One by one, the brown-eared bats squeeze through a six-inch hole and emerge into deepening twilight; an instant later, they've fluttered off to feed. At Kartchner Caverns, flocks of bats have repeated this ritual each summer evening for 40,000 years. But these days, with the advent of tourism, the bats are not the only creatures shuttling in and out of this labyrinthine world of darkness. Since Kartchner was opened to the public two years ago, tours have been selling out weeks in advance. So far the bats still appear to be thriving. But the cave itself may be dying.
Kartchner Caverns
Two cave enthusiasts discovered Kartchner Caverns in 1974 but kept their find a secret for 14 years. Now, 500 tourists daily go underground to visit the stunning flowstone formations. Photograph courtesy of Kartchner Caverns State Park
Located just 30 miles north of the Mexican border in southern Arizona's austere Whetstone Mountains, Kartchner is a pristine example of a living cave, with formations that are still moist and growing. The brilliant orange, red, and gold stalactites and stalagmites in the caverns have been formed and fed during the past 200,000 years by rainwater that combines with carbon dioxide from the air and carbon from the soil, trickles through limestone, and finally seeps through the earth to deposit mineral-laden droplets. The state of Arizona recently spent 12 years and $30 million to turn this subterranean fairyland of spires, turrets, and shields into what officials have dubbed the Environmental Cave, taking pains to protect it from the potential damage caused by tourism. Kartchner's formations depend on moisture, so humidity must be maintained at 99 percent or the fantastic structures will stop growing. A temperature variant of just half a degree can dry out the cave within weeks. But there's a scalding desert above and 500 tourists come through each day, so visitors must enter through two steel doors designed to keep the hot air from seeping in. Misters spray the cave floor to keep it damp.
