LAKE    SUPERIOR   REGION.  261 
Mousewake  Lake  and  Martins  Falls  hands  of  gneiss  arc  interstfatified 
with  the  schists,  and  just  at  Martins  Falls  the  latter  have  become 
entirely  replaced  by  red  and  gray  gneisses,  apparently  showing  a  con- 
formable passage  from  the  Hnronian  into  the  Lanrentian  rocks.  A 
similar  blending  of  these  formations  was  noticed  last  year  in  the 
neighborhood  of  White  Lake. 
Selwyn,  233  in  1873,  finds  between  Mille  Lacs  and  Separation  Lake 
and  the  Lake  of  the  Woods  a  series  of  parallel  bands  of  schistose  and 
slaty  layers  where  hitherto  was  supposed  to  be  almost  exclusively  the 
Lanrentian  gneiss.  The  facts  observed  lead  to  the  conclusion,  as 
stated  by  Bell,  that  the  two  series  are  in  conformable  sequence;  yet 
it  is  far  from  improbable  that  this  apparent  conformity  is  only  local 
and  that  a  more  extended  and  detailed  investigation  of  the  structure 
would  show  that  there  is  in  reality  a  very  considerable  break  between 
the  Lanrentian  gneiss  and  the  overlying  schistose  and  slaty  strata 
referred  to  the  Hnronian  rocks.  The  evidence  as  to  the  age  of  these 
latter  is  not  satisfactory.  They  resemble  as  closely  the  altered  rocks 
of  the  Quebec  group  as  they  do  the  Huronian  of  Lakes  Huron  and 
Superior. 
Bell,234  in  1873,  finds  in  the  country  between  Lake  Superior  and 
Lake  Winnipeg  rocks  belonging  to  the  Lanrentian,  Huronian,  and 
Upper  (  opper-bearing  series.  The  southern  shores  of  Mille  Lacs  are 
composed  of  Huronian  strata.  The  Lanrentian  gneiss  and  Huronian 
schists  at  many  places  alternate  with  each  other.  The  junction  of 
the  Lanrentian  rocks  on  the  north  with  the  Huronian  schists  on  the 
south  occurs  at  Rat  Portage  on  the  Lake  of  the  Woods.  The  two 
rocks  are  seen  almost  in  contact  with  each  other  and  have  the  same 
strike  and  dip.  The  rocks  classified  as  Huronian  consist  principally 
of  a  great  variety  of  crystalline  schists  in  which  a  greenish  color  pre- 
vails. In  addition  to  these  are  grayish  quartzites  and  schists,  some- 
times with  iron  ore,  diorites,  and  imperfect  gneisses.  The  areas  of 
granite  and  syenite  in  the  region,  which  vary  from  patches  to  areas 
many  miles  in  length,  are  ahvays  more  or  less  intimately  connected 
with  the  Huronian  bands.  The  distinction  between  the  Laurent  inn 
and  Huronian  rocks  is  chiefly  of  a  lithological  character,  the 
Huronian  appearing  to  succeed  the  Laurent  ian  conformably.  The 
Upper  Copper-bearing  series,  composed  of  slates,  marls,  sandstones, 
and  traps,  lie  nearly  horizontally  on  the  edges  of  the  Lanrentian  and 
Huronian  rocks. 
Hunt,235  in  1873,  applies  the  name  Animikie  group  to  the  lower 
division  of  Logan's  Upper  Copper-bearing  series  of  Lake  Superior 
as  it  occurs  at  Thunder  Bay,  where  it  includes  dark-colored  argillites 
and  sandstones  overlain  with  a  slight  discordance  by  red  and  white 
sandstones,  apparently  the  same  as  those  of  the  Keweenaw  district. 
The  dark-colored  sediments  of  the  Animikie  group  rest  directly  upon 
