1) Limestone caves can be spectacular structures filled with giant stalactites and stalagmites. These caves are formed when rainwater, which is a weak acid, dissolves calcite, or lime, out of limestone. Over time, the lime-laden water drips down into cracks, enlarging them into caves. Some of the lime is then redeposited to form stalactites and stalagmites.

2) Stalactites, which grow down from cave ceilings, are formed in limestone caves when groundwater containing dissolved lime drips from the roof of the cave and leaves a thin deposit as it evaporates. Stalactites generally grow only a fraction of an inch each year, but over time a considerable number may grow to be several yards long. In cases where the supply of water is seasonal, they may actually have growth rings resembling those on tree trunks that indicate how old the stalactites are.

3) Stalagmites are formed on the floor of a limestone cave where water containing dissolved lime has dripped either from the cave ceiling or from a stalactite above. They develop in the same way as stalactites, when water containing dissolved limestone evaporates. In some limestone caves with mature limestone development, stalactites and stalagmites grow together, creating limestone pillars that stretch from the cave floor to the cave ceiling.