OUTLINE OF THIS MONOGRAPH. XXVII 



Marquette iind Upper Marciiietto series, ;\nd between the uucout'ormable Lower Marquette scries and 

 the Archeau. Alter tbe last period of dynamic raetamorpbism it is believed that the crystals of horn- 

 blende, garnet, staurolite, andalusite, and chloritoid, which are now unstrained, developed, under 

 quiescent conditions. The metamorphism is much more i)rofound in the western part of the district 

 than in the eastern and central i)arts. This variation in metamorphism corresponds with the closeness 

 of folding;. 



During and subsequent to tlie later folding of the district the area has undergone vast denudation. 

 The character of the folding .shows that great mountaiu masses must have been produced, which have 

 been now reduced to approximate plains, so that the district is merely bluffy. 



The Lower Marquette and Upper Marquette series are correlated with the Lower Huronian and 

 Upper Huronian series of the north shore of Lake Superior. They are also correlated with the Lower 

 Menominee and Upper Menominee series. The correspondence of the formations of the Marquette 

 series to those of the Menominee series is only approximate. 



