CENTEAL AND EASTEEN NEVADA. 347 



almost perpendicular cliffs, in which a rude columnar structure is visible, and 

 which extend for a considerable distance north and south, curving slightly to 

 the eastward, and inclosing a semicircular basin at the head of the western 

 fork of the South Twin River; this one looks from the summit down an 

 almost sheer descent of three to four thousand feet. 



The rhyolite flow covers the long western slopes of the ridge, and prob- 

 ably extends along them to the north as far as that of San. Juan. 



The transverse ridge which connects the Toyabe with the next range 

 west, across the head of Reese River Valley, was not visited; rhyolite proba- 

 bly forms part of this range, however. 



BAEOMETEIOAL HEIGHTS. 



6,608, Barometrical station in Marshall's Canon. 



6,339, Clifton. 



7,512, Summit of road above Austin. 



8,256, Mount Prometheus. 

 10,994, Geneva Peak. 



6,400, Big Creek Canon mouth. 



8,922, Big Creek Pass. ' 



10,265, Big Creek Peak. 



9,610, Point of Rocks Peak. 



5,635, Martin's, Smoky Valley. 



6,782, Globe Canon mouth. 

 10,547, Globe Canon head. 

 11,237, Globe Peak. 



6,247, Kingston. 

 11,602, Bunker Hill, south peak. 

 11,735, Bunker Hill, north peak. 



8,075, San Juan. 

 10,982, San Juan Peak. 



9,057, Indian Pass. 



Note. — These lieiglits are based on the altitude of Camp Halleck, as determined 

 by Lieutenant G-. M. Wheeler. 



