The Natural Bridge Caverns are the largest known commercial

cave A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering of rock and often extend deep underground. The word ''cave'' can refer to smaller openings such as sea ...

rns in the U.S. state of

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

. The name is derived from the 60 ft natural

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

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 locally also known as ''vrtače'' and shakeholes, and to openi ...

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

San Antonio, Texas ("Cradle of Freedom") , image_map = , mapsize = 220px , map_caption = Interactive map of San Antonio , subdivision_type = Country , subdivision_name = United States , subdivision_type1= State , subdivision_name1 = Texas , subdivision_t ...

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 Ameri ...

next to the

Natural Bridge Wildlife Ranch Natural Bridge Wildlife Ranch is a ranch and wildlife refuge in Texas. The ranch is a Texas Land Heritage Property, certified by the State of Texas for being used for agriculture by the same family for over 100 years. It comprises over 400 acres ...

, 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 park ...

. The caverns feature several unique

speleothem A speleothem (; ) is a geological formation 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, depending on ...

s and other

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

formations. The temperature inside the cave is 21 degrees

Celsius The degree Celsius is the unit of temperature on the Celsius scale (originally known as the centigrade scale outside Sweden), one of two temperature scales used in the International System of Units (SI), the other being the Kelvin scale. The ...

(70° F) year-round and the humidity rate is a constant 99 percent. The deepest part of the public tour is 180 feet below the surface, although undeveloped areas of the cavern reach depths of 230 feet. The caverns are still slowly developing. Due to the porosity of the

, rainwater travels downwards through the layers of rock, where it dissolves out calcite, a weak mineral that makes up all of the speleothems at 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 ("Cradle of Freedom") , image_map = , mapsize = 220px , map_caption = Interactive map of San Antonio , subdivision_type = Country , subdivision_name = United States , subdivision_type1= U.S. state, State , subdivision_name1 = Texas , s ...

. On their fourth trip into the caverns, the men discovered/explored just over a mile of passage. Subsequent explorations revealed 2 miles associated with what became known as the "North Cavern." After discovery, Orion Knox Jr. assisted the landowners in obtaining information and suggestions for development. Mrs. Clara Wuest (the landowner), wanted to show the world the cave under her property. Orion approached both the

National Park Service The National Park Service (NPS) is an agency of the United States federal government within the U.S. Department of the Interior that manages all national parks, most national monuments, and other natural, historical, and recreational propertie ...

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. Mrs. Wuest then decided that she would fund development. Orion 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. Jack agreed to help and development began early in 1963. Mrs. 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 Mrs. Wuest-Heidemann, Mr. Heidemann, Jack Burch, Orion Knox, and Reggie Wuest (Mrs. 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. Natural Bridge Caverns became a registered

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

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 ...

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

arrow An arrow is a fin-stabilized projectile launched by a bow. A typical arrow usually consists of a long, stiff, straight shaft with a weighty (and usually sharp and pointed) arrowhead attached to the front end, multiple fin-like stabilizers c ...

heads, and

spear A spear is a pole weapon 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 hardened spears, or it may be made of a more durable material fasten ...

heads dating from 5,000 BC were found. Also, just inside the entrance, a jawbone and femur from an extinct species of

black bear Black bear or Blackbear may refer to: Animals * American black bear (''Ursus americanus''), a North American bear species * Asian black bear (''Ursus thibetanus''), an Asian bear species Music * Black Bear (band), a Canadian First Nations group ...

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 archaeological dig was recently done under the natural bridge. Archaeologists 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 90 feet 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 22 inches 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 150 feet 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 the summer of 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 1,600 feet 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 Natural Bridge Caverns including roosting areas and accumulation of bat

guano Guano (Spanish from qu, wanu) is the accumulated excrement of seabirds or bats. As a manure, guano is a highly effective fertilizer due to the high content of nitrogen, phosphate, and potassium, all key nutrients essential for plant growth. G ...

Bracken Cave Bracken Cave is the summer home to the largest colony of bats in the world. An estimated 20 million Mexican free-tailed bats roost in the cave from March to October making it the largest known concentration of mammals. The cave is located in sout ...

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

bat Bats are mammals of the order Chiroptera.''cheir'', "hand" and πτερόν''pteron'', "wing". 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 bi ...

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 the Americas, so named because its tail can be almost half its total length and is not attached to its uropatagium. It has been ...

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 excerpts by different authors. In genre fiction, the term ''anthology'' typically categ ...

television series A television show – or simply TV show – is any content produced for viewing on a television set which can be broadcast via over-the-air, satellite television, satellite, or cable television, cable, excluding breaking news, television adverti ...

, ''

Texas Country Reporter ''Texas Country Reporter'' is a weekly syndicated television program, hosted and produced by Bob Phillips and Kelli Phillips, which airs in all twenty-two Texas media markets, generally on weekends, and nationally on the satellite/cable channel ...

'', hosted by

Bob Phillips Robert Leon Phillips, known as Bob Phillips (born June 23, 1951), is an American television journalist best known for his long-running program ''Texas Country Reporter''. In 2005, Phillips was inducted into the Silver Circle of the Lone Star Ch ...

Natural Bridge Caverns Sinkhole Site

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 United States federal government's official list of districts, sites, buildings, structures and objects deemed worthy of preservation for their historical significance or "great artistic v ...

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

Gallery

File:NaturalBridgeCaverns1.jpg, The natural bridge outside the cave entrance. File: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. File:NaturalBridgeCaverns3.jpg, The cave contains large, switchback descents and ascents. File: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. File:NaturalBridgeCaverns5.jpg, Flowstone ceiling over a switchback. File:NaturalBridgeCaverns6.jpg, Tall, thin

stalagmite A stalagmite (, ; from the Greek , from , "dropping, trickling") 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 ...

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. ...

. File:NaturalBridgeCaverns7.jpg, More tall, thin

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

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