204 DESOEIPTIVE GEOLOGY. 



of the Upper Coal-Measures from the creKsts of tlie folds. They consist of a 

 lower series of calcareous sandstones and impure limestones, containing 

 some lignite seams, overlaid by a great thickness of remarkably fissile cal- 

 careous shales abounding in remains of fish and insects, which reach an 

 aggregate thickness of about 2,000 feet, and are characterized throughout 

 by their prevailing white color. The extent of the sea in which these beds 

 were deposited was somewhat less than that of the previous period, a strip 

 of land having been elevated above its level along the flanks of the Wah- 

 satch, and probably also a narrower strip along the shores of the Park 

 Range ; its beds, however, were deposited continuously over the ridge of 

 Vermillion Creekbeds, between the Bitter Creek Cretaceous uplift and the 

 Archaean body of Red Creek, and also probably connected, through the low 

 gap of the White River divide, at the eastern end of the Uinta Range, with 

 the region to the south, in which beds corresponding to these and to the 

 Bridger beds have been recognized, although their direct connection has not 

 yet been traced. There has been a slight local movement in these beds, 

 previous to the deposition of the Bridger beds, along the flanks of the Uinta 

 Mountains, but that this amounted to a!n actual non-conformity throughout 

 the basin we have only the negative evidence, that while there are gentle 

 undulations in the former, the beds of the latter, which have escaped ero- 

 sion, bear no evidence of having been disturbed, except locally, along certain 

 lines of fault. . 



The Bridger group consists of a thickness of about 2,500 feet of are- 

 naceous beds, with a small development of calcareous material, of a prevail- 

 ing dull greenish-gray color, characterized by the great quantity of verte- 

 brate remains which have .been buried in them. Its fauna, like that of the 

 former group, indicates a warm, semi-tropical climate. Its sea was of still 

 more limited extent than that of the previous period, and was probably 

 divided into two separate basins by the ridge, which connected the Bitter 

 Creek uplift with the Uinta upheaval at Red Creek. The level reached 

 by the upper beds deposited during this period is higher than the present 

 level of the Uinta Range along the course of Green River; but as no 

 remnant of these beds has as yet been discovered in the region, the actual 

 proof that they ever extended across the range at this point is wanting. 



