A World ApartBut the cave is not totally silent. Meiman says subtle sounds, colors and weather patterns fill the cave, especially at the lowest levels, over 300 feet below the surface, where water wears at the limestone. “It makes you more aware of light, sound, shadows,” Meiman says.
Winds like the one that greeted McCombs on his first visit often billow through the tunnels. Explorers can use these cave breezes to learn about what lies ahead, something McCombs wrote about in his poem, Cave Wind: “knowing/ its speed portends the cave we'll discover, whether we will/ walk or crawl, the breadth/ of its breath, its given.”
As Art Palmer, a hydrology professor at State University of New York-Oneonta who has studied Mammoth Cave for over 30 years, points out — if you are in a cave tunnel with air blasting through it, you know it goes somewhere. Breezes can form as cool air settles to the bottom of connected cave tunnels. This causes air to shift throughout the cave network. Local storms also lead to pressure changes at the surface that can create breezes within the cave.
Like many caves, Mammoth cave stays at a pretty constant 53 degrees Fahrenheit, and is extremely humid. When a heavy summer rain brings a rush of warm water into the cave, the moist cave air condenses and an eerie fog forms in cave tunnels near the underground river and cave openings. During such fogs, Meiman imagines the early explorers in the cave, not understanding why fog had suddenly clouded their lantern light.
Floods bring more than just fog. The cave environment is very low in nutrients, explains Tom Poulson, a biology professor from the University of Illinois. Occasional large floods renew the organic matter that feeds crustaceans and plankton, which in turn feed larger cave species like blind cave fish.
“Cave creatures live slow, live long, and reproduce seldomly,” Bill Pearson, a biology professor at the University of Louisville, Kentucky says. They also have enhanced senses to maneuver in the dark. Cave crayfish live well over 100 years, while their counterparts on the surface live only 10. Pearson says the often illusive, nearly colorless cave fish standout against the darkness of the cave when a beam of light catches them.
“Touched,/ they said, fish with no eyes! until I sloshed/ a pailful into light, reveled in their silence,” McCombs writes of these creatures in Bottomless Pit.
Cave Connection The cave’s presence alters the surrounding landscape as well. Water doesn’t typically flow in streams on the surface, but seeps underground through sinkholes, or bowl shaped depressions, Meiman says. The landscape beyond the sandstone cap is riddled with sinkholes that feed water down into the cave.
Sinkholes often plug up, and form ponds that can cover an acre or two of land, Palmer says. Heavy rains can shift the soil that plugs the bottom of these ponds, opening the sinkholes again, and causing these ponds to disappear overnight, as McCombs describes in his poem Ponds. “In Caveland, every pond's a fluke./ Let them be brief, then, as the land/ gives up the ghost of fog, morning.”
“We take it for granted here that the land is unstable,” McCombs says, “it never lets you forget it is combed by a vast network of cave.”