My companion above, seated on the brink of the stone wall, replied to my thoughts: "Your wish shall be granted. You have requested that which has already been laid out for you. You will explore where few men have passed before, and will have the privilege of following your destiny into a realm of natural wonders. A fertile field of investigation awaits you, such as will surpass your most vivid imaginings. Come and seat yourself beside me, for it is my duty now to tell you something about the land we are approaching, the cavern fields of Kentucky." CHAPTER XIII. THE PUNCH-BOWLS AND CAVERNS OF KENTUCKY.--"INTO THE UNKNOWN COUNTRY." "This part of Kentucky borders a field of caverns that reaches from near the State of Tennessee to the Ohio River, and from the mouth of the Cumberland, eastward to and beyond the center of the State. This great area is of irregular outline, and as yet has been little explored. Underneath the surface are layers of limestone and sandstone rock, the deposits ranging from ten to one hundred and fifty feet in thickness, and often great masses of conglomerate appear. This conglomerate sometimes caps the ridges, and varies in thickness from a few feet only, to sixty, or even a hundred, feet. It is of a diversified character, sometimes largely composed of pebbles cemented together by iron ore into compact beds, while again it passes abruptly into gritty sandstone, or a fine-grained compact rock destitute of pebbles. Sometimes the conglomerate rests directly on the limestone, but in the section about us, more often argillaceous shales or veins of coal intervene, and occasionally inferior and superior layers of conglomerate are separated by a bed of coal. In addition, lead-bearing veins now and then crop up, the crystals of galena being disseminated through masses of fluor-spar, calc-spar, limestone and clay, which fill fissures between tilted walls of limestone and hard quartzose sandstone. Valleys, hills, and mountains, grow out of this remarkable crust. Rivers and creeks flow through and under it in crevices, either directly upon the bedstone or over deposits of clay which underlie it. In some places, beds of coal or slate alternate with layers of the lime rock; in others, the interspace is clay and sand. Sometimes the depth of the several limestone and conglomerate deposits is great, and they are often honeycombed by innumerable transverse and diagonal spaces. Water drips have here and there washed out the more friable earth and stone, forming grottoes which are as yet unknown to men, but which will be discovered to be wonderful and fantastic beyond anything of a like nature now familiar. In other places cavities exist between shelves of rock that lie one above the other--monstrous openings caused by the erosive action of rivers now lost, but that have flowed during unnumbered ages past; great parallel valleys and gigantic chambers, one over the other, remaining to tell the story of these former torrents.