368 DBSCEIPTIVE GEOLOGY. 



gives a better opportunity for estimating the thickness of the beds, but shows 

 httle other than quartzite. and slate as the material of which they are com- 

 posed. 



Foot-hill Section. — The Cambrian body, along the line of the foot- 

 hills, extends northward from Big Cottonwood to a re-entering angle of the 

 range at the canon of a little creek next south from Mill Creek. The north- 

 ern face of this angle is formed by a body of green clay-slates standing at 

 50'^. A little distance up the canon, on its north side, are found some blue 

 limestones, which were at first thought to be Silurian, but their fossils j)rovo 

 them to belong probably to the lower part of the Wahsatch limestone. 



Frodudus semireticulatus. 



Spirifer f 



Zaphrentis f 



Crinoids. 

 The Ute limestone was not actually found therefore at this point, but 

 may yet be there, or be concealed by a fault, as it can hardly be Avant- 

 ing. The Wahsatch limestone, which forms the greater part of the spur 

 between this little creek and Mill Creek, has no good exposures along the 

 foot-hills. The mouth of Mill Creek Canon, however, as well as the greater 

 part of its course above, is in the Weber Quartzite, which, at the mouth, 

 is composed largely of beds of white quartzite, like those in Upper Big 

 Cottonwood, and dips 50° to 55° north, corresponding in strike with the 

 direction of the canon. The beds, as exposed along the foot-hills, are evi- 

 dently very much compressed, and perhaps folded so as to be reduplicated, 

 while higlier up they spread out to the north, giving a much wider line of 

 outcrop, due in part to a less steep dip, and in part doubtless to some sec- 

 ondary folds or faults which have not been noted. 



About a quarter of a mile north of the mouth of Mill Creek Canon, in 

 a body of blue limestone above these quartzites, were found the following 

 fossils, which were regarded as indicating the lower beds of the Upper Coal- 

 Measure group : 



Spirifer cameratus. 



Spirifer octopUcatus. 



Spiriferina pulcJira. 



. Productus siihJiorridus. 



