816 



H. F. CLELAND NORTH AMERICAN NATURAL BRIDGES 



"The opening of the archway is about 12 feet high by 8 feet wide, and the 

 thickness of the arch is something like 10 feet in a vertical direction by 7 feet 

 in a horizontal. The gorge is about 30 feet deep, with almost vertical walls. 

 The rock is a hard, rather blocky, light blue clay, showing typical bad-land 

 topography." 



?• 6'E.of OPai-i 



Figure 2. — Pont d'Arc (ArdSche) 

 Scale, 1 :400,000. The origin of the bridge Is evident from the map 



The origin of the bridge can be readily understood by a study of the 

 figure, which, with the illustration (plate 18, figure 2), is reproduced 

 from the article cited. 



