NATURAL BRIDGES OF UTAH 
219 
from the normal operation of this principle, except perhaps the 
Augusta bridge, and even in this instance there are some modi¬ 
fications. 
In the main description of any one of the bridges would suit 
equally as well for any of the others. Each of the three bridges 
mentioned is situated near the confluence of the main stream 
and one of its tributaries. Furthermore, in two cases the tribu¬ 
tary joins the principal stream at a small angle, thus leaving a 
long and comparatively narrow neck of higher land between them. 
Throughout the earlier stages of stream-entrenchmnt, and while 
the canyons, were still being cut into the upper massive sandstone, 
meandering was not easily accomplished; but when the soft, 
argillaceous member was encountered, the channel quickly became 
