296  PRE-CAMBPJAN    GEOLOGY   OF    NORTH    AMERICA. 
River  bands,  David  Katossin  claims,  and  Lost  Lake  claims  in  the 
western  range.     No  important  ore  deposits  have  yet  been  found. 
Burwash,293  in  1905,  describes  and  maps  the  Keweenawan  rocks 
making  up  the  Michipicoten  and  adjacent  islands.  The  succession 
and  thickness  are  as  follows : 
Keeweenawan  rocks   of  Michipicoten  and   adjacent  islands. 
Feet 
1.  Felsite  of  islands  off  the  south  shore 1,000 
2.  Pitchstone  bed 530 
3.  Quartzless  porphyry  of  Quebec  Harbor ^ 695 
4.  Melaphyre  porphyrites  of  Channel  Lake 1,660 
f  1 355 
5.  Quartz  porphyries-^  J  2 L_     1, 160 
|3 1,  493 
6.  Beds  exposed  at  lake  on  road 1,  575 
7.  Felsite 513 
8.  Diabase   porphyrite 463 
9.  Beds  underlying  farm  (3) 1,140 
10.  Several  beds  at  mine 645 
11,  229 
The  dips  vary  from  40°  to  55°  S.  Keweenawan  rocks  are  found  on 
the  mainland  to  the  north.  If  these  form  a  part  of  the  continuous 
succession  with  the  Keweenawan  rocks  of  the  island,  there  is  here  rep- 
resented a  minimum  thickness  of  34,860  feet  of  sediments,  unless 
faulting  is  present.  This  corresponds  with  Irving's  estimate  of  35,000 
feet  for  the  Keweenawan  series  on  Keweenaw  Point. 
Coleman,294  in  190G,  in  discussing  the  report  of  the  international 
geological  committee  on  the  Lake  Superior  region,  holds  that  the 
Coutchiching  series  of  the  Lake  of  the  Woods  region  was,  in  the  main, 
lower  than  the  Keewatin  as  held  by  Lawson,  though  the  mica  schists 
which  overlie  the  basal  conglomerate  at  Shoal  Lake  should  be  ex- 
cluded from  the  Coutchiching  series.  He  holds  also  that  the  term 
Laurentian  should  be  retained  in  its  old  sense  for  acidic  rocks  intru- 
sive into  the  Huronian.  Further,  the  Keweenawan  should  go  into  the 
Huronian  series  if  the  Animikie  is  placed  there.  Huronian  would 
then  mean  the  same  as  Algonkian  and  the  latter  term  should  be 
dropped. 
Silver,295  in  1906,  maps  and  describes  the  geology  of  the  Animikie 
iron  range  from  Port  Arthur  eastward  25  miles.  His  succession  and 
structure  are  essentially  the  same  as  those  previously  worked  out  by 
Smith  and  Allen,,  with  the  exception  that  he  classifies  certain  green- 
stones, called  Keewatin  by  Smith,  with  the  Lower  Huronian,  having 
failed  to  recognize  an  unconformable  break  between  them. 
Coleman,290  in  190T,  describes  and  maps  the  distribution  of  the 
iron  ranges  east  of  Lake  Nipigon,  Ontario,  in  the  neighborhood  of 
