How was the cave formed?
The cave was dissolved along cracks and faults in the limestone rock by sulfuric acid. The limestone was laid down about two-hundred and fifty million years ago, as part of a reef complex along the edge of an inland sea. Seventeen to twenty million years ago, the ancient reef rocks that had been buried under thousands of feet of younger rocks began to lift upwards. Tectonic forces pushed the buried rock layers up and erosion wore away softer minerals to expose the ancient reef as the Guadalupe Mountains. Deep in the basin, a brine originating from oil and gas deposits and rich in hydrogen sulfide was forced into the limestone at the edge of the basin. When this brine encountered oxygen-rich rainwater moving down through the rock, it created sulfuric acid. This acid dissolved the limestone creating cave passages.
