Carlsbad Caverns National Park, United States
These caves within a Permian fossil reef in the karst landscape of southern New Mexico, form a network of 113 known caves including Lechuguilla Cave 494m (1,604 feet) deep and 180 km (112 miles) long. They are outstanding for the size, profusion, diversity and beauty of their mineral formations. Lechuguilla Cave provides an underground laboratory where geological and biological processes can be studied in a setting which is virtually intact.
Located in the foothills of the Guadalupe Mountains near the New Mexican border with Texas, 200 km east-northeast of El Paso, centred on 32°10'N by 104°23'W.
Date and history of establishment
- 1898: J. White first discovered and explores the Caves;
- 1923: 291 ha created a National Monument by Presidential Proclamation 1679;
- 1930: Designated a National Park by the U.S. Congress under Public Law 216 with boundaries enlarged;
- 1930-1963: Further boundary adjustments made;
- 1978: 13,406 ha designated as wilderness under Public Law 95-625;
- 1993: 2,541ha of public land along the northern boundary withdrawn from mineral leasing, exploration and development by the Lechuguilla Cave Protection Act, U.S.Congress Public Law 103-169 (USDI-NPS, 1994).
The Federal government owns 18,788 ha; 137 ha are privately owned. The site is managed by the National Park Service (NPS) of the Department of the Interior.
18,926ha (46,766 acres)
1,095m to 1,987m (3,559’-6458’‘). Greatest depth 318m (1,034 ‘).
The Park overlies a segment of a 400 km long southwest-trending fossil reef that surrounds the Delaware Basin of southeastern New Mexico and western Texas which was a small reef-fringed inland sea in Permian times 280-250 mya. The reef was subsequently buried and preserved under layers of evaporite salts and sediments and between 65 and 6 mya was uplifted to form the Guadeloupe mountains. Three sections, back reef, main reef and fore reef are still visible, built up mainly of algae and sponges, preserving within their mass a rich diversity of bryozoans, pelecypods, gastropods, cephalopods, echinoderms, brachiopods, fusulinids and trilobites. Several deep canyons eroded in the 750m-thick limestone Capitan reef reveal cross-sections of other formations which are also exposed within the extensive cave system. The most notable example is found in Lechuguilla Cave (discovered only in 1986) where five are identifiable: the Yates, Seven Rivers, Queen, Capitan Reef and Goat Seep formations.
Unlike most caves which are produced by carbonic acid dissolution, the Caverns developed as hydrogen sulphide gas from underlying oil and gas deposits seeped upwards and combined with fresh water to form sulphuric acid which eroded the limestone into unusually large chambers. Gypsum, a by-product of this process, has been deposited in a variety of forms throughout many of the caves, ranging from thin crusts to beds more than 30m (98.4’) thick. Carlsbad Cavern with its large entrance and many miles of passages dropping over 310m (1,000’) is the largest of the 113 known caves within the Park. Lechuguilla Cave is not only the deepest at 494m (1,604 feet) and longest at 193 km (121 miles), but contains the largest collection of hydromagnesite balloon-like formations, subaqueous helictite formations and calcite speleothems. The number and quality of the stalactites, stalagmites, draperies, columns, soda straws, and sulphate mineral deposits found throughout the caves is outstanding (USDI-NPS, 1994).
The Park has a semiarid, continental climate with cool winters and occasional snow and ice storms, windy springs and warm to hot summers. The mean annual temperature is 19°C (66°F), the average annual maximum is 23°C (74°F) and the average annual minimum is 10°C (50°F). The average annual rainfall is 366mm (14.3in) with a monsoon season from July through September when violent thunderstorms drop much of the annual rainfall.
The interior climate of the Cavern network is complex and is only stable far from the entrance. The main portion (the Main Corridor, Big Room and Lower Cave) is a cold trap in winter when cold and usually dry air flows down from its mouth forcing warmer moist air up to the ceiling and out. Over time this has cooled the Big Room to an average of 56°F (13.3°C). The relative humidity there drops to 87.5% during winter but remains around 100% during summer when there is less airflow exchange. The climate at the cave’s lowest points remains a more constant 68°F (20°C) with closer to 100% relative humidity. This is the case with Lechuguilla Cave, which is extremely large and deep with only one very small entrance, though it has subtle variations that cannot easily be explained.
The Park lies at the intersection of the southern Rocky Mountain, northern Chihuahuan Desert, and southwestern Great Plains biogeographic provinces and is one of the few protected parts of the northern Chihuahuan Desert, the largest and wettest of the North American desert ecosystems which is predominantly a shrub desert without the large cacti and trees of the Sonoran Desert. It supports a diverse ecosystem, with habitat for many plants and animals at the geographic limits of their range. The lechuguilla Agave lechuguilla is the commonest indicator of Chihuahuan conditions. The Park’s primary vegetation is a variety of grasslands and desert shrublands with scattered woodlands at higher elevations where the ponderosa pine Pinus ponderosa reaches its extreme eastern limit. The Park’s list of vascular plants includes more than 900 species and subspecies.
The flora is typical of the northern portion of the Chihuahuan Desert. Species range from drought-resistant shrubs such as creosote bush Larrea tridentata and prickly pear Opuntia spp., sotol Dasilyrion wheeleri and Agave spp. to walnut Juglans spp., hackberry Celtis spp., oak Quercus spp. and soapberry trees Sapindus spp. in the richer soil of the canyons. Coniferous forest with twoneedle pinyon Pinus edulis, checkerbark and redberry junipers Juniperus deppeana and J. pinchotii is found at higher elevations. The park also contains the following four globally threatened plants: shining coral root Hexalectris nitida, Sneed’s pincushion cactus Escobaria sneedii, Lee pincushion cactus E. leei and Lloyd's hedgehog cactus Echinocereus lloydii. Other plants include giant helleborine orchid Epipactis gigantea, button cactus Epithelantha micromeris, Guadalupe jewelflower Streptanthus sparsiflorus, Havard's gumweed Grindelia havardii and resurrection plant Selaginella pilifera. A total of 94 fungi species from over 30 genera have been identified from Lechuguilla Cave, and many other species from other caves.
The deserts of the Southwest contain some of the greatest diversity of animals in the United States and the Park itself has a diversity of habitats, including permanent flowing water at Rattlesnake Springs. 67 mammals, 357 birds and 45 reptile and 9 amphibian species are recorded and 28 more species of reptiles and amphibians are tentatively identified; also 5 fish and at least 600 insect species (NPS, 2007). Of the 17 bat species, the seasonal breeding colony of Mexican free-tailed bat Tadarida brasiliensis mexicana is the most notable: its population is about a million bats which pour out to forage in the evenings. Other mammals include black footed ferret Mustela nigripes (extinct in the wild but reintroduced), occasional spotted skunk Spilogale gracilis leucoparia and black bear Ursus americanus amblyceps, grey fox Urocyon cinereoargenteus, coyote Canis latrans, bobcat Lynx rufus texensis and occasionally puma Puma concolor, javelina or collared peccary Pecari tajacu angulatus (reintroduced), pronghorn antelope Antilocapra americana (reintroduced), and mule deer Odocoileus hemionus crooki. There are two non-native introductions or escapees, Rocky Mountain elk Cervus elaphus and Barbary sheep Ammotragus lervia. Merriam’s elk Cervus merriami became extinct around the turn of the century, and desert bighorn sheep Ovis Canadensis nelsoni were extirpated from the Park in the 1960s. Five other species may have been extirpated since European settlement.
The avifauna includes golden eagle Aquila chrysaetos, bald eagle Haliaeetus leucocephalus, scaled quail Callipepla squamata, Mexican spotted owl Strix occidentalis lucida, great horned owl Bubo virginianus, roadrunner Geococcyx californina, loggerhead shrike Lanius ludovicianus, and cave swallow Hirundo fulva of which the Cavern Natural Entrance has the largest colony in the northern hemisphere which breeds there in the summer. Rattlesnake Springs, a rare desert wooded riparian area, has been designated an Important Bird Area (IBA) by the National Audubon Society, and draws birders from around the world to see some of the more than 300 species that have been noted there. Of the reptiles, several of which are at the edge of their range, three species of rattlesnake Crotalus spp. are known to occur (USDI-NPS, 1994). An invertebrate inventory is available (USDI-NPS, 1994).
Human occupation of the Guadelupe Mountains began with the arrival of a Palaeo-Indian hunting people around 14-12,000 B.C who left a stone scraper and two spear points of a Midland-style Palaeo-Indian projectile of some 10,000 years ago. These were followed by Archaic hunter-gatherers who settled in the region between 8000 BC and 1200 BC and by the Anazasi Basketmaker culture which left over 500 pictographs from three cultural periods in several caves, including the profusely decorated Painted Grotto, Upper Painted Grotto and Slaughter Canyon Cave. Pottery sherds, cooking ring sites and stone grinding tools, found at several of the Park's 125 archaeological sites, indicate that Indians living in the mountain region were influenced by other cultures such as the Jornado Mogollon to the west. In 1400 the Mescalero Apache settled the area just prior to the arrival of the Spanish who claimed the area between the 16th and 18th centuries. In 1821 Mexico took over the area until 1850 when the New Mexico Territory of the U.S.A. was established. During the first quarter of the 20th century a small bat-guano industry existed near the cave mouths (USDI-NPS, 1994).
Local human population
The land surrounding the Park's boundaries is now primarily used for ranching. However, oil and gas prospecting is likely to draw nearer to the area of the caves (NPS,2006).
Visitors and visitor facilities
Carlsbad Caverns have been attracting visitors since the 1880s. In 1994, approximately half of the Park's 617,087 visitors came during June, July and August (J. Thorsell, pers.comm.,1995) and the caves in 2007 draw more than 500,000 visitors a year (NPS). Present facilities include a visitor centre, parking, amphitheatres, picnic facilities, back-country camping and hiking trails. There are self-guided tours of the 8.2-acre Big Room and the Natural Entrance, and year-round guided tours of varying difficulty including crawls through narrow passageways in the Hall of the White Giant and Spider Cave. An unusual draw is the mass evening exodus of a million Mexican free-tail bats. The Park is accessible from U.S. Highway 62/180.
Scientific research and facilities
Geologists have been studying the fossil reef for many years and the cave passages and canyons are constantly being surveyed, mapped and monitored. Recent biological research in Lechuguilla Cave led to the discovery of unusual micro-organisms in pools, hydroaerosols in the cave air, and suspected lithotrophic bacteria which may derive metabolic energy from sulphur, manganese, and iron and ecosystems dependent upon these autotrophic bacteria (Davis et al.,1990; Cunningham,1991; Northup et al., 2000a,b). Ongoing research is looking into potential medical applications of these micro-organisms. The publication Research in Carlsbad Caverns National Park (1997) listed topics such as the relevance of cave bacteria to putative life on Mars, cave microbial life and climate, contamination from the ground facilities overhead, bat skeletons and wildlife on the surface. The discovery of the world's largest and most diverse collection of bacterially assisted speleothems found in Lechuguilla cave prompted calls for the establishment of a cave research institution which was founded in Carlsbad in 1998 as the National Cave and Karst Research Institute of the NPS. Scientists from all over the world visit the Park every year to study the structure and fauna of the reef. The caves are extremely well documented by scientific papers, books, newsletters and brochures. The archives in the Park museum, contain about 1,000,000 cultural resource specimens and a herbarium containing approximately 1,200 vascular plant specimens.
The Park preserves physical and biological formations of great aesthetic and scientific value in one of the few protected parts of the northern Chihuahuan Desert. It has the largest cave chamber in North America in the Big Room, and Lechuguilla cave is the deepest and third longest limestone cave in the country. There are in the deep cave of Slaughter Canyon over 500 Archaic period Indian pictographs spanning at least three cultural periods, and pottery shards and artefacts from later Indian eras have been found throughout the Park, alongside the remains of an extinct Pleistocene fauna (USDI-NPS, 1994). The Park lies within a WWF Global 200 Eco-region and is an Audubon-designated Important Bird Area.
The Park has two districts on the National Register of Historic Places: the Cavern Historic District and the Rattlesnake Springs Historic District. It is administered by the National Park Service and on-site management is the responsibility of the Superintendent. Each cave has been classified in one of six management categories. Category I covers highly developed caves such as those parts of the Caverns which provide visitors with maximum comfort and convenience: also minimally developed caves which provide relatively easy access with minimal modification of cave resources. Categories II to VI range from undeveloped caves which can only be visited with a National Park Service trip leader, to caves closed to use as they contain paleontological, archaeological or other resources of special scentific value. Many park caves are preserved and managed in a nearly pristine state to facilitate research. Guided tours rather than self-guided tours, have been introduced in the most delicate and fragile areas, to reduce human impact on the caves, and the use of security alarms to detect off-trail movement. There is also much increased ranger presence during the tourist season. The NPS completed a detailed General Management Plan in 1996 and planned to acquire the park land still in private hands (USDI-NPS, 1993).
During the first 25 years of this century, the entrance chambers of some of the caves were mined for bat guano but adverse effects were minimal since it was a small operation using mostly hand held tools. Current disturbances include permanent damage to speleothems which are often either broken or become dulled from dirt and repeated touching; graffiti, wondering off-trail, the accumulation of lint and organic litter which causes increased bacterial growth, and the pollution of cave pools by coins and other litter. The use of lighting for tourism has led to the growth of algae, moss, fungi and vascular plants in some places. The atmospheric moisture content has been greatly disrupted through the use of elevator shafts. McLean (1971) reported that each year approximately 100,000 litres of water are lost from the caves in this way.
A decline in the bat population has been associated with the former use of DDT which has been found in residual quantities in surrounding agricultural land and continues to be used in Mexico, where the bats overwinter. The colony is also affected by attempts to eradicate them in Mexico, where bats are perceived to be a threat to humans and other animals. The Park's northern, southern and eastern boundaries were threatened by oil and gas exploration and the construction of transmission and storage facilities by the Bureau of Land Reclamation, prohibited by law since 1993 but still a potential source of contamination. Grazing by trespassing livestock, invasion by exotic barbary sheep and puma hunting have also occurred (USDI-NPS, 1994).
There were 85 permanent and 40 temporary employees in 1994 (USDI-NPS, 1994).
The operating budget for the 1995 fiscal year was $4 million (J. Thorsell, pers. comm.,1995).
Natural World Heritage Site
1995: Inscribed on the World Heritage List under Natural Criteria vii and viii.
IUCN management category
II (National Park)
The principal source for the above information was the original nomination for World Heritage status.
- Boston, P. et al. (2001). Cave biosignature suites: Microbes, minerals and Mars. Astrobiology Journal 1(1): 25-55.
- Burgess,T. & Northington, D. (1981). Plants of the Guadalupe Mountains and Carlsbad Caverns National Parks: An Annotated Checklist.
- Cunningham, K. et al. (1995). Bacteria, fungi and biokarst in Lechuguilla Cave, Carlsbad Caverns National Park, New Mexico. Environmental Geology, 25: 2-8.
- Davis, D., Palmer, M. & Palmer, A. (1990). Extraordinary subaqueous speleothems in Lechuguilla Cave, New Mexico. National Speleological Society Bulletin 52: 70-86.
- Denham, B. & Fobes, F. (1995). A Review of the Vascular Plant Species Reported from Carlsbad Caverns National Park. Report for Patricia Barlow-Irick.
- Jagnow, D. et al. (2000). History of the sulfuric acid theory of speleogenesis in the Guadalupe Mountains, New Mexico. Journal of Cave and Karst Studies 62(2): 54-59.
- Kerbo, R. (1991). Lechuguilla Cave Action Plan, Carlsbad Caverns National Park. 6 pp.
- McLean, J. (1971). The Microclimate in Carlsbad Caverns, New Mexico. U.S. Geological Survey Report.
- National Park Service (2007).Carlsbad Caverns National Park, New Mexico. Department of the Interior, National Park Service.
- Northup, D. et al. (2000a). Evidence for geomicrobiological interactions in Guadalupe caves. Journal of Cave and Karst Studies. 62(2): 80-90.
- Northup, D, et al. (2000b). Biological investigations in Lechuguilla Cave, Carlsbad Caverns National Park.National Speleological Bulletin 55(1): 26 pp
- Rothman, H. & Holder, D. (1998). Promise Beheld and the Limits of Place. A Historic Resource Study of Carlsbad Caverns and Guadalupe Mountains National Parks and the Surrounding Areas. Department of the Interior, National Park Service, Washington, DC. 263pp.
- USDI-NPS (1994). Carlsbad Caverns National Park World Heritage Nomination. Department of the Interior, National Park Service. 28 pp. [Contains a comprehensive bibliography]
- USDI-NPS (1993). Carlsbad Caverns National Park Statement for Management. Department of the Interior, National Park Service. 37 pp.
- USDI-NPS (1989). Cave Management Plan for Carlsbad Caverns National Park. Department of the Interior, National Park Service. 19 pp.
- Vequist, G. (ed.)(1997). Research in Carlsbad Caverns National Park. Carlsbad Caverns Guadalupe Mountains Association and the National Park Service. 28pp.
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