222 H. L. Smyth — Lower Menominee, etc. 



If they are not, then the C line has no magnetic representa- 

 tive on the eastern, nor the B line on the western limb of the 

 fold. The probability is moreover strengthened by the litho- 

 logical affinities of the upper portion of the Michigamme 

 jasper, — the C line rock, — in some phases, to the lower Mar- 

 quette magnetite actinolite schist, in others, to the specular 

 jasper. 



If then these two rocks are regarded as equivalents, the 

 lower Marquette quartzite may, with nearly equal probability, 

 be taken to represent the lower quartzite portion of the C line 

 formation. The whole of the lower Marquette series would 

 thus be represented by the highest member of the lower Menom- 

 inee. What then becomes in the Marquette district of the 

 great thickness of limestone, quartzite and eruptives which lie 

 below the Michigamme jasper in the Menominee, and how is 

 its absence to be accounted for ? 



The most probable explanation is that the pre-Algonkian 

 basement sank continuously in both districts, but that the 

 Marquette was initially the more elevated, and as a whole was 

 dry land while the lower quartzite, limestone and slates were 

 going down in the Menominee. The transgressive movement 

 from the south reached it when the lower portion of the 

 Michigamme jasper was being deposited. On this view the 

 lower Marquette quartzite would generally represent the lower 

 quartzite horizon of the Michigamme jasper. But in going 

 from the more distant areas of lower Marquette rocks toward 

 the lower Menominee the base would gradually become the 

 equivalent of older horizons in the latter until it passed finally 

 into the lower Menominee quartzite. The absence of the 

 lower Menominee formations from the Marquette district 

 would thus be explained by overlap of the Michigamme 

 jasper. 



The Mt. Mesnard series of quartzite, limestone and slates, 

 as described by Wadsworth,* in the eastern part of the Mar- 

 quette area, between the Cascade range and Lake Superior has 

 many points of resemblance to that part of the lower Menom- 

 inee series below the Michigamme jasper. Its age is still 

 in doubt, but if it should prove to underlie the lower Marquette 

 (Wadsworth's Republic Formation), its position would prob- 

 ably indicate the limit of the old Marquette highland on the 

 eastern side. 



Conclusion. 



The views here presented are based in part on fact, and 

 in part on inference, and it is desirable in conclusion clearly 



* Report of the State Board of Geol. Survey, Michigan, Lansing, 1893. Wads- 

 worth is inclined to regard it as of upper Marquette age. 



