QUEBEC    NORTH    AND    WEST    OF    ST.    LAWRENCE    RIVER.  463 
ates,  thus  containing  much  material  of  undoubtedly  clastic  origin. 
The  whole  district  has  been  subjected  to  great  dynamic  action,  some 
of  the  pebbles  of  the  conglomerates  being  distorted  in  the  most  re- 
markable manner.  This  series  may  be  equivalent  to  a  part  of  the 
original  Laurentian,  may  follow  above  the  Grenville  series,  or  may 
prove  to  be  an  outlying  area  of  Huronian  rocks  folded  in  with  the 
Laurentian. 
The  whole  of  the  above  series  was  cut  by  various  acidic  and  basic 
rocks,  metamorphosed,  and  folded  before  upper  Cambrian  time, 
since  the  Cambrian  sediments  rest  upon  them  unconformably  and 
contain  fragments  of  the  lower  series  which  show  that  Avhen  de- 
posited they  were  in  their  present  condition. 
The  roche  moutonnee  surface  of  the  eroded  Laurentian  rocks 
was  impressed  upon  them  in  the  first  instance  in  pre-Cambrian 
time,  for  along  the  edge  of  the  nucleus  from  Lake  Superior  to  the 
Saguenay  the  Paleozoic  strata  may  be  seen  to  overlie  such  surfaces 
showing  no  traces  of  decay  and  similar  to  those  exposed  over  the 
uncovered  part  of  the  area.  To  what  extent  the  Cambrian,  De- 
vonian, and  Silurian  seas  passed  over  the  Laurentian  can  not  be 
determined,  but  it  seems  probable  that  in  Cambrian  time  a  not 
inconsiderable  part  of  the  Archean  nucleus  was  under  water,  as 
shown  by  various  outliers  of  these  rocks.  What  evidence  there  is 
indicates  that  the  area  in  later  Paleozoic,  Mesozoic,  and  earlier  Ter- 
tiary times  was  out  of  water,  being  subjected  to  deep-seated  decay 
and  denudation,  culminating  in  the  glaciation  of  Pleistocene  time. 
These  processes  removed  all  but  mere  remnants  of  the  Paleozoic 
strata. 
Adams,-''"  in  1894,  gives  a  preliminary  description  of  the  area  of 
sheet  118  of  the  Canadian  Survey,  an  area  of  about  3,500  square 
miles,  situated  north  of  Lake  Ontario,  in  the  counties  of  Victoria, 
Peterborough,  and  Hastings.  The  whole  area  is  occupied  by  the 
rocks  of  the  Laurentian  system,  with  the  exception  of  the  southeast 
corner,  which  is  underlain  in  part  by  the  Hastings  series.  In  the 
surrounding  eastern  portions  there  is  an  abundance  of  crystalline 
limestone,  and  the  rocks  have  all  the  characteristics  of  the  Grenville 
series  of  Sir  William  Logan.  In  the  northwestern  part  of  the  area 
the  country  is  apparently  occupied  by  gneiss  alone.  The  relations 
of  the  Grenville  series  to  the  gneiss  free  from  limestone  has  not  yet 
been  definitely  determined,  although  the  limestone  and  the  associated 
gneiss  seem  in  certain  cases  to  partially  inclose  areas  which  contain 
no  limestone.  Throughout  the  area  occupied  by  the  Laurentian 
rocks  the  dips  are  uniformly  in  an  easterly  direction,  usually  at 
moderate  angles.  Only  at  one  or  two  points  have  westerly  dips 
been  observed,  and  these  are  local.  The  relation  of  the  Hastings 
series  to  the  Laurentian  is  also  as  }Tet  uncertain.     One  of  the  most 
