These bridges are of sandstone of reddish cast, stained in many places with blackish or greenish lichens and rust. Like any other rock-forms, they are the product of various erosive forces--illustrating the survival of the fittest. Their material, being slightly more durable than that of the now vanished rocks, or possibly less severely tested, has endured while the other material has been dissolved and worn away. In the fashioning of the surface of the earth Nature sometimes makes beautiful and imposing statuary. She has done so here. In the surrounding country are turrets, cisterns, wells, conelike and dome-like caves and caverns, and nearly complete arches. In fact, arches and bridges showing every degree of completion and past prime condition may be seen. Near by are numerous deserted cliff dwellings. These unusual structures leave a lasting impression on every visitor. Plans are already under way to make these wonders easily accessible to the public. 3. MUKUNTUWEAP NATIONAL MONUMENT The Mukuntuweap National Monument, Utah, has as spectacular a cañon, and as stupendous an array of vast rock-forms, as is to be found anywhere in the world. This territory is often spoken of as "The Little Zion River Region." The Mukuntuweap Cañon has some of the forms shown in the Grand Cañon, and an array of colors not equaled in any other cañon known. In width it varies from half a mile to only a few rods across. It does not all tend in a straight direction. It curves. The cañon walls in places are sheer and rise from two thousand to three thousand feet. One of its most startling features is shown in the overhanging walls, which the water has undercut so that in places the walls prevent a person in the bottom from seeing the sky. In a recent report on this cañon, T. E. Hunt, of the Department of the Interior, wrote:-- At the south end, the cañon is about twelve hundred feet wide, but gradually narrows for a distance of seven miles, until a point is reached where with outstretching arms the finger tips touch the walls on either side. In a number of places the walls of this cañon rise vertically to a height of more than two thousand feet, thus exhibiting a plain surface of extremely hard, pink sandstone. The vast barren areas of the walls are broken by figures in relief, and statuary on the summits--all the carving of Nature. On the terraces and in the niches are growths of ash and oak, maple and spruce and other trees. In a number of places these walls are further enlivened and glorified by waterfalls that plunge grandly over them into the cañon. We thus have in this region an unexcelled variety of the best-known cañon effects--the vast sweep of vertical walls, the walls that are undercut so that they appear to lean, and extreme narrowness between the walls.