.       LAKE    SUPERIOR   REGlOtf.  293 
Mackenzie  station.  The  unconformity  between  the  Upper  Huronian 
and  the  Keewatin  and  Lower  Huronian  rocks  is  evidenced  by  the  atti- 
tude of  the  beds  and  by  conglomerates  observed  at  many  places. 
Conglomerates  at  the  contact  with  the  Lower  Huronian  graywackes 
are  found  in  the  explorations  south  of  Loon  Lake  and  in  the  area  to 
the  southwest,  at  the  contact  with  the  Keewatin  in  the  vicinity  of 
Current  River,  and  at  the  contact  with  the  granite  about  2J  miles 
south  of  milepost  110  on  the  Canadian  Pacific  Railway.  The  uncon- 
formity between  the  Keweenawan  and  the  Animikie  is  not  clearly 
apparent  in  difference  in  dips,  which  are  nearly  the  same,  but  the 
base  of  the  Keweenawan,  when  followed  for  a  considerable  distance, 
may  be  found  to  rest  successively  upon  the  different  members  of  the 
Upper  Huronian  series  and  upon  the  Lower  Huronian  series.  Near 
Deception  Lake,  south  of  Loon  Lake  station,  the  discordance  in 
structure  may  be  seen  within  an  area  of  a  few  yards.  The  contacts 
throughout  are  marked  by  conglomerates  containing  fragments  of 
the  underlying  rocks,  predominantly  granite  and  iron  formation. 
Van  Hise,  Bell,  Adams,  Miller,  Lane,  Seaman,  Smith,  and 
Leith,88  in  1904,  visited  the  area  about  Loon  Lake  and  Port  Arthur. 
In  the  Loon  Lake  area  the  succession  is  as  follows :  The  top  series  is 
the  Keweenawan,  here  consisting  of  sandstone  above  and  conglom- 
erate below,  with  interbedded  basic  igneous  flows  or  sills.  Below 
the  Keweenawan  is  the  Animikie.  The  contact  between  the  Kewee- 
nawan and  the  Animikie  was  seen  at  two  places.  At  one  of  these 
there  is  an  appearance  of  conformity,  but  at  the  other  the  eroded 
edges  of  the  Animikie  iron-bearing  formation  are  traversed  by  the 
Keweenawan  beds.  At  one  contact  the  base  of  the  Keweenawan 
rests  on  the  Animikie  slate  interst  rati  tied  with  the  iron  formation, 
and  at  the  other  on  one  of  the  members  of  the  iron-bearing  formation. 
At  both  localities  the  conglomerate  at  the  base  of  the  Keweenawan 
bears  detritus  from  the  underlying  series,  including  both  the  slate  and 
the  iron-bearing  formations  of  the  Animikie.  The  Animikie  succes- 
sion which  was  seen  near  Loon  Lake  includes  two  phases  of  the  iron- 
bearing  formation  with  an  interstratified  belt  of  slate.  The  Animikie 
here  has  in  general  rather  flat  dips,  although  locally  they  become 
somewhat  steeper. 
At  one  place  near  Loon  Lake  a  test  pit  has  been  sunk  to  the  bottom 
of  the  Animikie,  and  here  at  the  base  of  the  formation  is  a  conglom- 
erate bearing  fragments  of  the  next  underlying  series,  a  graywacke 
slate.  This  graywacke  slate  covers  a  large  area,  shows  cleavage  at  a 
high  angle,  and  is  evidently  an  important  formation  in  the  district. 
The  party  has  no  doubt  that  there  is  a  considerable  unconformity 
between  the  Keweenawan  and  the  Animikie,  and  a  very  important 
unconformity  between  the  Animikie  and  the  graywacke  slates. 
