HIGHLAND RANGE. 187 



Subsequently, during the summer of 1885, Mr. C. D. Walcott studied 

 the structure at Pioche, and also made an extended examination of the Cam- 

 brian and Silurian rocks of the main uplift of the Highland Range. He 

 estimated about 7,000 feet of strata between the summit of the Prospect 

 Mountain quartzite and the base of the Eureka quartzite, as against 9,000 

 feet at Eureka. Between Bennett Spring and Stampede Gap the lower mem- 

 bers of the group were carefully measured, the section presenting the beds 

 more in detail and showing greater variation of sedimentation, with more 

 interbedded siliceous material than observed in the corresponding horizons 

 at Eureka. Detailed lithological sections, however, across the Cambrian 

 rocks are perhaps of little value, owing to the rapid changes in the charac- 

 ter of the beds. Sections made across Prospect Mountain show considera- 

 ble difference in detail, but agree substantially in general features. The 

 section at Bennett Spring is as follows :' 



Feet. 



1. Dark reddish brown quartzite, evenly bedded and ripple-marked in places . 350 



2. Bluish gray limestone 35 



Fossils : Olenellus gilberti. 



3. Buff argillaceous and arenaceous shales, more or less solid near the base 



and laminated in the upper portions 80 



Fossils: Annelid trails and fragments of Olenellus in the lower part; 

 higher up the heads of Olenellus gilberti and 0. iddingsi occur in 

 abundance. 



4. Light colored gray limestone and bluish black limestone 16 



5. Sandy, buff colored shale 40 



Fossils : Annelid trails, Cruziana, sp. ? 



6. Dark bluish black limestone 46 



7. Finely laminated buff argillaceous shale 80 



Fossils : Hyolithes billingsi and Ptychoparia piochensis. 



8. Gray to bluish black compact limestone 18 



9. Buff arenaceous shales 64 



10. Compact cherty limestone 



11. Compact shaly sandstone in massive layers 40 



12. Hard siliceous gray limestone, almost quartzite at base 12 



13. Yellow to buff sandy shales . , 70 



14. Bluish black limestone 



'Second Contribution to the Studies on the Cambrian Faunas of North America. U.S. GoL Surv. 



Bull. No. 30, 1886, p. 34. 



