EUREKA MOUNTAINS. 3 



level, but by their broad, massive proportions, long, unbroken ridges, and 

 Alpine character, the boldest uplift on the Nevada plateau. Next west 

 from the Humboldt occurs the Diamond Range, followed by the Pinon 

 Range, with the broad Diamond Valley lying between them. Southward 

 the southern extremities of these two ranges enter the Eureka District and 

 form a part of its mountainous region. 



On the plateau, among the more marked exceptions to the long narrow 

 ranges which rib the surface of the country, may be mentioned the Rob- 

 erts Peak Group, connecting the Wahweah with the Pinon Range, the 

 White Pine Mountains, and the subject of the present report, the moun- 

 tains of the Eureka District. 



Eureka Mountains. The Eureka District forms a rough mountain block 

 standing out prominently by itself, except for its narrow connections with 

 both the Pinon and Diamond Ranges, almost as completely isolated from its 

 neighbors as the longer parallel ranges. As a mountain mass, however, 

 although well deserving such a distinction, it has never received any definite 

 appellation which would include all its members, it being made up of por- 

 tions of several ranges and short uplifted blocks sp intimately connected 

 and inosculated as to form both topographically and geologically a single 

 group, hemmed in on all sides by the characteristic detrital valleys. To 

 the north Diamond Valley, which may be taken as a type of the higher 

 valleys of the Great Basin, extends for over 40 miles in an unbroken plain, 

 the lowest part of the depression being covered in winter by a broad, shal- 

 low sheet of water, which, upon evaporation, presents during the greater 

 part of the year a hard, level floor, strongly impregnated with salt. Con- 

 siderable quantities of salt for metallurgical purposes have been collected 

 from the shores of the small lakes at the northern end of the valley. To 

 the south of the district lies the broad basin of Fish Creek Valley, con- 

 necting with Newark Valley on the east side of Diamond Range, while 

 the Antelope Valley cuts off" the Eureka District on the west side from the 

 neighboring mountains. All these valleys stand at about the same elevation 

 above sea level, and offer to the eye a monotonous olive-gray color derived 

 from a vigorous growth of the Artemcsia tridenlata which covers all the low- 

 lands except the central portions of the broader basins. 



