Xiaozhai Tiankeng Landscape, Fengjie, Chongqing
Reference work entry
This is a karst tiankeng limestone landform that formed above an underground river. It is located in Xinglong Town in Fengjie County on the southern bank of the Yangtze River. The associated rocks are the Lower Triassic Jialingjiang Formation limestone. The landform is mainly composed of peak cluster depressions at elevations of 1,300–2,000 m. The tiankengs of Xiaozhai have cave mouth diameters of 537–626 m, and the deepest is 662 m deep. These tiankengs formed above an underground river, and the river at the bottom of the cave (which is 100 to 150 m deep) has a maximum flow rate of 174 m 3/s. This section of the underground river flows in from Tianjing Gorge via the tiankeng at Xiaozhai and flows out from the cliff of the Migong (Maze) River Valley. Its total length is 8,500 m, and it has a water level drop of 364 m. The average hydraulic gradient is 42.8%, which provides excellent hydrodynamic conditions for the formation and evolution of the tiankeng of Xiaozhai (Fig. 5).
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