AUTHOR'S PEEFACE. XXV 



joined Professor Powell's survey and rapidly traversed the District of the 

 High Plateaus and portions of the region southwest of that district. Dur- 

 ing that year he succeeded in fixing the geological horizons of the chief 

 sedimentary beds there occuri-ing, and also began the study of the struc- 

 tural features of the northern part of the district in the Wasatch Plateau 

 and in the Puvant. In the following winter he withdrew from the survey 

 in order to engage in business, and left copious notes of his observations 

 and drawings of geological sections which I have had the privilege of con- 

 sulting. His drawings of the sections made by him in the northern part 

 of the district are embodied in this volume. He is entitled to high praise 

 for the ability and accuracy of his work, and it is much to be regretted 

 that he was induced to abandon geological fieldwork. 



I am also indebted to Mr. G. K. Gilbert for many valuable suggestions. 

 He has traversed this district several times on his way to and from his 

 own field of research and has given me information which has often proved 

 of great utility. 



The atlas has been lithographed by Mr. Julius Bien, of New York, and 



bears abundant evidence of his great skill and intelligence in that kind of 



work. 



C. E. DUTTON, 



Captain of Ordnance. 



