The Caverns of Sonora features a lovely array of calcite crystal formations, especially helictites. The cave is located on Interstate 10 in Texas, halfway between Big Bend National Park and San Antonio. It is located 15 miles southwest of Sonora. Along with guided tours of this cave, there are other activities including gemstone panning, exploring the nature trail, enjoying a workshop and camping out.
The Visitor Center and gift shop was built in 1961. It is a ranch barn design with vaulted ceilings and exposed oak beams. The store sells sterling silver and gemstone jewelry, rocks, minerals and fossil specimens from around the world. In 1966 the cavern was designated as a National Natural Landmark by the United States Department of the Interior. It is one of the most active caves in the world with over 95% of its formations still 'growing'.
The cave was discovered when a dog chased a raccoon into a 20-inch opening in a rock. Locals began exploring the cave sometime in the early 1920’s. They were able to go about 500 feet from the entrance to a fifty foot deep pit. This section of the cave was eventually known as Mayfield Cave. In 1955, three speleologists, Bob Crisman, Bart Crisman and James Estes from Abilene were exploring another cave in Sutton County. They headed to the Mayfield Ranch to take a look at another cave known as Mayfield Cave. The speleologists entered the cave and made their way to a large room. A deep pit blocked their progress. On the other side of this pit were seemingly inaccessible passages that continued on. They were pressed for time, so they left the cave.
This story was passed on other cavers. On Labor day weekend of 1955, Danny Sheffield, Jack Allen, Claude Head and Jack Prince crossed a narrow, sloping ledge, high on the top of the right hand side of the big pit. They reached the passages on the other side. Stories of bizarre formations and untold beauty began circulating among members of the caving community.
Jack Burch, a caver from Oklahoma saw the cavern for the first time in 1956. He began to see human impact in the caverns in places where there shouldn’t have been any damage. His vision was to develop the cavern to stop this destruction and preserve the cavern for future generations. Development started in 1959. The Caverns of Sonora was opened to the public on July 16, 1960.
The cave is formed in 100-million-year-old Cretaceous period Segovia limestone, from the Edward limestone group. The formation of the cave itself may have occurred between 1.5 to 5 million years ago. The stunning mineral formations, known as speleothems, formed after water had drained from the cave.