Niubizi tiankeng (Niubidong)

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, Qingkou, Shiwangdong (Shi Wang) and Taipingmiao tiankengs.

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.

Niubizi tiankeng

Niubizi tiankeng is located some 500 m to the north of the famous Qingkou tiankeng.

Like other tiankengs, Niubizi tiankeng has almost vertical walls. Its depth fluctuates from 100 to 195 m. The size of the opening is 380 by 100 m, area – 27,000 m². The approximate volume of this sinkhole is 3.5 million m³.

Walls of tiankeng are for the most part covered with moss, shrubs, and trees, but bottom – with dense vegetation. This patch of vegetation is a unique, isolated ecosystem.

The giant Er Wang Dong cave starts in the western side of tiankeng, connects this tiankeng to the nearby Qingkou tiankeng, and then continues to the south-west for many kilometers. The total length of the cave is more than 42 km and it contains some of the largest cave rooms in the world.

In the giant cave has formed its own climate with clouds and winds. These clouds appear also in Niubizi tiankeng. In fact, these clouds serve for weather forecast – when in tiankeng appears fog, soon will come rain.

References

1. Zhu Xuewen, Chen Weihai, Tiankengs in the karst of China. Speleogenesis and Evolution of Karst Aquifers. The Online Scientific Journal. Accessed in the 6th March 2018.