132 (1KOUH1Y OF THE EUltEKA DISTRICT. 



and southwest of Pinnacle Peak, the beds dipping to the southeast at a low 

 angle and striking northeast and southwest. These beds yielded the fol- 

 lowing forms: 



Thecia ramosa. Dystactella iusularis. 



Aulopora serpens. Conocardium nevadeusis. 



Chonetes deflecta. Loxonema subattenuata. 



Spirifera piiioneusis. Bellerophon perplexa. 



Atrypa retieularis. Tentaculites scalariformis. 

 Rhynchonella occidens. 



Nearly all these species occur in the shale belts of Atrypa Peak, Brush 

 Peak, and Combs Mountain, the exceptions being the three species, Thecia 

 ramosa, Aulopora serpens, and Dystactella insularis, which are, however, 

 characteristic of the upper Helderberg in New York and Ohio; Thecia 

 ramosa and Dystactella insidaris have only as yet been found at this one 

 locality at Eureka. A smaller but somewhat similar grouping of fossils 

 occurs in the limestone just west of Lookout Mountain, where they are 

 associated with Strophodonta canace, a species found by the writer in the 

 limestone at Treasure Hill, White Pine. 



On the west slope of Pinnacle Peak the beds dip toward the fault at 

 an angle of 10, reaching to within 150 feet of the summit and lying un- 

 conformably against the Eureka quartzite of the peak. Following the line 

 of the fault the beds trend off to the southeast, the quartzite belt gradually 

 narrowing until lost beneath the pumices, the Nevada limestone, on the 

 other hand, continuing southward in a low ridge bounded on the east and 

 west sides by igneous rocks. The beds exhibit much the same habit as 

 those to the northward, usually light in color and highly siliceous, but show- 

 ing more distinct lines of bedding. By reference to the map (atlas sheet xi) 

 the structure will be seen indicated by strikes and dips. South Hill, the 

 most prominent point on this southern extension, has a marked anticlinal 

 fold, the axis of the fold striking N. 40 to 45 east, with a dip of 15. 

 The brownish gray limestones are distinctly bedded and probably belong to 

 a somewhat higher horizon than any of those exposed in Grays Canyon. 

 South of the road, which traverses the ridge near its southern extremity, a 

 well defined but gentle synclinal fold may be seen crossing the ridge 



