EXDLici..] SWEETWATER REGION RESUME. 117 



crossed in the re^on of its lowest depression by a chain of metamorpliic 

 origin. This chain, so tar as the evidence collected permits us to speak, 

 is the direct result of an extensive upheaval along a curved line trend- 

 ing from north to south, southeast, and east. It seems smprising at 

 first that neither tlie older schists nor the prozoic granites are brought 

 to the surface by this extensive action. We must take into considera- 

 tion, however, the thickness of the youngest metamorphic series, as ex- 

 hibited farther nortlnvest, and it will be apparent that, unless consider- 

 able variations of the vertical dimensions occiu-red within a comi)ara- 

 tively sliort distance, the older series must remain hidden. Upon recog- 

 nizing the structure of the hills formed by this southeasterly outcrop of 

 metamorphics, we find in them a stratigraphical arrangement analogous 

 to that of the Wind lliver EaTige. Here, as there, we have a inedomi- 

 iiance of the one side of tlie anticlinal fold. In other words, the axis of 

 upheaval does not stand vertical. This fact is shown not only by the 

 non-ai)pearauce of the rex)etition of sti'ata on its ojjposite side, but is in- 

 dicated by the shape of the area of the metamorphics. Essentially this 

 forms a wedge, sho\\dng that the force applied was not an equal one at 

 all points. Were it so, then the outcrop would essentially represent a 

 symmetrical figiu'e. 



A second disturbance of metamorphic rocks is due to the more easterly 

 antich'nal upheaval. In this instance the i^rozoic granites appear to 

 have been affected somewhat thereby. Along a definite hue — one coin- 

 ciding with the longitudinal axis of the fold, we observe an ex])osure of 

 metamorphic beds which have undoubtedly been raised from their nor- 

 mal position by some locally-acting cause. This fold again may be 

 traced farther to the southeast, forming a curve nearly i^araUel with the 

 fh'st one. Where appearing in an unmistakable manner at the sm-face, 

 we find it to be analogous in direction, form, and results with the former. 

 Eeconstructing, then, a surface-pictiu'e of the region of the SAveetwater 

 prior to the invasion by Tertiary waters, we obtain a result totally differ- 

 ing from that i)reseuted to-day. Instead of a general slope to the east- 

 ward we find that the region now occui)ied by the valley was cut by two 

 ridges trending obliquely across it. Of these the western one was tlie 

 higher. For some distance near the line uoav occupied by the river 

 existed the divide fi-om which the drainage flowed to the northwest and 

 south. Farther downstream this line shifted toward tlie southeast and 

 the drainage was mainly to the north. Bare and rugged, as to-day, the 

 Granite Hills rose high above the siu-roimdiug country, never, i^robably, 

 having been entirely under water. This distribution of drainage ac- 

 counts for the primary erosion we find both to the north and south of 

 the Sweetwater region, more particularlj- in the former direction. The 

 dividing line was, in all probability, the eastward extension of the axis 

 along which the Wind Eiver Eange was elevated. Thus prepared, hav- 

 ing much of the seflunentary material removed by erosion, the successive 

 valleys were ready to receive the influx of Tertiary waters. The analogy 

 of the deposits with those found on Wind Eiver indicate that a former 

 connection between the two may have existed. They furthermore sub- 

 stantiate the conclusions drawn from pm^ely stratigraphical occurrences, 

 that the main drainage-connection of this region was to the north and 

 northeast. 



So far as the classification of the metamori)hics is concerned, which 

 here enter into consideration, we may refer them to the Huronian system. 



With regard to sedimentary formations, we may say that their appear- 

 ance, which in some hi stances seems contradictory, is fully explained 

 by the movements in which the older rocks have participated. When 



