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Rocking the Underground

Is bad-boy caver John Ackerman saving Minnesota caves—or destroying them?

Rocking the Underground
Photo by Per Breiehagen

(page 1 of 2)

JOHN ACKERMAN WAS EXPLORING a dead-end passage of an old commercial cave in southeastern Minnesota when he came to a narrow crevice through which a terrific wind was howling.

For most hobby cavers, that would have been the end: They would have conceded defeat and looked for larger passages elsewhere in the cave. But not Ackerman. Instead of giving up, he bought the property and, in 1989, laid explosives around the edge of the slot. Successive blasts during the next several months allowed him to remove enough rock that he could wriggle through. What he discovered astounded him—a network of “walk-though” passages and enormous rooms, an underground labyrinth that would eventually stretch 5 miles. What thrilled Ackerman most is that he was the first to lay eyes on the place. “That was a tremendous discovery.”

In his efforts to discover unseen passages and formations, Ackerman has fallen into subterranean pits, narrowly escaped being crushed by falling rock, become lost in winding passages, and nearly drowned in an underground river. “You wonder why haven’t more caves been opened up?” he says. “Well, I’ll tell you why, because people value their lives.”

Ackerman, it’s safe to say, has discovered more caverns than any other caver in Minnesota. The reason is attitude. Spelunking is often a passive activity. Usually, a passage happens to reveal itself at the surface through the vagaries of geology and erosion, and people explore it. But Ackerman goes out in search of caves. And unlike most other cavers, he has the financial resources to access caverns that others can’t touch. If a heap of rubble or a wall of rock happens to stand in his way, he simply brings in the heavy equipment, or shaves off slabs of rock with high explosives.

Ackerman is building nothing less than a cave empire, buying and cutting entrances into caves he has discovered, and roughly doubling the number of caverns open to local spelunkers. In the process, he has outmaneuvered many other cave owners, including the State of Minnesota, building entrances to caves they once thought they controlled.

Such behavior has earned him some appreciative friends. “What John has accomplished is to make available to scientists, cavers, and the general public an enormous resource that wasn’t there before,” says Calvin Alexander, a University of Minnesota geology professor and hydrogeologist. Joe Terwilliger, president of the Minnesota Speleological Survey, a local caving club, concurs: “Everybody in the club respects him for being as passionate as he is to discover new caves and make them accessible.”

But Ackerman’s forceful methods have also earned him harsh criticism from caving purists. “He is controversial,” says Ron Spong, who founded the Minnesota Speleological Survey 45 years ago. “He can be brash. He speaks his mind. He’s loved and hated at the same time.”

Photo by Per Breiehagen

AS A TEENAGER, Ackerman explored the artificial caverns mined from the Mississippi River bluff (“The St. Paul caves were cool because we could ride our motorcycles through them,” he says). It wasn’t until the late 1980s, however, that he became an avid spelunker. Among the areas he explored was Spring Valley Cavern, a cave in southeastern Minnesota that was first discovered in 1966. Run briefly as a commercial enterprise, Spring Valley eventually went bust. In the late 1980s, though, the farmer who owned the entrance to the cave said he was interested in selling some of his land. Ackerman, who owns a successful high-end furniture repair and restoration business, decided to buy 117 acres.
In Minnesota, property owners also own what’s below their land and to clamber through a cave without permission is considered trespassing, so Ackerman also negotiated with the landowner to buy the access rights to any caverns that might underlie the remaining acreage. Thus began the cave farm that Ackerman dubbed the Minnesota Karst Preserve.

Ackerman’s cave farm, like much of the karst country, is situated amid rolling farmland, pocked by copses of hardwoods that farmers can’t clear or plow because sinkholes (as many as 15,000 in Minnesota alone) lie beneath the surface. By digging into the sinkholes with his “Cave Finder”—a modified backhoe—Ackerman has discovered, at latest count, 32 caves of various lengths that he has opened to spelunkers, local nature groups, and scientists at the University of Minnesota.

On the day I visited the preserve, Ackerman led me down a path to an artificial limestone structure that was artfully hidden beneath the brow of a wooded hill. The building, sheltering the original entrance to the cave, provides a staging area and lockers for cavers and scientists working in the cavern, and cost Ackerman about $200,000 to construct. Dressed in coveralls, boots, gloves, and helmets with LED headlamps, we climbed down a short flight of concrete stairs to the opening of the cavern—the section where a previous landowner had hauled out dirt and gravel to improve access for commercial tours. Within about a half-hour, we squeezed through the slot Ackerman had long ago widened with explosives and entered a tight zigzagging passageway.

Ackerman sped ahead of me, disappearing down the crooked slot of rock. The more I hurried to keep up, the more trouble I had wiggling though the narrow crack. Panic gripped my chest as I felt a wave of nausea. I wanted to thrash my arms and run, but I was pinned between the rock walls. Ackerman, somewhere ahead, tried to reassure me. “There’s some crawling and some tight stuff, and after that, it’s open,” he said. “Out of the entire trip, this is probably the tightest part.”
I tried to relax, and began to notice stalactites, stalagmites, and ribbons of flowstone. As we explored, Ackerman pointed out flowstone formations, from delicate “soda straws” bristling from the ceiling to the massive Leaning Tower, the largest single “column” known in any Minnesota cave. He cautioned me to walk in the center of the passages and to touch the rock as little as possible. (In fact, he won’t allow visitors in what he calls “pristine” sections, where delicate features are especially abundant.) We straddled and then waded through a rushing stream with several small waterfalls. Finally, after squirming on our bellies though a foot-high gap for 100 yards, we came to the Colossal Room. More than 40 feet high, 35 feet wide, and 75 feet long, it was filled with the sound of flowing water. “This is it,” said Ackerman, rising to his feet and scanning the reaches of the chamber with his headlight. “This is why you go caving.”


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