Limestone rock formation is a type of geological formation that is created by the dissolution of calcium carbonate rocks, such as limestone, dolomite, and gypsum. This process is known as karst, which is a term derived from the German word for 'BARE' or 'BARREN'. Karst formations are characterized by sinkholes, caves, underground streams, and other features. Limestone rock formations are found in many parts of the world, including the United States, China, and Europe.