102 



GEOLOGY OF THE EUEEKA DISTRICT. 



pect Peak and Hamburg Ridge, the erosiou of the Secret Canyon shale is 

 not so well sliown as it would be if the section had been drawn either to the 

 north or south of this point, but it is quite sufficient to bring out the promi- 

 nence of the Hamburg Ridge, Avhich is everywhere parallel to the main 

 ridge. Overlying the Hamburg shale occurs thePogonip limestone, in turn 

 followed by the Eureka quartzite, wliich occupy the long slope down to 

 the Hoosac fault. The- entire series of beds dips to the east, with angles 

 varying from 75^ to 85°. The section across these beds from the axis of 

 the fold is as follows : 



Prospect Midge Section. 



Eureka quartzite . 



PogoDip limestone., 



Hamburg shale. 



Hambui"; limestone . 



Secret Canyon shale . 



Prospect Mountain limestone. 



Prospect Mountain quartzite . 

 Total thickness _. 



Compact vitreous white quartzite, indistinct bedding 



Massive siliceous dark gray limestone, occasionally black lime- 

 stone, and a narrow band of quartzite midway 



Fine grained, evenly bedded, ash gray limestone, with more 

 massive layers near the summit 



Calcareous shales, passing into thin-bedded limestones; bands 

 of arenaceous sandstones and siliceous limestones 



Yellow argillaceous shale, with thin layers of gray limestone; 

 layers of chert nodules throughout the bed; cherty siliceous 

 bands near the top 



Dark gray granular limestone; only slight traces of bedding; 

 in places highly siliceous ; beds brecciated in the upper portion 



Argillaceous shales, yellow and brown in color 



Massive-bedded gray limestone 



Argillaceous shales, yelow and brown in color 



Massive, light gray limestones, passing into bluish gray and 

 bluish black beds, with occasional bands of black limestone 

 and light gray on top 



Fissile calcareous shales, with a thin band of green and drab- 

 colored argillaceous shale, and bands of ahaly limestone 



Massive gray limestones 



Argillaceous shales, ash gray in color: weathering red and yel- 

 low ; -layers of more compact limestone 



Light gray compact limestone, with thin seams of calcite 

 through the massive layers 



Red and brown arenaceous shales 



(Bedded vitreous quartzite; weathering dark brown; inter- 

 calated thin layers of arenaceous shales; beds whiter near 

 the summit and more uniform in texture 



Along the line of this section there has been less faulting, crushing 

 and local displacement than anywhere else on the ridge. Such local 

 disturbance as has taken place in the uplifted mass is more apparent in the 

 Prospect Mountain limestone than in the other horizons, partly owing to 



