Explore Geology
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Carlsbad Caverns

National Park

New Mexico


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park geology subheading
Photo taken inside of a cavern at Carlsbad
Carlsbad Caverns National Park, New Mexico

A Journey Underground
Your encounter with Carlsbad Caverns National Park begins in the Chihuahuan Desert of the Guadalupe Mountains. But beyond the somewhat familiar surroundings of rugged mountains and broad plains is another world. Away from the sunlight, away from the flowering cactus, away from the songs of the desert birds and the howl of the coyote, lies the celebrated underground world of Carlsbad Cavern. It is an incomparable realm of gigantic subterranean chambers, fantastic cave formations, and extraordinary features. The first adventurers entering Carlsbad Cavern had no idea what to expect as they walked, crawled, and climbed down into the darkness. Today many of the wonders of Carlsbad Cavern are well known, yet the experience of exploring its chambers is every bit as exciting.

The Creation of the Cavern
The story of the creation of Carlsbad Cavern begins 250 million years ago with the creation of a 400-mile-long reef in an inland sea that covered this region. This horseshoe-shaped reef formed from the remains of sponges, algae, and seashells and from calcite that precipitated directly from the water. Cracks developed in the reef as it grew seaward. Eventually the sea evaporated and the reef was buried under deposits of salts and gypsum.

Then, a few million years ago, uplift and erosion of the area began to uncover the buried rock reef. Rainwater, made slightly acidic from the air and soil, seeped down into the cracks in the reef, slowly dissolving the limestone and beginning the process that would form large underground chambers. Many geologists believe that the fresh rainwater mixed with deeper salty water to form sulfuric acid. The added power of this very corrosive substance could explain the tremendous size of the passageways that formed. The exposed reef became a part of the Guadalupe Mountains and the huge underground chambers far below the surface became the natural wonder of Carlsbad Cavern.

The Cave is Decorated, Drop by Drop
The decoration of Carlsbad Cavern with stalactites, stalagmites, and an incredible variety of other formations began more than 500,000 years ago after much of the cavern had been carved out. It happened slowly, drop by drop, at a time when a wetter, cooler climate prevailed. The creation of each formation depended on water that dripped or seeped down into the limestone bedrock and into the cave. As a raindrop fell to the ground and percolated downward, it absorbed carbon dioxide gas from the air and soil, and a weak acid was formed. As it continued to move downward the drop dissolved a little limestone, absorbing a bit of the basic ingredient needed to build most cave formations - the mineral calcite. Once the drop finally emerged in the cave, the carbon dioxide escaped into the cave air. No longer able to hold the dissolved calcite, the drop deposited its tiny mineral load as a crystal of calcite. Billions and billons of drops later, thousands of cave formations had taken shape.
And, oh, the shapes they took!

  • Where water dripped slowly from the ceiling, soda straws and large stalactites appeared.

  • Water falling on the floor created stalagmites.

  • Sometimes a stalactite and stalagmite joined, forming a column.

  • Draperies were hung where water ran down a slanted ceiling. Water flowing over the surface of a wall or floor deposited layers of calcite called flowstone.

  • Cave pearls, lily pads, and rimstone dams appeared where pools of water or streams occurred in the cave.

    • Like oyster pearls, cave pearls were made as layer upon layer of calcite built up around a grain of sand or other tiny object.

    • Lily pads formed on the surface of pools, while dams formed where water flowed slowly on the floor.

  • Another type of cave formation that decorated cave walls and even other formations was popcorn, which may have formed when water evaporated and left behind calcite deposits.

  • Some of the more unusual formations to occur in Carlsbad Cavern are helictites, which grow seemingly without regard to gravity, their twisting shapes, impurities, and the force of water under pressure.

  • Other rare formations are those composed not of calcite, but of aragonite, a mineral chemically identical to calcite but with a different crystal structure. These formations tend to be small, delicate, and needle-like.

Exploring the Cave
You can explore the vast underground world of Carlsbad Cavern along two self-guided routes. See Cavern Tours page for details. The routes follow paved, well lighted trails. Underground facilities are limited to restrooms and the Underground Lunchroom, where you can buy sandwiches, box lunches, and drinks. You begin your tour at the visitor center. At the center, cave entrance fees are collected and a CD ROM tour guide and up-to-date information on the cave are available.

Slaughter Canyon Cave
Ranger-guided tours of Slaughter Canyon Cave take you into an underground wilderness without electricity, paved walkways, or other modern conveniences. In this wild cave, darkness is broken only by the light of lanterns carried by rangers and flashlights carried by tour members. Among the highlights of the 2-hour, 1¼-mile tour are the 89-foot-high Monarch, one of the world's tallest columns; the sparkling, crystal-decorated Christmas Tree column; and the Chinese Wall, a delicate, ankle-high rimstone dam. Old bat guano mining excavations also can be seen. Tours are given daily in the summer and on weekends the rest of the year. A fee is charged. Reservations must be made at the visitor center or by calling the park. You have to hike a strenuous ½-mile trail to reach the cave entrance, where the tour begins. Sturdy walking shoes, flashlights, and water are required.

Preserving a National Treasure
The protection and preservation of Carlsbad Cavern is the mission of the National Park Service and the responsibility of every visitor. Unfortunately, many of the cave's smaller and more delicate formations have been damaged over the years by careless visitors. Experimental techniques, such as those that enable rangers to match pieces of broken stalactites and painstakingly glue them back together, are sometimes successful, but in practically all cases damage is irreversible. Please assist the National Park Service in preserving Carlsbad Cavern by observing park regulations.

  • Touching cave formations is prohibited. Formations are easily broken and the oil from your skin permanantly discolors the rock.

  • Smoking, or any use of tobacco, is not permitted. Eating and drinking are not permitted except in the Underground Lunchroom.

  • Throwing coins, food, or other objects in cave pools is forbidden. Foreign objects ruin the natural appearance of the pools and are difficult to remove. Also, the chemical reaction between foreign objects, the water, and the rock can leave permanant stains.

  • Photography is permitted when you tour on your own, but not when you accompany a ranger-guided tour. Photographers should not rest tripods or other camera equipment on formations or step off the trails.

  • Strollers are not permitted because parts of the trails are steep and narrow.

Geologic Resource Evaluation Report – A detailed geologic report is available that provides an introduction to the geologic history of the park and its geologic formations, identifies geologic features and processes that are important to park ecosystems, describes key resource management challenges and possible solutions, and lists geologic research and monitoring needs.

park maps subheading

The General park map handed out at the visitor center is available on the park's map webpage.

View the park's map to create your own personal maps and images right here.

For information about topographic maps, geologic maps, and geologic data sets, please see the geologic maps page.

photo album subheading

A photo album for this park can be fond on the park's webpage.

For information on other photo collections featuring National Park geology, please see the Image Sources page.

books, videos, cds subheading

Currently, we do not have a listing for a park-specific geoscience book. The park's geology may be described in regional or state geology texts.

Please visit the Geology Books and Media webpage for additional sources such as text books, theme books, CD ROMs, and technical reports.

Parks and Plates: The Geology of Our National Parks, Monuments & Seashores.
Lillie, Robert J., 2005.
W.W. Norton and Company.
ISBN 0-393-92407-6
9" x 10.75", paperback, 550 pages, full color throughout

The spectacular geology in our national parks provides the answers to many questions about the Earth. The answers can be appreciated through plate tectonics, an exciting way to understand the ongoing natural processes that sculpt our landscape. Parks and Plates is a visual and scientific voyage of discovery!

Ordering from your National Park Cooperative Associations' bookstores helps to support programs in the parks. Please visit the bookstore locator for park books and much more.

geologic research subheading

Information about the park's research program is available on the park's research webpage.

For information about permits that are required for conducting geologic research activities in National Parks, see the Permits Information page.

The NPS maintains a searchable data base of research needs that have been identified by parks.

A bibliography of geologic references is being prepared for each park through the Geologic Resources Evaluation Program (GRE). Please see the GRE website for more information and contacts.

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NPS Geology and Soils Partners

NRCS logoAssociation of American State Geologists
NRCS logoGeological Society of America
NRCS logoNatural Resource Conservation Service - Soils
USGS logo U.S. Geological Survey

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Currently, we do not have a listing for any park-specific geology education programs or activities.

General information about the park's education and intrepretive programs is available on the park's education webpage.

For resources and information on teaching geology using National Park examples, see the Students & Teachers pages.
updated on 01/04/2005  I   http://www.nature.nps.gov/geology/parks/cave/index.cfm   I  Email: Webmaster
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