Karst landform is the most typical on the Karst Plateau along the Delia coast of southern Europe and Asia, so people call this landform in limestone area as karst landform. Many world-famous natural landscapes such as Guilin landscape in China, Cappadocia Stone Forest in Turkey and Mammoth Cave in the United States belong to karst landform. Karst landform is the result of long-term dissolution of groundwater in limestone area. The main component of limestone is calcium carbonate. When there is water and carbon dioxide, calcium carbonate, carbon dioxide and water will react chemically to produce calcium bicarbonate. Calcium bicarbonate is soluble in water, so the limestone will form a cavity and gradually expand, gradually forming a beautiful karst landform.
"Bottomless cave", also known as "sinkhole", is actually a kind of karst cave. It is a vertical cave formed when the water on the ground erodes along the limestone stratum. It is also the main channel for the surface water to flow into the underground river. "Bottomless cave" is generally more than 100 meters deep, and its bottom is difficult to see, so it is named.