334 



H. P. CLELAND NORTH AMERICAN NATURAL BRIDGES 



2. B7 A ROCK SEPARATED FROM ONE BANK AND LEANING AGAINST THE 



OPPOSITE BANK 



A bridge of unusual origin, and one which, as far as known, has no 

 parallel in the United States, is illustrated by the accompanying section 

 (figure 11). This bridge, which spans the gorge of the Emme, in Switz- 

 erland, is formed as follows: A rock of about 35 meters in height was 



Figure 11. — The "Rebloch" at Schangnau, in the Valley of the Emme, Switzerland 

 Redrawn from Kaufmann 



separated from the left bank of the gorge, and finally leaned against the 

 wall of the right bank. The wedge-shaped crevice opening upward was 

 then partly filled with debris, and became nicely leveled. The crevice on 

 the left bank formed by the breaking away of the block is also more or less 

 filled with debris.^® 



E. Bridges formed by Deposition 



1. BY DEPOSITION OF TRAVERTINE 



The only case of a valley of erosion spanned by a travertine deposit re- 

 ported from North America occurs near the little Mormon village of 

 Pine, about 90 miles south of Flagstaff, Arizona, and can be reached by a 



^ J. Friih : Ibid., p. 361. 



