CHAPTER  V. 
PAET  OF  QUEBEC  NORTH  AND  WEST  OF  ST.  LAWRENCE 
RIVER,  INCLUDING  THE  ORIGINAL  LAURENTIAN  AND 
HASTINGS  AREAS. 
SUMMARY    OF   LITERATURE. 
Logan,1  in  1847,  describes  a  metamorphic  .series  of  rocks  between 
Ottawa  and  Mattawa  rivers,  which,  in  its  highly  crystalline  charac- 
ter, belongs  to  the  order  named  by  Lyell  Primary.  They  are  called 
metamorphic  because  their  aspect  is  such  as  to  lead  to  the  theoretical 
belief  that  they  may  be  ancient  sedimentary  formations.  A  red  sye- 
nitic  gneiss,  in  which  hornblende  and  mica  are  arranged  in  a  parallel 
direction,  is  the  predominant  rock.  The  thickness  of  the  gneiss  is  not 
ascertained.  South  of  the  Mattawa  and  Ottawa  are  important  beds 
of  crystalline  limestone  interstratified  with  the  gneiss  in  a  conform- 
able manner,  although  this  conformity  would  not  be  seen  in  a  small 
area  because  of  the  minor  complicated  contortions.  One  section  at 
High  Falls,  on  the  MadawTaska,  has  a  thickness  of  1,351  feet,  and  con- 
sists of  gneiss,  crystalline  limestone,  and  a  small  amount  of  micaceous 
quartz  rock,  the  gneiss  greatly  predominating.  The  areas  which  bear 
limestone  are  so  distinct  that  they  are  placed  as  a  separate  group  of 
metamorphic  strata,  supposed  from  their  geographical  position  and 
general  attitude  to  overlie  the  syenitic  group  conformably.  Both  of 
the  metamorphic  groups  are  frequently. traversed  by  dikes  and  veins, 
including  those  of  a  granitic  and  pyroxenic  character.  From  the 
vicinity  of  Quebec  the  limestone  group  ranges  along  the  St.  Lawrence, 
a  distance  varying  from  10  to  20  miles,  reaches  the  seigniory  of  Argen- 
teuil,  where  it  makes  a  turn  toward  the  valley  of  the  Ottawa,  is  seen 
above  Grenville,  and  is  last  seen  about  halfway  between  Fort  AYilliam 
and  Joachim  Falls,  and  at  Portage  de  Talon,  on  the  Mattawa.  In  the 
vicinity  of  Grenville  the  limestone  is  plumbaceous. 
Logan,2  in  1852,  finds  a  metamorphic  and  gneissic  series  of  wide- 
spread occurrence  along  the  River  du  Nord  and  in  the  country  to  the 
west.  The  Potsdam  formation  rests  unconformably  upon  the  meta- 
morphic series. 
Murray,3  in  1852,  describes  a  metamorphic  series  along  and  north 
of  the  upper  St.  Lawrence.  On  the  Thousand  Islands  are  micaceous 
and  hornblendic  gneisses.  Crystalline  limestones,  quartzites,  and  con- 
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