vanhise.]  THE    GREAT    NORTHERN   AREA.  219 
Logan/1  in  1854,  describes  the  district  north  of  the  St.  Lawrence 
river,  between  Montreal  and  cape  Tourment,  below  Quebec.  To  the 
metamorphic  sediments  the  word  Lauren ti an  is  applied.  It  is  used  to 
cover  all  of  the  prefossiliferous  rocks.  The  name  is  founded  on  that 
given  by  Mr.  Garneau  to  the  chain  of  hills  which  the  Laurentian 
series  compose.  At  St.  Maurice  the  Potsdam  sandstone  rests  upon  the 
gneiss. 
Dawson,42  in  1861,  describes  the  Laurentian  rocks  exposed  on  the 
coast  cliffs  of  Murray  bay.  At  one  place  the  succession  includes 
gneiss,  white  quartz  rock,  impure  limestone,  and  hornblende  slate,  but 
the  beds  are  so  inverted  that  little  reliance  can  be  placed  on  apparent 
superposition.  The  crystalline  limestone,  dolomite,  and  serpentine  are 
together  14  feet  thick.  The  Silurian  rocks  rest  unconformably  upon 
the  Laurentian  beds. 
Eichardson,43  in  1870,  describes  the  Laurentian  and  Labradorite 
rocks  on  the  north  shore  of  the  lower  St.  Lawrence.  The  Laurentian 
gneiss  has  sometimes  little  appearance  of  stratification.  The  dips  are 
high,  approaching  the  vertical.  The  Labradorite,  with  moderate  dips, 
rests  unconformably  upon  the  Laurentian.  At  one  place  there  occurs 
in  the  gneiss  a  bed  12  feet  thick  of  coarsely  crystalline  limestone.  The 
Labradorite  rocks  have  a  wide  extent.  Both  the  Laurentian  gneiss  and 
labradorites  are  cut  by  granitic  veins. 
Eichardson,44  in  1872,  reports  on  the  prefossiliferous  rocks  in  the 
country  north  of  lake  St.  John.  They  are  classified  under  two  heads: 
First,  Laurentian  gneiss,  including  a  little  crystalline  limestone ;  sec- 
ond, crystalline  schists,  consisting  of  chloritic  and  epidotic  rocks,  with 
dolomites,  serpentines,  and  conglomerates.  The  Laurentian  occupies 
much  the  largest  area  of  country  and  includes  gneissic  rocks  cut  by 
granite  veins,  limestones,  quartzites,  and  hornblende  rocks.  The  lime- 
stones and  quartzites  are  comparatively  unimportant,  but  the  former  is 
said  to  be  in  thickness  not  less  than  500  or  600  feet.  The  rocks  of  the 
second  class  immediately  succeed  the  Laurentian  near  the  north  end  of 
lake  Abatagomaw.  Large  expanses  of  the  conglomerate  of-'this  series 
are  composed  entirely  of  rounded  fragments  of  Laurentian  gneiss  of 
gray  and  red  colors.  In  some  places,  without  close  examination,  the 
conglomerate  might  be  mistaken  for  the  Laurentian  gneiss.  Sandstones 
and  shales  are  met  with  which  show  lines  of  deposition.  It  is  remarked 
that  whatever  the  geological  horizon  of  this  series  of  rocks,  it  will  be 
prudent  for  the  present  to  withhold  an  opinion  until  further  investiga- 
tions are  made.  The  only  indication  as  to  the  geological  age  of  this 
series  is  given  by  an  obscure  fossil  occurring  in  a  limestone  which 
Billings  thinks  is  a  coral. 
LaFlamme,45  in  1885,  gives  geological  observations  on  the  Saguenay 
region.  The  pre  Cambrian  rocks  are  divided  into  two  series,  a  gneissic 
and  a  labradorite  series,  which  are  together  included  in  the  Laurentian, 
although  nothing  is  said  as  to  their  structural  relations. 
