320 THE CAMBRIAN. [bull. 81. 



by the Wheeler survey. It is probable, however, that as in the case of 

 the Big Cottonwood section, Olenellus gilberti occurs at the base of the 

 shale, and the other two species at a higher horizon. At Antelope 

 Spring, in western Utah, there is a considerable development of the 

 Middle Cambrian zone corresponding to No. 21 of the Highland Range 

 section and a portion of the Prospect Mountain limestone of the Eureka 

 section. The section at this locality as measured by Mr. G. K. Gilbert 

 is as follows i 1 



Feet. 



1. Gray, massive limestone 200 



2. Blue gray, calcareous shale ; fossils (as corrected by C. D. 



W.); Acrothele subsidua, Jgnostus interstrictus, Olenoides 

 nevadensis, Piychoparia kingi, P. housensis, and Asaphiscus 

 uheeleri 200 



3. Gray limestoue, light and dark, chiefly massive 900 



4. Vitreous sandstone, umber-brown on weathered face; base 



not seen 1, 000 



Total 2,300 



No. 4 of this section corresponds to the basal quartzite of the Eureka 

 and Highland Range section, and No. 3 with the Prospect Mountain 

 limestone. No. 2 may correspond to the upper portion of the latter 

 limestone or to the lower portion of the Secret Canon shale of the 

 Eureka district. There is not enough known of the Antelope Spring 

 section to enable us to make any closer correlation. 



A comparison of the sections of Utah with those of Nevada shows 

 that in the former the earlier conditions of sedimentation were appa- 

 rently the same from the base of the Wasatch Mountains westward 

 into central Nevada. But during the deposition of the Middle and 

 Upper Cambrian rocks the immediate vicinity of the Wasatch was an 

 area of minimum deposition, while that of central Nevada was one of 

 maximum deposition of sediments. What the conditions were during 

 the deposition of late Middle and Upper Cambrian time in the Wasatch 

 area are unknown. The appearance of the rocks indicate a shallow 

 sea with very little deposition of sediment. 



IDAHO. 



What is known of the Cambrian rocks of Idaho is obtained from the 

 writings of Messrs. Bradley and Peale. The report of the former is 

 more that of an explorer who, passing over the ground, made such geo- 

 logic notes as time permitted. In the vicinity of Malade City, in south- 

 eastern Idaho, he discovered in a limestone resting on a quartzite, 

 fifteen species of trilobites of the genera Couocoryphe, Bathyurus, Di- 

 kelocephalus, Agnostus, etc., five brachiopods, two gasteropods, and 

 one pteropod. He referred this fauna to the Quebec group, and the 



' Report on the geology of portions of Nevada, Utah, California, and Arizona examined in the years 

 l«71 and 1872. Report on Geog. and Geol. Expl. and Survey west of the 100th merid., in charge of 

 Lieut. Geo. M. Wheeler, vol. 3, Geology, 1875, p. 167. 



