BULL. GEOL. SOC. AM. 



VOL. 21, 1909, PL. 28 



Figure 1. — Size axd Character of the Opening under the Arch of the Natural 

 Bridge near Pine^ Arizona 



The ladders lead to a cave which is situated near the arch of the bridge. Height, ahout 

 75 feet to underside of arch 



Figure 2. — Character of the Travertine of the Natural Bridge near Pine, Arizona 

 (See also plate 27, figure 2) 



ILLUSTRATIONS OF NATURAL ROCK BRIDGES 



