4 GEOLOGY OF THE EUREKA DISTRICT. 



It is doubtful if any urea of equal extent iu Nevada possesses more 

 varied physical features with such strongly marked contrasts than the Eu- 

 reka District. In close proximity may be seen long serrated ridges, broad 

 summits, gently inclined tables of nearly horizontal sedimentary beds, with 

 abrupt escarpments along canyon walls, and highly tilted strata in rough 

 irregular spurs. And, as might be expected in a country made up of indi- 

 vidual blocks and parts of ranges and so interlocked as to form one broad 

 mass, the region is characterized by broad shallow basins, long narrow 

 ravines, and winding valleys, presenting a more than ordinarily accidented 

 surface with an intricate structure. Above the broad base of the surround- 

 ing sage-brush valleys rise many prominent peaks from 2,500 to 4,500 feet. 

 Diamond Peak, in the northeast corner of the district, at the southern ex- 

 tremity of Diamond Range, is the culminating point, measuring 10,637 feet 

 above sea level, and, with the exception of the high summits in the East 

 Humboldt Range, is one of the loftiest peaks on the Nevada plateau. 

 Prospect Peak, on the central ridge, and the second point in the district, 

 measures 9,604 feet, while Atrypa Peak, to the southwest on the same 

 ridge, has an altitude of 9,063 feet above sea level. Other points are White 

 Cloud Peak, the highest point on a broad plateau-like ridge, 8,950 feet; 

 Alpha Peak, 8,985 feet; and Woodpecker's Peak, 8,598 feet; all of them 

 being formed of sedimentary rocks. Among volcanic mountains may be 

 mentioned Richmond Mountain, just east of the town of Eureka, which rises 

 to a height of 8,392 feet, and Pinto Peak, an isolated cone in the center of 

 the district, reaches an altitude of 7,880 feet above sea level. 



Up to the time of the rapid development of the mining interests upon 

 Ruby Hill and Prospect Mountain, the slopes and ridges about Eureka 

 were exceptionally well supplied with an arborescent growth, a condition 

 which was due partly to the number of high peaks but in great part to 

 broad masses of mountains acting as condensers of desert moisture. To- 

 day, so great has been the demand for wood B,nd charcoal in the reduction 

 of lead ores, that the mountains are as bare of trees as any part of the 

 Great Basin. Several species of pines, dwarfed junipers (Juniperus occiden- 

 talis), and mountain mahogany (Cercocarpus Icedifoliits), which attains a 

 height of over 20 feet, are, or rather were, the prevailing trees, but are now 



