© 2021 University of Missouri - KBIA
Play Live Radio
Next Up:
0:00
0:00
Available On Air Stations
Science and Technology
“The show me state” isn’t the only nickname Missouri goes by — it’s also called “the cave state,” and for good reason. These caves are the cause of why the US Geological Survey listed Missouri as one of seven states most prone to sinkholes. In Missouri alone there are more than 15,000 sinkholes. And while sinkholes have a reputation of being a dangerous nuisance in southern Missouri, they are fewer and less troublesome in Boone County.00000178-cc7d-da8b-a77d-ec7d2f890000The map below from the Missouri Dept. of Natural Resources shows mapped sinkholes in the state. The sinkhole areas seem clustered around towns and highways because those are the areas that are purposefully mapped.00000178-cc7d-da8b-a77d-ec7d2f890003 “What we've found, just like [in the area] from Springfield to Nixa is when we intentionally make a map, we discover a lot of sinkholes," Sinkhole expert Doug Gouzie said. 00000178-cc7d-da8b-a77d-ec7d2f880000The state of Missouri has been implementing sinkhole related programs and regulations since 1853. As the timeline below shows, by the early 1970s Boone County began taking steps to regulate sinkhole prone areas in an effort to keep wildlife and community residents safe and healthy. Major Sinkhole Related Events in Boone County 00000178-cc7d-da8b-a77d-ec7d2f8a0000

Part 1: How are sinkholes formed?

nixasinkhole2006_MODNR.jpg
Missouri Department of Natural Resources
/

What exactly is a sinkhole?

A sinkhole forms when the surface layer of ground collapses into a cavity underneath. Associate Professor of Geology at MU Martin Appold explains these features in more detail:

“They’re holes in the ground that form as a result of caves developing below the ground’s surface that come close enough to the ground’s surface that at some point the rock can’t support its own weight.”

“Ultimately the cause is from ground water that is percolating through the fractures, usually in limestone bedrock,” Appold said. 

sinkholedevelopmentsteps_MODNR.jpg
Credit Missouri Department of Natural Resources
/

And there is plenty of limestone bedrock in Missouri. Limestone is softer than other kinds of bedrock and more easily dissolved by groundwater. We have a kind of geography called Karst topography, referring to the landscape formed by this limestone bedrock. Limestone is composed of calcium carbonate and according to the Missouri Department of Natural Resources, 59% of the state has such carbonate rock underneath the surface. 

sinkholemap_USGS.gif
Credit United States Geological Survey
/
According to US Geological Service maps, Karst features cover—or rather, lie underneath, over half of the state.

Are sinkholes an issue in Columbia?

According to Appold not really, or at least, not yet. Most of the land the town sits on isn’t on top too many Karst features. A little further south, though, is.

“I haven’t observed sinkholes really in the city itself. Having said that, the city is expanding southward into an area where we know there are sinkholes— in the region of Rock Bridge State Park,” Appold said, “Particularly if I lived in the southern part of the city, I might be a little concerned about that. I would want to know before I bought a house if someone had looked [into possible sinkhole activity].”

A place where sinkholes are an issue in further down in the state, places like Springfield and Nixa. Sinkholes there are pose real hazards if they open up under a street or home.

KBIA will be doing more reporting on sinkholes in the coming weeks. If you have any questions that you would like us to ask a sinkhole expert or have a sinkhole experience to share, tweet at us @CoMoExp or comment below.