CAVERNS OF SONORA
CAVERNS OF SONORA. The Caverns of Sonora are ten miles southwest of Sonora in Sutton County (at 30°33' N, 100°49' W). Their formation began during the Cretaceous Period, several million years ago, while the area was submerged. Limestone pockets were dissolved by acidic groundwater, and when the sea receded, empty chambers were left underground. Millions of years of dripping water subsequently deposited a variety of colorful formations. The cave entrance was discovered on Stanley Mayfield's ranch in 1900, but extensive exploration did not begin until 1955. A 1,800-foot section of the cave was opened to the public in 1960, and an additional 1,700 feet was made accessible in 1961; by mid-1979 the cave's public tour was 1½ miles long. Although small in size-the 7½-mile cave has no huge rooms or giant formations-the Caverns of Sonora have been ranked as one of the most spectacular cave complexes in the world. It has been said that the caverns' beauty "cannot be exaggerated, even by Texans." Unlike most caves, the caverns have hundreds of helictites, ranging in shape from soda straws to fish fins. The most famous attraction is a pair of symmetrical fishtail helictites that form a butterfly shape.
The people who prepared the cave for public viewing took care to preserve the cave's natural humidity levels, and the temperature inside is a constant 71° F. Ninety-five percent of the cave is "alive," with formations still growing. The Caverns of Sonora were named a National Natural Landmark in 1966. In addition to the underground tours, the caverns offer aboveground facilities for camping and picnicking. In the 1990s visitors averaged 40,000 annually.
George Macias, "Cave of the Butterfly," Texas Co-op Power, April 1991. Laurence Parent, "Caverns of Sonora," Texas Highways, March 1987. Jerry and Dorothy Sinise, Texas Show Caves (Austin: Eakin Press, 1983).