318 



H. F. CLELAND NORTH AMERICAN NATURAL BRIDGES 



In the walls of these canyons, which are said to be from 400 to 1,000 

 feet deep, are numerous cliff dwellings, many of which are in an excellent 

 state of preservation, together with hieroglyphics, pottery, and stone and 

 bone implements. 



The streams rarely have water in them after April, except at the time 

 of rains and cloudbursts, at which time their erosive power must be great, 

 since the volume of water is very large. It is reported that there is evi- 

 dence that in places the water reaches a depth of 100 feet. 



Figure 3. — -Diagram showing Origin of the Caroline Natural Bridge, Utah 

 Modified from diagram by H. L. A. Culmer In a letter to the writer 



The rock of which the bridges are composed is a buff to dull red Trias- 

 sic (?) sandstone; horizontally bedded and often strongly cross-bedded. 

 The three bridges which have been so often described, the Edwin, Caro- 

 line, and Augusta, are within three miles of each other. A fourth bridge, 

 called Nonnezoshi, northwest of J^avajo Mountain, and about 50 miles 

 southwest of the above, discovered by Utah Archasological Expedition 

 last summer (1909), has a length of 273 feet and a height of 308 feet, 

 making it, as far as known, the largest natural bridge in the world. 



