Caverns of Sonora
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The Caverns of Sonora, a National Natural Landmark [1], is a unique cave located eight miles west of the town of Sonora, Texas. It is a world-class cave due to its stunning array of calcite crystal formations, especially helictites. These helictites are found in extreme abundance, often with a rare purity and complexity. One formation is so densely packed with them it has been dubbed the "Snake pit". The founder of the National Speleological Society, Bill Stephenson, said of the cave after his first visit: "This is the most indescribably beautiful cave in the world, its beauty cannot be exaggerated, not even by a Texan."
The cave has been operated commercially by the Mayfield family since July 16, 1960. [2] Today, two miles of trail have been developed out of the seven miles of explored cave. The development of the trails was done by Jack Burch, starting in 1959 and completing in 1979. Burch revolutionized cavern development world-wide with his "conservation through commercialization" approach to the project.
The cave is formed in 100 million-year-old (Cretaceous) Segovia limestone, of the Edward Limestone Group. The formation of the cave itself probably occurred between 1.5 to 5 million years ago. The cave is formed primarily along a fault. This fault allowed gases to rise up from depths of around 1.5 miles to then depths of about 300 feet. At this depth the gases mixed with water in the aquifer. The resulting highly acidic water dissolved out the limestone, forming the cave. Between 1–3 million years ago, the water drained form the cave. The famous mineral formations, known as speleothems, all formed after the water drained from the cave. The cave's most famous formation is the Butterfly. It is the only known formation like it in the world. It is formed by two fish tail helictite growths that share the same attachment point of the cave wall.
On November 21, 2006, the butterfly formation was vandalized by a member of a tour group. Specifically, 60% of the top right tip of the wing was broken off of the formation. There is a $20,000 reward for any information that leads to the recovery of the missing piece. Since the butterfly is active (still growing), the formation can still be repaired if the piece is recovered soon.
