CRETACEOUS UPLIFT OF BITTER CREEK. ' 227 



dip 4° to the northward, while the conglomerates slope only 1°. Through- 

 out this region, the beds of the Vermillion Creek series are exposed in gen- 

 eral in the deeper cuts, as indicated on the map, while those of the Green 

 River series, though not always recognizable, have been indicated as cover- 

 ing them on the higher benches, because their position and angle, as 

 observed on the surrounding points where they could be distinctly recog- 

 nized, would carry them over these benches. 



On the eastern borders of the Cretaceous uplift of the Bitter Creek 

 ridges, it has been impossible to trace with accuracy the dividing line 

 between the Tertiary and Cretaceous formations, owing to the close litho- 

 logical resemblance of the lower beds of the Vermillion Creek series with 

 those of the Laramie group, and to the fact that in both are found coal 

 seams, and that the difference of angle between the two, along this line, is 

 scarcely appreciable. It is evident, however, that detached portions of the 

 Tertiaries have been left overlying the Laramie beds; their continuity with 

 well-recognized Vermillion Creek beds to the eastward being broken by 

 erosion, and probably by some dislocation. To this fact, doubtless, is due 

 much of the confusion in the minds of palaeontologists with regard to the 

 age of the coal-bearing strata, in which fresh-water forms have been found 

 apparently mixed up with marine shells. To the northward, beyond the 

 limits of the map, the Vermillion Creek beds sweep around the exposures 

 of the Laramie series, and directly north of the Leucite Hills seem to be 

 entirely covered by the light chalky beds of the Green River series, which 

 come in contact with the latter, thus affording another argument in favor 

 of the supposed non-conformity between these two groups. 



Cretaceous Uplift of Bitter Creek. — This is the main pre-Tertiary 

 flexure in the basin country between the Rocky Mountains and the Wah.- 

 satch, and, as will be observed by reference to the map, is approximately 

 on the same north and south line as the Archaean body of Red Creek, and 

 the complicated system of folds and dislocations in the Uinta Range, along 

 the lower canon of Green River. This fact points to the probable exist- 

 ence of a north and south submerged Archaean ridge, or continuation of 

 the Red Creek body, which has been the determining course of the flexures 



