In a number of the cañons, ruined cliff houses are numerous, and a few of these are found far north in Glen Cañon. The walls, in places, are marked with picture writing. This probably was the work of the cliff dwellers or of the Indians. Much of the cañon region may well be called the "No Man's Land" of the continent. In it are a numerous and assorted lot of men with unknown histories. Mingling with these are Indians, miners, health-seekers, and strange and interesting characters, among whom are aged trappers and prospectors and real cowboys who have survived the days of adventures. Water is the great sculptor of the face of nature. The gentle raindrop grapples with mountains of solid rock, and with never-ending persistence drags them piecemeal into the sea. Here the material is redeposited in sedimentary strata, and this may emerge into the light in the ages yet to be. A narrow ditch in the earth will widen by the caving-in of its sides. If the ditch be deepened, the caved-in matter being removed, it will continue to widen. And so it is with this cañon; the weathering or the caving-in of these walls goes ever on. The sharpness of the walls, and many of their striking features, are due to the peculiar climatic conditions that exist in this region--the short rainy seasons and long dry periods. Had there been a more even and abundant precipitation, it is probable that more vegetation would have been produced, which would have had a marked influence upon the walls, giving them a more rounded and less interesting form. The cañon broadens with the years. Cut narrow by the river, it has gradually widened by the caving-in of the walls. If it had remained as the river cut it, it would now be as narrow at the top as it is in the bottom--a cañon about a mile deep, only a few hundred feet wide, and with perpendicular walls. As it is, the walls rise through a series of shattered inclines, precipitous slopes and terraces, with here and there a vertical section.