THE CENOZOIC GEOUPS. 165 



carried away prior to the deposition of the middle beds. These facts are 

 illustrated in Fig. 15. I do not think that the base of the Bitter Creek series 

 is found exposed in this vicinity. The displacement here has evidently been 

 exceedingly complex, and its study is rendered difficult by unconformities, 

 and it is not always easy to determine to which class of agencies certain 



500 2000 1500 * NoTtll 



B. C. Bitter Creek Group. P. E. Point of Rocks Group. 

 Fig. 15. 



phenomena are due. In some portions of the line of displacement the beds 

 are marked by certain late Tertiaries of Brown's Park age as will be more 

 fully explained hereafter. 



West of Bishop Mountain, stretching across the many tributaries of the 

 Vermilion, there is a broad expanse of country where the beds of this age 

 are exposed in naked bad-land hills, and on either flank of the Aspen Mount- 

 ain uplift they are seen usually forming regions sterile and desolate. 



At the head of Little Bitter Creek there is a stretch of table land where 

 beds of Bishop Mountain Conglomerate are found. In the late redistribu- 

 tion of this conglomerate its materials have been carried quite over the line 

 separating the Bitter Creek from the Point of Rocks Group, so that the 

 junction is completely masked, but in the escarpment south of the plateau 

 which faces Quien Hornet Mountain the junction is well revealed ; and the 

 same is true farther to the north in lateral canons along the upper course of 

 Little Bitter Creek. The conglomerates found at the base of the series on 

 the flank of the Uintas are not seen on the flanks of the Aspen Mountain 

 uplift, and the Bitter Creek beds attenuate toward the north. From these 







facts I infer that the materials of the Bitter Creek Group were derived in 

 large part at least from the Uinta region, that is that the bad-land rocks 

 of Mesozoic Age were carried from the Uinta region and redistributed as 

 bad-land beds of the Bitter Creek period. 



In this great fresh water basin conditions favorable to the deposition of 



