National Geographic : 2014 Jul
CHina Caves 125 photo of Eavis is displayed in the local museum. To reach Hong Meigui each day, we drive to a parking lot not far from town, where we change into coveralls and don harnesses and helmets and headlamps, then walk for a minute or two to an unremarkable-looking opening in the forested mountainside. Past a concrete cistern farmers use to collect water dripping from an overhang- ing roof, the cave swiftly becomes colder and steeper and darker. Soon enough, we are in an- other world. Two short rappels—maybe 15 feet and 50 feet—have been rigged by the group’s two ablest cavers, Tim Allen and Mark Richardson. Otherwise the approach is on foot. For much of an hour on my first descent, I follow Tim’s wife, Jane Allen, another expert caver, down a stair- case of pools shimmering in our headlamps and into a tubelike passage where the surface looks like—and sometimes surely is—a river of mud. The sensation when we enter Hong Meigui Chamber itself is both dizzying and familiar. I can see that it is big simply because I can’t see much at all; no longer does my light bounce off a ceiling or walls. Particles float in the air, for not even the wind can reach here. A boulder the size of a dump truck has fallen to the floor from someplace dramatically high above, its crater ringed by a shock wave of mud; the team names it “the meteorite.” Somewhere far on the other side of the room—exactly how far is hard to gauge— the beam of someone’s lamp bobs along. Only when I begin scrambling up a rubble slope does the experience seem familiar. The slope is so big, the progress so gradual, the terrain so rough, it feels like mountain climbing on a starless night. Given the irregular shapes of caves, it can be hard to decide where each room ends, where to draw the boundary lines. What constitutes a cave chamber, and what a mere passage? This semantic question will be constantly argued over by expedition members, for one of the eventual goals of 3-D scanning—a ranking of the world’s largest chambers by volume—is impossible if cave explorers can’t agree on a definition. The largest known is Sarawak Chamber in Ma- laysia, which Eavis and two others discovered in 1980 and helped scan in 2011. Its estimated volume is 338 million cubic feet—more than three times the size of the new Dallas Cowboys stadium in Texas. My layman’s answer to the definition question is that we never argue over whether something is a full-blown hall or a hallway; you know it when you see it. In the case of caves, you can’t entirely see it. But you know it: There is the unmistakable impression of Wright balances atop a spire in the Stone Forest. Deposited in a shallow sea 270 million years ago, the limestone here was eroded by heavy tropical rains. McKenzie Funk’s new book is Windfall: The Booming Business of Global Warming. Carsten Peter’s photos of Vietnam’s caves appeared in our January 2011 issue.