Giant Karst Sinkhole Discovered in China With Forest Inside

A 192-metre-deep China sinkhole with huge 40-metre trees, plants and potential new species found in Guangxi region.

Sat 08 Jul 23


A giant karst sinkhole, more than 620 feet (or 190 metres) deep, was discovered by Leye County in the Guangxi region in southern China, containing a well-preserved primitive forest alongside the potential of new species.

The karst sinkhole named ‘The Eagle’ is 490 feet (or 150 metres) wide, and with its volume exceeding 5 million cubic metres, it is categorized as a large sinkhole. 

As Geographical reports, these sinkholes are called ‘Heavenly pits’ or ‘Tiankeng’ in Chinese.

‘The Eagle’ is part of a series of sinkholes interconnected via a cave system and an underground river, making the largest cluster ever discovered south of the Tropic of Cancer, according to Zhang Yuanhai, a member of the team organized by the Institute of Karst Geology of China Geological Survey.

Previously giant sinkholes have been discovered in the region.

After abseiling over 100 metres to the bottom of the pit with other team members, the leader of the Guangxi 702 cave expedition team Chen Lixin noted the ancient trees at the bottom were almost 40 metres high, with some plants growing at shoulder height.

“The tree vines were entangling us like spider webs, and you have no idea how deep your next step was going to be,” according to Lixin. 

“The plants were so brittle that you could pull them down with your hands, but they’d recover just as quickly. When we returned [up], the path was hidden again.”

“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.” 

What is a karst landscape?

Karst is a land composed of limestone, a soft rock that can dissolve easily in water, and covers around 13 per cent of eastern and southeastern Asia.

Sinkholes can form in karst areas as rainwater containing carbon dioxide becomes slightly acidic and erodes the bedrock. 

If enough cracks form in the bedrock, a sinkhole can open up.

Karst landscapes can include features such as gorges, like the Longshuixia Fissure Gorge in Chongqing, southwest China. (Image Credit: Shutterstock via Geographical)

Typical karst landscape features include gorges, sinking streams, natural bridges, natural springs, and sinkholes, as seen in the recent discovery in the Guangxi Province. 

Large karst sinkholes also act as a conduit to underground water reservoirs or aquifers – providing a primary water source for over 700 million people worldwide – and over 80 World Heritage Sites and 70 UNESCO Global Geoparks were designated entirely, or partially for their karst and caves. 

The South China Karst, which includes the province of Guangxi, among several others, is a Unesco World Heritage Site due to its unique karst features and landscapes. 

Covering 97,125 hectares, it contains many significant types of karst landforms, including tower karst and pinnacle karst.

The Guangxi Province is a prime example of a mature karst landscape of cone karst. These landscapes are developed due to deep layers of limestone and dolomite bedrock covering large sections of southeastern China. 

Due to the region’s high rainfall, this bedrock is easily dissolved. 

According to UNESCO, “the [South China Karst] 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.”

Last month Chinese researchers discovered Asia’s largest tree

It comes at a time when, last month, Chinese researchers discovered Asia’s tallest tree – which is the second tallest tree ever found.

In a major ecological discovery, the researchers discovered the 335-foot (or 102 metres) cypress tree in Tarlung Tsangpo’s Grand Canyon, which has a maximum depth of 19,714 feet (or 6,010 metres).

Researchers from Peking University stand with 102.3-metre-tall Himalayan cypress, Yurlung Zangbo Grand Canyon National Nature Reserve, in China's southwest Xizang Autonomous Region. (Photo credit: Peking University)
Researchers from Peking University stand with 102.3-metre-tall Himalayan cypress, Yurlung Zangbo Grand Canyon National Nature Reserve, in China’s southwest Xizang Autonomous Region. (Photo credit: Peking University)

The tree has a girth of 9.2 feet (or 2.9 metres) and was discovered in May 2023 in Bome County’s Nyingchi city in Tibet, according to researchers from the Chinese Academy of Sciences (CAS).

The exact species of the tree remains unclear, but China’s state media hinted it could be a Himalayan cypress (Cupressus torulosa) or a Tibetan cypress (Cupressus gigantea).

The team created a 3D cypress model using a 3D laser scanner and lidar technology, providing distance measurements via light beams to confirm that it is the tallest tree in Asia.

  • Download the 3D image here.

The tree is also notable for its supporting roots and is partially buried, according to Peking University professor Guo Qinghua.

According to the Chinese-state-run Global Times, the tree has a complex system of branches and a vertical structure that creates “ideal microclimates and habitats for some endangered plants and animals,” according to a statement from Peking University.


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