166 GEOLOGY OF THE EUREKA DISTRICT. 



mately parallel with the trend of the canyon, which in turn coincides with 

 that of the Hoosac fault. The beds dip uniformly to the southeast with an 

 average inclination of 30. There is no direct means of determining the 

 base of the Lower Coal-measures anywhere in the Spring Hill block, 

 although the lower beds of New York Hill are probably not far from the 

 base of the epoch and occur as low down in the series as any strata to be 

 found along the east side of the Hoosac fault. Between the base of the 

 Lower Coal-measures at Diamond Peak and those of New York Hill some 

 resemblance may be traced, but lithological evidence is not of much 

 value, as the beds change rapidly in the character of their sedimentation. 

 On the west slope of New York Hill, Coal-measure fossils may be found 

 scattered through the beds and in one locality in a shaly limestone near 

 the summit the following species were collected : 



Fusilina cylindrica. Productus nebrascensis. 



Fusilina robusta. Productus prattenianus. 



Productus semireticulatus. 



At the extreme northeast end of New York Hill the drainage channel, 

 instead of following closely the line of the fault between the Silurian and 

 Carboniferous rocks, deviates to the northward, cutting through, for some 

 unexplained reason, the Lone Mountain strata, leaving a portion of the 

 latter limestone resting upon the slope of New York Hill on the south side 

 of the canyon. At the northeast end of New York Hill, but east of the 

 Silurian limestone, occurs 100 feet or more of thinly bedded clays, grits, 

 and argillaceous limestones, passing into purer beds, which are apparently 

 unconformable with the main body of limestones as they dip to the north- 

 ward, toward the fault, at an angle of 30. They occupy only a small area, 

 but it seems difficult to tell just how they are related to the main body of 

 limestone, or to connect them in the section with the southeasterly dipping 

 beds. That they are low down in the limestones is evident from the fact 

 that they can be con-elated with the beds on the east side of Eureka Can- 

 yon which lie near the base of the uplifted strata, dipping under Richmond 

 Mountain. Their geological position would be of no importance except 

 that it is in these beds that the fresh and brackish water shells occur which 

 have already been described in the chapter devoted to the Carboniferous 



