514  PEE-CAMBEIAN"   GEOLOGY   OF   NORTH   AMERICA. 
lated  it  with  the  Laurentian  of  Canada,  and,  like  the  original  area  of 
the  Laurentian,  the  Ottawa  rocks,  he  divided  it  into  an  "  Upper  "  and 
a  "  Lower  Laurentian,"  the  lower  consisting  of  various  massive  and 
laminated  rocks,  all  presumably  of  igneous  origin  whatever  their  age, 
and  the  upper  group  including  all  limestones,  sandstones,  slates,  and 
conglomerates — that  is,  all  which  are  certainly  clastic  in  character. 
Associated  with  this  upper  group  are  eruptives  of  the  same  character 
as  those  found  in  the  "  Lower  Laurentian." 
These  two  parts  of  the  Laurentian  were  first  described  as  in  appar- 
ent unconformity.  The  detailed  evidence  for  this  conclusion  it  has 
not  been  possible  fully  to  give  in  the  foregoing  summary.  A  close 
scrutiny  of  the  evidence  seems  to  point  more  strongly  toward  the  later 
intrusive  character  of  the  so-called  "  Lower  Laurentian,"  but  it  is  not 
certain  that  a  portion  of  the  so-called  "  Lower  Laurentian  "  may  not 
be  of  greater  age  than  the  clastic  "  Upper  Laurentian  "  rocks. 
The  gold-bearing  series  referred  to  the  pre-Cambrian  in  southern 
Nova  Scotia  is  nowhere  found  in  contact  with  the  pre-Cambrian  of 
northern  Nova  Scotia  and  Cape  Breton.  As  has  been  said,  we  only 
know  that  the  gold-bearing  slates  are  unconformably  below  the  Car- 
boniferous, but  Ave  believe  them  to  be  pre-Cambrian.  The  supposed 
pre-Cambrian  rocks  of  northern  Nova  Scotia  and  Cape  Breton  are 
known  only  to  be  unconformably  below  the  Paradoxides-hearing 
slates. 
SECTION  3.     NEWFOUNDLAND. 
SUMMARY  OF  LITERATURE. 
Jukes,71  in  1843,  divides  the  lower  formations  of  Newfoundland,  in 
descending  order,  into  an  upper  slate  formation,  a  lower  slate  forma- 
tion, and  a  gneiss  and  mica  slate  formation.  The  igneous  rocks  con- 
sist of  various  kinds  of  trap,  greenstone,  serpentine,  hypersthene,  por- 
phyry, syenite,  and  granite.  The  upper  slate  formation  is  believed  to 
be  lower  than  the  coal  formation,  although  nowhere  found  in  contact 
with  it.  The  thickness  of  the  upper  slate  must  be  many  hundreds  of 
feet.  In  one  instance  beds  of  upper  slate  rest  unconformably  upon 
those  of  the  lower  slate  formation.  The  mica  slate  and  gneiss  or 
quartz  rock,  chlorite  slate,  and  Primary  limestone  occur  together. 
Nearly  the  whole  of  the  province  of  Avalon  is  composed  of  the  lower 
slate  formation.  On  Conception  Bay  at  several  places  beds  of  varie- 
gated slate  overlap  and  cover  the  edges  of  the  lower  slate  in  a  per- 
fectly unconformable  position. 
On  Newells  Island  the  junction  of  the  gneiss  and  mica  slate  with 
the  granite  is  found.  The  mica  slate  in  approaching  the  granite  be- 
comes more  crystalline  and  gneisslike  in  certain  layers.  On  continu- 
ing to  approach  the  granite  there  appear  thin  beds  of  granite,  which 
are  not  veins  from  the  granite,  but  an  integral  part  of  the  beds.    The 
