Page:Popular Science Monthly Volume 7.djvu/551

Rh Conceive of three geographic terraces, many hundred feet high, and many miles in width, forming a great stairway, from the Toom' pin Wu-near' Tu-weap' below, to the valley of the Uinta, above. The lower step of this stairway, the Orange Cliffs, is more than 1,200 feet high, and the step itself is two or three score miles in width. The second step, the Book Cliffs, is 2,000 feet high, or more, and a score of miles in width. The third, or upper step, is more than 2,000 feet high. Passing along this step, for two or three score miles, we reach the valley of the Uinta; but this valley is not 5,000 or 6,000 feet higher than the Toom'-pin Wu-near' Tu-weap', for the stairway is tipped backward.

Climb the Orange Cliffs, 1,200 feet high, and go north to the foot of the Book Cliffs, and you have gradually descended, so that at the foot of the Book Cliffs you are not more than 100 feet above the foot of the Orange Cliffs. In like manner the foot of the Brown Cliffs is but 200 feet higher than the foot of the Book Cliffs, and the valley of the Uinta is not quite 300 feet higher than the foot of the Brown Cliffs.

To go by land from the valley of White River to the Toom'-pin Wu-near' Tu-weap', you must gradually, almost imperceptibly, climb as you pass to the south, for a distance of forty or fifty miles, until you attain an altitude of 2,500 or 3,000 feet above the starting-point. Then you descend from the first terrace, by an abrupt step, to a lower. Still continuing to the south, you gradually climb again, until you attain an altitude of more than 1,000 feet, when you arrive at the brink of another cliff, and descend abruptly to the top of the lowest terrace. Still extending your travels in the same direction, you climb gradually for a third time, until you reach the brink of the third line of cliffs, or the edge of the escarpment of the lower terrace, and here you descend by another sudden step to the plane of the river, at the foot of Labyrinth Cañon. In coming down by the river, of course you do not ascend, but you pass these terraces along the plane of the river, the upper terrace through the Cañon of Desolation, the middle terrace through Gray Cañon, and the third through Labyrinth Cañon.

The bird's-eye view (Fig. 1) is intended to show these topographic features. The escarpment below, and in the foreground, represents the Orange Cliffs, at the foot of Labyrinth Cañon; the second escarpment, the Book Cliffs, at the foot of Gray Cañon; the third, away in the distance, the Brown Cliffs, at the foot of the Cañon of Desolation. It will be seen that the three tables incline to the north, and are abruptly terminated by cliffs on the south. For want of space the whole view is shortened.

In the three Cañons there are three distinct series of beds, belonging to three distinct geological periods. In the Cañon of Desolation we have Tertiary sandstones; in Gray Cañon, Cretaceous sandstones, shales, and impure limestones; between the head of Labyrinth Cañon