150 
PRE-CAMBRIAN    GEOLOGY    OF    NORTH   AMERICA. 
Van  Hise,61  in  1893,  gives  the  following  as  the  ascending  succession 
in  the  iron-producing  part  of  the  Marquette  district:  (1)  Basement 
Complex,  consisting  of  granites,  gneisses,  schists,  and  greenstone  con- 
glomerates, the  whole  intricately  intermingled,  and  the  schists  in- 
truded by  the  granites  and  gneissoid  granites;  unconformity; 
(2)  Lower  Marquette  series,  having  at  its  base  a  conglomerate  and 
quartzite  formation,  upon  which  rests  an  iron-bearing  formation; 
unconformity;  (3)  Upper  Marquette  series,  which  looked  at  broadly 
is  a  great  shale,  mica  slate,  and  mica  schist  formation,  but  it  often  has 
at  its  base  quartzites  and  conglomerates,  and  several  hundred  or  a 
thousand  feet  from  its  base  an  iron-bearing  formation  similar  to  that 
of  the  Lower  Marquette  series.  Included  within  both  the  Lower  and 
the  Upper  Marquette  series  are  many  basic  intrusive  dikes  and  bosses 
of  diabase,  and  also  contemporaneous  volcanics,  which  are  largely 
tutfaceous. 
At  the  east  end  of  the  Marquette  district  is  the  Mesnard  series,  the 
position  of  which  has  not  yet  been  determined. 
Hulst,05  in  1893,  gives  a  resume  of  the  general  geology  of  the 
Menominee  district  as  explained  by  Brooks,  and  detailed  sections  of 
several  of  the  mines.  The  descending  succession  at  the  Millie  ore 
body  and  Chapin  mine  is  as  follows: 
Quartzite 
Jasper  
Quartzite 
Quartzite  and  jasper 
Quartzite,  slate,  and  jasper.. 
Slate 
Quartzite  and  slate 
Quartzite  and  jasper 
Banded  ore,  containing  Millie  ore  body 
Quartzite  and  slate 1 
Slate J 
Jasper 
Ore  body. 
Gray  slate 
Ore" 
Gray  slate „ '. 
Jasper  
Gray  slate 
Jasper  G 
Gray  slate 
Jasper 
Ore 
Gray  slate 
Limestone. 
Feet. 
140 
300 
55 
170 
185 
