Xiaozhai Tiankeng
The Xiaozhai Tiankeng, also known as the Xiaozhai Heavenly Pit, is the world's deepest sinkhole. It is located in Fengjie County of Chongqing Municipality in China.
Dimensions
The Xiaozhai Tiankeng is long, wide, and between deep, with vertical walls. Its volume is 119,349,000 m³ and the area of its opening is 274,000 m2. This material has been dissolved and carried away by the river. The sinkhole is a doubly nested structure—the upper bowl is deep, the lower bowl is deep, and the two bowls are on average across. Between both these steps is a sloping ledge, formed due to soil trapped in the limestone. In the rainy season, a waterfall can be seen at the mouth of the sinkhole.
Discovery
The Xiaozhai Tiankeng has been well known to local people since ancient times. Xiaozhai is the name of an abandoned village nearby and means "little village", and "Tiankeng" means Heavenly Pit, a regional name for sinkholes in that part of China. A 2,800-step staircase has been constructed in order to facilitate tourism.
The Tiankeng formed over the Difeng cave, which in turn had been formed by a powerful underground river which still flows underneath the sinkhole. The underground river starts in the Tianjin fissure gorge and reaches a vertical cliff above the Migong River, forming a waterfall. The length of this underground river is approximately and during these 8.5 kilometers, it falls The median annual flow of this river is 8.77 m3 per second, but its flow rate can reach 174 m3/s. Both the river and Difeng Cave were explored and mapped by China Caves Project in 1994.
1,285 species of plants, including the ginkgo, and many rare animals, like the clouded leopard and the Chinese giant salamander, have been found in the sinkhole.