Last year, a Champions Tour event made history by becoming the first PGA Tour-sanctioned tournament to be held partly on a par-3 course. his April, the same tournament returned to the same course, called Top of the Rock, and if the timing had been slightly different it might have made history again. Just a month after the tournament (the Bass Pro Legends of Golf at Big Cedar Lodge, won by Billy Andrade and Joe Durant), four sinkholes opened up near the driving range. Nobody was hurt, but the sinkholes were big enough to have held the full field, with plenty of room left for just about the entire Golf Writers Association of America. Sheets of fake white bunker sand and closely-mown artificial turf drooped over the edges of the main opening, like fondant icing on a wedding cake. The drop to the deepest part was forty feet.
Top of the Rock was designed by Jack Nicklaus. It’s in southwestern Missouri, in a gently mountainous region called the Ozarks, and it’s virtually next door to the town of Branson, which is sort of what Disney World would be if you replaced Epcot Center with Dolly Parton. The bedrock underlying the area is mostly limestone, which consists of the solidified, calcium-rich remains of many millions of years’ worth of dead sea creatures. Rainwater becomes mildly acidic as it picks up carbon dioxide from the atmosphere. When it lands on terrain like that, it seeps through the soil and into fractures in the rock, then gradually enlarges the fractures into fissures and conduits and caves and subterranean streams, creating a Swiss cheese-like landscape of a type known as karst. If the voids become large enough, the ground above them can collapse. In 1981, a sinkhole in Winter Park, Florida, near the center of another golf-and-karst region, swallowed five Porsches, a three-bedroom house, and the deep end of a public swimming pool.
Randall Orndorff is a geologist for the United States Geological Survey. Between 1995 and 2005, he spent a lot of his professional time in southern Missouri looking into sinkholes, crawling through caves, and mapping the geology of a formation called the Salem Plateau, which is the rock that’s next to the rock that Top of the Rock is on top of. I spoke with him recently, and he said that a neighbor who saw him using a garden hose to wash cave mud off his clothes once told him, “Thank god my husband’s a lawyer.” He also said that, although natural sinkholes are common in karst areas, human activity can accelerate their development.”
The photo above is of a sinkhole in Florida called Big Dismal. I visited it a couple of years ago while researching an article about sinkholes for The New Yorker—which you can read here
. I also spent some time with a group of divers whose hobby is exploring sinkholes and underground streams.
In 2007, two of them set a world record by making a seven-mile traverse through Florida’s Swiss cheese, from an opening called Turner Sink to Wakulla Springs, a state park about fifteen miles south of downtown Tallahassee. The average depth of the traverse was close to 300 feet—about the same as the wreck of the Lusitania—and the total submerged time was 21 hours. Here two of them are getting ready to make another dive in Turner Sink:
Where do golf-course sinkholes come from? “There are a lot of factors,” Orndorff told me. “When you’re on a slope, you have more groundwater draining, and draining more rapidly—almost like flushing a toilet. The pond you see in those pictures of Top of the Rock is man-made, so now you’re changing the hydrodynamics of the area, and collecting water that used to percolate into the ground; you’re also adding weight to the surface. Something we see in suburban development is collapses near the outlets of retention ponds, where erosion is the greatest.”
I grew up in Kansas City, about two hundred and twenty miles north of Top of the Rock, and when I was a kid my family visited the Ozarks fairly often. During one trip, I got into trouble for standing behind my father and pulling his hat down over his eyes while he was driving. (This was the era when dads wore fedoras and nobody wore seat belts.) My sister and I would beg him to stop whenever we passed a billboard advertising a cave, as we seemed to do every couple of miles. He always refused, saying the caves were just holes in the ground and could give way at any time. Now, half a century later, I guess I can see his point—although I still think we should have stopped.
“Some people are asking why they didn’t close the golf course,” Orndorff said. “But that whole area is prone to sinkholes, and the next one could be miles away.” He also said that, as far as my father’s speluncaphobia was concerned, “You don’t hear of too many caves collapsing and killing tourists. In fact, I don’t know of any.”