Xinhua News AgencyGetty Images
- A sinkhole in southern China is part of the karst landscape, shaped by water and a home for trees, plants, and animals.
- A team exploring the three cave entrances and sinkhole floor are looking for any new species that might live there.
- Sinkholes are created when water erodes the bedrock beneath the surface.
Sinkholes can be terrifying, especially if one opens up directly beneath you. Consider the 2016 monstrous pit that made a section of five-lane highway suddenly disappear in Fukuoka, Japan, in 2016.
But they can also be wonders of nature, like this unexpectedly verdant, sunken forest in southern China shows. The enormous pit, 630 feet deep, is home to a lush green haven of tall, ancient trees, dense undergrowth and probably, say researchers, animals that haven’t yet been found elsewhere.
The discovery didn’t shock a team of speleologists (who study caves) and spelunkers (who rappel into them for fun) exploring the sinkhole. On May 6, the Chinese team plunged into its depths. They found three cave entrances in the chasm, which measures 1,004 feet long and 492 feet wide. “I wouldn’t be surprised to know that there are species found in these caves that have never been reported or described by science until now,” the expedition’s team leader Chen Lixin says in a news release about the discovery.
A sinkhole as massive as this one in the Guangxi Zhuang Autonomous Region is called “tiankeng,” a Mandarin name meaning “heavenly pit.” Sinkholes that open suddenly in the ground are a feature of karst topography, an endemic part of the local landscape here. As rainwater runs through the soil, bedrock is dissolved and becomes more acidic with carbon dioxide. Gradually, acidic water begins to open up new tunnels in the rock, which can lead to cave-like formations. The ground eventually sinks in, opening up a sinkhole.
Variations in the local geology, climate, and other factors affect the way a karst appears at the surface, says international cave expert George Veni in a news release. Veni, who is the Executive Director of the National Cave and Karst Research Institute in the U.S., was not involved in the expedition. So in China, you can see this visually stunning karst that has enormous sinkholes and huge cave entrances. You might not notice any differences in other parts of the globe if you are walking on the karst. Sinkholes can be a mere meter in diameter, so they might seem quite small. Cave entrances might be very small, so you have to squeeze your way into them.”
This particular sinkhole isn’t the only one in the world teeming with life. One cave in West Texas supports a lot of tropical ferns thanks to migrating bats who brought the spores along on their journey to South and Central America. In the United States, 25 percent of land is karst, carved by water, or pseudokarst, carved by volcanics or wind, Veni says. About 20 percent of the world’s landmass is made of karst landscapes, with China boasting the largest sinkhole in the world. Discovered in 1994, an underground river in a forest hollowed out this “do