Edition: U.S. / Global


Published: April 14, 1992

Cavernous Caves

Q. What is the deepest below the surface people have gone in a cave? What is the longest passageway system known?

A. "The deepest cave found to date is in France, the Reseau Jean Bernard," said John Scheltens, president of the National Speleological Society, which has its headquarters in Huntsville, Ala. "Its total depth, not just the length of its shaft, is 5,256 feet, almost a mile straight down."

The longest system of passageways in the world is the Mammoth Cave system in Kentucky, he said. The numbers change with new exploration, but as of June 1991, the sum of all known passages was 340 miles, he said.

The deepest cave in the United States is a new discovery, Lechuguilla Cave, in Carlsbad Caverns National Park, N.M., he said. Its depth is 1,565 feet.

"A large part of the United Sates is underlain by cavernous limestone aquifers," said Mr. Scheltens. The Mammoth Cave National Park system was basically formed by the solution of limestone, he explained. As water falls on the surface of the earth, it mixes with organic matter and forms a weak solution of carbonic acid, "like weak Coca-Cola," he said.

"Given sufficient times, perhaps millions of years, the solution feeds into the cavities of the limestone and gradually creates a cave," he said. "It's sort of like tooth decay."

Amateur exploration of caves is an important source of knowledge about them, he said, and can be safe if undertaken by properly trained and supervised people.

From the standpoint of structural stability, caves are relatively much safer than mines, said Mr. Scheltens, who is also a civil engineer. He moved to South Dakota to be near Wind Cave National Park and Jewel Cave National Monument, the second- and third-largest cave systems in the United States.
