152 GEOLOGY OF THE EUREKA DISTRICT. 



Rescue Hiii. Scarcely any mention need be made here of this locality as 

 the essential structural features and the list of species obtained in the upper 

 beds have been given in the chapter describing the Devonian rocks. The 

 hill is a block of limestone faulted over 1,000 feet below its true strati- 

 graphical position. It lies in the angle formed by the intersection of the 

 Rescue and Silverado faults. The beds lie inclined at a very low angle 

 presenting an excellent section for comparative purposes with beds found 

 elsewhere. Owing to the faulting of this block the variegated beds of Red 

 Ridge can not be followed on Rescue Hill, but to the north they are 

 easily traceable on Island Mountain and Sugar Loaf. 



Century Peak Ridge. Rescue Canyon severs the Century Peak Ridge from 

 the main body of Silverado Hills, a separation which is intensified by the 

 rhyolitic outbursts along the line of the canyon. Structurally the country 

 east of the canyon differs in a most striking manner from Red Ridge and 

 Rescue Hill, the horizontal, plateau-like character of the former giving way 

 to a narrow ridge with steep slopes. This ridge, of which Century Peak is 

 the highest point, presents a sharp, anticlinal fold, the beds dipping away 

 from the axis at angles varying from 70 to 80. The axis of the fold 

 follows closely the crest of the ridge, with a strike approximately north 

 and south. On the summit of Century Peak occurs one of the many 

 intercalated beds of quartzite found in the Nevada limestone, and here 

 forms the greater part of the west slope, extending down the ridge nearly 

 to the line of rhyolite. Just where this quartzite belt belongs in the lime- 

 stone was not determined, but the entire uplift is of Upper Devonian age, 

 as is shown by the lithological character of the beds. No fossils identify- 

 ing any special horizon were obtained, but those found were forms having a 

 wide vertical range, such as Atrypa reticularis. The corals belong to the 

 upper portion of the limestone and, although too obscure for specific iden- 

 tification, closely resemble the forms found in the limestones at the northern 

 end of the Mahogany Hills. Along the line of the Silverado fault the 

 rocks give evidence of considerable disturbance and folding with abrupt 

 flexures and breaks. For the greater part of the distance along the canyon 

 the Nevada limestone may be seen south of the fault, with the White Pine 

 shale on the north or opposite side of the gorge resting unconformably 



