SUGGESTED CORRELATION 529 



small fragments of the different quartzites to satisfactorily trace the origin 

 of a loose piece. 



Suggested Correlation 



In accord with this view of the stratigraphic relations, the following 

 correlation is suggested : 



The basal quartzite (Cambrian) of the Wasatch is still a basal quartzite 

 in the Uintas. 



The "Ute limestone" (Silurian) appears eastward as shales — the py- 

 ritiferous, black, and other shales of Iron creek — Iron Creek shales. 



The u Ogden quartzite " (Devonian) is represented by a quartzite of 

 precisely the type described in the Wasatch, even to the intermixture of 

 rounded and polished pebbles. 



The " Wasatch limestone " is much reduced and is represented by 

 heavy limestone at the base, a series of shales in the middle, and cherty 

 limestone followed by an erosion interval at the top. 



The " Weber " is also greatly reduced. In part it is represented by 

 the erosion unconformity and its upper portion by 1,000 to 1,500 feet of 

 quartzite. 



A generalized diagram suggesting this relationship is attempted in 

 plate 88. 



With this interpretation of relations the apparent discrepancy in strati- 

 graphic position of the unconformities noted in the two districts (Powell's 

 eastern Uinta and the writer's western Uinta) is conceivable as one and 

 the same ; for it is believed that the basal sandstone rises in the geo- 

 logicjscale eastward, so that its upper margin may not represent the Cam- 

 brian there as it does in the Wasatch, but may be much later. Allow- 

 ing then for a withdrawal of the sea slowly westward to and beyond the 

 area studied by the writer and a more rapid readvance to its former 

 boundaries, it is conceivable that the missing interval in the Green River 

 region may be equivalent to not only the interval itself, 50 miles farther 

 west, but also to some thickness of sediments both above and below. 



The accompanying chart of geologic sections for the Wasatch, western 

 Uintas, and eastern Uintas, drawn approximately to scale, exhibits more 

 concisely the views outlined in this article. 



In conclusion, one is obliged to regret that not only in the first at- 

 tempt, but in every subsequent one, made at correlation of these forma- 

 tions, there has been insufficient organic evidence to close the argument 

 from that additional side ; but this is sure to be found sooner or later. 

 The loss of a considerable collection of fossils from the formations under 

 discussion in the common accidents and limitations of field transporta- 

 tion is a great handicap to the writer. Without the material as evidence, 



