492  PRE-CAMBPJAN   GEOLOGY   OF   NORTH   AMERICA. 
Hind,9  in  1865,  in  a  geological  sketch  of  the  Province  of  New  Bruns- 
wick, finds  no  rocks  older  than  the  Lower  Silurian.  The  belts  of 
granite  are  regarded  as  of  Devonian  age,  being  apparently  thrust  up 
through  the  Lower  Silurian  and  Devonian  strata  before  the  beginning 
of  the  Carboniferous  epoch.  The  Quebec  group  includes  gneiss,  anor- 
thosite,  mica  schist,  hornblende  rocks,  diorite,  various  schists,  and 
other  crystalline  rocks. 
Mattheav  and  Bailey,10  in  1870,  divide  the  metamorphic  rocks  of 
New  Brunswick  and  Maine  into,  first,  a  Laurentian  series,  which  con- 
sists of  gneiss,  often  granitoid  in  aspect,  including  (1)  crystalline 
limestone  and  interstratified  beds  of  quartzite  and  diorite,  and  (2)  a 
Labra dorian  or  Upper  Laurentian  series,  which  consists  of  feldspar 
rock  associated  with  hypersthene  and  magnetite;  and,  second,  a  Cam- 
brian or  Huronian  series.  The  granites  of  St.  Johns  River  are  of 
Devonian  age. 
Bailey  and  Matthew,11  in  1872,  find  the  Laurentian  system  to  have 
a  rather  widespread  distribution.  The  rocks  are  placed  in  the  Lau- 
rentian because  they  are  older  than  the  Silurian  rocks,  which  contain 
a  Primordial  zone,  as  well  as  on  account  of  their  general  lithological 
resemblance  to  the  ancient  rocks  of  the  Laurentian  system.  The  Lau- 
rentian is  separated  from  the  Primordial  beds  by  an  accumulation  of 
trappean  and  tufiaeeons  strata  which  is  supposed  to  be  of  Huronian 
age.  The  lower  division  of  the  Laurentian  consists  of  diorites,  syen- 
ite, granitoid  gneiss,  etc.,  while  its  upper  division  consists  of  crystal- 
line limestone  with  diorite  at  intervals,  greenish  gray  gneiss,  quartz- 
ite, argillite,  and  slate  conglomerate.  The  contact  of  the  granite  with 
the  schistose  rocks  is  peculiar.  In  the  granite  are  long  irregular 
blocks  of  the  schistose  rock.  Their  occurrence  suggests  either  a 
softening  of  the  older  series  through  metamorphism  subsequent  to  the 
deposition  of  the  upper  series,  or  else  the  intrusive  character  of  the 
granites.  One  section  of  gneiss  and  granite  in  the  Lower  Laurentian 
has  a  thickness  of  12.G00  feet.  The  maximum  thickness  of  limestone 
and  quartzite  of  the  Upper  Laurentian  is  not  more  than  a  thousand 
feet. 
In  the  Huronian  series  are  placed  the  Coldbrook.  Coastal,  and 
Kingston  groups,  which  together  occupy  a  wide  area.  The  Coldbrook 
group  at  several  points  was  observed  to  rest  upon  the  gneissic  and 
granitic  rocks  referred  to  the  Laurentian  S}^stem,  and  in  turn  to  be 
conformably  overlain  by  the  slates  of  the  St.  John  group  containing 
Primordial  fossils.  The  Coldbrook  group  consists  of  diorite,  chlo- 
rite schists,  black  slates,  micaceous  shales,  argillites,  gneissoid  rocks, 
and  other  varieties.  The  rocks  of  the  Coastal  group  consist  of  f elsites 
and  conglomerates,  gray  limestones  and  gray  clay  slates,  gray  chloritic 
grit  and  schists,  micaceous  slate  and  gray  dolomite,  green  and  red  clay 
slate,  and  diorite.     The  Kingston  group  consists  of  shales,  felsites,  dio- 
