A team of scientists in China has discovered a massive sinkhole with a forest inside it, Xinhua news agency reported.
The discovery was made in the country’s southern Guangxi Zhuang Autonomous Region -- home to giant sinkholes and caves, science news website Live Science reported.
The US Geological Survey defines sinkholes as depressions which have no natural external surface drainage.
Sinkholes are most common in karst terrains. "These are regions where the types of rock below the land surface can naturally be dissolved by groundwater circulating through them," USGS added. "When water from rainfall moves down through the soil, these types of rock begin to dissolve. This creates underground spaces and caverns."
In China, the Guangxi Zhuang Autonomous Region has been designated as UNESCO world heritage site because of its striking karst terrain.
Last week, a team from the Institute of Karst Geology of the China Geological Survey travelled down the 192-metre-deep sinkhole in the region to discover a well-preserved forest.
Apart from China, such massive sinkholes have been found in Papua New Guinea and Mexico.
International cave expert George Veni told Live Science that the appearance of such formations differed with climate, geology and other factors.
"So in China you have this incredibly visually spectacular karst with enormous sinkholes and giant cave entrances and so forth," he said. "In other parts of the world you walk out on the karst and you really don't notice anything. Sinkholes might be quite subdued, only a meter or two in diameter. Cave entrances might be very small, so you have to squeeze your way into them."
But why are these sinkholes significant? Experts say it is possible they host some yet-to-be-discovered species