Group of Qingkou tiankengs
More information about tiankengs is in the article about Xiaozhai tiankeng.
Out of 45 – 50 known tiankengs of China (and China has by far most tiankengs in the world) five belong to the group of Qingkou tiankengs. These are Daluodang, Niubizi, Shiwangdong (Shi Wang), Taipingmiao and finally – Qingkou tiankeng itself, which is described here.
These tiankengs have formed at the border of Paleozoic sandstone and thick layer of Lower Ordovician limestone, which is rich with underground streams – tributaries of Muzong River. These underground streams have formed some of the most magnificent caves in the world – such as San Wang Dong and Er Wang Dong caves. In some places the roof of caves has collapsed, creating sinkholes of gargantuan size – tiankengs.
Most tiankengs are formed by the collapse of giant cave rooms. But sometimes these giant holes are created by surface water which finds a crack in the limestone and falls down, until it reaches the base of layer. As the time goes, the hole is washed out, larger and larger until an enormous hole – tiankeng – is created.
Such tiankengs are called erosional tiankengs. Typically rivers fall IN these tiankengs as spectacular waterfalls and then continue underground, in caves.
Best erosional tiankeng in China
Qingkou tiankeng is typical erosional tiankeng and most likely – finest one in China. It receives two larger streams – one from the north-west, another – from the east. Both fall down in the tiankeng, each forming some 150 – 200 m tall waterfall. During the rainy periods the sound of waterfalls in the tiankeng is almost unbearable.
Qingkou tiankeng is 295 – 195 m deep, with almost vertical walls. Area of tiankeng is 40,700 m². It has formed at the area, where sandstone and shale overlays thick layer of Lower Ordovician limestone. Streams reach here the border where this standstone ends and starts limestone. In this place has formed Qingkou tiankeng.
It seems that tiankeng was not that deep initially – older caves start from the walls of tiankeng, marking former levels of the bottom of this sinkhole. In total there are dozens of such caves.
Waterfalls form a single stream and disappear in an enormous cave – the giant Er Wang Dong Cave, section named Tiankeng Express. In the winter the stream almost disappears but in summer, during the rain it can become powerful, with a force of several m³ per second.
Most likely local people knew well about this giant hole in the ground – but scientific world learned about Qingkou tiankeng only on March 25, 2001, when doctor Zhy Xiewen first visited it.
Already in October 2003 Qingkou tiankeng and surrounding landscape – Wulong Karst – were protected as national geopark. In 2007 it became a part of UNESCO World Heritage monument – "South China Karst" and since then it is becoming increasingly popular tourist destination.
Tiankeng and Er Wang Dong cave are explored by Hong Meigui Cave Exploration Society.
|Coordinates:||29.6026 N 108.0043 E|
|Values:||Geology, Biology, Visual|
|Rating:||(4.5 / 5)|
|Address:||Asia, China, Chongqing Municipality, Wulong County, some 40 km north-east (direct line) from Wulong|
|Name in Chinese:||箐口天坑|
|Alternate names:||Qing Kou tiankeng|
|Depth:||195 – 295 m|
|Volume:||9.2 million m³|
|UNESCO World Heritage status:||part of "South China Karst", 2007, No.1248|
This is the first study of the karst areas of China to be carried out by a Western geomorphologist, and almost all the sources are from Chinese works, as yet unpublished in the West. Karst areas are sensitive to environmental influences and Chinese attempts to deal with these are discussed here, as are Chinese methods of studying karst since they differ somewhat from those in the West.