THICKNESS OF POGOXIl' BEDS. 123 



comes in ;i sliar|) iiuticliiu', Ixivoiid which the beds dip uiiitonnly to the 

 west. At tlie western end nf tliis ridge occurs n small knoll or hill of Eureka 

 quartzite, its g-eoloji'ical [)o.sitiou being" determined by the Itccrptdcidifcs fauna 

 immediately underlying it. 



At the eastern end ot" this ridge, just west of Wood Cone, a fauna was 

 obtained which indicated a horizon not far above the base of the Pogonip, 

 being largely made up of species found near the summit of the Cainbi-ian, 

 associated with others never as yet recognized below the Pogonip. It is a 

 fauna charai-teristic of the lower portions of the epoch and (juite like a 

 grouping found on the east side of Hamburg Ridge. In other words, they 

 may be correlated with the transition beds just above the Ilanilmrg shale. 

 Many of the species also characterize the Pogonip of White Pine. Among 

 the species identified were the following: 



Liiigiilf|iis iiKi-ra. Orthis lianiburgeusis. 



Liugiila iiiaiiti(;iila. Triplesia calcil'era. 



Lepta'ua mclita. Bathyurus cougeiieris. 



Illa'iiurns cuicUeiisis. Bathyurus tuberculatus. 



No accurate measurements of the Pogonip along this ridge can be 

 made, owing to the great irregularities of dip and strike, but it is })robable 

 that the beds exceed 3,000 feet in tliickness. From the fauna obtained 

 just below the Eureka quartzite, and that from the base of the limestone 

 west of Wood Cone, it is evident that the entire development of Pogonip 

 is represented in this ridge. Tliis gives a somewhat greater development 

 for the epf>ch than has been recognized east of the Prospect Uidge, but, on 

 the other hand, it does not reach the very great thickness found on Pogonip 

 Mountain at White Pine, estimated at 5,000 feet. 



REGION BF.rWKEX I'l.SH CKEEIC ilOtlNTAIXS AND PROSPECT KIDOE. 



This region possesses .some distinctive features unlike eitlu'r of the 

 mountain blocks that adjoin it, yet at the same time it shows the iniiuence 

 of the forces that uplifted Prospect Ridge on the northeast and Fish Creek 

 Mountains on the southwest. It is .sharplv defined from Prospect Ridge in 

 geological stnicture by the Sien-a fault, which brings the Silurian up 

 against the lower Cambrian of Pn)spect Ridge. The anticlinal structm-e 



