158 



THE CAMBRIAN. 



•[BULL. 81. 



tine grained limestone, which contains abundant organic remains. 

 Two species were recognized, Dikelocephalus quadriceps and Conocep- 

 pkalites subcoronatus. 1 The reference of the fossils at Call's Fort and 

 Muddy Canon to the Quebec group was on the authority of the paleon- 

 tologists. More recent studies of this fauna, by Mr. Walcott, in con- 

 nection with the section at Big Cottonwood Canon prove that the fauna 

 mentioned at these localities is a portion of the Middle Cambrian fauna, 

 and that the Upper Cambrian strata are absent in the section by non- 

 deposition. 



In the Weber Canon region of the Wasatch Mountains, 800 to 1,000 

 feet beneath limestones referred to the Devonian, there were obtained 

 from a shaly limestone three forms of trilobites, which Mr. Emmons 

 thought probably indicated the horizon of the Potsdam group. One 

 was identified as Ogygia parabola and another as Crepicephalus allied to 

 C. diadematus. 2 



In the Oquirrh Mountains, at Ophir City, Utah, the section discloses 

 a thickness of about 400 feet of compact reddish white Cambrian 

 quartzite, above which are about 100 feet of greenish yellow clay slate, 

 in which numerous trilobites and primordial fossils occur. 3 



In the Schell Creek Mountains of Nevada there are limestones in 

 which primordial fossils have been found overlying heavy bodies of 

 quartzite. Among the organic remains of this range two species have 

 been identified : Crepicephalus {Loganellus) anytus and Lingulepis moeraS 



At the northern end of Pogonip Ridge, of the White Pine Mountains 

 of central Nevada, Mr. Arnold Hague mentions the presence of obscure 

 outcrops of mica slates and black arenaceous and argillaceous slates 

 and shales, in turn overlaid by an undetermined thickness of a compact, 

 vitreous, steel-gray quartzite, closely resembling the Cambrian quartz- 

 ites of other Nevada localities. Above this quartzite, and forming the 

 lower beds along the greater part of the ridge, occurs the Pogonip lime- 

 stone, which extends to the top of Pogonip Mountain, with a thickness 

 of from 3,000 to 4,000 feet of strata. They dip with an angle of 24° to 

 30° eastward. The lower beds are a fine-grained, somewhat siliceous, 

 black limestone, varying considerably in compactness and bedding, and 

 frequently passing into calcareous shales. Higher up in the series, they 

 develop more of a dark blue color, banded with layers of fine arena- 

 ceous limestones and occasional cherty bands a few inches in thickness. 5 

 From the lower beds of the limestone series he collected thirteen species 

 of Upper Cambrian fossils. 



Mr. Hague states that in Eureka mining district, northwest of White 

 Pine, tbe section of Prospect Mountain has the same lithologic habit as 

 that at White Pine, and carries throughout the greater part of the forma- 



'Op. cit., p. 410. 

 2 Op. cit., p. 377. 

 6 Hague, Arnold, and S. F. Emmons : 

 Clarence King, vol. 2, 1877, pp. 542,543. 



Descriptive Geology. 



3 Op. cit, p. 444. 

 4 Op. cit., p. 486. 

 U. S. Geol. Expl. of the 40th Par. ; 



