OWI YU-KUTS PLATEAU. 271 



The crescent-shaped valley to the north of Garnet Canon is one, which 

 has been eroded out of the clay beds of the Colorado Cretaceous, and in 

 which only a few exposures of yellow and blue clays with thin sandstone 

 seams are found. As is generally the case with this formation, the surface 

 is covered by clayey soil, and the exact relation of these beds with the 

 crystalline rocks is consequently somewhat obscure. The valley is bounded 

 to the north by another sandstone ridge, curving outward to the north like 

 the Bighorn Ridge, which has been, from its position and lithological char- 

 acter, referred to the same group, namely, the Fox Hill series ; a few 

 fragments oi Baculites and Inoceramus were found in the clays at its base. 

 At Red Creek Gap, these heavy-bedded sandstones, showing a thickness of 

 several thousand feet, dip 25° to the northward, and may be traced continu- 

 ously westward to their contact with the Azoic body on the divide between 

 Red Creek and Green River, where, as already mentioned, they stand 

 almost vertical. To the north of this point, a second high ridge is formed of 

 yellowish-red and chocolate-colored sandstones and clays, dipping about 10° 

 northward, representing the overlying and unconformable beds of the Ver- 

 million Creek series which are exposed in the upper basin of Red Creek. 



In the bottom of Red Creek, just above the gap, are found other sandstone 

 beds conformable with those at the gap, containing Mactra arenaria, which 

 are considered to represent the lower part of the Laramie series. To the 

 east of Red Creek Gap, these sandstone ridges disappear under red and 

 chocolate clays and sandy beds, having a dip of 5° to 7° north, and forming 

 the higher points overlooking these valleys, which are supposed to be the 

 upper portions of the Vermillion Creek series. In the upper part of the 

 Eastern Fork of Red Creek, along the northern slopes of Bruce Mountain, 

 these Tertiary beds are concealed by forest growth and surface debris to 

 such, an extent that it was impossible to determine accurately the relations 

 between Tertiary, Cretaceous, and Archaean formations ; fragments of the 

 latter are found in the debris of the valley-slopes, and the position of the 

 Mesozoic beds farther eastward would indicate that they probably sweep 

 well round to the northward, though their continuous covering of Tertiary 

 renders this merely a matter of speculation. 



Owi-YU-KUTS Plateau. — Between Red and Vermillion Creeks is a pla- 



