Cave formations are made up of the mineral calcite (a crystalline form of calcium carbonate). As water filters through soil and limestone above the cave, it dissolves calcium carbonate. When this mineral-rich water drips into the cave it deposits the calcium carbonate as speleothems (stalactites, stalagmites and flowstone) Stalactites grow down from the ceiling. Stalagmites grow up from the floor. Broad sheets of calcite flow over the cave walls and floors to create draperies and flowstone.