Tiankengs in the karst of China

China has the most extensive and diversified karst terrains in the world and most of them are rich in caves and dolines. The cone karst (fengcong) and tower karst (fenglin) developed in the humid climate in southern China form the most distinctive karst landscapes. Tiankengs are giant dolines that are a feature in some areas of the cone karst. In recent years, more than fifty tiankengs have been discovered in the cone karst in southern China, notably in the provinces of Chongqing, Guangxi, Sichuan and Guizhou. Current research indicates that tiankengs develop in specific environments of geomorphology, geology and hydrogeology, and are therefore distinguished from normal karst dolines.