Carlsbad Caverns National Park

World-famous Carlsbad Caverns National Park was established to preserve Carlsbad Cavern and numerous other caves within a fossil reef located in the Chihuahuan Desert in southeastern New Mexico west of the Pecos River. This karst landscape comprises over 300 known caves beneath the surface, 109 of which are located within the park. These caves are outstanding not only for their size (they are some of the biggest and longest caves in the world), but also for the great quantity, diversity and beauty of their mineral formations.

Carlsbad Cavern has one of the world’s largest underground chambers and countless formations. It is the most famous of the park’s caves and can be toured year-round. Lechuguilla Cave stands out as the nation’s deepest limestone cave (1,604 feet) and third longest (over 112 miles). It provides an underground laboratory where geological and biological processes can be studied in a pristine setting. This cave is restricted to scientific and exploration groups, who have made promising discoveries concerning microbes that produce enzymes capable of destroying cancer cells.

Carlsbad Caverns National Park was included on the UNESCO’s World Heritage list of natural sites in 1995 because it was found 1) to contain superlative natural phenomena or areas of exceptional natural beauty and aesthetic importance; 2) to be an outstanding example representing major stages of earth’s history, including the record of life, significant on-going geological processes in the development of landforms, or significant geomorphic or physiographic features.

History and Culture
American Indians have lived in the Guadalupe Mountains within the present day boundaries of the park since prehistoric times (12-14,000 years ago). Spanish explorers arrived on the scene in the 1500s and claimed the southwest until 1821, when Mexico gained independence. This was only short-lived, as Mexico lost the territory to the United States in the late 1840s. The New Mexico Territory was created in 1850 and conflict continued for another 30 years between the government and the Indians.

Carlsbad Cavern was discovered by American settlers in the 1800s by seeing bats emerge from the cave to feed in the evening. The first known explorer of the caves, Jim White, probably descended for the first time in 1898 – on a 60 ft. wire ladder. His reports of the caves were widely disbelieved, until the first photos of the cavern’s Scenic Rooms and Big Room were taken between 1915 and 1918. They stimulated interest in the caverns, which are first surveyed and mapped in 1923. Carlsbad Caverns was established as a National Monument that same year and later as a National Park in 1930. Many early visitors to Carlsbad Cavern entered the cave via a 170-ft. descent in an old guano mining bucket!

Fauna and Flora
The diversity of habitats in the park, aided by its location at the intersection of the southern Rocky Mountains, northern Chihuahuan Desert, and southwestern Great Plains provinces, has allowed for a large array of wildlife. The deserts of the Southwest contain some of the highest diversity of mammals, birds, reptiles, and insects in the United States. The park provides important year-round habitat for predators such as cougars, and nesting habitat for migratory species such as the large colonies of cave swallows and Brazilian (Mexican) free-tailed bats that number 400,000 in the summer. Rattlesnake Springs, a rare desert wooded area fed by permanent flowing water, draws bird watchers from around the world to see some of the 300-plus species that have been spotted there.

Bones from ice age animals like jaguars, camels, lions and giant sloths have been found in the entrance areas of some caves in Carlsbad Caverns National Park.

Also benefiting from the park’s location, flora in Carlsbad Caverns National Park is diverse and, in several cases, unique. The Chihuahuan Desert, of which the park is a part, is the most biologically diverse desert in the Western Hemisphere and one of the most diverse in the world. It has more species of cacti than any other desert, although shrubs, rather than cacti, dominate the landscape. Of the 85 documented plant associations, one-third are new associations that were not previously described elsewhere.

Natural Features, Geologic Formations, and Ecosystems
Underlying the Guadalupe Mountains and the Chihuahuan Desert (the largest and wettest of the North American deserts), Carlsbad Caverns is one of the most important geologic resources in the United States. The Guadalupe Mountains are recognized as the best-preserved Permian-aged fossil reef in the world, its limestone range being the uplifted portion of a fossil reef that thrived along the edge of an inland sea over 250 million years ago. The bodies of sponges, algae, snails, nautilus, and other animals are preserved in the rocks from this ancient sea, showing that the reef was built of algae and sponges and not by coral, like many of today’s reefs. Scientists come from all over the world each year to study the structure and fauna of the reef.

Local faulting and stresses of the earth’s crust during the past 20 million years has uplifted these reef sediments almost ten thousand feet. Erosion due to wind, rain, snow, and time peeled away the overlying younger sediments and now the ancient reef is exposed once again, able to be viewed from inside the caves.

The caves are the most famous of all the geologic features in the park. They were formed when sulfuric acid dissolved the surrounding limestone, creating some of the largest caves in North America. Since the development of the caves is much older than the surrounding landscape, we see very few of the typical karst features found when caves and the landscape develop at the same time (a karst area is usually characterized by numerous caves, sinkholes, springs, and little surface drainage).

Many park caves are preserved and managed in a nearly pristine state, so researchers can understand the unique ecosystem within them. Scientists are only beginning to understand the complex, microscopic organisms that inhabit the caves. Study has shown that some of the organisms may help serious human diseases such as cancer. Although caves are a fragile, non-renewable resource, they are a continual source of exploration and discovery. They are affected by both natural and human activities above and belowground.

How Carlsbad Cavern was Formed
The National Park Service describes it best:
“Most of the world’s limestone caves are created when surface water (rainwater) flows down through cracks in limestone rock and slowly enlarges the passageways. In all surface water, there is a weak acid called carbonic acid. This acid slowly dissolves and scours out the rock in more than 90 percent of the world’s limestone caves. These types of caves are typically very wet and have streams, rivers and sometimes lakes or large waterfalls in them. However, there are no flowing rivers or streams in any of the hundreds of caves in the Guadalupe Mountains—and no evidence that these huge cave chambers were dissolved by carbonic acid.

Between 4 and 6 million years ago hydrogen-sulfide-rich (H2S) waters began to migrate through fractures and faults in the Capitan Limestone. This water mixed with rainwater moving downward from the surface. When the two waters mixed, the H2S combined with the oxygen carried by the rainwater and formed sulfuric acid (H2SO4). This acid dissolved the limestone along fractures and folds in the rock to form Carlsbad Cavern. This process left behind massive gypsum deposits, clay, and silt as evidence of how the cave was formed.

As the Guadalupe Mountains uplifted little by little, the level of the water table dropped in relation to the land surface; therefore, the highly aggressive “acid bath” drained away leaving a newly dissolved cave behind. With time, the active level dropped to form deeper cave passages. In abandoned cave passages above, blocks fell from the ceiling and speleothems (cave formations) began to grow. Around 4 million years ago, speleogenesis ceased in the area around Carlsbad Cavern and the cave began to take on the look that it has today.

One of the many by-products of this sulfuric acid dissolution of limestone is a mineral called gypsum. Huge gypsum blocks still line the floor of the Big Room of Carlsbad Cavern. Other by-product minerals have been radioactively dated to show when this “sulfuric acid bath” occurred. It is now evident that Carlsbad Cavern was one of the last caves to be dissolved in the Guadalupe Mountains—around 4 to 6 million years ago. This method of sulfuric acid dissolution created seemingly endless mazes of both narrow and huge passageways that look to many visitors like Swiss cheese. Because these caves were dissolved deep underground, not all caves here have an opening to the world above.”

Surface erosion and collapse a couple of million years ago at the top of the cave created the natural entrance of Carlsbad Cavern. This opened previously hidden underground cave passageways to the world above for the first time. As a result, airflow began to circulate through the cavern and allowed for the last stage of geologic development-the growth of cave decorations.

The Decorated Caves
The cave formations that continue to grow and decorate Carlsbad Cavern are due to rain and snowmelt soaking through limestone rock, then eventually dripping into and evaporating in a cave below. A small amount of mineral-mostly calcite is left behind wherever that water drop evaporates and releases carbon dioxide in an air-filled cave. Thus, Carlsbad Cavern has slowly been decorating itself drip by drip over the past million years.

The slowest drips tend to stay on the ceiling long enough to deposit their mineral there. Common formations found on the ceiling may be stalactites, soda straws, draperies, ribbons, or curtains. The faster the water drips, the more likely it is to leave some type of decoration on the floor. These include totem poles, flowstone, rim stone dams, lily pads, shelves, cave pools, and stalagmites.

Because of the dry desert climate in which the caves are located, there are few formations inside any Guadalupe Mountains caves that are wet and actively growing. Most formations inside Carlsbad Cavern would have been much more active during the last ice age (up to 10,000 years ago). The dripping heard today inside the cavern is a mere echo of what would have been heard long ago.

Today, Carlsbad Cavern is not dead or alive, it’s just mostly inactive.

Park Activities
More than 300,000 visitors come to Carlsbad Cavern each year to catch a glimpse of the underground worlds preserved under the desert above. A variety of cave tours are available, from the self-guided areas of the Big Room to crawling through narrow passageways in the Hall of the White Giant or Spider Cave. Hiking and backcountry camping are also possibilities, as well as attending programs in the visitor center and watching the exodus of hundreds of thousands of Mexican free-tail bats out of Carlsbad Cavern at dusk in summer.