DUCHESNE FORK. 313 



In this canon, a section is afforded almost at right angles to the strike, 

 and all the beds from the Weber Quartzite to the Tertiaries of the Uinta 

 Valley and the Wyoming Conglomerate are shown with more or less dis- 

 tinctness. The shalloAV dips of 5° and 10° continue from the head of the 

 canon down to within about 3 miles of Stanton Creek, the main western 

 branch of the Duchesne. On the broad flat surface of Rhodes' Spur, which 

 forms the western boundary of the main canon, the drab limestones of the 

 Upper Coal-Measures are left for a considerable distance in the shallower 

 dips. From them, the following Carboniferous species were obtained : 



Chonetes granulifera. 

 Mariinia lineata. 

 Syringopora multattenuata. 

 Syringopora f 

 Zaphrentis f 

 Lithostrotionf 

 Eiiomphalus f 



Of these fossils^ the two latter would seem to indicate a lower horizon 

 than the Upper Coal-Measure series, having been found elsewhere only in 

 the limestones of the Lower Coal-Measure group. 



The line of change of dip from 10° to 45° south is marked by the east 

 and west ridge, which borders Stanton Creek on the north, and the effect of 

 this change of dip is seen in a bend of the canon, where the stream has been 

 deflected from its course by striking the face of a harder, more resisting bed. 

 Stanton Creek runs approximately in the strike of the steep-dipping beds of 

 the southern flanks, and is apparently worn out of the softer shales of the 

 Permo-Carboniferous. The ridge to the south of this creek affords an excel- 

 lent section of the massive buff and cross-bedded red sandstones of the Tri- 

 assic, which are here also developed in an unusual thickness, dipping 45° 

 south, while the next parallel creek to the south is cut through the shale beds 

 and limestones of the Jurassic. Beyond this, the lower beds of the Creta- 

 ceous, including the white sandstones at the base of the Colorado group, are 

 found dipping conformably at 45° to the south, and overlaid unconformably 

 by the horizontal beds of the Uinta Eocene, which form the mass of Black-tail 

 Mountain. In the curvings of the ridge, which separates this stream from 



