DlSTKlBrTlO^ Ol' THE PALEOZOIC. 205 



if not far beyond. Throutiliout this entire distance, wlierever they have 

 been studied, these limestones maintain a oreat thickness of strata. At the 

 southern end of this belt near Quartz Peak, the Silurian and Devonian 

 limestones are estimated at (!, 400 feet, and at Ravens Nest, just south of 

 the Huml)oldt River, the estimate gives f),")!)!) feet, while at Eureka thev 

 present even a o-reater thickness. 



As yet we know but little about the occurrences and distriliulion ot' the 

 Hiamond Peak (luartzite. According to the section at Quartz Peak it is 

 wholly wanting-. In the I)iamond Range at Eureka, it attains a thickness 

 of 3,000 feet; on the opj)osite side of tlie valley in the Pinon Range it can 

 not measure less, ;md at Ravens Nest it attains a development of 7,000 

 feet. In the northern part of Nevada we see an enormous develo]>ment of 

 arenaceous l)eds se|)arating a l)e\'oin"an from a ( 'ailxmifei'ous fauna. This 

 material thins out to the south, and in place of it we iind a contiinious 

 limestone IxxK' extending all the wav from the iMu'eka (piartzite we]] 

 up into the Carboniferous, without anv well detined intervening sili- 

 ceous horizon. Too few o])servations have been made to determine 

 the geological history or geograj)hical distribution of the Upper 

 Silurian and Devonian rocks. As to the cliaracter of their .sedi- 

 mentation eastward, the thickening or thinning out of strata, or their 

 lithological transitions, we know but little. It is a most signiticant fact, 

 and one liy no means ea.sy to explain, that the entire series of beds included 

 within the second period in which the Paleozoic rocks of Eureka have Iteen 

 classed, based upon their physical liistorv, .should appareiitlv be wanting 

 over such large areas in Ttali and eastern Nevada. in other localities, while 

 they may not be wholly wanting, they ap})ear to be represented by thin 

 beds of Lone ^lountain strata, identitied by a stray Hali/sitcs, and the Devo- 

 nian 1)\' an occasional Afri/pa. 



Another interesting fact as regards the position of these rocks is this: 

 Notwithstanding the enormous thickness of the llp])er Silurian and Devo- 

 nian beds at Eureka, the .same i-elative position which has been observed in 

 so many places elsewhere, with the Coal-measures resting upon the under- 

 lying Pogonip, may be seen here, the F))per Silurian and Devonian being 

 absent. The occurreiirc of the two limestone bodies Iving in juxtaposition 

 may be .seen all along the east l)ase of Pro.spect Kidge, wiiere the lloo.sac 



