220 DESCKIPTIVE GEOLOGY. 



the summit of the chff. Of these, the upper 950 feet have been referred to 

 the Green River series, and the remaining 1,050 feet, whose beds were 

 largely concealed by the ddbris accumulations of the slopes, have been 

 referred to the Vermillion Creek series. The section, in descending geo- 

 logically, is as follows : 



Green Biver series. 



Feet. 



Coarse brownish saudstone, with iutercalated browu calcareous shales 100 



White calcareous shales, with half inch seams ol' gypsum and a four-inch seam 



of agatized Unios , 45 



Drab concretionary limestone, with brown sandstone-shales 85 



White and brown argillaceous shales 120 



Eusty arenaceous shales 100 



Beds of soft light colored argillaceous and calcareous shales, .'■ome of which are 

 impregnated with carbonaceous material, and have a light-blue color on the 



weathered surface, containing also thin seams of gypsum 400 



White sandstones and clays 100 



Vermillion Creel( series. 

 Eeddish clayey arenaceous beds 1, 050 



About 7 miles south of Sunny Point, the dip suddenly becomes steeper, 

 and the Green River beds reach the level of the river on its western side. 

 From here to Elk Gap, there seems to have been a local disturbance 

 resulting in the flexure and probable dislocation of these strata, as seen on 

 the western side of the canon through which the river runs at this point. 

 The beds are mostly of loosely-aggregated grayish-drab sandstones, want- 

 ing in characteristic features. Just above the canon, the dip changes for a 

 short distance from south to north ; but, at Elk Gap, the beds dip again to 

 the southward at an angle of 10". At this point exists a singular non-con- 

 formity. The lower beds, which have been considered to represent the upper 

 part of the Vermillion Creek series, dipping at an angle of only 10° to the 

 south, are overlaid by a series of sandstones, having at the base a prominent 

 seam of red shale, which dips 29° to the south and west. Above these, at 

 some little distance down the river, are apparently conformable beds of fine 

 white calcareous and siliceous material, sloping off gently into the basin of 

 the Lower Snake and Yampa Rivers, which forms the easterly continuation 

 of the depression of Brown's Park. 



Godiva Ridge is capped by white calcareous beds, containing the 



