The geological authorities of both states have for many years mentioned the beauty and importance of these regions, and urged their claims to public attention, but have been prevented, by the pressure of other duties, from giving to the caves such careful study and full reports as they deserve, as it would have been a pleasure to give, and as has been possible in states of less extent where the general work of the department is more advanced, and the volume of tourist travel created an early demand for scientific explanation.

Without any great difficulty we can understand the process of cave excavation by the action of percolating acidulated water on the limestone, and its subsequent removal as the volume of surface drainage diverted to the new channel gradually increased.  But it is not so easy to offer a reason for the varied forms with which the caves are afterwards decorated.  Why is it the charmed waters do not leave the evidence of their slow passage only in plain surfaces of varying widths, and the stalactites and stalagmites whose formation we can readily account for?  And why do not the deposits take the same forms in all caves with only such variations as would naturally result from differences in topography?  The law is written, but in unfamiliar characters that render our reading slow and uncertain.  Yet it is conspicuously noticeable that those caves showing the most delicately fragile and wonderfully varied forms of decoration are those traversed by the most sweeping and changeable, or even reversible, currents of air; which might lead to the conclusion that the moisture is sprayed or converted into a light, misty vapor, and then deposited in exactly the same manner as the beautiful frost-work at Niagara:  the direction and force of the current determining the location of the frail deposits.

Since the largest and most important caves occur in limestone, a little special attention to the cause of their occurrence there may serve to show that although speleology has only recently received its name and been elevated to the rank of a separate and independent science, it is one of the earth’s ancient institutions.

Our geologists, who have unearthed many secrets not dreamed of even in Humboldt’s “good phylosopy,” have settled the question of how the different kinds of caves were formed, according to the character of rocks they are in, or their location and depth, and the natural agencies to whose action they show signs of having been subjected.

Dr. H.C.  Hovey, in his “Celebrated American Caverns,” says:  “In visiting caves of large extent, one is at first inclined to regard the long halls, huge rifts, deep pits and lofty domes, as evidences of great convulsions of nature, whereby the earth has been violently rent asunder.  But, while mechanical forces have had their share in the work, as has been shown, the main agent in every case has been the comparatively gentle, invisible gas known as carbonic acid.  This is generated by the decay of animal and vegetable substances, and is to a considerable degree soluble in water.  Under ordinary circumstances one measure of water will absorb one measure of carbonic acid; and the eye will detect no difference in its appearance.  Under pressure the power of absorption is rapidly increased, until the water thus surcharged has an acid taste, and effervesces on flowing from the earth, as in Saratoga water.