Drone footage: Here's what Top of the Rock sinkhole looks like today
Excavation crews have removed 25,000 truckloads of rock and soil at the Top of the Rock sinkhole, which is now 100 feet deep and is destined to become a tourism draw, according to Bass Pro Shops officials.
Tall pillars of rock are being exposed by excavator crews who are trying to find the bottom of the massive pit. The sinkhole that opened up on May 22 last year was initially 70 feet wide; now it is 200 feet across and getting deeper by the day. It would take a lot of holes in one to fill it: Bass Pro Shops calculated the sinkhole could hold more than 2.3 billion golf balls.
Although state officials recommended packing the sinkhole with rocks, Bass Pro Shops founder Johnny Morris chose to dig farther to find out what the sinkhole might reveal.
"A treasure hunt is underway and we hope to one day discover a new natural wonder lying below," Morris said in a news release. He was away on a hunting trip with his son and didn't attend the news conference about the status of the sinkhole.
Morris hopes to find out if the sinkhole might be part of a large cave system beneath the golf course.
Excavators are trying to uncover a connection to a cave that Morris discovered on the property 23 years ago. When the sinkhole collapsed, water and mud gushed out of that cave about 2,000 feet away.
On Wednesday, four large excavator machines were continuing to scoop rock from the hole, reaching the deepest depths through rock ramps cut into the sides of the sinkhole.
The project is taking place right next to the golf course pro shop. The grinding sounds of the heavy excavation equipment didn't seem to faze golfers practicing their shots at the driving range about 100 yards beyond the sinkhole.
Project supervisor Jimmy Wolfinbarger said the machines are focusing on a curved rock tower that appears to be funneling water deeper underground. On Wednesday, one of the machines dug wet rock and soil from the base of a curved pillar in hopes it might lead to an opening and passageway to the distant cave.
"When we had that big rain in December we thought there would be a big pond here," Wolfinbarger said. "But the water doesn't stay, it leaves. It makes you think something's down there."
He said crews will continue digging deeper until they hit bedrock — or crack open an entrance to the subterranean structure that channeled sinkhole water to the cave.
Martin Mac Donald, Bass Pro's director of conservation, said Morris hired a team shortly after the sinkhole formed to do ground-penetrating radar surveys of the area.
The data indicated air chambers deep underground, and a possible connection to Morris's cave.
The sinkhole and its geologic history likely will be turned into a tourist destination adjacent to the Top of the Rock Pro Shop, Mac Donald added. Visitors already have a front-row seat to the dig by looking just beyond the sinkhole's the steep edge.
A writer with National Geographic magazine got a tour of Morris's cave in 1995 and described the towering stalactites and cave features as "an underground chapel."
"What knits this story together is the gushing of water from the sinkhole that went some way, somehow out the passage of that cave," Mac Donald said. "He hopes to find a massive cave system that we hope is between here and there."
Crews with Barrows Excavating have been digging at the sinkhole site since August. Material removed from the sinkhole is being trucked away and will be used on other golf course projects, Mac Donald said. He said he had no idea how much the project has cost so far.
"We do have a vision to make this something special, a tourist destination place," he said.
The sinkhole, estimated to be 60 feet in diameter and 30 to 40 feet deep when it first collapsed, drew national media attention. A man-made pond was built on the golf course, and portions of land around it were covered with artificial turf, some of which hung into the sinkhole from its edges.
An investigation by the Missouri Department of Natural Resource's Environmental Geology section concluded that water seeping through the pond's clay liner likely caused the sinkhole to form. The state advised the golf course owners to fill the sinkhole with rocks and install a plastic liner on top of a clay barrier to prevent future sinkholes from forming.
"It is likely that the pond had a significant influence on the formation and rapid growth of this sinkhole, providing a source of water to carry soil particles into underlying bedrock conduits," the report states. "This piping action likely caused the formation and rapid growth of a subsurface void that eventually collapsed."
Bass Pro to update reporters on future of gigantic Top of the Rock sinkhole
Bass Pro Shops owns the golf course at Ridgedale, south of Branson. Mac Donald confirmed that water flowing into the sinkhole had made its way into a cave that Bass Pro Shops founder Johnny Morris discovered explored on the property in 1993.
"Water from the sinkhole is filtering into the cave he discovered, and the speculation now is that there's a new cave system theoretically unearthed down there," Mac Donald said on May 26.
Bass Pro Shops contacted DNR after the sinkhole developed for technical advice, and DNR geology experts visited the sinkhole on May 28.
The report indicates the northern section of Top of the Rock Golf Course was built "in a collapsed structure that previously contained a sinkhole pond" on either side of U.S. 65 highway. The sinkhole formed about 1,000 feet south of that sinkhole structure, according to the report.
