98 



ANNALS NEW YORK ACADEMY OF SCIENCES 



the shale beds by the writer was not rewarded by the discovery of Cam- 

 brian fossils within the Cottonwood district. At Ophir, in the Oquirrh 

 Mountains, and at Santaquin, the Middle Cambrian fauna which Dr. 

 Walcott found 100 feet above the OJenellus fauna in Big Cottonwood 

 Canyon are also found, and at least in one place at Ophir in the same 

 relation to the Lower Cambrian fossil horizon. A later search at Santa- 

 quin may reveal the Olenellus fauna there. 



If we accept Olenellus gilherti as the index fossil of the Lower Cam- 

 brian, then it seems that Dalv must be mistaken in the statement that that 



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FIG. 3. SECTION FROM BIG COTTONWOOD CANYON NORTHWARD TO WILLARD, 



BOX ELDER CO., UTAH 



Relation of the Algonkian (AL) slate and quartzite series to the Archean (AR) gneiss 

 and schist, and the Cambrian (C) quartzite and shale 



horizon is not represented by the Brigham quartzite and part of the over- 

 lying shale. That the shale beds of the great quartzite series below the 

 unconformity have yielded no fossils after careful searching by many 

 workers seems to argue against their Cambrian age. It is conceded by 

 everyone who has seen them that tlie sliales are well enough preserved to 

 show good fossils, if any had been imbedded in them. There is, of course, 

 still the possibility that fossils may yet be found in these lower shales, but 

 the probability is not great. That the unconformity represents only a 

 brief interval of time seems also to be incorrect from the manner in which 

 it is disposed over the truncated edges of the lower series, as represented 

 in the accompanying diagram. Fig. 3. 



