With an understanding of the two water zones, and the demarcation line between, we can more readily comprehend just how the Caverns were formed.
Geologists are now pretty well in agreement that the enclosing rocks of the Caverns were located in the ground-water zone under saturated conditions. As we already know, large cracks existed in the otherwise solid limestone.
Then, for many, many years the ground water dissolved the limestone, enlarging the cracks bit by bit, until the huge Caverns were formed. At this point the water table was lowered, and, in time, the Caverns ceased to exist in the ground-water zone. Following the lowering of the water table, the Caverns were nothing more than empty holes in the earth. Now the second phase of their "growth" was to begin.
When the ground water could no longer continue its constant gnawing action on the limestone, the Caverns had reached their maximum size. From now on they would begin to fill up again.
The second of the two cycles consisted of mineral deposit brought about by water seeping downward from the surface, carrying lime for the secondary formations which are today one of the great features of the Caverns.
Water in the vadose zone, seeking the ground-water level, would seep into the top of the many rooms and galleries. Each drop contained a minute portion of limestone.
Some drops would remain on the ceiling, where the moisture would evaporate, leaving a tiny ring of limestone deposit behind. As these limestone deposits accumulated they formed a pendant mass resembling an icicle which is called a stalactite. Drops falling to the floor would produce deposits known as stalagmites.
Sometimes the stalactites and stalagmites would join and a solid pillar would be formed.
In the rocks enclosing the Caverns are various deposits of other minerals such as iron oxide which are often carried in minute quantities within the seeping water and deposited on the stalagmites and stalactites. These minerals are responsible for the many different colors that may be seen in many places within the rooms of the Caverns.
Some of the formations have a very live and transparent appearance, looking somewhat as though they might have just been given a thorough coat of wax. Actually, these formations are still active. That is, they are still covered with water and the age-old process of depositing the small particles of carbonate of lime contained in the water is still going on. In cave parlance they are "alive", that is, they are still growing.