LAKE  SUPERIOR  REGION.  285 
of  the  folding  of  the  series  it  is  believed  to  be  older  than  the  Ani- 
mikie  strata  of  Thunder  Bay. 
Animikie  rocks  occur  in  a  small  area  in  the  southeast  corner  of  the 
Shebandowan  region.  They  overlie  unconforinably  the  Keewatin 
and  Laurentian  rocks,  and  from  their  stratigraphical  relations  to  the 
overlying  formation  farther  east  on  Lake  Superior  they  are  believed 
to  be  of  Lower  Cambrian  age. 
Coleman,274  in  1899,  discusses  areas  mapped  by  Logan  as  Huronian 
north  of  Lake  Huron  and  the  east  end  of  Lake  Superior.  The  two 
contacts  described  by  Irving  and  Van  Hise  as  contacts  of  the  Lower 
Huronian  and  Laurentian  rocks  were  examined.  At  the  first,  on 
the  islands  4  miles  east  of  Thessalon,  jasper  and  chert  fragments  were 
found  in  the  conglomerate  above  the  Laurentian,  indicating  that  the 
conglomerate  is  probably  a  part  of  an  upper  series,  younger  than  a 
series  of  rocks,  not  Laurentian,  from  which  the  jasper  must  have  been 
derived.  At  the  other  contact,  on  the  road  between  Sault  Ste.  Marie 
and  Garden  River,  it  is.concluded  that  the  conglomerate  is  possibly 
a  crushed  conglomerate  formed  by  faulting,  instead  of  a  water- 
formed  rock. 
Certain  green  and  gray  schists  inclosed  in  the  Laurentian  gneisses 
are  believed  to  represent  the  western  Keewatin  of  Lawson. 
The  Laurentian  and  Huronian  contact  at  Goulais  and  Batchawana 
bays  was  found  to  be  in  general  of  the  nature  of  an  eruptive  contact, 
although  a  clear  example  of  the  inclusion  of  a  typical  Huronian  rock 
in  the  Laurentian  was  not  observed. 
The  slate  conglomerate  of  Dore  River  contains  no  -bowlders  that 
are  distinctly  Laurentian.  It  contains  only  fragments  of  schists  and 
erupt ives  from  rocks  which  have  been  called  Huronian.  It  probably 
has  closer  affinities  to  Lawson's  Keewatin  than  to  Logan's  Original 
Huronian. 
On  the  shores  of  Heron  Bay  the  schist  conglomerate  and  slate  were 
examined.  The  conglomerate  contains  fragments  mainly  of  granite. 
These  rocks  are  more  closely  allied  to  the  Keewatin  than  to  the  Origi- 
nal Huronian  type. 
In  general  it  is  believed  that  Logan  mapped  as  Huronian  rocks 
which  are  really  Huronian  and  Keewatin. 
The  ascending  succession  for  the  region  as  indicated  by  the  above 
facts  is  as  follows:  Keewatin,  consisting  mainly  of  basic  green  schists; 
Laurentian,  consisting  mainly  of  moderately  acidic  eruptives,  and 
Huronian.  The  term  Laurentian  is  confined  to  areas  of  granite  and 
granitoid  gneiss  corresponding  to  the  Ottawa  gneiss  of  eastern  Can- 
ada and  having  eruptive  relations  to  the  Keewatin. 
The  Keeweenawan  rocks  of  the  various  areas  on  the  north  shore  of 
Lake  Superior  were  studied,  but  no  important  conclusions  were 
reached  differing  from  those  of  Irving.     One  variety  of  conglom- 
