CHAPTEK VI. 

 GENERAL DISCUSSION OF THE PALEOZOIC ROCKS. 



Paleozoic shore-line. Between the Wasatch Range, which incloses the 

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

 central Nevada, the sedimentary beds which make up the greater part of 

 the meridional mountain ranges may, as regards their broader divisions, be 

 fairly well correlated with each other. In most instances paleoutological 

 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. Differences in the character of these sediments exist, but they 

 are mainly those dependent upon distance from land areas and depth 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 easteni Nevada the beds at many geological horizons indicate 

 deep water or off-shore deposits quite unlike those of corresponding age 

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

 evidences of ancient land areas may be found. In central Nevada, how- 

 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 parallel nearly 300 

 miles. It is by no means definitely established that the waters rolled un- 

 broken, from shore to shore, across this broad surface free from all land 



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