A speleological expedition has recently reported a curious finding: a large sinkhole that housed a forest inside, as pointed out by the Chinese news agency Xinhua. It is unknown how long this forest has been in this situation of disconnection from its surroundings, but it offers an ideal environment both for geological science and for fauna and flora research.
The discovery. The expedition descended into the sinkhole on May 6, and after spending a good part of the day checking the area, they returned to the surface the same day. The team was led by Chen Lixin, who has spent years exploring sinkholes and caves in the area. The cave is located in the Guangxi autonomous region, southeast of China, more specifically in Leye County.
The place the explorers found. The sinkhole has three entrances to caves, apparently belonging to the same cave system on which the land would have been located before it sank and created the sinkhole. This was explained by Zhang Yuanhai, from the Institute of Karst Geology belonging to the China Geological Survey, in the agency’s note giving an account of the finding.
The sinkhole would be 192 meters deep, 306 meters long and 150 meters wide. The expeditionists also speak of the forest they found in the place, with trees about 40 meters high and dense low vegetation that would reach “up to the shoulders” of a person.
An ideal region for the appearance of sinkholes.
In Mandarin, the name given to these large sinkholes is “tiankeng”, which could be translated as “heavenly pit”. Guangxi is a propitious area for the appearance of these natural sinkholes thanks to its Karstic terrain. This landscape has been registered, since 2007, as a World Heritage Site on the UNESCO list.
Karst areas are prone to the appearance of cave systems, but due to the variety of environmental circumstances, landscapes can vary greatly. This is explained by cave expert George Veni, executive director of the American National Cave and Karst Research Institute (NCKRI), to the Science Alert portal. This means that sinkholes are not always present in these geological areas.
The Great Sink.
The Iberian Peninsula has an important region of karstic surface. It expands on both sides of the Ebro river, in various areas from the Iberian system to the Basque mountains. Surely the best known sinkhole here is in the province of Burgos, in the archaeological site of Atapuerca, also declared a World Heritage Site by UNESCO. La Gran Dolina is also a place of great interest, not so much geological as anthropological.
Biodiversity. In Arthur Conan Doyle’s novel, The lost Worlda team of researchers ascended to a remote plateau in a tropical forest, very similar to the Amazonian tepuis, to discover that, isolated from the rest of the world, it had preserved a peculiar habitat: dinosaurs survived there.
Without reaching the limits of science fiction, the team of discoverers of this geographical feature (a kind of inverted plateau) speculates that it may represent an ecosystem jewel. Its partial isolation from the rest of the forest and its particular microclimatic conditions may be favorable for the appearance of species not found in other parts of the world.
Image: Patrick Xu