CHAPTER   I. 
THE    ORIGINAL    LAURENTIAN    AND    HURONIAN   AREAS, 
SECTION  T.  EASTERN  ONTARIO  AND  WESTERN  QUEBEC. 
LITERATURE. 
Logan,1  in  1847,  describes  between  the  Ottawa  and  Mattawa  rivers,  a 
metamorphic  series  of  rocks,  which,  in  its  highly  crystalline  character, 
belongs  to  the  order  named  by  Lyell  Primary.  They  are  called  meta- 
morphic,  because  their  aspect  is  such  as  to  lead  to  the  theoretical  be- 
lief that  they  may  be  ajicient  sedimentary  formations.  A  red  syenitie 
gneiss,  in  which  hornblende  and  mica  are  arranged  in  a  parallel  direc- 
tion, is  the  predominant  rock.  The  thickness  of  the  gneiss  is  not  ascer- 
tained. South  of  the  Mattawa  and  Ottawa  are  important  beds  of 
coarse  crystalline  limestone  interstratifled  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  Madawaska,  has  a  thickness  of  1,351  feet,  and  eon 
sists  of  gneiss,  crystalline  limestone,  with  a  small  amount  of  micaceous 
fjuartz  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  gen- 
eral attitude  to  overlie  the  syenitie  group  conformably.  Both  of  the 
metamorphic  groups  are  frequently  traversed  by  dikes  and  veins,  in- 
cluding those  of  a  granitic  and  pyroxenic  character.  From  the  vicin- 
ity of  Quebec  the  limestone  group  ranged  along  the  St.  Lawrence,  a  dis- 
tance varying  from  10  to  20  miles,  reaches  the  seigniory  of  Argentenil, 
where  it  makes  a  turn  toward  the  valley  of  the  Ottawa,  is  seen  above 
Grenville,  and  is  last  seen  about  half  way  between  Fort  William  and 
Joachim  falls,  and  at  Portage  de  Talon,  on  the  Mattawa.  In  the  vicin- 
ity of  Grenville  the  limestone  is  plumbacenns. 
Logan,2  in  1852,  finds  a  metamorphic  and  gneissic  series  of  a  wide-' 
spread  occurrence  upon  the  river  du  Nord  and  the  country  to  the  west- 
ward. The  Potsdam  formation  rests  unconformably  upon  the  meta- 
morphic series. 
Murray,3  in  1852,  describes  a  metamorphic  series  upon  and  north  of 
the  Upper  St.  Lawrence.  On  the  Thousand  isles  are  micaceous  and 
hornblende  gneisses.  Crystalline  limestones,  quartzites,  and  conglom- 
merates  are  all  found  upon  the  mainland,  and  the  latter  is  cited  as 
decisive  evidence  of  the  metamorphic  character  of  the  series  as  a  whole. 
'For  notes  see  end  of  chapter,  p.  48. 
23 
