BULL. GEOL. SOC AM. 



VOL 21, 1909, PL. 27 





^^^^ 











Figure 1. — View of the Vallev of Fixe Cheek, Arizoxa 



Showing the flat valley floor composed of travertine. The top of the bridge is at the 

 far end (south) of the travertine floor. Tlie springs wliich have supplied the lime are 

 on the left. (See also plate 28, figures 1 and 2.) 



Figure 2. — The Travertixe Natural Bridge, near Pine, Arizona, from the South 



(See also plate 28, figures 1 and 2) 



ILLUSTRATIONS OF NATURAL ROCK BRIDGES 



