WHITE.] FLEXURES. 51 



of Eed Eock Basin; bnt indications were observed that at least the 

 upper or southern branch of the flexure just referred to passes through 

 the mass to the northwestward. 



TJie Raven Ridge Flexure. — This flexure forms the southern and steeper 

 side of Eaven Park Uplift. It has already been mentioned as having a 

 dip of about 60° opposite the middle of Eaven Park, which dip rapidly 

 diminishes as the Uplift fades out both eastward and westward. Oppo- 

 site Eaven Park the strata of the Fox Hills, Laramie nnd Wasatch 

 groups are involved, the former constituting that part of Eaven Eidge 

 and the latter passing under the nearly horizontal strata of the Green 

 Eiver Group, by a monoclinal flexure. Although the flexure itself dimin- 

 ishes very rapidly to the northwestward, Eaven Eidge itself is con- 

 tinued much farther in that direction, where it is successively made up 

 of the strata of the Fox Hills, Laramie, Wasatch, and Green Eiver 

 groups; those of the first two groups leaving the ridge successively as 

 they spread out to the northeastward of the ridge. 



CONCLUDING EEMAEKS. 



The facts observed in, and in the neighborhood of, this district show 

 conclusively that, although the Uinta and Park ranges of mountains 

 have their axes at right angles, and are also separated by a consider- 

 able space of country, the two mountain systems are intimately con- 

 nected by continuous and interplicated displacements. These facts, to- 

 gether with the further one that there are no displacements between the 

 two systems that can in any way be regarded as breaking their connec- 

 tion, seem to suggest the approximately simultaneous elevation of both 

 systems. This idea is further strengthened by the fact that a mountain 

 axis may be traced, at least indistinctly, from the main range of the 

 Eccky Mountains, northwestwardly through the Park Eange, describing 

 a curve, which, if produced, would point in the direction of the axis of 

 the Uinta Eange. 



It has already been suggested that the various movements of dis- 

 placement in the Uinta system were not uniform in their rate of prog- 

 ress, and only in part simultaneous. It should, therefore, not be ex- 

 pected that the details of elevation of the two systems were all simultane- 

 ous with each other. It is nevertheless probable that the whole Eocky 

 Mountain system, including the Park Eange, as we find it developed in 

 Colorado, and the Uinta system, have had essentially a common phys- 

 ical history ; although each system presents some charaeteristics pecu- 

 liarly its own, or at least different from the other* 



