320 



H. F. CLELAND NORTH AMERICAN NATURAL BRIDGES 



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/. Bridges of Le Perle 

 Creek, Wyoming, and 

 Buffalo Gap, South Da- 

 kota.— The information 

 concerning these two 

 bridges is so meager that 

 nothing can be said of 

 their origin except that 

 they should possibly be 

 included in this group. 

 The Le Perle Creek 

 bridge is composed of 

 'Tensleep sandstone, a 

 white massive formation, 

 moderately hard and pre- 

 sumably with siliceous 

 cement ; the span is abont 

 35 feet, the greatest 

 height 10 feet, and the 

 width about 25 feet." ^ 



The Buffalo Gap bridge 

 is composed of "Unkpapa 

 sandstone, fine grained, 

 massive, pinkish in color, 

 and with supposed silice- 

 ous cement. The span is 

 about 8 feet and the 

 width 6 feet."^ 



g. Discussion of a for- 

 mer natural bridge of 

 this type in Oklahoma, — 

 Through the courtesy of 

 Prof. C. N. Gould,« I am 

 able to use the following 

 series of maps (figure 5) 

 showing the location of 

 the courses of the pres- 

 ent and former channels 

 of the Washita Eiver 



5 N. H. Darton in a letter to the writer, February 17, 1907. 

 « A letter from C. N. Gould, January, 1910. 



