COLOSSAL CAVERN, a cave in Kentucky, U.S.A., the main entrance of which is at the foot of a steep hill beyond Eden Valley, and 112 m. from Mammoth Cave. It is connected with what has long been known as the Bed Quilt Cave. Several entrances found by local explorers were rough and difficult. They were closed when the property was bought in 1896 by the Louisville & Nashville railway and a new approach made as indicated on the accompanying map. From the surface to the floor is 240 ft.; under Chester Sandstone and in the St Louis Limestone. Fossil corals fix the geological age of the rock. The temperature is uniformly 54° Fahr., and the atmosphere is optically and chemically pure. Lovely incrustations alternate with queer and grotesque figures. There are exquisite gypsum rosettes and intricately involved helictites.
Tremendous forces have been at work, suggesting earthquakes and eruptions; but really all is due to the chemical and mechanical action of water. The so-called “Ruins of Carthage” fill a hall 400 ft. long by 100 ft. wide and 30 ft. high, whose flat roof is a vast homogeneous limestone block. Isolated detached blocks measure from 50 to 100 ft. in length. Edgar Vaughan and W. L. Marshall, civil engineers, surveyed every part of the cave. Vaughan’s Dome is 40 ft. wide, 300 ft. long, and 79 ft. high. Numerous other domes exist, and many deep pits. The grandest place of all is the Colossal Dome, which used to be entered only from the apex by windlass and a rope reaching 135 ft. to the floor. This is now used only for illumination by raising and lowering a fire-basket. The present entrance is by a gateway buttressed by alabaster shafts, one of which, 75 ft. high, is named Henry Clay’s Monument. The dome walls arise in a series of richly tinted rings, each 8 or 10 ft. thick, and each fringed by stalactites. The symmetry is remarkable, and the reverberations are strangely musical. The Pearly Pool, in a chamber near a pit 86 ft. deep, glistens with countless cave pearls. The route beyond is between rows of stately shafts, and ends in a copious chalybeate spring. Blind flies, spiders, beetles and crickets abound; and now and then a blind crawfish darts through the waters; but as compared with many caverns the fauna and flora are not abundant. It is conjectured, not without some reason, that there is a connexion, as yet undiscovered, between the Colossal and the Mammoth caves. It seems certain that Eden Valley, which now lies between them, is a vast “tumble-down” of an immense cavern that formerly united them into one. (H. C. H.)