Adventure Underground

image of man in cave

Cave exploring is wet, cold, muddy--and enlightening.

By Cary Griffith

My head lamp illuminates a crawl space big enough for a house cat to squeeze through. The hole flattens out beneath a 5-ton slab of limestone. Beyond, everything is pitch black. But I can hear the animated voices of the nine group members who have already pulled themselves through the hole.

This isn't a nightmare, just the first dicey section of a three-hour wild-cave tour. Two guides are leading us through a latticework of crawl ways, dark holes, dramatic cave formations, running water, pools, and slippery clay. We have already seen bats, stalactites, stalagmites, crystal-flecked walls, and some geologic oddities so wondrous they defy imagination. And until now it has been worth every remarkable, easy walking step. But after an hour, we've come to a point that requires much more than a simple crouch and scuttle.

"You OK?" one of the guides calls back through the hole.

"Sure," I answer, lying.

On this side of the limestone slab, I get down on hands and knees and watch the boot bottoms of a 58-year-old fellow caver disappear. When I first saw this hole, I felt certain it was impassable. But in the past couple of minutes, I have seen two men almost twice my size wriggle through it. Finally, it's my turn.

Flattening myself against the cave floor, I see a rocky protuberance jutting up in front of me, making the space appear even tighter. I crawl into the gap, no more than 18 inches high, and ease my body forward with fingers and toes.

My helmet strikes the limestone slab overhead. I turn my head sideways to get over the jutting rock. Once over it, I find myself hugging the clay floor of the coffin-sized space. Until this moment I'd never considered myself claustrophobic. But in this tight spot, with tons of earth and rock between me and the surface--cave ahead and cave behind--a small wave of anxiety begins to crest into full-fledged panic. My breath comes in shallow bursts, and all I can think is: I have to get the hell out of here.

Long Passage. This cave complex is part of Forestville/Mystery Cave State Park in southeastern Minnesota, and one of the largest cave complexes in North America. Of the more than 13 miles of -passageways, about one mile is open for public tours that require nothing more strenuous than an occasional crouch.

Exploration of the other 12 miles of wild cave requires a knowledgeable guide. One of our guides is Allen Lewerer, president of the Minnesota Speleological Survey. (Speleology is the technical term for the science or study of caves.)

Unlike public tours, this excursion requires much more equipment than a lantern and jacket. We wear kneepads, elbow pads, helmets with two lights (one a backup), gloves, coveralls or other warm clothes, and boots with ankle support and gripping bottoms.

Discovered in 1937, Mystery Cave has been largely surveyed and named. Some sections are named for peculiar geologic formations. Some straight, wide, and clear stretches have street names.

During the first hour of caving, our route took us down Fifth Avenue--a long, straight stretch as wide as a subway tunnel in places. From there we crossed 17 Layer Rock, climbed over fallen slabs into the Dome Room (where water drips from the ceiling into a glistening pool), then proceeded to Diamond Caverns (where tiny crystals sparkle in limestone) and Blue Lake (where 6-foot pillars hulk beneath the blue water). We traveled across the Hills of Rome, down Fourth Avenue, and finally into the Smoking Chamber, where we entered this coffin-sized hole.

Deep Breathing. In my tight spot, all I can think about is getting out from under. I take a deep breath and try to get a hold of myself. I'm low enough to see lamplight flickering ahead, on what appears to be the walls of a spacious cavern. Thankful for the beacons, I belly crawl forward.

I find enough room to rise onto my hands and knees, and Allen reaches down to offer a helping hand.

"You sure you're OK?" he asks.

"Sure," I say, my pulse still jiggering.

"Good," Allen says, smiling. And I smile back, because I am beginning to feel what cavers describe as the thrill of the crawl.

After a 10-minute rest, we scrabble through more amazing passages. One passage requires us to step sideways through a canyon that's only a foot wide. Another requires creeping over a mud-caked floor. These passages are more thrilling than scary. We see fossils, flowstone, ribbons, draperies, and other remarkable formations. Allen explains how each was formed. (See "Limestone, Water, and Time,")

Finally, after two hours underground, we reach the edge of Enigma Pit. Two jagged rock walls drop 30 feet down into a narrow canyon. Water drips from the walls and vanishes into this dark pit. We could reach several hundred more cave feet through an opening in the wall on the other side of the chasm. Allen edges across to three natural footholds, and climbs to the top and back down unassisted. It is a feat for anyone, but Allen is old enough to be a grandfather, and he's a big man. I'm impressed, but the rest of us decide to skip it.

We retrace the remarkable passages we crossed to reach Enigma Pit, and I'm only slightly unnerved by the prospect of having to wriggle back through that narrow hole. There's only one way back. After almost three hours of caving, I follow another pair of boots into the opening. This time, buoyed by our adventure in this remarkable geology, I am more exhilarated than anxious.

Before long we reach the surface. My clothes look like they've been swabbed with clay--colored paint, and my boots are caked. I'm happy to be out in the open again, with new appreciation for sunlight, fresh air, trees--and the haunting beauty that lies below.

Editor's note: Well-intentioned underground travelers can cause permanent damage to caves if they're not careful. A cave's dripstone and crystal formations are extremely fragile. Plus untrained cavers can blunder into life-threatening situations. Organizations of cavers throughout the country provide proper instruction in cave conservation and safety. The DNR encourages people to go caving with these groups--for the welfare of both the cave and the individual.

Limestone, Water, and Time

Many of Minnesota's caves are in the southeast, a region relatively untouched by the last glacier to move across Minnesota. Here limestone bedrock remained at or close to the earth's surface. Over eons, underground water has dissolved the limestone, forming caverns and cave complexes with an amazing assortment of geologic formations, such as these:

  • Stalactites form on the ceiling as mineral-rich water drips down.
  • Stalagmites, also formed by -mineral-rich water, rise from the cave floor.
  • Raft cones look like underwater stalagmites. They're formed from calcite particles floating in a mineral-rich lake. The ebb and flow of water deposits calcite on the cones, which rise from the lake bottom and take millennia to form.
  • Fossils are hardened remains or imprints of once-living things embedded in mud that turns to limestone over millennia.
  • Flowstone forms slowly from a seeping flow of calcite-rich water. While much of Mystery Cave's massive flowstones are 12,000 years old or less, the oldest are more than 350,000 years old.
  • Ribbons and draperies take shape as calcite-rich water flows in a continuous ribbon from the ceiling and along the walls.

Cary Griffith, Rosemount, is a freelance writer and outdoor enthusiast.

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