THE CARBONIFEROUS PLATEAU. 



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It is impossible on the scale of the section to illustrate accurately this 

 sudden dip, but it is sufficiently well shown to indicate the main features 

 of the uplift. The upturned edges of the varie- 

 gated sandstone forming the peaks (c) are 

 broken and rugged, and with their brilliant 

 red color are conspicuous features as seen from #>g 

 the west. 



Another fact worthy of notice is illustrated 

 by the section. It is observable almost every- 

 where on the slopes of the Hills, but more strik- 

 ingly here, that in regions of elevation the in- 

 clining strata do not make their entire ascent 

 in one continuous dip, but rise from their nearly 

 horizontal position to their highest elevation by 

 steps or waves, between which there may be 

 considerable intervals with little or no inclina- 

 tion. This feature is not peculiar to the Hills, 

 but has been observed in many regions the 

 geology of which has been accurately studied. 

 It is characteristic of the district of the Col- 

 orado plateaus, and is well exhibited in the 

 Coal Measures in portions of the Alleghany 

 Coal Field. 



The basal member of the Carboniferous 

 is shown at various places along the eastern 

 margin of the southern portion of the plateau, 

 and is distinguished by the great quantity of 

 fragments of crinoidal columns it contains. 

 The gray and silicious limestones, just as at 

 the north, are the surface rocks of the top of the 

 plateau. The alternating limestones and sand- 

 stones are well exposed in canons across the western edge, and especially 

 in the vicinity of Fanny Peak, where a number of dry branches of Beaver 

 Creek score the slope of the plateau. 



