Caverns of Sonora Click on Map below for a larger image COSmap6_2048x741.png)
Directions: Head west on IH 10 from Sonora, go eight miles to the Caverns of Sonora exit (Exit 392), and follow the signs for 7 miles to the cave. Description: Caverns of Sonora is internationally recognized as one of the most beautiful caves in the world. Don't miss it! NSS founder Bill Stephenson once said "The beauty of Caverns of Sonora cannot be exaggerated… not even by a Texan!" The natural entrance to the cave was originally about 0.6 m in diameter and the cave's first few hundred meters consists of unremarkable passages. However, a high lead off a large room leads into several kilometers of some of the world's most beautiful passages. The cave cannot be described without superlatives. Its basic layout is a complex 3-dimensional maze formed along a few parallel or near-parallel fractures. The passages are not exceptionally large, averaging about 2-4 m in diameter, but most of the passages are lined with sparkling speleothems the floors, walls and ceilings of many passages are completely covered. Visitors frequently compare sections of the cave to the inside of a crystal-lined geode. Many speleothems are intricately layered; stalactites hang from calcite wall crusts, with off-shooting straight and branching helictites covered with coral, and soda straws dripping from the multiple coral and helictite tips onto flowstone, stalagmites and coral trees below. Onion ring, saw-tooth, and ricocheting helictites, dog tooth spar, angel wings, and other speleothems both common and uncommon occur in great abundance throughout the cave. Every trip reveals something new. Several new and enchanting areas have been added to the tour since the last NSS convention in Texas. Long and short tours are available; the short tour enters and exits via an artificial tunnel into the back part of the cave, while the long tour enters through he natural entrance and leaves from the tunnel. Local ranchhands knew of "Mayfield's Cave" for many years. In the early 1950s cavers began to explore the area up to the room known as the Devil's Pit. A passage was seen to continue from the top of the room, and in 1955 a group from Dallas crossed a narrow, steep ledge over a 14 m drop to discover the major decorated portion of the cave. The discovery was kept quiet for a few years, except to show unbelievably beautiful photos of "Secret Cave" to envious cavers. In 1960, Caverns of Sonora opened to the public. One of the primary developers of the cave, Jack Burch was a caver who pioneered techniques revolutionary for their time in developing, showing, and maintaining a cave in as natural a condition as possible. Some exploration and survey continued into the early 1960s but was curtailed by the owners because of damage to the cave. Some damage resulted from carelessness, but many areas could not be explored without breaking something. The owners felt that preserving the cave was more important than exploring it. In 1990 the owners initiated a careful and detailed survey and scientific study of the cave which is expected to last for several years. Caverns of Sonora has had minimal biological study. A new troglobitic species of spider (Cicurina barri) was described from the cave in 1992 from a 1959 collection. With further study additional new species are likely to be found in Sonora, but they will be endemic to the cave only so long as there continue to be virtually no collections from other caves in that part of the Edwards Plateau. The current survey has found almost no invertebrate fauna away from the entrances. While Sonora is moist enough to support a diverse fauna, the speleothems and calcite crusts which encase most of the passages may prevent organic aterial (nutrients) from entering much of the cave. Sonora has a complex but poorly understood geologic history. The cave developed within the Segovia Member of the Edwards Limestone, and most passages formed by slow-moving phreatic groundwater. The various passage levels reflect the recession of past water levels to their current elevation, 40 m below the cave's deepest known section. Collapse connected many of the passages, and some floodwater mazes formed as a result. The reason for the abundance and nature of the speleothems is unclear. Several features in the cave suggest that rising hydrogen sulfide gas, and/or descending sulfate-rich groundwaters may have played a significant role in the cave's development. Data collection continues, but currently evidence is insufficient to support or refute such a hypothesis. Good examples of airflow condensation-corrosion occur in the cave; speleothems that once bedecked the now barren upper levels were stripped by this phenomenon. Bibliography: Burch, J. 1992. Personal communication. Part owner of Caverns of Sonora. Fieseler, R. G., J. Jasek, and M. Jasek. 1978. An introduction to the caves of Texas. NSS Convention Guidebook, 19, p. 77-79. Gertsch, W.J. 1992. Distribution patterns and speciation in North American cave spiders with a list of the troglobites and revision of the cicurinas of the subgenus Cicurella. Speleol. Monogr.: 3, Texas Mem. Museum, Univ. Texas, Austin, p. 116-117. Palmer, A.N. 1992. Personal communication. State University of New York, Oneonta. Texas Speleological Survey. 1991. Report on the 60 longest and deepest caves. Texas Caver, 36(6):122. Veni, George, and Associates. 1992. Geology manual for the guides at Caverns of Sonora. Unpublished draft report, 16 pp.
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