292 S. F. EMMONS UINTA MOUNTAINS 



between them and the Cambrian. Below the latter, in other parts of the 

 range, a still larger body of qiiartzite is found, having a thickness of at 

 least 12,000 feet. To one or the other of these quartzites it was evident 

 the Uinta quartzite must correspond. Its lithological constitution re- 

 sembled the latter more than the former, though the resemblance was 

 not very close and as a factor of correlation it was not considered of 

 pi'ime importance. To correlate it with this formation involved the 

 assiimption of an unconformity as the only way of accounting for the 

 disappearance of the Devonian and Silurian formations of the Wasatch 

 section, which were evidently unrepresented. No such unconformity had 

 been observed, however, and one of the rules laid down by Mr King for 

 geological mapping was not to represent any such features as faults or 

 unconformities which were not proved by actual evidence in the field. 

 Hence, with some misgivings, but as the only alternative, the doubtful 

 quartzite was correlated with the Weber, and so mapped. That such 

 an unconformity had actually been observed by Major Powell in the deep 

 canyons of Green river, which we had been vmable to explore through 

 want of boats, was only known to us some years later, for the following 

 reason : 



Major Povvell''s Investigations 



At the close of the field season of 1871 Major Powell paid me the com- 

 pliment of asking me to explain to him my ideas of the Uinta structure, 

 saying that his observations in his boat journeys down the Colorado, 

 being necessarily confined to the immediate vicinity of the river, were 

 difficult to coordinate, and he felt it would be of great help to him in 

 working them out to thoroughly understand the Uinta uplift, which was 

 evidently the key to the whole section. At that time he did not mention 

 the unconformity by erosion, nor was the question of the origin of Green 

 river discussed; but in other respects we compared notes freely and 

 agreed in all essential points. 



When, a few years latei', after he had borrowed a proof-sheet of our 

 topography of that region, it was learned that he proposed to publish a 

 volume on the Uinta mountains in the near future, it was realized that 

 he would probably secure a priority of publication over us, since, though 

 the part of my manuscript relating to the Uintas was already Avritten, it 

 must necessarily wait until the report of the entire Fortieth Parallel 

 region was completed before it could be published. 



In a vain attempt to obviate this, Mr King, on November 15, 1875, 

 caused 12 printed copies of the geologically colored Green Eiver basin 



