288 DESCRIPTIVE GEOLOGY. 



which, however, differs from the deep red of the Weber Quartzite, and may 

 probably represent a larger development of the pink beds exposed in Ver- 

 million Creek Canon. 



Summit Eegion west of Lodore Canon. — To the west of the canon of 

 Lodore, the line of bluffs which forms the southern wall of Summit Valley 

 presents approximately the northern limit of the remaining beds of the Upper 

 Coal-Measures. In the lower portion of this valley, toward the canon of Lo- 

 dore, the existence of a fragment of Tertiary beds has been reported. They 

 were not, however, found by our parties, and their age or lithological char- 

 acter is not known. This fact suggests the interesting question, whether any 

 other Tertiary besides the Wyoming Conglomerate over covered this portion 

 of the range. At Ute Peak, the most easterly point visited on this side of the 

 river, an opportunity was had of observing the actual contact of the Upper 

 Coal-Measures with the Weber Quartzite group. On the northern base of 

 the peak, the upper beds of the Weber Quartzite are coarse-grained red sand- 

 stones, glistening on the surface, of loose texture, and weathering into large, 

 massive blocks with rounded edges. In direct contact with the sandstones is a 

 bed of reddish decomposed limestone, which has the external appearance of 

 a porphyry, from the fact of its containing fragments of white crystalline 

 calcite, some of which have a circular form, as if they had once been casts 

 of corals. An analysis of this impure limestone was made by Mr. B. E. 

 Brewster, with the following result : 



Silica... 27.713 



Soluble silica 0.227 



Alumina 



^ . ., 0.347 



rernc oxide 



Lime • 39.542 



Magnesia 0.287 



Carbonic acid — . 31.686 



Water and organic matter 0.247 



100.049 



Carbonate of lime 70.610 



Carbonate of magnesia ^ .-. . 0.603 



