PRE-CAMBRIAN NORTH AMERICAN LITERA TURE 749 



The Lower Marquette series in the western part of the Marquette 

 area consists in ascending order of 



1. A basal conglomerate, quartzite, quartz-schist — probably less 

 tlian I oo feet. 



2. An iron-bearing formation which may be divided into a lower 

 actinolitic schist and an upper banded red jasper and specular hema- 

 tite. The iron-bearing member has a maximum thickness of more 

 than looo feet. 



The magnetic jasper of Michigamme mountain by means of out- 

 crops and magnetic work, has been traced within one and one-half to 

 two miles of the iron-bearing formation of the Marquette series, and 

 the two are regarded as equivalent. If this be true, the Lower Mar- 

 quette quartzite may represent the lower quartzitic portion of the 

 Michigamme jasper formation, in which case the whole of the Lower 

 Marquette series would be represented by the highest member of 

 the Lower Menominee. 



The absence in the Marquette district of the equivalent of the 

 great thickness of limestone, quartzite, and eruptives below the Michi- 

 gamme jasper in the Menominee district is accounted for by supposing 

 that the Marquette area was more elevated, and that the transgression 

 of the ocean from the south reached the Marquette district when the 

 lower portion of the Michigamme jasper was being deposited. If the 

 above correlation be correct it further follows that the principal ore 

 formation of the Menominee has no equivalent in the Marquette 

 district. 



The Mount Mesnard series of quartzite, limestone, and slates, as 

 described by Wadsworth, in the eastern part of the Marquette area, 

 between the Cascade range and Lake Superior, has many points of 

 resemblance to that part of the Lower Menominee series below the 

 Michigamme jasper. The age of the Mount Mesnard series is still in 

 doubt, but if it should prove to underlie the Lower Marquette (Wads- 

 worth's Republic formation), its position would probably indicate the 

 limit of the old Marquette highland on the eastern side. 



COMMENTS. 



One point upon which additional evidence seems to be necessary 

 is that the slates bearing iron ores in the Menominee district proper 

 are really equivalent to the slates associated with eruptives farther 

 north. If these are not equivalent, it is possible that the Michigamme 



