412  PRE-CAMBRIAN   GEOLOGY   OF    NORTH   AMERICA. 
the  lower  slate  conglomerate  and  the  second  as  the  upper  slate  con- 
glomerate. At  the  junction  of  the  Sudbury  branch  of  the  Canadian 
Pacific  Kailway  with  Vermilion  Kiver  an  arenaceous  slaty  rock,  hav- 
ing a  dip  45°,  rests  on  a  different  schist  having  a  different  dip.  At 
this  locality,  according  to  Lawson,  the  unconformity  is  similar  to  that 
at  Penokee  Gap,  Wisconsin.  The  lower  rock  is  a  fine  micaceous 
gneiss  or  mica  schist,  and  the  upper  rock  is  interbedded  quartzite  and 
gray  argillite.  At  Echo  Lake  is  the  following  series,  in  descending 
order:  Slate  conglomerate  and  quartzite,  with  a  dip  of  about  20°; 
after  this  is  an  interval  of  a  third  of  a  mile,  and  then  appears  a 
quartzose  slate  conglomerate  comparable  with  the  Ogishki  conglom- 
erate; this  is  followed  by  quartzite,  and  this  by  alternations  of 
quartzite,  quartz  schist,  and  various  slates,  schists,  and  argillites, 
the  series  having  a  dip  of  75°  to  80°  SW.,  and  being  as  a  whole  more 
crystalline  than  the  upper  system.  It  is  concluded  that  the  name 
Huronian  must  be  restricted  to  the  upper  or  lower  system;  and  if 
restricted  to  the  upper  system  it  remains  attached  to  the  best  known 
and  most  characteristic  portion  of  the  old  complex  Huronian.  For 
the  older  system,  not  distinctly  named  Keewatin  by  Lawson  until 
1886,  the  term  Kewatian  is  proposed. 
Bell,28  in  1891,  describes  the  geology  of  the  district  of  Sudbury. 
The  main  outlines  of  the  great  Huronian  area  of  this  region  are 
given.  Within  the  region  are  many  inliers  of  gneiss  and  red  quartz 
syenite,  which  correspond  with  Laurentian  types  of  rock,  and  it  is 
uncertain  whether  they  are  protrusions  of  the  older  rocks  from  be- 
neath or  whether  some  of  them  may  not  be  portions  of  the  Huronian 
itself  which  have  undergone  further  metamorphism.  In  the  Sudbury 
district  many  of  the  areas  consist  of  separate  masses,  like  large  and 
small  bowlders,  the  interspaces  being  filled  by  a  breccia  with  a  dioritic 
paste,  suggesting  that  these  rocks  may  be  underlain  at  no  great  depth 
by  diorite  which  was  in  a  soft  condition  after  the  gneiss  and  syenite 
had  been  consolidated.  At  some  places  within  the  syenite  area,  as,  for 
example,  about  2  miles  west  of  Cartier,  a  massive  fine-grained  rock 
like  some  varieties  of  graywacke  may  be  seen  passing  into  thoroughly 
crystalline  quartz  syenite.  The  rocks  in  greatest  quantity,  and  those 
which  constitute  the  lowest  member  of  the  Huronian  series  between 
Lakes  Huron  and  Wahnapitae,  are  quartzose  graywackes  and  quartz- 
ites,  with  occasionally  a  little  felsite.  In  this  member  of  the  series 
crystalline  diorites  occur  as  intruded  masses,  varying  from  a  half  mile 
to  10  miles  in  length ;  associated  are  obscurely  stratified  varieties  of 
quartz  diorite  and  of  dioritic  and  hornblende  schists,  and  also  com- 
pact brown-weathering  dolomite.  The  next  member  of  the  series  in 
ascending  order  is  a  black  volcanic  glass  breccia  consisting  of  angu- 
lar fragments  crowded  together.  The  highest  rocks  of  the  series,  or 
those  which  occupy  the  center  of  the  trough,  are  evenly  bedded  argil- 
