van  msE.]  LAKE    SUPERIOR    REGION.  193 
from  the  somewhat  regular,  little  altered  granite- gneiss  which  acts  as 
a  subsequent  intrusive. 
The  early  Canadian  geologists  used  the  term  Huronian  to  cover  all  the 
fine  grained  schistose  and  clastic  rocks  between  the  Keweenaw  an  or  Up- 
per Copper-bearing  rocks  and  the  Laurentian.  The  same  is  true  of  many 
of  the  American  geologists.  It  is  clear  that  the  fine  grained  crystalline 
schists  which  constitute  a  part  of  the  Archean  can  not  here  be  included. 
Huronian  can  include  only  that  part  of  the  Algonkian  between  the  Ke- 
weenawan  and  Archean,  and,  as  has  been  seen,  this  Huronian  is  sep- 
arable into  two  uncomformable  series.  On  the  part  of  the  Canadian 
geologists  of  late  there  has  been  a  tendency  to  restrict  this  term  to  the 
lower  series,  as  shown  by  the  exclusion  of  the  Animikie  from  the  Hu- 
ronian, but  if  this  is  done  the  greater  part  of  the  Original  Huronian 
must  itself  be  excluded  from  the  Huronian.  Upon  the  other  hand,  Irv- 
ing and  the  Profs.  Winchell  have  advocated  restricting  Huronian  to  the 
upper  series  alone.  The  recognition  of  a  general  stratigraphical  break 
in  the  rocks  heretofore  included  by  most  authorities  in  the  Huronian 
leads  to  the  natural  suggestion  that  for  the  superior  division  Upper 
Huronian  shall  be  used,  and  for  the  inferior  Lower  Huronian.  The  fact 
that  it  has  been  recently  maintained  that  in  the  Original  Huronian  area 
itself  both  of  these  series  exist  but  renders  this  suggestion  more  ap- 
propriate. Further  in  favor  of  this  position  is  its  conservative  char- 
acter, although  it  is  recognized  that  the  rules  of  good  nomenclature 
point  rather  to  the  restriction  of  Huronian  to  the  upper  or  lower 
series.  If  restricted  to  one  it  should  clearly  be  the  upper,  for  it  is  cer- 
tain that  the  greater  part  of  sediments  of  the  Original  Huronian  mapped 
in  detail  here  belongs.  Hence,  as  advocated  by  Alex.  Winchell,  is 
placed  as  an  alternative  to  Lower  Huronian  in  the  following  tabulation 
Lawson's  term  Keewatin.  This  term  was  first  defined  to  cover  a  series 
of  elastics  with  some  crystalline  schists  about  the  lake  of  the  Woods.  It 
was  later  more  clearly  defined  and  restricted  to  the  unmistakable  elas- 
tics and  altered  volcanics  about  Eainy  lake.  By  the  Profs.  Winchell  it 
was  applied  to  the  Vermilion  lake  iron-bearing  series,  which  was  be- 
lieved by  them  to  be  the  equivalent  of  the  Eainy  lake  Keewatin.  In 
many  respects  the  greater  part  of  these  series  is  like  the  Lower  Mar- 
quette, Felch  mountain,  Lower  Menominee,  Hunters  island,  and  Lower 
Kaministiquia  series.  If  this  supposed  equivalence  were  demonstrated 
it  would  be  preferable  to  adopt  this  term  to  cover  all  the  series  included 
under  t\  i  Lower  Huronian.  It  is,  however,  by  no  means  clear  that  the 
Keewat|  will  not  prove  to  be  a  complex  series,  just  as  have  the  Mar- 
quette i ;  nd  Vermilion  lake  rocks,  consequently  it  is  only  tentatively 
placed f  n  the  general  column.  One  other  term  has  been  proposed  for 
this  place,  Marquettian ;  but  this  term  is  objectionable  because  as  used 
it  included  both  Upper  and  Lower  Marquette. 
Lawson  has  proposed  the  term  Ontarian  to  cover  the  Keewatin  and 
Coutchiching,  It  appears  to  us  that  the  purposes  of  geology  are  bet- 
Bull.  86 13 
