120 ANNALS NEW YORK ACADEMY OF SCIENCES 



thickness before the Weber quartzite is reached. Tliis series is described 

 as consisting of numerous alternations of sandstones and sandy limestones, 

 many of the beds presenting for considerable dis'tances complete inter- 

 mediate stages between the more calcareous on the one liand and the 

 more arenaceous on the other. The presence of marine fossils through- 

 out the series, in the more calcareous layers, may be taken as good proof 

 that the deposit was formed in the sea and probably not far from the 

 shore. The lime muds from the great limestone area toward the east 

 became mingled with the sands of the shore, giving rise to the calcareous 

 sandstones which are so prominent a part of these intercalated beds. 

 The Mercur report leaves much to be desired in the matter of details 

 concerning the organic record. With the excellent exposures to be had 

 there and the obvious importance of knowing what fossils are imbedded 

 in these rocks, it is to be hoped that this section will soon receive the 

 careful study which it deserves. Enough has been done, however, to de- 

 termine the age of the series as a whole, and to warrant the comparison 

 that is here made. Following Spurr's report, we may assume that depo- 

 sition was continuous in the Oquirrh Mountains. The hiatus, therefore, 

 in the Wasatch and Uinta sections, represents a long erosion interval, 

 comparable in time to the period necessary for the deposition of the 6,000 

 to 10,000 feet of intercalated limestones and sandstones. It seems also 

 probable that it was even much longer, as will be brought out in the dis- 

 cussion of the Weber quartzite problem (see Fig. 4). 



PENNSYLVANIAN" STRATA 



Weber Quartzite 



Following the basal Pennsylvanian conglomerate in the Big Cotton- 

 wood section is a quartzite 1000 feet thick, in which no fossils were 

 found. The sand grains are of fairly uniform size, giving a rock of 

 even, rather fine-grained texture. The bedding is prominent and regular 

 in layers of moderate thickness. While the surface has a brownish ap- 

 pearance, the freshly broken rock is quite colorless. Eipple marks, cross- 

 bedding and other shallow water characters seem singularly wanting, yet 

 the fine detrital nature of the deposit certainly points to shallow water 

 deposition. In the upper portion, thin limestone layers are intercalated 

 between the sandy l)eds, and a succession of mainly cherty blue and white 

 limestones follow, making up several hundred feet in thickness. These 

 are well exposed on the north side of the canyon, just opposite the gov- 

 ernment forest station. Above these limestone beds, the quartzites reap- 



