The formation of karst caves is the result of long-term dissolution of groundwater in limestone areas. Insoluble calcium carbonate in limestone can be converted into slightly soluble calcium bicarbonate under the action of water and carbon dioxide. Due to the different calcium content and erosion degree of each part of limestone layer, it is gradually dissolved and divided into independent, changeable, steep and beautiful peaks and caves, and the landscape is strange. For example, the world-famous Guilin Cave and Beijing Shihua Cave are masterpieces created by the slow erosion of water and carbon dioxide. When water dissolved with calcium bicarbonate drips from the top to the bottom of the cave, the solubility of carbon dioxide will decrease and calcium carbonate will be precipitated due to the evaporation of water or the decrease of pressure and the change of temperature. After millions of years of accumulation, these sediments gradually formed stalactites, stalagmites and so on. If water with dissolved calcium bicarbonate drips from the top of the cave, with the evaporation of water and carbon dioxide, the precipitated calcium carbonate will accumulate into stalactites, stone curtains and stone flowers. When stalactites at the top of the cave are connected with stalagmites on the ground, strange stone pillars will be formed.

In nature, rainwater containing dissolved carbon dioxide will partially dissolve limestone strata and convert calcium carbonate into soluble calcium bicarbonate.