182  PRE-CAMBRIAN    ROCKS    OF    NORTH    AMERICA.  [bull.  86. 
the  one  between  the  Lower  Vermilion  and  the  Upper  Vermilion  which 
bears  fragments  of  the  lower  series.  The  only  published  detailed  suc- 
cession of  the  Vermilion  series  is  that  by  Willis.  His  chloritic  schists 
and  jasper  (I,  n,  and  in)  belong  in  the  lower  series,  while  his  con- 
glomerate and  black  clay-slate  (V  and  vn)  belong  in  the  upper  series. 
The  position  of  the  magnetitic  quartzite  (iv)  is  uncertain,  while  the 
quartz-diorite  (vi)  is  probably  an  eruptive  rock. 
It  has  been  long  well  known  that  near  Port  Arthur,  Ontario,  the 
Animikie  and  underlying  Kaministiquia  series  are  unconformable. 
McKellar,  who  for  many  years  has  been  familiar  with  this  district,  has 
proved  this  conclusively.  Therock  series  here  un  conform  ably  underlying 
the  Animikie  are  identical  with  the  Vermilion  lake  iron-bearing  series. 
Considering  the  foregoing  evidence  and  the  complete  likeness  of  this 
lower  series  with  that  bearing  iron  at  Vermilion  lake,  it  can  no  longer 
be  doubted  that  there  is  a  great  physical  break  between  the  Animikie 
and  Lower  Vermilion  series  in  northeastern  Minnesota,  although  the 
equivalenceof  the  Animikie  and  Upper  Vermilion  may  yet  be  maintained. 
In  the  last  few  years  the  difference  of  opinion  has  been  sharp  as  to 
the  equivalence  or  nonequivalence  of  the  Animikie  with  the  Vermilion 
lake  and  equivalent  iron-bearing  series.     Irving  has  maintained  that 
the  Animikie  series  in  its  lithological  character  is  like  the  Penokee  and  I 
Marquette,  these  like  the  Vermilion,  and  therefore  the  Animikie  in  alii 
probability  the  equivalent  of   Penokee,   Marquette,   and  Vermilion. 
Alex.  Winchell,  having  visited  the  Lower  Marquette  series  and  seeing 
but  little  of  the  ground  in  which  the  Upper  Marquette  is  found,  and 
consequently  not  appreciating  that  in  area  and  in  volume  this  series 
probably  surpasses  the  Lower  Marquette,  has  maintained  that  the  Mar- 
quette rocks  are  the  equivalent  of  the  Vermilion  lake  iron-bearing  se- 
ries, but  that  the  Animikie  series  is  separated  from  that  at  Vermilion 
lake  by  a  great  unconformity.     He,  however,  aprneciated  that  in  the 
Marquette  district  are  certain  slates  which  in  lithological  character  are 
like,  and  might  be  equivalent  to,  the  Animikie.     Both  Irving's  and! 
Winchell's  positions  probably  have  an  element  of  truth  and  an  element; 
of  error.    The  Upper  Marquette,  Upper  Vermilion,  Upper  Hunter's 
island  (Ogishki),  in  their  lithological  characters  and  gentle  folding,  aret 
closely  analogous  to  the  Animikie,  and,  as  maintained  by  Irving,  are 
its  probable  equivalent;  while  the  Lower  Marquette  and  Lower  Ver 
milion  lake,  as  maintained  by  Alex.  Winchell,  unconformably  uuderln 
the  Animikie.    The  physical  break  within  the  clastic  series  in  the 
Marquette,  Vermilion,  Hunters  island,  and  Kaministiquia  districts  is 
then,  provisionally  identified  with  the  great  physical  break  recognizee 
by  everyone  at  the  base  of  the  Animikie. 
It  is  only  fair  to  say  that  Lawson  considers  the  unconformity  at  tin 
base  of  the  Animikie  at  a  higher  horizon  than  the  physical  break  de 
scribed  in  these  various  districts.  He  regards  the  Animikie  series  ai 
separated  by  another  great  unconformity  from  the  Upper   Marquette 
