190  PRE-CAMBRIAN    ROCKS    OF    NORTH    AMERICA.  [bull.  86. 
whether  certain  of  the  iron  ranges,  as  for  instance  that  of  Teal  lake,  are 
Upper  or  Lower  Marquette,  although  it  is  very  probable  that  the  one 
mentioned  belongs  to  the  Upper.  Also  it  is  a  serious  question  what 
part  of  the  green  schists  and  schist-conglomerates,  some  of  which  are  cut 
by  granite,  belong  in  the  Lower  Marquette  series.  Eecent  work  ap- 
pears to  indicate  that  much  if  not  all  of  this  surface  volcanic  material 
belongs  here,  although  it  can  not  be  asserted  that  surface  volcanic  ma- 
terial does  not  occur  with  the  green  schists  of  the  Archean. 
SUCCESSIONS    AND    EQUIVALENTS    OF   THE    MENOMINEE   AND    FELCH    MOUNTAIN    DIS- 
TRICTS   SERIES. 
Passing  now  to  the  Menominee  and  Felch  mountain  districts,  infor- 
mation is  less  exact.  It  is,  however,  clear  that  in  both  of  these  areas 
the  fundamental  complex  is  found;  that  is,  the  granites  and  gneisses 
associated  with  crystalline  schists  having  the  usual  eruptive  contacts. 
Above  this  complex,  Pumpelly,  with  whom  this  whole  subject  lias  been 
discussed  and  who  has  great  familiarity  Avith  the  entire  lake  Superior 
region,  suggests  as  exceedingly  probable  that  in  the  Felch  mountain 
iron-bearing  series  only  the  equivalent  of  the  Lower  Marquette  occurs, 
the  upper  series,  if  it  once  existed,  having  been  removed  by  erosion; 
while  in  the  Menominee  district  both  representatives  of  the  Lower  and 
LTpper  Marquette  are  present.  The  Menominee  proper — that  is,  that 
part  of  the  area  which  includes  the  Chapin,  Ludington,  and  Norway 
mines,  those  in  which  a  cherty  limestone  is  found — are  Lower  Mar- 
quette, while  the  western  district,  including  such  mines  as  the  Com- 
monwealth, Florence,  and  many  others  occurring  in  the  upper  black 
slate,  are  Upper  Marquette.  That  between  these  two  is  a  probable 
unconformity  has  already  been  shown. 
EQUIVALENTS    OF    THE    BLACK    RIVER    FALLS    SERIES. 
The  Black  river  falls  iron-bearing  schists  of  Wisconsin  have  not  such 
observable  structural  relations  as  to  enable  one  certainly  to  determine 
their  position.  They  are,  however,  thoroughly  crystalline  schists,  and 
are  in  vertical  attitude.  On  these  grounds  they  are  provisionally 
placed  as  the  equivalent  of  the  Lower  Marquette. 
SUCCESSION  AND  EQUIVALENTS  OF  WESTERN  ONTARIO  AND  NORTHEASTERN  MINNESOTA 
SERIES. 
Combining  the  work  of  Dawson  and  Lawson  about  Eainy  lake  and  the 
lake  of  the  Woods,  Smyth  about  Steep  Kock  lake,  the  Winchells  and 
Irving  in  northeastern  Minnesota,  the  succession  appears  to  be  granite 
gneiss  schist  (Ooutchiching  ?)  complex,  unconformity,  Keewatin,  uncon- 
formity, Aniniikie,  unconformity,  Keweenawan.  There  are  also  \u 
this  district  great  masses  of  granite-gneiss  at  least  as  late  as  the 
Keewatin.  Included  in  the  granite  gneiss  schist  basal  complex  are 
onby  such  granite-gneisses  as  arc  more  ancient  than  the  oldest  sedi- , 
