220  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,   1903.  [bull.  225. 
The  iron  ore  is  believed  by  Weidman  to  be  mainly  a  product  of 
metamorphism  of  what  was  originally  a  deposit  of  nearly  pure  ferric 
hydrate,  deposited  in  shallow  lagoons  and  protected  bays  and  formed 
in  a  manner  similar  to  bog  and  lake  ore  at  the  present  day,  through 
chemical  and  organic  processes  acting  upon  and  within  shallow  waters 
unusually  rich  in  iron.  The  evidence  of  shallow  water,  and  not  deep 
sea,  in  which  the  iron  was  originally  deposited,  is  furnished  by  the 
numerous  sun  cracks  in  the  ferruginous  carbonaceous  slate  imme- 
diately associated  with  the  ore  strata  and  the  presence  of  carbonaceous 
matter  in  the  iron  ore  and  associated  rocks.  The  process  of  meta- 
morphism, it  is  believed,  has  been  mainly  that  of  dehydration  of  the 
original  ferric  hydrate  analogous  to  the  partial  dehydration  of  the 
originally  hydrated  silicates,  chlorite,  and  kaolin  of  the  underlying 
Seeley  slate. 
CANADIAN  PORTION  OF  THE  LAKE  SUPERIOR  REGION. 
Ore  has  been  found  by  drilling  in  the  Animikee  series  (the  eastward 
continuation  of  the  Mesabi  series)  near  Loon  Lake,  east  of  Port  Arthur. 
The  iron  formation  is  similar  to  that  of  the  Mesabi  range,  although  it 
is  thin  and  intruded  by  Keweenawan  sills.  If  the  ore  deposit  is  here 
found  to  be  of  commercial  size  and  grade,  it  will  be  the  first  of  its 
kind  discovered  in  the  Animikee  series  between  the  eastern  portion  of 
the  Mesabi  range  and  the  north  shore  of  Lake  Superior,  a  distance  of 
160  miles. 
Exploration  has  been  active  in  the  Attikokan  and  Matte  wan  districts, 
although  apparently  without  decisive  results. 
Exploration  has  been  active  in  many  other  localities  from  the  Atti- 
kokan district,  on  the  west,  to  Georgian  Bay,  on  the  east,  and  has 
resulted  in  a  considerable  extension  of  the  areas  of  known  iron  for- 
mation. The  increased  activity  in  exploration  on  the  Canadian  side 
of  the  boundary  is  largely  due  to  the  entrance  of  American  companies, 
and  signifies  to  a  considerable  extent  diminution  in  the  discoveries 
and  of  the  area  available  for  exploration  in  the  parts  of  the  Lake 
Superior  region  within  the  United  States. 
