REPORT ON THE GEOLOGY OF THE YELLOWSTONE NATIONAL 



PARK. 



By W. H. Holmes. 



Office United States Geological Survey, 



Washington, D. (J., August 2, 1879. 



Sir : Herewitli I have the honor to transmit a brief report of my geo- 

 logic work in the Yellowstone Park dnriug the summer of 1878. 



With a deep sense of my obligations to you for opportunities afforded. 

 and a lively appreciation of your uniform liberality and kindness, 

 I remain, very sincerely, yours, 



W. H. HOLMES. 

 Dr. F. V. Hayden, 



United States Geologist. 



INTBODUCTOBY. 



In presenting a report upon the geology of the Yellowstone Park, I feel 

 it incumbent upon me to state, candidly, a few facts in regard thereto. 



It is well known that already three or four reports have been written 

 which dwell to some extent upon the geology of the Park, and it may 

 be asked why another report is to be prepared upon this region. 



It is probably not generally known that the so-called "Yellowstone 

 country " over which the early explorations were carried, comprises an 

 area of not less 10,000 square miles; neither is it known that the time 

 spent in collecting the data embodied in any one of these reports falls 

 short of 90 days duration, nor that the geology of this whole region is 

 more varied and complicated than that of any equally large area in the 

 Eocky Mountains. 



With these facts in view, however, it will not seem strange that up 

 to this time geologists have but glanced at the surface ff^atures of the 

 country, and that the more profound and intricate problems remain 

 almost untouched. 



With regard to my own work, I wish to state that if I could have 

 consumed years instead of mouths in the study of the 3,400 square miles 

 comprising the Park, I might justify myself in i)utting my observations 

 on paper. Scarcely two months were passed within the Park, and dur- 

 ing nearly one-half of this time storms of rain and snow i)revailed to 

 such an extent as to greatly interfere with the work. I have, conse- 

 quently, gone just far enough to get glimpses of the splendid problems 

 of the rocks, and to enable me in the future to appreciate and under- 

 stand the classic chai)ter tliat Ihis district will some day add to the 

 great volume of written geology. 

 1 H, PT II 



