Natural Bridge.—The western pat of Barber and the eastern portion of Comanche counties furnish specimens of natural bridges, which are located in the gypsum deposits of that locality. These bridges represent remnants of old caves or underground water channels, whose roofs have partly fallen in. One of the best specimens of these bridges is found on Bear creek, south of Sun City, Barber county, and is thus described by Prof. F. W. Cragin: "This bridge spans the canon of the creek, here about 55 feet from wall to wall. The height of the bridge above the bed of the creek is at the highest point 47 feet, at lowest 31, and at middle 38. The width of the bridge at the middle is 35 feet. The upper surface of the bridge declines toward the down-stream side, but not so much that a wagon drawn by a steady team could not be driven across it. The thickness of the arch is therefore greater on the up-stream side, where it measures 26 feet, than on the down-stream. The relief of the vicinity seems to indicate that at a geologically recent time Bear creek here flowed to the east of its present course, and that its waters, becoming partially diverted by an incipient cave, enlarged the latter, and finally were entirely stolen by it, the cave at length collapsing, save at the portion now constituting the natural bridge."