tan  hise.]  DISCUSSIONS    OF    PRINCIPLES.  501 
condition.  This  series,  in  its  structural  and  lithological  characteris- 
tics is  remarkably  like  the  Keweenawan  of  lake  Superior,  and  its  dis- 
tance from  the  nearest  area  of  this  series,  the  Nipigon,  is  not  very 
great,  so  that  its  correlation  with  the  Keweenawan  can  be  made  with 
a  fair  degree  of  probability.  There  are  then  about  Hudson  bay,  between 
the  Cambrian  and  the  Archean,  at  least  two,  and  perhaps  three,  series 
of  rocks,  the  uppermost  of  which  rests  upon  the  lower  series  uncon- 
formably. 
OTHER  REGIONS  OF  NORTHERN  CANADA. 
Too  little  is  known  of  the  vast  expanse  of  pre-Cambrian  rocks  which 
constitute  the  northern  parts  of  Canada  to  make  any  definite  state- 
ments. It  is,  however,  evident  that  rocks  lithologically  like  the 
Archean  of  the  previous  regions  discussed  constitute  the  great  area. 
It  is  equally  plain  that  within  this  area,  at  various  districts,  are  rocks 
which  show  undoubted  evidences  of  clastic  characters  as  shown  by  the 
presence  of  limestones,  schistose  conglomerates,  volcanic  elastics,  etc., 
which  have  a  lithological  likeness  to  the  Keweenawan,  Upper  or  Lower 
Huronian  of  lake  Superior,  but  which  can  not  yet  be  closely  located. 
The  Huronian  area  of  the  north  channel  of  lake  Huron  extends  to  an 
unknown  distance  in  a  north  and  northeast  direction.  Also,  it  is  by 
no  means  certain  that  many  of  the  rocks  referred  by  Dawson  to  the 
Cambrian  are  not  really  pre-Cambrian,  as  used  in  this  essay.  The 
Coppermine  series,  for  instance,  in  its  lithological  character  and  posi- 
tion, is  such  as  to  lead  to  a  comparison  of  it  with  the  Keweenawan  or 
Animikie  of  the  lake  Superior,  or  both.  But  the  structural  work  in 
this  vast  area  can  be  considered  but  as  barely  begun. 
THE  EASTERN  TOWNSHIPS. 
In  the  Eastern  Townships  there  is  unconformably  below  the  fossilifer- 
ous  Cambro- Silurian  a  series  of  little  altered  slates  which  rests  uncon- 
formably upon  crystalline  or  semicrystalline  schists.  These  have  been 
regarded  by  the  Canadian  geologists  as  Lower  Cambrian,  although  in 
them  no  fossils  have  been  found.  In  position  and  lithological  charac- 
ter they  are  compared  with  the  gold-bearing  slates  of  Nova  Scotia.  As 
the  Canadian  Geological  Survey  uses  the  term  Cambrian,  including  the 
Auimikie  and  Keweenawan,  this  series  is  probably  Cambrian,  but,  mak- 
ing the  basal  Cambrian  as  is  done  in  this  essay  the  series  bearing  the 
Olenellus  fauna,  it  is  probable,  although  not  certain,  that  this  series  of 
slates  is  pre-Cambrian  and  Upper  Algonkian.  Of  the  series  of  schists 
unconformably  below  this  series  there  are  no  very  lull  descriptions.  It, 
however,  includes  mica-slates,  staurolitic  schists,  crystalline  limestones, 
argillites,  and  graphitic  schists,  and  with  these  volcanic  elastics.  This 
is  certainly  a  clastic  series  in  part  at  least.  The  whole  is  associated  with 
granites  which  are  regarded  by  Ells  as  intrusives  in  the  schists,  and 
one  of  the  causes  of  their  metamorphism,  but  by  Selwyu  are  supposed 
