Scientists discover a stunning forest inside a massive sinkhole in China

Blackholes far away in space are known to hide mysteries of the universe, but one wouldn't expect to find much in a sinkhole on Earth. But, a recent discovery by cave explorers in China has shed light on how these pits can actually nurture an entire ecosystem within. According to Smithsonian Magazine, the explorers stumbled upon a huge sinkhole with an ancient forest at the bottom of it. George Veni, the executive director of the National Cave and Karst Research Institute who wasn't part of the research team, shared his thoughts on the discovery with the Washington Post. Veni believes that the wide variety of plants and animal species found within the forest are still unknown to science.

Xinhua, the Chinese government's state-owned news agency, revealed that the sinkhole measures more than 1,000 feet in length, is almost 500 feet wide and 630 feet deep. It has a total volume of over 176 million cubic feet as well. In Chinese, the sinkhole is also called tiankeng which means heavenly pit, and is located in Guangxi Zhuang Autonomous Region which falls in Leye County. The county already has several sinkholes and the recently discovered one takes the tally to 30.

The team exploring the pit used rappelling devices to descend more than 320 feet down the sinkhole, additionally trekking for several hours to reach the bottom. The pit held undergrowth foliage that was as tall as the explorers and trees that towered over 100 feet, as mentioned by Chen Lixin, leader of the exploration team, per the Xinhua news release. Veni, who works for a sister agency of the organization that explored the Chinese sinkhole, told Live Science that the discovery of another sinkhole is not surprising since southern China typically has what they call a karst topography. 

Karst is a type of landscape where the dissolving of the bedrock has created sinkholes, sinking streams, caves, springs, and other characteristic features. The karsts mostly comprise of minerals like limestone, marble, and gypsum as per the National Park Service. These are formed when rainwater picks up carbon dioxide when it falls through the atmosphere resulting in the creation of carbonic acid or H2CO3. The acidic water passes through the fractures of rocks on the surface and ends up dissolving calcite, which is a mineral in limestone, marble, and dolostone leading to the reaction that forms sinkholes.

Accuweather’s Marianne Mizera shared that "karst areas are ideal for storing groundwater because the water flows quickly through the porous rock but they are still highly vulnerable to contamination." Even today, about 700 million people worldwide depend on karst aquifers as their primary water source. “Because of local differences in geology, climate, and other factors, the way karst appears at the surface can be dramatically different,” Veni told Live Science. “So in China, you have this incredibly visually spectacular karst with enormous sinkholes, giant cave entrances, and so forth. 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.”

The karsts in southern China have also been declared a UNESCO World Heritage Site due to their unique features. “The property contains the most spectacular, scientifically significant and representative series of karst landforms and landscapes of South China from interior high plateau to lowland plains and constitutes the world’s premier example of humid tropical to subtropical karst: one of our planet’s great landscapes,” UNESCO mentioned, adding that it is a serial site spreading over the provinces of Guizhou, Guangxi, Yunnan and Chongqing and covers an area of 97,125 hectares.