Below this sinkhole lies a vast and complex underground cave system, rated by experts as a “world-class” natural wonder.
During a recent expedition to a sinkhole in the forest of Guangxi, a team of geologists unexpectedly discovered an extremely intricate underground cave system.
Giant sinkhole in the forest.
The cave system has a volume of up to 6.7 million cubic meters – a remarkable figure that leads experts to classify it as a “geological wonder at a world-class level.”
Specifically, the expedition was a collaboration between specialists from the UK and China, led by Dr. Zhang Yuanhai from the Chinese Academy of Geological Sciences, alongside Andy Eavis, the president of the British Caving Association.
From October 4 to 8, 19 members of the research team descended into the tiankeng (also known as heavenly pit – the term used by the Chinese for large, unusual sinkholes) using only a rope. From there, they began to explore and map the entire cave system.
“The cave entrance was actually discovered by an expedition team from Hong Kong in 2017,” Yuanhai stated.
“This time, we aimed to determine the volume, scale, and world-class status of the cave through a 3D scanning system.”
According to recorded data, the sinkhole has a width of about 100 meters, a length of 200 meters, and a depth of at least 118 meters. As it slopes downwards towards the southeast, the sinkhole gradually leads into an extremely intricate cave system. This cave system consists of every possible component: from chambers, volcanic craters, collapse rocks, to limestone… These connect to an underground river that flows into the Panyang River.
The advanced 3D scanning system also allowed experts to understand the formation of this gigantic sinkhole.
This cave system connects to an underground river flowing into the Panyang River. (Photo: BBC).
“This area has many signs indicating the collapse of a volcanic crater, along with several traces of the formation of the heavenly pit,” Yuanhai noted.
Essentially, tiankengs are typically formed due to the collapse of underground cave systems – often due to natural causes such as water erosion over time. For example, the world’s deepest tiankeng – Xiaozhai (626m) was formed due to the collapse of a nearby limestone cave caused by the strong flow of an underground river.
Xiaozhai Tiankeng – the largest natural sinkhole in the world.
“They are all natural caves, and the cause of the subsidence is due to the impact of the underground rivers,” Yuanhai stated.
“However, this process does not happen overnight. It usually takes over 2 million years to form a sinkhole.”
