TEUCKBE EANGE. 809 



of this bench are a immber of conical mounds, formed of nearly pure sel- 

 enite, from 6 to 12 feet in height and from 10 to 30 feet in diameter, and, in 

 general, having a truncated top, the sides broken by radial lines, cutting the 

 selenite into broad sections. On the top of many of these cones were aper- 

 tures several inches in width, extending downward a long distance, at least 

 as far as the eye could reach ; others were closed, but gave, when struck 

 with a hammer, a ringing, hollow sound. This selenite is-remarkably clear 

 and transparent, and so cleavable that thin sheets may be obtained 3 or 4 

 feet high by as many broad, a peculiarity taken advantage of by the early 

 settlers of this portion of the State to replace the broken panes of window- 

 glass in their houses. It is also exceedingly flexible, and, where exposed to 

 pressure, presents a wavy, folded structure. That the formation is the result 

 of thermal action, now extinct, there would seem to be no doubt. 



Returning to the southern end of the range, opposite the southeast 

 corner of Winnemucca Lake, where the granite bodies terminate, there are 

 found resting upon them highly-altered limestones and quartzitic schists, 

 which have been referred to the Triassic formation, although, it must be 

 stated, without any positive evidence of their age. They have been but 

 little studied, and indeed are so much disturbed by intrusions of the older 

 series of eruptive rocks, probably diabase, and still later by immense masses 

 of parti-colored rhyolites and black basalts, that their structural relations 

 would seem to be of little importance. Facing Winnemucca Lake is a long 

 ridge of these sedimentary beds, striking northwest and southeast, and dip- 

 ping steeply toward the lake, while to the southward, resting upon an iso- 

 lated body of granite, similar beds are found striking in the opposite direc- 

 tion, that is, northeast and southwest, and dipping eastward into the range. 

 The limestone belt is several hundred feet in thickness, of a dark-blue color, 

 and the specimen examined indicated the presence of but little magnesia. 

 The low depression of Nache's Pass separates topographically the already- 

 described portion of the range from the broad southern end, while the flow 

 of volcanic material which occupies the pass cuts it off geologically from 

 the Triassic region of Miner's Canon. 



Here at Miner's Canon occurs quite a large area of thinly laminated 

 quartzitic schists, slates, and metamorphosed argillites, carrying more or 



