WASHAKIE BASIK 221 



silicified seam made tip of" casts of Goniohasis, so prevalent throughout tlie 

 'Jertiaries to the north, which have a general dip to the southward, but on 

 the spurs toward the river incline about 3° to the northwest. They are 

 underlaid by the red beds of the Vermillion Creek series, which are exposed 

 along the northern flanks of the ridge, and extend out into the country to 

 the east, Avhere they have a geheral dip of 5^^ to the northward. There is 

 apparently a non-conformity of angle between the overlying beds and 

 those of the Vermillion Creek Tertiary, though much less marked than 

 that observed at Elk Gap. To the northwest of Elk Gap, the strata 

 descend toward the basin, in w^hich, according to geologists who have visited 

 the region since our explorations of 1871, there exists a remnant of the 

 characteristic green clays and marls of the Bridger series. 



The characteristic exposures of the beds of the Green River series are 

 found in the Vermillion Bluffs, which bound the basin of Vermillion Creek 

 on the southeast. At the most nortlieasterly point of these bluffs visited 

 by us, about 15 miles from the canon of Vermillion Creek, they are 

 capped by a remnant of the AVyoming Conglomerate, which here consists 

 of a thickness of about 50 feet of structureless conglomerate, composed of 

 coarse pebbles of red quartzite. Beneath the conglomerate is a thickness 

 of 500 to 600 feet of calcareous beds, made up largely of the characteristic 

 paper-shales of the Green River series ; below, a thickness of about 800 

 feet of the characteristic red beds of the upper Vermillion series, underlaid 

 by coarse sandstones and gravel beds of a grayish-drab color, which extend 

 out over the basin, covering the upturned edges of the Upper Cretaceous 

 strata. At this point, the beds dip only about 2"^ to the east and south; but 

 toward Vermillion Creek CaGon, the easterly dip gradually steepens to 12'^. 

 The dividing line between the Green River series and the Vermillion beds 

 can be traced along the line of the bluffs, descending somewhat toward 

 the canon, while the summit of the ridge, which separates the basin of 

 Vermillion Creek and Brown's Park, to the east of the canon, is made up of 

 beds of white calcareous Tertiary, which slope off on the south of the ridge 

 into the basin of Brown's Park at an angle of 5° to 7°. On the crest of 

 this ridge, to the east of the canon, where, by the denudation of the Ter- 

 tiary beds, the underlying Triassic sandstones have been exposed, are 



