226 DESCIilPTlVE GEOLOGY. 



bird-bones were found in the gravelly strata, unfortunately not sufficiently 

 well preserved to permit the identification of their species. In general, 

 the beds of this formation, as far as observed, are singularly barren of fossil 

 remains. 



To the northwest of Diamond Peak, the Tertiaries reach a very con- 

 siderable height, covering the edges of the Upper Coal-Measure lime- 

 stones, and are capped by beds of the Wyoming Conglomerate, which 

 also form the surface of the broad plateau of Bishop's Mountain. 



From a little west of Bishop's Mountain, whose meridian represents 

 approximately the divide between the eastern and western Tertiary basins, 

 the strata incline gently to the east, descending into the semicircular basin 

 at the head of Red Creek. The beds exposed in this basin are largely 

 coarse red and chocolate-colored sandstones, containing more or less admix- 

 ture of clayey material. These beds form the base of the line of bluifs 

 extending from Bishop's Mountain to Quien Hornet Mountain, which 

 encloses the basin on the north. In the upper part of these bluffs, they are 

 overlaid by the beds of the Green River series, which are probably non- 

 conformable, although no direct discrepancy of angle was observed. The 

 angle of dip of the Vermillion Creek beds in this basin is about 5° to 7^^ to 

 the north, while the underlying Cretaceous rocks dip 25° at the gap of Red 

 Creek. The Tertiaries extend high up on to the hills on either side of this 

 gap, covering the edges of the Cretaceous strata, and in the high hills to 

 the Avest of the gap have a dip of 10° to 15°, which points to a probable 

 movement in these beds in connection with the faulting of the Archaean 

 body, which will be noticed farther on. From the basin of Red Creek 

 northward to Quaking Asp Mountain extends a high plateau region, whose 

 continuity is only broken by the deeply-cut valleys of Sage Creek and the 

 southern branches of Bitter Creek. Its surface is covered by debris result- 

 ing from the decomposition of the Wyoming Conglomerate, which, it may be 

 supposed, once spread out as a sheet over this whole region, but which has been 

 indicated on the map only at those points where its beds have been observed 

 in an undecomposed state. It lies unconformably over the Tertiaries of the 

 Green River and Vermillion Creek groups, as observed on the northern 

 flanks of Quien Hornet Mountain, where the buff limestones of the former 



