It is not just swallow holes that are formed in underground limestone landscapes. Deposition landforms also occur forming stalactites and stalagmites . Water containing calcium carbonate in solution, continually drips form the ceilings of underground caves. Although it is cold in these areas, some evaporation does take place and the formation of these structures take place. As water drips onto the floor beneath the stalactite further deposition of calcium carbonate produce more rounded stalagmites.
Pillars are the result of stalactites and stalagmites joining together.