NEW    BRUNSWICK,    NOVA    SCOTIA,    NEWFOUNDLAND,    ETC.       503 
what  extent  the  Grenville  is  itself  divisible  into  two  series,  its  rela- 
tions to  the  igneous  rocks  and  gneisses,  and  to  what  extent  it  is  to  be 
correlated  with  the  Algonkian  or  Huronian. 
The  difficulty  of  the  geology  of  this  region  is  shown  by  the  manner 
in  which  these  groups  have  been  shifted  from  one  place  to  another. 
In  the  days  of  the  earlier  work  none  of  them  were  regarded  as  pre- 
Cambrian,  and  a  portion  was  given  as  high  a  place  as  the  Devonian. 
The  Kingston  group  in  1865  was  called  "  Upper  Silurian  "  and  was 
regarded  as  overlying  the  St.  John ;  in  1872  it  was  called  "  Upper 
Huronian;"  in  1876  was  again  placed  as  "Silurian;"  in  1879  was 
again  placed  with  the  "  Upper  Huronian ;"  and  now  is  assigned  to 
the  Silurian.  The  "  Coastal,"  first  placed  in  the  fossiliferous  series, 
in  1872  was  placed  in  the  "Middle  Huronian  series;"  in  1878  was 
doubtfully  referred  to  the  "  Laurentian,"  and  in  1879  was  again 
returned  to  "  Middle  Huronian."  The  Coldbrook  group  has  been 
reckoned  as  Huronian  since  1865,  but  on  the  discovery  of  fossils  in 
similar  rocks  between  the  Etcheminian  and  "  Grenvillian  "  rocks  of 
Cape  Breton.  Matthew  has  concluded  that  the  Coldbrook  could  not  be 
separated  from  the  Cambrian. 
NORTHERN    AND    CENTRAL    NEW    BRUNSWICK. 
In  central  New  Brunswick  are  numerous  areas  of  granites,  gneisses, 
and  schists,  associated  with  other  rocks  which  are  plainly  of  sedi- 
mentary origin,  including  mica  schists,  quartzites,  and  slate.  Felsites 
are  also  found.  Granite,  syenite,  and  diorite  in  certain  places  are 
intercalated  with  the  sedimentary  rocks,  and  in  other  places  cut  them. 
From  the  descriptions  it  appears  clear  that  there  are  Algonkian  rocks 
in  this  area.  Whether  crystalline  rocks  older  than  the  Algonkian 
also  exist  can  not  be  decided  from  the  information  available. 
There  is  little  difficulty  in  separating  the  intrusives  from  the  fos- 
siliferous rocks,  but  on  account  of  the  more  crystalline  character  of 
the  older  series  and  its  likeness  in  mineralogical  composition  to  cer- 
tain of  the  subsequent  intrusives,  and  further,  on  account  of  the 
intimate  mingling  which  occurs  between  these  two  classes  of  rocks,  it 
is  difficult  to  make  the  separations  with  the  same  degree  of  sharpness. 
This  difficulty  is  not  improbably  further  increased  by  the  presence  of 
intrusives  earlier  than  those  which  cut  the  Cambro- Silurian  rocks. 
SECTION  2.     NOVA  SCOTIA  AND  CAPE  BRETON. 
SUMMARY   OF  LITERATURE. 
Jackson  and  Alger,43  in  1832,  in  remarks  on  the  mineralogy 
and  geology  of  Nova  Scotia,  find  the  granite-  to  protrude 
through  the  clay  slates.  They  arc.  however,  regarded  as  older  than 
the  slates,  the  latter  having  been  deposited  on  them   in  a  horizontal 
