Page:Popular Science Monthly Volume 78.djvu/434

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THE POPULAR SCIENCE MONTHLY.


PSM V78 D434 Pine arizona travertine natural bridge formation.png

Fig. 8. Block Diagram to show the Formation of the Travertine Natural Bridge at Pine, Arizona. This bridge was formed by the deposits of travertine derived from the springs on the east. (In the diagram the height of the bridge is exaggerated.)

country of this sort, the brilliant green of the irrigated valley of which the natural bridge is a part seems remarkably beautiful and is a sight not soon forgotten. Not only is the bridge composed of this limestone

PSM V78 D434 Natural bridge of swift camp creek near campton ky.png

Fig. 9. Two Views of the Natural Bridge across Swift's Camp Creek near Campton, Kentucky. (See Fig. 10.)