{{For|the caverns in Virginia|Natural Bridge (Virginia)}} {{Use mdy dates|date=October 2022}} {{Use American English|date=November 2023}} {{Infobox Protected area | name = Natural Bridge Caverns | logo = Natural Bridge Caverns Logo.jpg | map = Texas#USA | relief = 1 | location = [[Comal County, Texas|Comal County]], [[Texas]], [[United States]] | nearest_city = [[San Antonio, Texas|San Antonio]] | coordinates = {{coord|29|41|31.16|N|98|20|34.26|W|format=dms|display=inline,title}} | established = July 3, 1964<br>(Discovered in March 1960) | module = {{designation list | embed = yes | designation1 = NNL | designation1_date = 1971 }} | website = https://naturalbridgecaverns.com }} [[File:NaturalBridgeCaverns11.jpg|thumb|right|300px|Natural Bridge Caverns]] The '''Natural Bridge Caverns''' are the largest commercial [[cave]]rns in the US state of [[Texas]]. The name<ref>{{cite book |last=Cooke |first=Paul |title=Natural Wonders of Texas |publisher=Country Roads Press |year=1995 |page=[https://archive.org/details/naturalwondersof0000cook/page/175 175] |isbn=978-1-56626-109-8 |url-access=registration |url=https://archive.org/details/naturalwondersof0000cook/page/175}}</ref> is derived from the {{Convert|60|ft|m|adj=on}} natural [[limestone]] slab bridge that spans the amphitheater setting of the cavern's entrance. The span was left suspended when a [[sinkhole]] collapsed below it.
The caverns are located near the city of [[San Antonio, Texas]], in the [[Texas Hill Country]] next to the [[Natural Bridge Wildlife Ranch]], a drive-through wildlife [[safari park]]. The caverns feature several unique [[speleothem]]s and other [[geological]] formations, including magnificent stalactites that hang from the ceiling . The temperature inside the cave is {{Convert|21|C|F|order=flip}}<ref>{{cite journal |last1=Sharpe |first1=Patricia |last2=Thompson |first2=Helen |year=1985 |title=Around the State |journal=Texas Monthly |issue=August 1985 |pages=22}}</ref> year-round and the humidity rate is a constant 99 percent. The deepest part of the public tour is {{Convert|180|ft|m}} below the surface, although undeveloped areas of the cavern reach depths of {{Convert|230|ft|m}}.
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<ref name="Texas Caves">{{cite book |last1=Pittman |first1=Blair |last2=Abernethy |first2=Frances Edward |title=Texas Caves |publisher=TAMU Press |year=2000 |pages=65–77 |isbn=978-0-89096-899-4}}</ref> from [[St. Mary's University, Texas|St. Mary's University]]<ref>{{Cite web |title=Natural Bridge Caverns Discovery |publisher=Texas Historical Marker |url=http://www.9key.com/markers/marker_detail.asp?atlas_number=5091003552 |access-date=May 11, 2010 |url-status=dead |archive-url=https://web.archive.org/web/20110313000300/http://www.9key.com/markers/marker_detail.asp?atlas_number=5091003552 |archive-date=March 13, 2011}}</ref> in nearby [[San Antonio]]. On their fourth trip into the caverns, the men discovered/explored just over {{One2a|{{convert|1|mi|km|spell=in}}}} of passage. Subsequent explorations revealed {{Convert|2|mi|km|spell=in}} associated with what became known as the "North Cavern".
After discovery, Knox assisted the landowners in obtaining information and suggestions for development. Clara Wuest<ref name="50 years of Natural Bridge Caverns" /> (the landowner) wanted to show the world the cave under her property. Knox approached both the [[National Park Service]] 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.<ref>{{Cite news |title=50 years since discovery of largest-known caverns in Texas |last=George |first=Patrick |date=March 23, 2010 |newspaper=[[Austin American-Statesman]] |url=http://www.statesman.com/news/local/50-years-since-discovery-of-largest-known-caverns-425529.html |access-date=May 11, 2010 |archive-url=https://web.archive.org/web/20100324220242/http://www.statesman.com/news/local/50-years-since-discovery-of-largest-known-caverns-425529.html |archive-date=March 24, 2010 |url-status=dead}}</ref> Knox dropped out of school to assist. He also approached Jack Burch, who had just finished work on developing the [[Caverns of Sonora]] near [[Sonora, Texas]]. 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).<ref name="Texas Caves" /> Development on the cavern began in 1963 and work on lights and trails continued until opening day, July 3, 1964.<ref name="Natural Bridge Caverns">{{Handbook of Texas |name=Natural Bridge Caverns |id=rqn01 |retrieved=May 11, 2010}} Texas State Historical Association</ref> 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]] in 1971.<ref>{{Cite web |url=https://www.nps.gov/subjects/nnlandmarks/site.htm?Site=NABR-TX |title=National Natural Landmarks - National Natural Landmarks (U.S. National Park Service) |website=[[National Park Service]] |language=en |access-date=March 30, 2019 |quote="Year designated: 1971"}}</ref>
During excavation of the entrance trail, a human tooth, [[arrowhead]]s, and [[spear]]heads dating from 5000 BCE were found. Also, just inside the entrance, a jawbone and femur from an extinct species of [[American black bear|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 {{Convert|90|ft|m}} 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 {{Convert|22|in|cm}} 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<ref>{{Cite web |title=Jaremy Room |publisher=Show Caves |url=http://www.showcaves.com/english/usa/showcaves/NaturalBridgeTX.html |access-date=May 11, 2010}}</ref> 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.<ref name="Texas Caves" /> This shaft also penetrated a large void approximately {{Convert|150|ft|m}} below ground. As before, the initial shaft was enlarged and people dropped down into the unknown. Explorations revealed another half-mile ({{Convert|0.5|mi|km|disp=output only}}) of cavern extending to the south. This then became known as the South Cavern.
==Recent exploration== Exploration continues to date.<ref name="50 years of Natural Bridge Caverns">{{Cite news |title=50 years of Natural Bridge Caverns |last=Weilbacher |first=Eric J |date=March 27, 2010 |newspaper=[[New Braunfels Herald-Zeitung]] |url=http://herald-zeitung.com/story.lasso?ewcd=46cd78773ecd5351 |access-date=May 11, 2010}}{{dead link |date=February 2018 |bot=InternetArchiveBot |fix-attempted=yes}}</ref> 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 ({{Convert|1|mi|km|disp=output only}}) 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 {{Convert|1600|ft|m}} 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.<ref>{{cite news |first=Priscilla |last=Aguirre |url=https://www.mysanantonio.com/news/local/article/Explorers-find-new-incredible-discoveries-at-14290474.php |title=Explorers find new discoveries at historic Natural Bridge Caverns |date=August 8, 2019 |work=[[San Antonio Express-News]] |access-date=June 11, 2020}}</ref>
==Passages renamed== In 2008, the caverns' owners changed the names for the passages.<ref name="Texas Caves" /> 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]]. [[Bracken Cave]], near the Natural Bridge Caverns, is home to one of two large [[bat]] colonies in Texas. The bats that inhabit Bracken Cave are a small species called [[Mexican free-tailed bat]]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 [[Broadcast syndication|syndicated]] [[anthology]] [[television series]] ''[[Texas Country Reporter]]'', hosted by [[Bob Phillips]].<ref>{{cite web |url=http://www.naturalbridgecaverns.com/(S(2wlp3cibtcnuiw45bfxdvp2x))/whiteNoseSyndrome.aspx |title=Natural Bridge Caverns is going to bat for the bats. |website=Natural Bridge Caverns |access-date=July 19, 2003 |archive-url=https://web.archive.org/web/20101126082050/http://www.naturalbridgecaverns.com/whiteNoseSyndrome.aspx |archive-date=November 26, 2010 |url-status=dead}}</ref>
==Natural Bridge Caverns Sinkhole== {{Infobox NRHP | name = Natural Bridge Caverns Sinkhole Site | location = {{Address restricted}}, Natural Bridge Caverns, Texas | added = October 29, 2004 | area = <{{Convert|1|acre|ha}} | refnum = 04001202<ref name="nris">{{NRISref|version=2010a}}</ref> }} Located on the property is the '''Natural Bridge Caverns Sinkhole Site''', an archeological site listed on the [[National Register of Historic Places]]. The location of the site is not publicly disclosed in order to preserve artifacts in their context for ongoing research.<ref name="ARCombinedNote" />
==Gallery== <gallery mode="packed"> NaturalBridgeCaverns1.jpg|The natural bridge outside the cave entrance NaturalBridgeCaverns2.jpg|[[Flowstone]] 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]]s and [[speleothem|columns]] NaturalBridgeCaverns7.jpg|More tall, thin [[stalagmite]]s NaturalBridgeCaverns8.jpg|A large column NaturalBridgeCaverns9.jpg NaturalBridgeCaverns10.jpg|Closeup of flowstone NaturalBridgeCaverns11.jpg|A large room full of [[speleothem]]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 </gallery>
==See also== {{Portal|National Register of Historic Places|Texas}} * [[National Register of Historic Places listings in Comal County, Texas]] * [[List of National Natural Landmarks in Texas]]
==References== {{Reflist}}
==External links== {{commons category|Natural Bridge Caverns}} * [http://www.naturalbridgecaverns.com Natural Bridge Caverns official website] * {{Handbook of Texas|id=rqn01|name=Natural Bridge Caverns}}
{{National Natural Landmarks in Texas}} {{NRHP in Texas}} {{Comal County, Texas}}
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[[Category:Caves of Texas]] [[Category:Natural arches of Texas]] [[Category:Landforms of Comal County, Texas]] [[Category:National Natural Landmarks in Texas]] [[Category:Show caves in the United States]] [[Category:Tourist attractions in San Antonio]] [[Category:Tourist attractions in Comal County, Texas]] [[Category:Texas Hill Country]]