Southwestern China is renowned for its extraordinary karst landscapes, featuring numerous giant sinkholes known locally as ‘tiankeng,’ meaning ‘heavenly pits.’ These enormous pits are a testament to the region’s unique geological history, formed by the gradual erosion of limestone bedrock over hundreds of thousands of years. Rainwater trickling down through the soil dissolves the limestone, creating cracks and tunnels that eventually widen into caverns. When the rock ceiling can no longer support the weight above, it collapses, resulting in the formation of these vast sinkholes.
Tiankeng are characterized by their steep sides and often have rivers or underground streams flowing along their bottoms. The largest known tiankeng is Xiaozhai Tiankeng in Fengjie County, southern-central China, which boasts a depth of over 100 meters. China is home to around 200 tiankeng, with the highest proportion of surface area affected by karst formations globally. These heavenly pits harbor diverse ecosystems, including ancient forests with towering trees and dense undergrowth. Despite their size, tiankeng can be difficult to spot amidst the rugged mountains and lush forests that cover much of southwestern China, leading to the discovery of numerous new sinkholes in recent years.
In May 2022, a cave exploration team descended into a newly discovered sinkhole near the village of Ping’e in Leye County, Guangxi. The pit measured 630 feet deep and 1,004 feet across, adding to the growing number of known tiankeng in the region. The bottom of the sinkhole was carpeted in a pristine forest with ancient trees reaching heights of up to 131 feet. Such discoveries highlight the ongoing exploration and research into these fascinating geological formations, revealing the hidden wonders that lie beneath the surface of southwestern China.