| Natural Bridge Caverns | |
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| Location | Comal County, Texas, United States |
| Nearest city | San Antonio |
| Coordinates | 29°41′31.16″N 98°20′34.26″W / 29.6919889°N 98.3428500°W |
| Established | July 3, 1964 (Discovered in March 1960) |
| Website | https://naturalbridgecaverns.com |
| Designated | 1971 |
The Natural Bridge Caverns are the largest commercial caverns in the US state of Texas. The name[1] is derived from the 60-foot (18 m) 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 speleothems and other geological formations. The temperature inside the cave is 70 °F (21 °C)[2] year-round and the humidity rate is a constant 99 percent. The deepest part of the public tour is 180 feet (55 m) below the surface, although undeveloped areas of the cavern reach depths of 230 feet (70 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.
- ^ Cooke, Paul (1995). Natural Wonders of Texas. Country Roads Press. p. 175. ISBN 978-1-56626-109-8.
- ^ Sharpe, Patricia; Thompson, Helen (1985). "Around the State". Texas Monthly (August 1985): 22.