At the time the limestone beds were beginning to crack, which we noted was some 60,000,000 million years ago, the huge reptiles and other prehistoric animals were playing hide and seek on the surface above the site of the developing Caverns. At that time the cave hadn't yet been formed--the underground seepage of water was just beginning to find the crevices below the gypsum and rock salt and begin its erosion which was to continue slowly for so many centuries. Recent forms of life seem to have a more or less direct bearing on the bat, and scientists remain quiet on what forms of life, if any, used the cave for their domicile between the earliest times and the arrival of the bat. At least, the nocturnal creature is a sure resident, for he still makes his home there, and in numbers running into the millions. But when did the bat first inhabit the cave? That is difficult to answer, except to say that it was several thousands of years ago. How can scientists be so sure the years are so many? There are several ways in which they have been able to establish that the centuries have been numerous since the bats first discovered this haven. One of the best is by the guano deposits found on the floor of the cave. Observations have shown that the excrement from the bats accumulates at the rate of approximately one-half inch per year. Thus 25 years is required for a foot of the substance to materialize. This would indicate it would require about 1,000 years for 40 feet to accumulate. Unfortunately, the exact thickness or depth of the guano deposits was not carefully measured when my father first discovered them, but I have heard him describe them many times as being at least 100 feet deep in places. That would be almost conclusive proof that the bats had been living in the cave for at least 2,000 years! It should also be remembered that as guano ages and dehydrates, it sort of packs down, so that although a half inch of guano might be deposited in a year's time, several years later this guano will have decayed and packed down to half that thickness. This would extend the time to far more than the estimated 2,000 years, but just how much is extremely difficult to estimate. Also, the amount of guano growth varies with the years, for when insects are plentiful, bats gorge themselves and the guano deposits are much greater than in lean years when their food supply is low, sometimes to the extent that the bats will go elsewhere for one or two seasons, at which times there is no guano accumulation at all. At one time, during an exploration of the cave some years ago, a scientist discovered the remains of a bat sticking out of the side of a stalagmite where it had undoubtedly fallen from its perch above, having perchance died of old age.