372  PRE-CAMRRIAN    GEOLOGY   OF    NORTH    AMERICA. 
identical  with  those  reached-  by  Lawson  as  to  the  relations  of  the  dif- 
ferent series  on  the  north  shore ;  that  is,  the  dioritic  group,  the  lowest 
Huronian,  is  regarded  as  remelted  metamorphosed  Huronian  sedi- 
ments, the  more  crystalline  character  of  the  rocks  being  due  to  their 
closer  proximity  to  the  volcanic  forces ;  and  while  the  great  masses  of 
granite  gneiss  are  below  the  dioritic  group,  these  rocks  are  also  inter- 
spersed with  and  cut  the  dioritic  rocks,  the  whole  granitic  group 
being  regarded  as  of  igneous  origin  and  later  in  age  than  the  sedi- 
mentaries.  The  likeness  of  the  dioritic  group  and  Lawson's  Kee- 
watin  at  once  suggests  itself.  As  has  been  seen,  Rominger's  later 
studies  led  him  materially  to  modify  his  opinions  and  to  bring  them 
more  nearly  in  harmony  with  the  conclusions  of  Brooks  and  Irving. 
Van  Rise's  examination  of  the  Rainy  Lake  and  Lake  of  the  Woods 
region  led  him  to  the  conclusion  that  Lawson's  "  Coutchiching,"  in- 
stead of  being  beneath  the  Keewatin,  really  belongs  unconformably 
above  it  and  constitutes  the  basal  portion  of  the  Huronian  series,  a 
conclusion  subsequently  corroborated  by  the  joint  committee  of  United 
States  and  Canadian  geologists. 
Coleman  adopted  Lawson's  classification  for  the  Rainy  Lake  and 
Lake  of  the  Woods  areas. 
W.  H.  C.  Smith  followed  Lawson's  classification  in  the  mapping  of 
Hunters  Island  and  adjacent  areas,  putting  at  the  base  the 
"  Ontarian,"  divided  into  "  Coutchiching"  below  and  Keewatin  above. 
These  are  intruded  by  Laurentian  granites  and  gneisses. 
Mclnnes  also  followed  Lawson  in  his  mapping  northwest  of  Port 
Arthur,  finding  the  Laurentian  to  intrude  the  "  Coutchiching  "  and 
Keewatin  rocks. 
A  part  of  the  Hunters  Island  area,  mapped  by  Van  Hise,  Clements, 
Bayley,  Leith,  and  Grant  in  connection  with  the  mapping  of  the 
Vermilion  district  of  Minnesota,  showed  the  same  general  succession 
as  held  by  the  United  States  Geological  Survey  for  the  region  as  a 
whole — that  is,  Animikie  or  upper  Huronian;  unconformity;  lower 
Huronian ;  unconformity ;  Keewatin  green  schists ;  Laurentian  gran- 
ites intrusive  into  the  Keewatin;  also  granites  intrusive  into  the 
lower  Huronian. 
The  same  was  found  by  W.  N.  Smith  in  the  Loon  Lake  region  east 
of  Port  Arthur. 
Van  Hise  found,  beneath  the  Animikie,  rocks  that  he  regarded  as 
typical  of  the  basement  complex  about  Thunder  Bay  and  at  other 
points  on  the  north  and  east  shores  of  Lake  Superior. 
Clements  found  representatives  of  both  the  basement  complex  and 
the  lower  Huronian  beneath  the  Keweenawan  rocks  of  Lake  Nipigon. 
For  the  Michipicoten  district,  on  the  northeast  shore  of  Lake  Supe- 
rior, Coleman  and  Willmott's  succession  is:  Upper  Huronian  sedi- 
ments   (including  Dore  conglomerate);   unconformity;  lower  Hu- 
