144 GEOLOGY OF THE HIGH PLATEAUS 



comjDOsed almost wholly of Carboniferous strata, bent and faulted after the 

 manner peculiar to the Basin Ranges. Although yielding characteristic 

 fossils, none of these Carboniferous exposures present sufficient materials for 

 special study. The great fields of Carboniferous rocks are found in the 

 Kaibabs to the southward and in the basin to the westward. 



THE SHInArUMP. • 



Resting everywhere upon the Carboniferous of the Plateau Country is 

 a series of sandy shales, which in some respects are the most extraordinary 

 group of strata in the West, and perhaps the most extraordinary in the 

 world. To the eye they are a never-failing source of wonder. There are 

 especially three characteristics, either one of which would render them in the 

 highest degree conspicuous, curious, and entertaining. First may be men- 

 tioned the constancy with which the component members of the series pre- 

 serve their characters throughout the entire province. Wherever their proper 

 horizon is exposed they are always disclosed, and the same well-known fea- 

 tures are presented in Southwestern Utah, in Central Utah, around the junc- 

 tion of the Grand and Green, in the San Rafael Swell, and at the base of the 

 Uinta Mountains. As we pass from one of these localities to another, not a 

 line seems to have disappeared nor a color to have deepened or paled. So 

 strongly emphasized are the superficial aspects of the beds and so persist- 

 ently are they maintained, that only careful measurement and inspection of 

 each constituent seam can impair the prima facie conviction that these 

 widely-separated exposures are absolutely identical. Detailed examination, 

 however, does show some variation in thickness and slight changes in the 

 constituent members ; but, on the whole, the constancy is, so far as known 

 to me, without a parallel in any formation in any other region. The sculp- 

 tured cliffs of the Shindrump reveal the edges of the component layers as 

 rigorously parallel as if a skillful stonemason had laid them down, and nar- 

 row bands can be followed for miles without any visible change in their 

 aspect. 



A second striking feature is the powerful coloring of some of the beds. 

 With the exception of the dark, iron-gray shales of the Cretaceous, the tints 

 of the other formations are usually bright, lively, and often extremel)' deli- 



