LEARNING TO SEE IN THE DARK
Still, Richards has had unnerving experiences in caves. Nine years ago, during a week-long expedition into Lechuguilla Cave, the park's largest known cavern, he awoke from a nightmare to see a soft yellowish glow outlining his body in the cave's total darkness. For months he told no one, expecting that they would think he'd been hallucinating. Then he encountered two cave microbiologists who had had identical experiences in the same cave. One possible explanation: After days in total darkness, human eyes may "learn" to see infrared light.
Visitors to Carlsbad Caverns generally have less spooky experiences, even though the park has greatly expanded the menu of cave tours in recent years. A thorough Carlsbad visit now can stretch across two or three days and 10 or more hours of underground exploration, most of it escorted by rangers. Only Carlsbad Cavern's Big Room, which would swallow nine football fields, and the Natural Entrance remain open to self-guided exploring. The National Park Service studies completed in 1993 found that more than 16,000 formations had been stolen or vandalized, so rangers took control of the herds in all the delicate areas.
Under a ranger's watchful guidance, visitors can take walking tours of several branches of Carlsbad Cavern. The Hall of the White Giant tour is as close to enthusiast caving as most casual visitors ever get; tour groups are limited to eight, and there's plenty of crawling and slippery passages. The Lower Cave tour requires a rope-assisted descent into chambers of ethereal Gothic architecture some 90 feet below the cavern's Big Room. Slaughter Canyon Cave, discovered in 1937, is another cave system within the park; its entrance is a 23-mile drive west of the park's visitor center.