364 DESGEIPTIVE GEOLOGY. 



Primordial fossils. The Ute body shows a thickness of about 1,000 feet, 

 above which are from 100 to 200 feet of dark slates, containing fucoids, 

 very much metamorphosed, and in places quite crystalline, which, with a 

 body^ of white quartzite about 800 feet in thickness forming a saddle in 

 the ridge, constitute the Ogden Devonian. 



Emma Hill proper, in which are most of the important mines of the 

 district, is formed of the lower part of the Wahsatch limestone, here a 

 crystalline, generally white or whitish-blue rock, having a normal dip of 

 45° to the northeast. Its beds are generally massive, and the limestone 

 comparatively pure, though even the purest parts contain more or less silica, 

 which is left in the form of sand after the lime has been dissolved out. It 

 can also be detected by the microscope as forming small, rounded grains, as 

 in the Ute limestone. The mineral deposits, though at this point more 

 abundant in this limestone, are not confined to any particular bed or for- 

 mation, and, in regard to their distribution, it may be remarked that they 

 are mostly concentrated within a radius of 6 or 7 miles from Clayton's 

 Peak. They have followed pre-existing fissures and cracks in the beds, 

 generally in the neighborhood of lines of fault, and frequently spread out 

 in lenticular-shaped masses within the stratification. 



The fossil remains obtained near Alta were mostly too indistinct for 

 specific identification. They are : 



Spirifer cameratus. 



Spirifer planoconvexus. 



Spirifer, sp.? (like S. disjunctus). 



Syringopora^ sp.? 



Dipliyphyllum. 

 And from the bed above the Flagstafi" Mine : 



Spirifer lineafus. 



Spirifer, sp. ? (like S. disjunctus'). 



Atliyris subtilita. 



Euomplialus, sp. ? ' 



Zaphrentis, sp. ? (like Z. centralis). 

 Which in general seem to belong to the Lower Coal-Measure horizon. 



On the northern side of the ridge, east of the Eeed and Benson mine, 



