MAJOR Powell's investigations 293 



map, signed and dated in his own handwriting, to lie distributed to as 

 many of the leading geologists of the country. 



When the Powell report appeared (without any reference; to our pre- 

 vious studies) the most important difference between his determinations 

 and mine was as to the age of the Uinta quartzites, which he tentatively 

 assigned to the Devonian, having found an unconformity by erosion 

 between them and the overlying Carboniferous. As Whirlpool canyon, 

 in which the unconformity was seen, was in a region of very : complicated 

 faulting and folding, Mr King thought it possible he might have been 

 misled in his observations by the effect of perspective in obsei-ving faulted 

 outcrops. It was, however, impossible at that late date to verify this 

 fact, but we were certain that a quartzite series of that thickness could 

 not be Devonian. A foot-note was therefore inserted in our report,* 

 stating that if such unconformity exists, the quartzite ^series, which we 

 had called "Weber," must represent rather the great quartzite formation 

 underlying the Cambrian of the Wasatch. My later geological work in 

 the West has confirmed this conclusion, as I stated in my article "Oro- 

 graphic movements in the Rocky mountains."! 



Eecent Investigations 



It still remained, however, to determine what part of the Wasatch sec- 

 tion is represented in the western Uintas, whether the unconformity can 

 be detected there, and what is the true correlation between the formations 

 there represented and the Grand Canyon section, on which Powell had 

 based his divisions. I had hoped that long ere this these questions would 

 have been finally settled by an areal survey of the region, made by geolo- 

 gists of the U. S. Geological Survey, and have hence deferred any further 

 reference to them. In the summer of 1903, at my suggestion, Mr J. M. 

 Boutwell made a reconnaissance examination of the iron ore deposits on 

 Ehodes spur, in the course of which he obtained an undoubted Mississip- 

 pi an fauna from the limes tones J overlying the great quartzite series, thus 

 definitely proving that the latter could not be Weber. 



During the same summer Mr Charles P. Berkey had an opportunity of 

 studying in considerable detail the geology of the region around the 

 Duchesne river, and discovered a considerable thickness of shaly beds 

 beneath the limestones and separated by a fault from the Uinta quartz- 

 ites, neither of which had been noted by me. He also claimed to have 

 found two unconformities by erosion in the Paleozoic series, and on the 



* Descriptive Geology, vol. ii, p. 199. 

 t This Bulletin, vol. 1, 1879, p. 256. 

 t U. S. Geological Survey Bulletin no. 225, p. 225. 



