Formations at times suggest the ancient cliff dwellings found at Mesa Verde, and one wonders if the early Indian did, by chance, ever inhabit them. Suddenly, as the descent drops rapidly, the ceiling is some 125 feet above and the visitor finds himself at the Whale's Mouth, a formation with slender stalactites enhanced by clever lighting which indeed does resemble the interior of that sea-going mammal's jaws. As the ceiling rises still more, the party enters the Main Corridor, a tunnel almost a mile long which leads directly to the most picturesque rooms of the Caverns. The descent is for the most part uneventful and rapid, and the guide points out some of the unique formations along the route such as the American Eagle, which has a wingspread of 12 feet, the Baby Hippo, others resembling sea foam and waves, and the three Little Monkeys perched well towards the ceiling overhead. [Illustration: The Lunchroom ] Along the walls of the Main Corridor one may see small openings which reveal an inky blackness that may cover up some mysterious room or hallway. Someone in the party asks the guide about it. He explains that there are many such openings in other rooms of similar nature, but since they have nothing different to offer from what is already being seen, the Parks Department has not opened them to public view. Have the Caverns been fully explored, someone asks. No, he replies. To date about 23 miles have been mapped and surveyed, and many openings into large chambers are known to exist, but their size is unknown. Perhaps even larger rooms lie close by. No one knows. The formations continue to change in size, shape, and contour. Stalactites hanging from the ceiling look as though some little elf might have hung them there the night before, using a spindly stalagmite to stand on as he did so. The visitor has been so absorbed in what he has been seeing that he is startled to hear the guide announce that the party is now 600 feet below the surface. That is further than the Washington Monument is high. The most picturesque portions are now to begin, he says, but the first of them will require some climbing. For that reason, those not quite up to the task may take a short cut to the lunchroom which is a brief jaunt to the left. The rest will head on past the Iceberg, the largest "loose" rock in the Caverns, which is estimated to weigh about 200,000 tons. It once "fell" from the ceiling, but the fall was gradual. The delicate stalactites grew later. The ceiling at this point is some 358 feet above.