The Natural Bridge Caverns are the largest commercial

cave Caves or caverns are natural voids under the Earth's Planetary surface, surface. Caves often form by the weathering of rock and often extend deep underground. Exogene caves are smaller openings that extend a relatively short distance undergrou ...

rns in the US state of

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

. The name is derived from the natural

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

slab bridge that spans the amphitheater setting of the cavern's entrance. The span was left suspended when a

sinkhole A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are also known as shakeholes, and to openings where surface water ...

collapsed below it. The caverns are located near the city of

San Antonio, Texas San Antonio ( ; Spanish for "Anthony of Padua, Saint Anthony") is a city in the U.S. state of Texas and the most populous city in Greater San Antonio. San Antonio is the List of Texas metropolitan areas, third-largest metropolitan area in Texa ...

, in the

Texas Hill Country The Texas Hill Country is a geographic region of Central and South Texas, forming the southeast part of the Edwards Plateau. Given its location, climate, terrain, and vegetation, the Hill Country can be considered the border between the Ame ...

next to the Natural Bridge Wildlife Ranch, a drive-through wildlife

safari park A safari park, sometimes known as a wildlife park, is a zoo-like commercial drive-in tourist attraction where visitors can drive their own vehicles or ride in vehicles provided by the facility to observe freely roaming animals. A safari par ...

. The caverns feature several unique

speleothem A speleothem (; ) is a geological formation made by mineral deposits that accumulate over time in natural caves. Speleothems most commonly form in calcareous caves due to carbonate dissolution reactions. They can take a variety of forms, depen ...

s and other

geological Geology (). is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth s ...

formations. The temperature inside the cave is year-round and the humidity rate is a constant 99 percent. The deepest part of the public tour is below the surface, although undeveloped areas of the cavern reach depths of . The caverns are still slowly developing. Due to the porosity of the limestone, rainwater travels downward through the layers of rock, where it dissolves out calcite, a weak mineral that makes up all the speleothems at the Natural Bridge Caverns. After exiting the limestone, water enters the caverns where it flows and drips constantly throughout, causing the formations to retain a waxy luster that can be seen in a few caverns.

History

The caverns were discovered on March 27, 1960, by students Orion Knox Jr., Preston Knodell Jr., Al Brandt, and Joe Cantu from St. Mary's University in nearby

San Antonio San Antonio ( ; Spanish for " Saint Anthony") is a city in the U.S. state of Texas and the most populous city in Greater San Antonio. San Antonio is the third-largest metropolitan area in Texas and the 24th-largest metropolitan area in the ...

. On their fourth trip into the caverns, the men discovered/explored just over of passage. Subsequent explorations revealed associated with what became known as the "North Cavern". After discovery, Knox assisted the landowners in obtaining information and suggestions for development. Clara Wuest (the landowner) wanted to show the world the cave under her property. Knox approached both the

National Park Service The National Park Service (NPS) is an List of federal agencies in the United States, agency of the Federal government of the United States, United States federal government, within the US Department of the Interior. The service manages all List ...

and the Texas Park System. While both entities agreed that the cavern was substantial and merited development, both groups told the landowners that funds did not exist for their respective groups to undergo such an endeavor. Wuest then decided that she would fund development. Knox dropped out of school to assist. He also approached Jack Burch, who had just finished work on developing the

Caverns of Sonora The Caverns of Sonora, a National Natural Landmark, is a unique cave located west of the small city of Sonora, the seat of Sutton County, Texas. It is a world-class cave because of its stunning array of calcite crystal formations, especially hel ...

near

Sonora, Texas Sonora is a city in and the county seat of Sutton County, Texas, United States. The population was 2,502 at the 2020 census. Geography and climate Sonora is located at (30.568166, –100.644163). According to the United States ...

. Burch agreed to help and development began early in 1963. Wuest remarried Harry Heidemann, a retired Texas Highway Patrolman, in the early 1960s. Together, they started work on developing the cavern. The full-time development crew included Wuest (now Wuest-Heidemann), Heidemann, Burch, Knox, and Reggie Wuest (Wuest-Heidemann's son). Development on the cavern began in 1963 and work on lights and trails continued until opening day, July 3, 1964. Texas State Historical Association The cavern has been opened ever since and is still owned and operated by family members. The Natural Bridge Caverns became a registered US

National Natural Landmark The National Natural Landmarks (NNL) Program recognizes and encourages the conservation of outstanding examples of the natural history of the United States. It is the only national natural areas program that identifies and recognizes the best e ...

in 1971. During excavation of the entrance trail, a human tooth,

arrowhead An arrowhead or point is the usually sharpened and hardened tip of an arrow, which contributes a majority of the projectile mass and is responsible for impacting and penetrating a target, or sometimes for special purposes such as signaling. ...

s, and

spear A spear is a polearm consisting of a shaft, usually of wood, with a pointed head. The head may be simply the sharpened end of the shaft itself, as is the case with Fire hardening, fire hardened spears, or it may be made of a more durable materia ...

heads dating from 5000 BCE were found. Also, just inside the entrance, a jawbone and femur from an extinct species of black bear were discovered. This leads many to believe that the uppermost areas of the cavern were used as a shelter by early peoples and animals at some point. An archeological dig was recently done under the natural bridge. Archeologists recovered arrowheads and other tools which further indicate the presence of early peoples at some point in history.

Further exploration

In 1967, speculation on a southern extent to the North Cavern was confirmed when test drilling indicated the presence of a large void approximately beneath the surface. A camera was sent down the narrow shaft and photographs revealed a large chamber filled with formations. This original shaft was reamed out to and three men were lowered into the ground. They discovered a large breakdown chamber and numerous formations. The first three men to enter this room were Jack Burch, Reggie Wuest, and Myles Kuykendall. By combining the first two letters of each man's first name, they arrived at JAREMY, and thus this newly discovered room was called the Jaremy Room. Further investigation near the bottom of the Jaremy Room revealed a strong likelihood that another passage existed beyond a pile of rocks and boulders. In 1968, the drillers were once again brought out to the property and another exploratory shaft was sunk into the ground. This shaft also penetrated a large void approximately below ground. As before, the initial shaft was enlarged and people dropped down into the unknown. Explorations revealed another half-mile () of cavern extending to the south. This then became known as the South Cavern.

Recent exploration

Exploration continues to date. During mid-2005, several hundred feet were added to the current surveyed length of the cave. It is believed that as much as another mile () could be added to the survey by just mapping the known passages which have not yet been surveyed. Additional unexplored leads exist in sections of the Discovery Passages (North Cavern). Since May 8, 2019, a team of cave explorers have discovered over of new never before seen passages. As explorers move deeper into the cavern, each expedition takes longer, with the latest taking more than 19 hours to complete.

Passages renamed

In 2008, the caverns' owners changed the names for the passages. The "North Cavern" was changed to "Discovery Passages". and the "South Cavern" was changed to "Hidden Passages". According to the landowners, the change in names better reflects the discovery and exploration history of the cavern and removes some confusion for guests.

Wildlife

There is recent evidence of bats residing in the Natural Bridge Caverns including roosting areas and accumulation of bat

guano Guano (Spanish from ) is the accumulated excrement of seabirds or bats. Guano is a highly effective fertiliser due to the high content of nitrogen, phosphate, and potassium, all key nutrients essential for plant growth. Guano was also, to a le ...

Bracken Cave Bracken Cave is a cave located in southern Comal County, Texas, outside the city of San Antonio. The -wide crescent shaped opening to the cave lies at the bottom of a sinkhole, formed when the roof of the cave collapsed. It is the summer home t ...

, near the Natural Bridge Caverns, is home to one of two large

bat Bats are flying mammals of the order Chiroptera (). With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most birds, flying with their very long spread-out ...

colonies in Texas. The bats that inhabit Bracken Cave are a small species called

Mexican free-tailed bat The Mexican free-tailed bat or Brazilian free-tailed bat (''Tadarida brasiliensis'') is a medium-sized bat native to North, Central, and South America and the Caribbean, so named because its tail can be almost half its total length and is not a ...

s. Bats control the insect population, help to pollinate plants, and are a food source for other animals, making them a valuable part of the ecosystem. The cave was the focus of a 2013 episode of the syndicated

anthology In book publishing, an anthology is a collection of literary works chosen by the compiler; it may be a collection of plays, poems, short stories, songs, or related fiction/non-fiction excerpts by different authors. There are also thematic and g ...

television series A television show, TV program (), or simply a TV show, is the general reference to any content produced for viewing on a television set that is broadcast via over-the-air, satellite, and cable, or distributed digitally on streaming plat ...

'' Texas Country Reporter'', hosted by Bob Phillips.

Natural Bridge Caverns Sinkhole

Located on the property is the Natural Bridge Caverns Sinkhole Site, an archeological site listed on the

National Register of Historic Places The National Register of Historic Places (NRHP) is the Federal government of the United States, United States federal government's official United States National Register of Historic Places listings, list of sites, buildings, structures, Hist ...

. The location of the site is not publicly disclosed in order to preserve artifacts in their context for ongoing research.

Gallery

NaturalBridgeCaverns1.jpg, The natural bridge outside the cave entrance NaturalBridgeCaverns2.jpg,

Flowstone Flowstones are sheetlike deposits of calcite or other carbonate minerals, formed where water flows down the walls or along the floors of a cave. They are typically found in "solution caves", in limestone, where they are the most common speleothe ...

is a dominant feature of the caverns. NaturalBridgeCaverns3.jpg, The cave contains large, switchback descents, and ascents. NaturalBridgeCaverns4.jpg, The only living plant in the cave—a small fern. The spores were believed to have been tracked in on a workers clothing, then germinated next to a light. The fern has since been removed. NaturalBridgeCaverns5.jpg, Flowstone ceiling over a switchback NaturalBridgeCaverns6.jpg, Tall, thin

stalagmite A stalagmite (, ; ; ) is a type of rock formation that rises from the floor of a cave due to the accumulation of material deposited on the floor from ceiling drippings. Stalagmites are typically composed of calcium carbonate, but may consist ...

s and

columns A column or pillar in architecture and structural engineering is a structural element that transmits, through compression, the weight of the structure above to other structural elements below. In other words, a column is a compression member ...

NaturalBridgeCaverns7.jpg, More tall, thin

s NaturalBridgeCaverns8.jpg, A large column NaturalBridgeCaverns9.jpg NaturalBridgeCaverns10.jpg, Closeup of flowstone NaturalBridgeCaverns11.jpg, A large room full of

s NaturalBridgeCaverns12.jpg, The King's Throne—a large stalagmite NaturalBridgeCaverns13.jpg, Water on calcite shimmers in the cave's lighting NaturalBridgeCaverns14.jpg NaturalBridgeCaverns15.jpg, "Grendel's Canyon" NaturalBridgeCaverns16.jpg, The ascent out of the cavern contains more massive rooms. NaturalBridgeCaverns17.jpg NaturalBridgeCaverns18.jpg, The view back into the cavern from near the exit Formations in Natural Bridge Caverns.jpg, Formations Natural Bridge Caverns - Pluto's Anteroom.jpg, Pluto's Anteroom Natural Bridge Caverns - Enterance.jpg, Cave entrance Natural Bridge Cavern Entrance.jpg, Cave entrance Natural Bridge Cavern The Chandelier.jpg, The Chandelier—In the Castle of the White Giants Natural Bridge Cavern Pluto's Anteroom.jpg, Pluto's Anteroom Natural Bridge Cavern - Valley of the Fallen Lords.jpg, Valley of the Fallen Lords Natural Bridge Cavern The Watchtower.jpg, The Watchtower Natural Bridge Cavern Grendel's Canyon.jpg, Grendel's Canyon Natural Bridge Cavern Mount of the Landlord.jpg, Mount of the Landlord—In the Castle of the White Giants

References

External links

Natural Bridge Caverns official website
* {{authority control Caves of Texas Natural arches of Texas Landforms of Comal County, Texas National Natural Landmarks in Texas Show caves in the United States Tourist attractions in San Antonio Tourist attractions in Comal County, Texas Texas Hill Country