CAMBEIAN AND LOWER ORDOVICIAN. 99 



In the Eureka district of central Nevada the fauna is confined to a narrow belt of arenaceous 

 shales, with some intercalated limestone. The fauna consists of but seven species: Girva- 

 nella? sp. 1, Kutorgina prospectensis, Scenetta conula, Olenellus gilberti, 0. iddingsi, Olenoides 

 quadriceps, Ptychoparia suhcoronata, and Anomocare parvum. Of these, two species, Olenoides 

 quadriceps and Scenella conula, are found 500 feet higher up in the section. In the Highland 

 Range section of Nevada the rocks are essentially of the same character as in the Eureka section; 

 the two species, Olenellus gilberti and 0. iddingsi, occur in an arenaceous shale associated with 

 Cruziana sp.? In the Pioche section more limestone is interbedded in the arenaceous shale 

 and the fauna of the Olenellus zone is larger. It includes Eocystitesf? , LinguleUa eUa, Kutor- 

 gina pannula, Acrothele suisidua, Acrotreta gemma, OrtJiis JiigJilandensis, Olenellus gilberti, 

 ZacantJhoides levis, Crepicephalus augusta, G. liliana, and OryctocepJialus primus. Of these, 

 Kutorgina pannula, Acrothele subsidua, Acrotreta gemma, and HyolitJies billingsi pass to the 

 zone above that carrying Olenellus. In limestones of the Olenellus zone at Silver Peak, in 

 western Nevada, the following species were collected by Mr. Clayton: GirvaneUa? sp.?, Spiro- 

 cyathus atlanticus, EtTimopJiyUum meeJci, E. whitneyi, Kutorgina cingulata, HyolitJies princeps, 

 Olenellus gilberti. 



Detailed sections are given in a bulletin by Walcott^* published in 1886. In 

 1895 Walcott^^ stated: 



The only Lower Cambrian rocks of California known to me occur in the White Mountain 

 Range of Inyo County, east of Owens Valley, with the single exception of one small mass west 

 of Big Pine, which is in the foothOls of the Sierra Nevada. 



During the summer of 1894, accompanied by Mr. F. B. Weeks, I crossed the range over 

 the toll road leading from Big Pine to Piper's ranch, in Fish Lake valley, and penetrated into 

 it from the western side in Waucobi, Black, and Silver canyons. 



The ascending section exposed in the ridge on the north side of Black Canyon is as follows: 



Feet. 



1. Gray and yellowish arenaceous limestone, occurring in low hills above the Quaternary 200 



2. Massive-bedded compact fine-grained, often saccharoidal light-gray eiliceoiis and arena- 



ceous limestone (strike N. 10° W. (mag.), dip 20° E.). At 100 feet from base of this divi- 

 sion a dike of basalt 40 feet in thickness cuts through and displaces the limestone in the 

 vicinity of the dike, so as to give it a dip of from 70° to 80° E. Above the dike the dip 

 of 20° is very quickly resumed. At 160 feet from the base a band of white limestone 

 occurs, which contains numerous small concretions of limestone. At 230 feet above the 

 dike occurs a band of shaly limestone, which has buff -colored partings; and irregular, 

 buff-colored, sandy laminations occur in thin layers in the thick-bedded limestone. 

 No. 2 may be subdivided as follows: 



a. Light-gray and white limestone 500 



b. Buff and gray, more arenaceous limestone, with a band of cherty limestone 20 to 



25 feet thick at 125 feet from its base • 170 



c. Gray arenaceous limestone, cherty at top 115 



d. Shaly and thick-bedded sandy limestone, cross-bedded in places, with yellowish- 



buff layers, also with two bands of brown thick-bedded and shaly quartzite. . 145 



e. Massive-bedded coarse arenaceous gray limestone, passing into buff-colored and 



cherty beds above 85 



f. Buff-colored shaly limestone 5 



g. Bluish-gray banded limestone 30 



h. Gray arenaceous limestone, with bands of buff-colored, mostly thick-bedded 



limestone 70 



i. Thick-bedded bluish-gray limestone 10 



j. Brownish and buff-colored calcareous sandstone, with inclosed brecciated thin- 

 bedded brown sandstone 5 



k. Dark banded quartzite 30 



1 Massive-bedded gray arenaceous limestone 225 



1, 525 



3. Dark irregular thin-bedded siliceous slates with interbedded dark quartzitic sandstone (dip 



25°-30° E. (mag.), strike north and south) 635 



The section is terminated at this point by a fault line. 



