van  rise.]  LAKE    SUPERIOR    REGION.  181 
indicated  by  these  conglomerates  is  supported  by  Brooks's  major  di- 
visions of  the  Menominee  rocks.  His  inferior  Huronian  comprises  the 
lower  quartzite  of  great  thickness,  a  great  marble  formation,  and  the 
great  iron  ore  horizon,  consisting  of  magnetitic,  hematitic,  and  jaspery 
schists,  with  deposits  of  iron  ore.  In  this  formation  are  the  Norway, 
Quinnesec,  Lndington,  Chapin  mines,  etc.  Brooks's  middle  Huronian, 
presumably  above  the  unconformity,  includes  quartzites,  clay-slates, 
and  obscure  soft  schists.  Within  these  soft  slates  is  the  upper  iron- 
bearing  horizon,  including  such  mines  as  the  Commonwealth,  those  at 
Crystal  falls,  etc. 
In  the  Penokee  district  this  unconformity  is  represented  by  the  basal 
conglomerates  of  the  Quartz-Slate  member,  containing  numerous  frag- 
ments of  chert  and  a  few  of  jasper,  which  were  in  their  present  condition 
when  derived  from  the  Oherty  Limestone  and  Iron-bearing  members. 
The  lower  series  is  now  represented  by  the  Oherty  Limestone  member 
alone,  while  the  upper  series  includes  the  Quartz  Slate,  Iron-bearing, 
and  Upper-Slate  members. 
That  there  is  a  similar  unconformity  within  the  clastic  series  between 
the  Lower  Vermilion,  Hunters  island,  and  Lower  Kaministiquia  series 
and  the  conglomerates  at  these  places  bearing  abundant  material 
derived  both  from  the  ore-bearing  formation  and  from  the  green  schists, 
is  inferred  because  the  water- worn  fragments  of  schist,  jasper,  and  ore 
are  in  precisely  the  same  condition  in  the  conglomerates  that  they  are 
in  their  original  position.  In  none  of  these  places  have  actual  contacts 
been  described.  The  unconformity  is  further  indicated  in  the  Vermilion 
lake  district  by  a  strongly  developed  schistose  structure  in  a  nearly 
vertical  position  in  the  Lower  Vermilion  series,  while  the  overlying  con- 
glomerates at  places  on  the  islands  of  Vermilion  lake  are  found  to  be 
gently  folded. 
The  work  of  the  Profs.  Winchell  also  gives  evidence  of  this  uncon- 
formity. 1ST.  H.  Winchell,  in  tracing  the  flat  lying  Animikie  series  to 
the  westward  from  Gunflint  lake,  finds  that  it  becomes  more  steeply  in- 
clined and  takes  on,  at  times,  a  slaty  cleavage.  It  is  traced  as  far  as 
Agamok  lake,  near  the  great  Ogishki  conglomerate,  and  the  latter  is 
consequently  placed  with  the  Animikie.  To  these  statements  Alexander 
Winchell  agrees  so  far  as  to  Agamok  lake,  but  places  the  Ogishki  con- 
glomerate as  a  part  of  the  Lower  Vermilion  series,  for  he  traces  this  con- 
glomerate all  the  way  to  Vermilion  lake  and  he  recognizes  no  break  be- 
tween the  Vermilion  lake  conglomerate  and  the  Lower  Vermilion.  Tak- 
ing the  positive  evidence  given  by  Profs.  Winchell  and  disregarding 
their  partial  conclusions,  it  would  seem  to  indicate  that  there  is  a  gra- 
dation and  actual  continuity  between  the  flat-lying  Animikie  and  the 
conglomerates  with  a  vertical  superinduced  structure  at  Ogishki  and 
Vermilion  lakes.  That  between  the  Animikie  and  the  Lower  Vermilion 
there  is  a  great  physical  break  is  now  denied  by  no  one,  ami  if  the  lore- 
going  reasoning  is  true,  it  shows  that  this  break  is  arcontinuation  of 
