame duck Congressional session of 2010. This was largely due to a desire for a "buffer" zone along the border and a perception that wilderness status would inhibit the detection of illegal immigrants.
Mountain range
A mountain range is a single, large mass consisting of a succession of mountains or narrowly spaced mountain ridges, with or without peaks, closely related in position, direction, formation, and age; a component part of a mountain system or of a mountain chain...
in south central Doña Ana County, New Mexico
Doña Ana County, New Mexico
-2010:Whereas according to the 2010 U.S. Census Bureau:*74.1% White*1.7% Black*1.5% Native American*1.1% Asian*0.1% Native Hawaiian or Pacific Islander*3.0% Two or more races*18.5% Other races*65.7% Hispanic or Latino -2000:...
. They are located approximately 25 miles (40 km) west of El Paso
El Paso
El Paso, a city in the U.S. state of Texas, on the border with Mexico.El Paso may also refer to:-Geography:Colombia:* El Paso, CesarSpain:*El Paso, Santa Cruz de TenerifeUnited States:...
, Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
, 30 miles (50 km) southwest of Las Cruces
Las Cruces, New Mexico
Las Cruces, also known as "The City of the Crosses", is the county seat of Doña Ana County, New Mexico, United States. The population was 97,618 in 2010 according to the 2010 Census, making it the second largest city in the state....
, New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
, and 30 miles east of Columbus
Columbus, New Mexico
Columbus is a village in Luna County, New Mexico, United States. The population was 1,765 at the 2000 census. The town is named after 15th century explorer Christopher Columbus.-History:...
, New Mexico. The southern tip of the range is less than 5 miles (8 km) from the Mexican border. The mountains and most of the surrounding acreage are located on land owned by the Bureau of Land Management
Bureau of Land Management
The Bureau of Land Management is an agency within the United States Department of the Interior which administers America's public lands, totaling approximately , or one-eighth of the landmass of the country. The BLM also manages of subsurface mineral estate underlying federal, state and private...
. Access to the general vicinity is through New Mexico State Road 9
New Mexico State Road 9
State Road 9 is a long state road in the U.S. state of New Mexico. The highway spans Hidalgo, Grant, and Luna counties from to at the Doña Ana county line.-Route description:...
, and several unpaved county roads.
Geology
The East Potrillos can be generally described as an uplifted west-tilted fault-block. The mountains are located near the western margin of the Rio Grande RiftRio Grande Rift
The Rio Grande Rift is a north-trending continental rift zone. It separates the Colorado Plateau in the west from the interior of the North American craton on the east. The rift extends from central Colorado in the north to the state of Chihuahua, Mexico in the south. The rift zone consists of four...
, a major structure that stretches from the vicinity of Leadville, Colorado
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...
, through central New Mexico, and into the Mexican state of Chihuahua. In southern New Mexico, several large basins are associated with the rift, including the Mimbres
Mimbres River
The Mimbres River is a river in southwestern New Mexico. It forms from snow pack and runoff on the south-western slopes of the Black Range and flows into a small endorheic basin east of Deming, New Mexico. The uplands watershed are administered by the US Forest Service, while the land in the...
basin to the west of the Potrillos, and the Mesilla basin to the east. A large intra-rift horst lies between those two basins, and the range is situated on the horst. The uplifting of the Potrillos, together with the subsidence of nearby grabens, occurred in the late Tertiary
Tertiary
The Tertiary is a deprecated term for a geologic period 65 million to 2.6 million years ago. The Tertiary covered the time span between the superseded Secondary period and the Quaternary...
. The eastern boundary of the horst is the active Robledo fault, which has created a scarp
Scarp
-Landforms and geology:* Cliff, a significant vertical, or near vertical, rock exposure* Escarpment, a steep slope or long cliff that occurs from erosion or faulting and separates two relatively level areas of differing elevations...
on the eastern side of the range.
The basal rocks in the range are sedimentary, and consist of limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
, dolomites
Dolomites
The Dolomites are a mountain range located in north-eastern Italy. It is a part of Southern Limestone Alps and extends from the River Adige in the west to the Piave Valley in the east. The northern and southern borders are defined by the Puster Valley and the Sugana Valley...
, and silty beds of Middle Permian
Permian
The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...
age. The thickness of these beds is approximately 950 feet (300 m). Disconformably above these beds are layers of Lower Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
limestone, siltstone
Siltstone
Siltstone is a sedimentary rock which has a grain size in the silt range, finer than sandstone and coarser than claystones.- Description :As its name implies, it is primarily composed of silt sized particles, defined as grains 1/16 - 1/256 mm or 4 to 8 on the Krumbein phi scale...
, sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
, and conglomerate
Conglomerate (geology)
A conglomerate is a rock consisting of individual clasts within a finer-grained matrix that have become cemented together. Conglomerates are sedimentary rocks consisting of rounded fragments and are thus differentiated from breccias, which consist of angular clasts...
. These rocks are about 1,800 feet (570 m) in thickness on the northern part of the range, but thin to the south. These Cretaceous rocks are correlative with the Hell-to-Finish Formation (Aptian
Aptian
The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous epoch or series and encompasses the time from 125.0 ± 1.0 Ma to 112.0 ± 1.0 Ma , approximately...
age) and the U-Bar Formation (late Aptian to middle Albian
Albian
The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous epoch/series. Its approximate time range is 112.0 ± 1.0 Ma to 99.6 ± 0.9 Ma...
) found in other parts of southwestern New Mexico. Quaternary
Quaternary
The Quaternary Period is the most recent of the three periods of the Cenozoic Era in the geologic time scale of the ICS. It follows the Neogene Period, spanning 2.588 ± 0.005 million years ago to the present...
deposits include alluvial fans and wind-blown sands.
Climate
The East Potrillo Mountains lie within the Chihuahuan DesertChihuahuan Desert
The Chihuahuan Desert is a desert, and an ecoregion designation, that straddles the U.S.-Mexico border in the central and northern portions of the Mexican Plateau, bordered on the west by the extensive Sierra Madre Occidental range, and overlaying northern portions of the east range, the Sierra...
. The climate is arid and continental. Weather records in nearby El Paso, Texas show that the average daily maximum temperature over the course of the year is 77.3 degrees Fahrenheit, with an average daily minimum of 50.1 degrees Fahrenheit. Average monthly maximum temperatures range from 96 degrees in June, to 58 degrees in January. Average monthly minimum temperatures range from 30 degrees in January to 70 degrees in July. Average annual precipitation in El Paso is 8.81 inches, with monthly averages ranging from .2 inches in April to 1.7 in September. Over half of the annual precipitation falls in the form of summer rains between June and September, although some snow can be expected in the winter.
Ecology
The East Potrillo Mountains impose extreme demands on ecological communities. Water management is a critical factor for residents. No perennial streams originate in the range, and none flow nearby. There is very little permanent water in the area, other than stock tanks and surface impoundments. Precipitation quickly evaporates, runs off, or soaks into the ground, leaving little for plants or animals. Slopes that face south or west tend to have both a higher solar exposure and a higher rate of water evaporation than those facing north and east. This can result in great species variation between communities that happen to be located on slopes with different aspects.Soils on the mountains are generally rocky and thin. On the flats below, soils are somewhat deeper, and frequently consist of windblown dunes.
Plant communities can be generally characterized as Chihuahuan desert scrublands, creosotebush desert, and desert grasslands. Dominant shrub species include creosote bush
Creosote bush
Larrea tridentata is known as Creosote bush as a plant, chaparral as a medicinal herb, and as "gobernadora" in Mexico, Spanish for "governess," due to its ability for inhibiting the growth of nearby plants to have more water. In Sonora, it is more commonly called "hediondilla." It is a flowering...
(Larrea tridentata), honey mesquite
Honey Mesquite
Prosopis glandulosa, commonly known as honey mesquite, is a species of small to medium-sized flowering tree in the legume family, Fabaceae. It is native to the Southwestern United States and Mexico, growing as far north as southern Kansas and as far east as the eastern fifth of Texas, where...
(Prosopis glandulosa), soaptree yucca
Soaptree yucca
The Soaptree yucca is a perennial plant in the genus Yucca. It is native to southwestern North America, in the Sonoran Desert and Chihuahuan Desert in the United States , and northern Mexico .This plant grows from 1.2-4.5 m tall, with a sparsely branched trunk...
(Yucca elata), and four winged saltbush (Atriplex canescens
Atriplex canescens
Atriplex canescens, Chamiso, Chamiza, Four wing saltbush, Four-wing saltbush, and Fourwing saltbush, is a species of evergreen shrub in the Amaranthaceae family, which is native to the western and mid-western United States....
). Common grasses include black grama
Black grama
Bouteloua eriopoda, commonly known as Black Grama, is a perennial prairie grass that is native to the Southwestern United States. Its main means of reproduction is by stolons, as its ratio of viable seeds to sterile ones is naturally low. The disparity may play a role in its lack of tolerance to...
(Bouteloua eriopoda), blue grama
Blue grama
Blue Grama, Bouteloua gracilis, is a long-lived, warm season, C4 perennial grass native to North America. It is most commonly found from Alberta east to Manitoba and south across the Rocky Mountains, Great Plains, and Midwest states to Mexico...
(Bouteloua gracilis), sideoats grama
Sideoats grama
Bouteloua curtipendula, commonly known as sideoats grama, is a perennial, short prairie grass that is native throughout the temperate and tropical Western Hemisphere, from Canada south to Argentina.-Description:...
(Bouteloua curtipendula), and alkali sacaton (Sporobolus airoides
Sporobolus airoides
Sporobolus airoides is a species of grass known by the common name alkali sacaton. It is native to western North America, including the Western United States west of the Mississippi River, British Columbia and Alberta in Canada, and northern and central Mexico...
).
Common animals/ mammals include mule deer
Mule Deer
The mule deer is a deer indigenous to western North America. The Mule Deer gets its name from its large mule-like ears. There are believed to be several subspecies, including the black-tailed deer...
(Odocoileus hemionus), coyotes (Canis latrans), Black-tailed jackrabbit
Black-tailed Jackrabbit
The black-tailed jackrabbit , also known as the american desert hare, is a common hare of the western United States and Mexico, where it is found at elevations from sea level to up to...
(Lepus californicus), desert cottontail
Desert Cottontail
The Desert Cottontail , also known as Audubon's Cottontail, is a New World cottontail rabbit, a member of the family Leporidae....
, (Sylvilagus auduboni) and kangaroo rats (Dipodomys merriami and Dipodomys spectabilis). Common birds include golden eagles (Aquila chrysaetos), Swainson's hawk
Swainson's Hawk
The Swainson's Hawk , is a large buteo hawk of the Falconiformes, sometimes separated in the Accipitriformes like its relatives. This species was named after William Swainson, a British naturalist...
(Buteo swainsoni), Northern harrier (Circus cyaneus), burrowing owl
Burrowing Owl
The Burrowing Owl is a tiny but long-legged owl found throughout open landscapes of North and South America. Burrowing Owls can be found in grasslands, rangelands, agricultural areas, deserts, or any other open dry area with low vegetation. They nest and roost in burrows, such as those excavated...
(Athene cunicularia), roadrunner
Roadrunner
Roadrunners are birds of the genus Geococcyx.Roadrunner or Road Runner may also refer to:* Wile E. Coyote and Road Runner, an animated character based on the bird** The Road Runner Show, compiled cartoons including the character...
(Geococcyx californianus), quail
Quail
Quail is a collective name for several genera of mid-sized birds generally considered in the order Galliformes. Old World quail are found in the family Phasianidae, while New World quail are found in the family Odontophoridae...
(Callipepla gambelii and Callipepla squamata), doves
Doves
Doves are an English alternative indie rock band, originating from Wilmslow, Cheshire. The band comprises brothers Jez Williams and Andy Williams , and Jimi Goodwin . The members started working seriously together after meeting at The Haçienda in Manchester. Doves' unofficial fourth member is...
(Zenaida macroura and Zenaida asiatica). Common reptiles include Collared lizards (Crotaphytus collaris), Roundtail Horned Lizard
Roundtail Horned Lizard
The roundtail horned lizard is one of the smaller species of horned lizard. Their specific epithet is from the Latin word modestum meaning modest or calm...
(Phrynosoma modestum), Striped whipsnake
Striped Whipsnake
The Striped Whipsnake is a species of nonvenomous colubrid snake that is closely related to the California Whipsnake . It is native to the western United States and northern Mexico....
(Masticophis taeniatus), and Western diamondback rattlesnake (Crotalus atrox
Crotalus atrox
Crotalus atrox, the "western diamondback rattlesnake", is a venomous rattlesnake species found in the United States and Mexico. It is likely responsible for the majority of snakebite fatalities in northern Mexico and the second greatest number in the USA after C. adamanteus. No subspecies are...
). Common amphibians include New Mexico Spadefoot Toad (Spea multiplicata
Spea multiplicata
The New Mexico Spadefoot Toad is a species of American spadefoot toad found in the southwestern United States and Mexico. Like other species of spadefoot toad, they get their name from a distinctive spade-like projections on their hind legs which enable them to dig in sandy soils...
), Great Plains Toad (Bufo cognatus
Bufo cognatus
The Great Plains Toad is a relatively large species of toad. It ranges from southern Alberta, throughout the midwest United States and the inland western United States into northern Mexico....
), Green Toad (Bufo debilis
Bufo debilis
Anaxyrus debilis, also classified as Bufo debilis, is a species of toad found in the Southwestern United States in the states of Arizona, New Mexico, Colorado, Kansas and Texas, as well as in northern Mexico in the states of Tamaulipas, San Luis Potosí, Durango and Zacatecas...
), and Red-spotted Toad (Bufo punctatus
Bufo punctatus
The Red-spotted toad is a small toad species growing to 3.7 to 7.5 centimeters in length. It has a flattened head and body, and a light grey, olive or reddish brown dorsum with reddish or orange skin glands. It has a whitish or buff venter with or without faint dark spotting, and round parotoid...
)
Items of Interest
Although they are relatively close to two large cities, the East Potrillo Mountains receive few visitors. This is due to the rugged topography, and the lack of water or shade. The range is long and narrow, with an orientation trending NNW to SSE. The maximum elevation of the range is approximately 5,300 feet, which provides a relief of nearly 1000 feet (300 m) above the flats to the east. Mount Riley and Cox Peak draw hikers because of their excellent views of the East Potrillo Mountains, and the nearby West Potrillo MountainsWest Potrillo Mountains
The West Potrillo Mountains are a mountain range in south central Dona Ana County, New Mexico, United States. They are located approximately 40 miles northwest of El Paso, Texas, 25 miles southwest of Las Cruces, New Mexico, and 35 miles southeast of Deming, New Mexico...
. Although these peaks are located very close to the main spine of the East Potrillo Mountains, they are igneous, and more closely related geologically to the West Potrillo Mountains.
Of particular interest to visitors are a series of nearby maar
Maar
A maar is a broad, low-relief volcanic crater that is caused by a phreatomagmatic eruption, an explosion caused by groundwater coming into contact with hot lava or magma. A maar characteristically fills with water to form a relatively shallow crater lake. The name comes from the local Moselle...
, or phreatomagmatic craters, which are located approximately 5–10 miles to the north and east of the main spine of the range. The craters include Kilbourne Hole
Kilbourne Hole
Kilbourne Hole is a maar volcanic crater, located west of the Franklin mountains of El Paso, Texas, in the Potrillo Volcanic Field of Doña Ana County, New Mexico. Nearby Hunt's Hole lies several miles just south of Kilbourne Hole. These holes are rare examples of volcanic action without a...
, Hunt's Hole, and Phillips Hole. These formations are estimated to have an age of between 24,000 and 50,000 mya. They are associated with the Potrillo volcanic field
Potrillo volcanic field
The Potrillo Volcanic Field is a monogenetic volcanic field located on the Rio Grande Rift, in a portion of its rift valley, in southern New Mexico, USA and northern Chihuahua, Mexico...
. That field includes the West Potrillo Mountains
West Potrillo Mountains
The West Potrillo Mountains are a mountain range in south central Dona Ana County, New Mexico, United States. They are located approximately 40 miles northwest of El Paso, Texas, 25 miles southwest of Las Cruces, New Mexico, and 35 miles southeast of Deming, New Mexico...
and the Aden
Aden
Aden is a seaport city in Yemen, located by the eastern approach to the Red Sea , some 170 kilometres east of Bab-el-Mandeb. Its population is approximately 800,000. Aden's ancient, natural harbour lies in the crater of an extinct volcano which now forms a peninsula, joined to the mainland by a...
lava flows to the north and west.
The name Potrillo means "colt" in Spanish. The Bureau of Land management considered, but rejected Wilderness Study Area
Wilderness study area
A wilderness study area contains undeveloped United States federal land retaining its primeval character and influence, without permanent improvements or human habitation, and managed to preserve its natural conditions...
status for a 26,300 acre unit that includes the range. A larger area (159, 972 acres) that includes the nearby West Potrillo Mountains has been designated as a Wilderness Study Area. Full wilderness status for this area was proposed, but defeated in the lame duck Congressional session of 2010. This was largely due to a desire for a "buffer" zone along the border and a perception that wilderness status would inhibit the detection of illegal immigrants.