Karst, or karst, refers to the geological action of water on soluble rocks (carbonate rocks, gypsum, rock salt, etc.). ), mainly chemical dissolution, supplemented by mechanical effects such as scouring, undercurrent and collapse of running water, and the general name of the phenomena produced by these effects. The landform formed by karst is called karst landform.

"Karst" was originally the name of the limestone plateau in the Istra Peninsula in northwest Yugoslavia, which means rock. There is a typical karst landform there. The word "karst" is synonymous with karst landform. China is the earliest country in the world to record and study karst landforms, which was recorded as early as the Jin Dynasty, especially the Travels of Xu Xiake written by Xu Hongzu (1586 ~ 164 1) in the Ming Dynasty.

Geographical distribution Karst landforms are distributed in soluble rock areas all over the world. There are three types of soluble rocks: ① carbonate rocks (limestone, dolomite, marl, etc. ). ② Sulfate rock (gypsum, anhydrite, mirabilite). (3) Halide rocks (potassium, sodium, magnesium salt rocks, etc. ). The total area is 5 1× 106 square kilometers, accounting for 10% of the total area of the earth. Karst landform develops from tropical zone to cold zone, and from mainland to island. Famous areas include China, Guangxi, Yunnan, Guizhou, northern Vietnam, Dunac Alps in Yugoslavia, Alps at the junction of Italy and Austria, French Central Plateau, Russian Urals, southern Australia, Kentucky and Indiana in the United States, Cuba and Jamaica. The karst landforms in China are widely distributed and cover a large area. It is mainly distributed in the exposed area of carbonate rocks, covering an area of about 9 1 ~ 1.3 million square kilometers. Among them, Guangxi, Guizhou and eastern Yunnan have the largest areas and are one of the largest karst areas in the world. Tibet and some northern areas are also distributed.