H A ? T K R y I . 

 GENERAL DISCUSSION OF THE PALEOZOIC ROCKS. 



Paleozoic Shore-line.— Betweeii the Wasatcli Raiigc, which iiicU>ses the 

 Great Basin <iii the east, and the western border of the Paleozoic area in 

 central Nevada, the sedinientarv beds which make np the greater part of 

 the meridional mountain ranges may, as regards their Ijroader divisions, lie 

 fairly well correlated with each other. In most instances paleontological 

 evidences are sufficient to determine at least the age of one or more of the 

 great bodies of limestone usually found in these mountain uplifts, and the 

 sequence of strata correlates the geological position of overlying and under- 

 lying beds. Diifereuces in the character of these sediments exist, l)nt they 

 are mainly those dependent upon distance from land areas and de])th of 

 water in which the material was originally deposited. Along- the Wasatch 

 the sequence of strata exhibits much the same physical conditions of deposi- 

 tion, and the horizons may be recognized and their positions determined in 

 great measure by similarity of sedimentation. Over a large part of central 

 Utah and eastern Nevada the beds at many geological horizons indicate 

 deep water or otf-shore deposits quite unlike those of coiTesponding age 

 found both to the east and west. Here and there over this region some 

 e\ddences of ancient 4and areas may be found. In central Nevada, liow- 

 ever, there occurs throughout the beds abundant evidence of deposition 

 in shallow seas. The western limit of this Paleozoic ocean across the 

 broadest expansion of the Great Basin was not far from longitude 117° 30'. 

 In width it measured along the line of the fortieth j)arallel nearly 300 

 miles. It is l)y no iik-mus definitely estalilished that the waters rolled nn- 

 l)roken, from shore to shore, across this br()ad snrfiicc free iVoin all l;iiii] 



