vanhise.]  LAKE    SUPERIOR    REGION.  101 
quette  district.     It  lias  evidently  been  transformed  under  the  coopera- 
tion of  heat  and  partially  brought  into  a  plastic  condition. 
In  the  eastern  part  of  the  Menominee  region  the  rocks  found  com 
prise,  in  descending  order,  the  lake  Hanbury  slate  group,  perhaps  2,000 
feet  in  thickness;  the  Quinnesec  ore  formation,  which  comprises  mica- 
ceous and  argillitic  strata,  containing  ore  bodies,  not  less  than  1,000  feet 
thick y  and  the  Norway  limestone  belt,  at  least  1,000  feet  thick.  The 
Commonwealth  mine,  in  the  western  part  of  the  Menominee  district,  rep- 
resents a  higher  horizon  than  the  Quinnesec  ore  formation. 
Wii^CHELL  (1ST.  H.),111  in  1888,  describes  in  the  Marquette  district  the 
conglomerate  overlying  the  ore  and  jasper  formation  at  several  mines, 
and  places  the  overlying  quartzite  in  the  Potsdam.  North  of  Bessemer 
is  a  basal  conglomerate  of  the  Cupriferous  series  which  is  inferred  to  lie 
unconformably  upon  the  Gogebic  iron-bearing  rock.  This  conglomerate 
appears  to  be  the  equivalent  of  the  overlying  Potsdam  conglomerate  of 
the  Marquette  region,  which  makes  the  Gogebic  series  pre-Potsdain. 
The  granite  underlying  the  Huronian  slates  at  the  Aurora  mine  was 
originally  a  conglomerate,  but  it  has  acted  the  role  of  an  eruptive  rock 
and  has  flowed  over  the  adjoining  sedimentary  strata.  This  granitic 
conglomerate  is  parallelized  with  the  Ogishki  conglomerate  of  Minn- 
esota, and  the  overlying  sedimentary  rocks  are  the  equivalent  of  the 
Animikie. 
Winchell  (Alex.),112  in  1888,  finds  the  Marquette  iron-bearing  rocks 
to  have  the  same  geological  position  with  respect  to  the  crystalline 
schists  and  gneisses  and  to  consist  of  sediments  of  the  same  character 
as  those  of  the  Vermilion  range.  At  Deer  lake  furnace  is  a  peculiar 
conglomeratic  rock  which  appears  sedimentary,  but  is  much  altered  and 
has  a  quasi-eruptive  aspect.  This  conglomerate  is  like  that  of  Stuntz 
island  in  Vermilion  lake.  Near  Negaunee  is  an  argillite  which  has  a 
lower  dip  than  a  greenish  chloritic  quartzose  rock  across  a  railroad  from 
it,  and  the  two  are  therefore  unconformable. 
The  rocks  of  Marquette  are  older  than  the  Huronian  because  they 
differ  from  them  lithologically ;  because  the  Canadian  Huronian  is  imme- 
diately succeeded  by  the  Paleozoic  system,  while  the  Marquette  strata 
is  not;  because  some  evidences  are  found  that  in  the  Marquette  dis- 
trict there  is  an  overlying  unconformable  sub-Paleozoic  system;  and 
because  the  Marquette  series,  being  the  equivalent  of  the  Vermilion,  is 
older  than  the  Animikie  slates,  which  are  the  equivalent  of  the  Huro- 
nian. 
The  rocks  of  the  Gogebic  range  are  regarded  as  the  equivalent  of 
those  of  the  Marquette  region  because  they  resemble  them  lithologic- 
ally, and  because  they  are  in  an  analogous  position  to  the  crystalline 
rocks.  Between  the  Penokee  series  and  the  underlying  schists  there  is 
a  marked  unconformity,  the  Penokee  rocks  dipping  to  the  north,  while 
the  hornblende-schists  dip  to  the  south.  The  Penokee  series  strata  are 
lithologically  unlike  the  ore-bearing  strata  of  Gogebic,  Marquette,  and 
