78 GEOLOGY OF THE EUEEKA DISTRICT. 



nearly 5,000 feet of strata. No line of demarcation can be drawn 

 here between the Lone Mountain and Nevada epochs. Fossils were 

 rarely met with except in well denned strata, separated by long ver- 

 tical intervals. The Trenton horizon, which is well represented, is esti- 

 mated at 300 feet in thickness, resting immediately upon the Eureka beds. 

 From the top of the Trenton the section across the beds is strikingly similar 

 to those observed at Atrypa and Brush peaks. Careful estimates place the 

 fossiliferous shale at 1,700 feet above the Trenton or 2,000 feet above the 

 Eureka quartzite. This is the same vertical distance above the quartzite 

 assigned to the shale belt at Atrypa Peak, although at the latter locality 

 the Trenton limestone is not recognized either by its physical features or 

 its organic forms. From the shale belt to the top of the ridge the only 

 species secured were corals having a wide vertical range or else fragments 

 too imperfect for specific description. A comparison of the species obtained 

 in the three shale belts, taken together with the stratigraphy of the beds, 

 proves without much doubt the equivalency of the Combs Mountain shale 

 with those at Atrypa and Brush peaks. 



In the County Peak body of limestone the lowest organic remains 

 obtained occur midway in the siliceous limestone beds of No. 6, of the 

 County Peak section (p. 68). Here the gray and blue limestone of No. 

 8 is assigned to the base of the Devonian, which places the fossil-bearing 

 bed about 1,000 feet above the Silurian. The species recognized are 

 Edmondia pinonensis, Atrypa reticularis, Spirifera sp. ?. and Cladopora sp. I. 



Passing upward for 2,000 feet above this last bed, or 3,000 feet above 

 the base, and in about the middle of the great limestone belt (No. 2), there 

 occurs in a thinly bedded bluish gray limestone an interesting grouping of 

 species characteristic of the middle Devonian, or rather a mingling of 

 species from both upper and lower horizons. The bed, owing to its 

 marked lithological features, may be traced by the eye for long distances 

 along the slope of the mountains. At Woodpeckers Peak, where the col 

 lection was made, the fauna is by no means as large or as varied as that 

 found in the lower shale belt. While many species are identical with those 

 found at the lower horizon, and present a decided Lower Devonian aspect, 

 the greater part of them are common to both Upper and Lower beds. It is 



