LAKE  SUPERIOK  REGION.  323 
Eparchean  interval.  Emphasis  is  placed  on  the  marked  lithological 
similarity  in  the  sedimentary  series  below  the  Eparchean  break  in 
the  Lake  Superior  and  Lake  Huron  regions  and  on  the  probable  cor- 
relation of  these  rocks  with  the  Original  Huronian  series.  Sum- 
marized in  tabular  form,  the  correlation  proposed  is  as  follows : 
Cambrian  (upper  division  or  Potsdam  only). 
Unconformity. 
Paleozoic -^  [Keweenawan. 
Algonkian <         Unconformity. 
[Animikie=Penokee==  Upper  Marquette. 
Eparchean  interval. 
Huronian =Upper  Keewatin  =  Lower  Marquette,  etc. 
Unconformity. 
Laurentian,  so  called,  granite  gneisses,  etc.  (intrusive  in  the  Onta- 
rian)  and  the  Carlton  anorthosites. 
Keewatin= Lower  Huronian  ^crystalline  schists  of 
south  shore  invaded  by  granite  gneisses. 
Unconformity. 
Coutchiching. 
Archean. 
Ontarian 
Coleman,337  in  1902,  discusses  the  Huronian  question,  his  argument 
being  mainly  against  the  correlation  of  the  Animikie  series  of  the 
Lake  Superior  region  with  the  Upper  Huronian  series.  Evidence 
that  the  Animikie  is  unconformable  above  his  Upper  Huronian  series 
is  summarized,  and  emphasis  is  placed  on  the  point  that  both  the 
Upper  Huronian  and  the  Lower  Huronian  differ  lithologically  from 
the  Animikie;  they  are  metamorphosed  and  schistose  as  compared 
with  the  Animikie,  and  they  are  much  folded  and  highly  tilted,  in 
marked  contrast  to  the  Animikie. 
Willmott,338  in  1902,  discusses  the  nomenclature  of  the  Lake  Supe- 
rior formations,  this  being  practically  a  consideration  of  Van  Hise's 
Iron-Ore  Deposits.*1  He  argues  principally  against  the  correlation  of 
the  Animikie  series  with  the  Upper  Huronian  of  the  Original  Huro- 
nian area.  He  states  that  there  can  be  no  doubt  that  Logan  in  1803 
included  within  his  Huronian  two  series — the  one  typically  repre- 
sented by  the  banded  jaspers,  the  other  by  the  slate  conglomerate  and 
the  jasper  conglomerate.  This  has  been  uniformly  followed  since  that 
time  by  all  Canadian  and  many  American  geologists,  the  vertical 
green  schists  and  their  interbedded  banded  jaspers  being  considered 
Lower  Huronian.  Willmott  doubts  the  advisability  of  attempting 
the  separation  of  the  green  volcanics  and  sediments  except  in  limited 
areas  of  economic  value.  Here  each  would  be  given  formational 
names,  just  as  Van  Hise  has  done  with  the  Ely  greenstone  and  the 
Soudan  iron  formation.  In  other  places  the  volcanics  and  eruptives 
will  take  the  name  of  the  sediment  with  which  they  are  associated. 
°  Van  Hise,  C.  R.,  The  iron-ore  deposits  of  the  Lake  Superior  region :  Twenty-first  Ann. 
Rept.  U.  S.  Geol.  Survey,  pt.  3,  1901,  pp.  305-434. 
