January 28, 2023

Ancient forest found at bottom of a huge sinkhole in China


The mountains around Guilin are limestone, and the constant movement of water through the rocks has led to a vast network of sinkholes, caves and underground tunnels. Here are two of them, hidden behind the foliage. You can see one quite clearly while the second one is lower down amidst the brush.
Credit – shankar s. from Dubai, united arab emirates. CC SA 2.0.

At the bottom of a 630-foot sinkhole in China lies a green surprise: an ancient forest with trees stretching nearly 130 feet (40 meters) out of the depths. Scientists believe it could contain undiscovered plant and animal species.

The sinkhole was first discovered by cave explorers in , who in turn, alerted scientists to their find, according to The Guardian.

Of the 30 known sinkholes in Leye County, this is the largest, at 306 meters (1004 feet) long, 150 meters (492 feet) wide, and 192 meters (630 feet) deep.

Zhang Yuanhai, a senior engineer at the Institute of Karst Geology of the China Geological Survey, told the state news agency Xinhua that the site had three caves in its walls and a well-preserved primitive forest at the bottom.

Chen Lixin, who led the expedition team, said the team trekked for hours to reach the base of the sinkhole. He said that as well as the trees there was dense undergrowth on the floor that came up to his shoulders.

“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,” he said.

Lixin’s team completed their expedition on May 6, USA TODAY reported. The sinkhole has a total of three caves and has a total volume of 5 million cubic meters, This means it would take 2,000 Olympic swimming pools to fill it.

https://www.youtube.com/watch?v=C3QTq6tQfhY

Karst topography

Karst is a type of topography, ideal for geological wonders like the sinkhole in Leye County, created by groundwater dissolving the limestone rock beneath the surface, according to the U.S. Geological Survey.

Karst terrain is created from the dissolution of soluble rocks, principally limestone and dolomite. Karst areas are characterized by distinctive landforms, such as springs, caves, and sinkholes.

NPR.org reports that about 20 percent of the United States is made up of karst landscapes, including attractions such as Carlsbad Caverns in New Mexico and Mammoth Cave in Kentucky.

About 13 percent of China is covered by karst topography, according to NASA, with the Guangxi region being a prime example of its beauty.

George Veni, executive director of the National Cave and Karst Research Institute, told Live Science that Karst landscapes can vary in size and shape, depending on the climate.

“In China, you have this incredibly visually spectacular karst with enormous sinkholes and giant cave entrances and so forth,” Veni 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.”

Veni said the presence of the ancient forest was not necessarily surprising.  “It’s not unusual to have trees growing out of cave entrances. It’s just that this [sinkhole] is particularly large and particularly deep, so it’s not the sort of thing that most people would expect.”

Still, he acknowledged to Live Science, “This is cool news.”