56 



GEOLOGY OF THE EUREKA DISTRICT. 



section is iiumljered from the top downward, the numbers inclosed in 

 brackets coinciding witli the specimen number in the collection. Through- 

 out the section the quartzite is for the most part vitreous without partings 

 parallel to the bedding, the coloring, however, being in nearly horizontal 

 planes, passing insensibly from one tint to another. 



1 (391) 10 feet of Avbite vitreons quartzite. 



2 (390) 10 feet grayish wbite, with segregation of fer- 

 riigiuous inateriiil. 



3 (389) 30 feet white and ^■itreolls. 



4 (388) 10 feet purple and white, vitreous. 



5 (387) I 30 feet iiurplish white, with three narrow bands 

 Tm (386) \ of dark gray granular quartzite. 

 C (385) 10 feet dark gray quartzite. 



7 (384) ) 20 feet white, banded \\\\h steel gray; dark gray 

 7« (383) \ quartzite bands in No. 7. 



8 (382) 20 feet dark gray and white, banded and mottled. 



9 (381) 20 feet light gray, tine granular. 



L^q\ [ 40 feet white and pinkish white. 



No. 11 (378) j 60 feet dark gray passing into light gray, with 



No. llrt (377) > bands more or less calcareous, weathering 



No. lib (376) ) red. 



No. 12 (375) 20 feet gray, having cross bedding brought out 

 by weathering. 



No. 13 (374) 20 feet dark steel gray quartzite, somewhat cal- 

 careous. 



No. 14 (373) 20 feet siliceous limestone. ) Pogonip 



No. 15 (372) 40 feet black compact limestone. ) limestone. 



No. 

 No. 



No. 

 No. 



No. 

 No. 

 No. 

 No. 

 No. 

 No. 

 No. 



No. 10 



The junction between the quartzite and the underh'ing limestone pre- 

 sents a sharp line of demarcation and indicates an alji'upt change in the 

 deposition of sediments. 



Although the Eureka quartzite is probably not more than a few hun- 

 dred feet in thickness, it can be estimated onlj" approximately, as an uncon- 

 formity exists between it and the next overlying group. Over the large 

 area covered by the exposures of the quartzite, evidences of denudation 

 \)v'wv to the deposition of the Lone Mountain limestone may be observed in 

 the mountains connecting the Fish Creek Range with Prospect Ridge, but 

 uo satisfactory estimate of the amount seems possible. Again, not only 



