248  PRE-CAMBRIAN    HOCKS    OF    NORTH    AMERICA.  [bull. 86. 
rock,  chlorite  slate,  and  primary  limestone  occur  together.  Nearly  the 
whole  of  the  province  of  Avalon  is  composed  of  the  lower  slate  forma- 
tion. On  Conception  bay  at  several  places  beds  of  variegated  slate 
overlap  and  cover  the  edges  of  the  lower  slate  in  a  perfectly  uncon- 
formable position. 
On  Newell's  island  the  junction  of  the  gneiss  and  mica-slate  with  the 
granite  is  found.  The  mica-slate  in  approaching  the  granite  becomes 
more  crystalline  and  gneiss-like  in  certain  layers.  On  continuing  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  granite 
becomes  more  abundant  in  getting  toward  the  main  mass  of  this  rock, 
the  alternations  increasing  in  frequency,  until  after  passing  over  the 
edges  of  many  beds,  the  red  and  flesh-colored,  perfectly  crystalline 
granite,  with  no  appearance  of  any  lamination  or  bedding  whatever,  is 
imperceptibly  reached.  In  the  granite  itself,  for  some  distance  from 
the  junction,  nodular  masses  of  black  rock,  consisting  of  minute  scales 
of  mica  were  observed.  In  other  places  the  mica-slate  and  gneisses 
alternate  with  each  other  and  are  cut  by  distinct  granite  veins. 
The  cleavage  of  the  slate  rocks  is  frequently  parallel  to  the  planes  of 
stratification,  but  often  cuts  them  at  all  angles.  The  strike  of  the 
cleavage  is  in  a  great  majority  of  instances  parallel  to  the  strike  of  the 
beds,  but  not  invariably  so.  The  cleavage  is  much  more  constant  as 
regards  its  strike  and  dip  than  is  the  strike  and  the  dip  of  the  beds. 
The  dip  of  the  cleavage  is  never  at  a  less  angle  than  45°,  while  in  the  ma- 
jority of  instances  it  is  nearly  perpendicular.  Its  strike  was  not  in  any 
instance  found  to  vary  more  than  10°  or  15°  from  a  NNE.  and  SSW. 
bearing.  Certain  of  the  granites  are  newer  than  the  mica- slate  and 
gneiss.  Also  some  of  the  porphyritic  granite  is  more  modern  than  some 
of  the  shales.  In  other  cases  the  red  igneous  rock,  generally  the  syen- 
ite, is  in  all  probability  one  of  the  oldest  rocks  in  the  country,  as  no 
veins  were  observed  to  proceed  from  it  into  the  adjoining  formations, 
and  a  rounded  pebble  of  a.precisely  similar  rock  is  found  in  a  bed  be- 
longing to  the  older  slate  formation  in  Great  Plaeentia. 
Murray,07  in  1865,  describes  the  geology  of  the  northeastern  part  of 
Newfoundland.  Here  is  found  a  Laurentian  group,  which  consists 
mostly  of  gneisses,  but  contains  in  places  layers  of  mica-slate  and  whitish 
quartzite.  These  rocks  are  placed  in  the  Laurentiau  because  they  have 
a  lithological  resemblance  to  the  Laurentian  of  Canada,  and  because 
they  are  covered  unconformably  by  the  Lower  Silurian  strata .  No  crys- 
talline limestones  such  as  are  associated  with  the  Laurentian  of  Canada 
are  found  inter  stratified  with  the  gneisses.  The  rocks  of  the  overlying 
Potsdam  and  Quebec  group  are  fossil  iferous. 
Murray,68  in  1868,  gives  an  account  of  a  part  of  the  coast  of  Notre 
Dame  bay.  A  section  of  rocks  in  this  locality  consisting  of  slates, 
quartzites,  dolomites,  with  various  eruptives,  is  referred  in  part  to  the 
Quebec  group.    Among  the  intrusives  are  syenite  and  diorite.    At 
