CHAPTER 



STRUCTURAL GEOLOGY. 



In the preceding chapters many of the facts relating to the structural 

 geology of the region under discussion have been presented, but they were 

 given only to serve purposes relating to the subjects of which I was then 

 treating. In the first chapter it was necessary to refer to this region in 

 characterizing the three provinces; in the second, other facts were presented 

 in explanation of the grouping of the sedimentary rocks; and in the fourth, 

 still other facts were given in discussing geographic distribution. I now pro- 

 pose to assemble these facts with others relating to structural geology, for 

 the purpose of more clearly setting forth the geological structure of the 

 Uinta Mountains, Yampa Plateau, Junction Mountain, Diamond Peak, the 

 Dry Mountains, Brown's Park, and the Aspen Mountain district in the order 

 thus indicated. 



DESCRIPTION OF ILLUSTKATIONS. 



For the purpose of more clearly setting forth these facts certain illus- 

 trations have been prepared and will be found in the atlas. 



Structure Sections. On Plate I is grouped a series of sections through 

 the Uinta Mountains, from south to north, and six miles apart. In each 

 section the structure observed has been projected below the line of sight 

 to the level of the sea, that the facts observed might be represented in a 

 more graphic manner. This hypothetic projection represents the most prob- 

 able condition of underground structure to that depth, yet there may be 

 unconformities unknown to us and of which no hint is given in the stra- 

 tigraphy at the surface or in the structural' geology . of the surrounding 

 country ; but from the absence of these indications, such unconformities 

 are rendered improbable. 



As the Uinta upheaval began at the close of the Point of Rocks period, 



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