THE AGE OF THE DOMES AND ANTICLINES 305 



form the south side of the mountains. In some places high on 

 the flanks of the mountains the sedimentary beds are vertical or 

 even slightly overturned. 



To the southeast of the Ferris Mountains this sharp folding is 

 replaced by faulting with thrust from the north, so that the crystal- 

 line rocks of the Seminoe Mountains now lie against the Cretaceous 

 rocks of the Lost Soldier-Ferris district. The fault plane along 

 which this overthrusting took place probably was almost vertical, 

 and the horizontal displacement therefore slight, but even so the 

 adjacent sedimentary beds of the Lost Soldier-Ferris district are 

 somewhat overturned. It seems very probable that this over- 

 thrusting continues eastward as far as the Freezeout Hills. West- 

 ward from the Ferris Mountains the folding changes into faulting, 

 but in this direction the amount of overthrusting is not so great as 

 to the southeast. 



The Sweetwater uplift, like the Rawlins uplift, is considered to 

 have been developed mainly in pre- Wasatch time, but it differs 

 from the Rawlins uplift in that the main deformation was followed 

 by later movements of considerable magnitude. The importance 

 and relations of these later movements are discussed below. 



AGE OF THE FOLDS 



The points to be brought out are two: (i) The folds of the 

 Lost Soldier-Ferris district were not produced by the same forces 

 that formed the Rawlins uplift, on which they were superimposed, 

 but were produced by the forces that formed the Ferris and Seminoe 

 mountains, to the north and northeast. (2) The Ferris and 

 Seminoe mountains are considerably younger than the Sweetwater 

 uphft, on whose south margin they rise, and probably represent a 

 relatively late readjustment along this margin. If these points 

 are established it follows that the folds of the Lost Soldier-Ferris 

 district are younger than the Rawlins uplift and also younger than 

 the main development of the Sweetwater uplift. 



I, With the geographic settins: of the Rawlins and Sweetwater 

 uplifts in mind (PI. Ill), attention should be directed to the align- 

 ment of the minor folds in the Lost Soldier-Ferris district. The 

 downfold that structurally separates the Rawlins and Sweetwater 



