﻿174 
  Adams, 
  Barlow 
  and 
  Ells 
  — 
  Canadian 
  Laurentian. 
  

  

  ably 
  its 
  principal 
  development 
  along 
  the 
  southeastern 
  margin,, 
  

   although 
  as 
  the 
  exploration 
  of 
  this 
  vast 
  area 
  is 
  continued, 
  new 
  

   and 
  possibly 
  more 
  extensive 
  areas 
  of 
  these 
  rocks 
  may 
  yet 
  be 
  

   found. 
  Strata 
  belonging 
  to 
  this 
  series 
  are 
  already 
  known 
  to 
  

   occur 
  on 
  the 
  upper 
  Manicuagan 
  River, 
  the 
  lower 
  Hamilton 
  

   River, 
  on 
  the 
  Manouan 
  Branch 
  of 
  the 
  Peribonka 
  and 
  on 
  the 
  

   lower 
  part 
  of 
  the 
  Ungava 
  River, 
  in 
  the 
  Labrador 
  peninsula 
  ; 
  

   while 
  similar 
  rocks, 
  which 
  would 
  seem 
  to 
  belong 
  to 
  this 
  series, 
  

   but 
  which 
  have 
  not 
  as 
  yet 
  been 
  thoroughly 
  examined, 
  have 
  

   been 
  met 
  with 
  about 
  southern 
  Baffin's 
  Land, 
  and 
  possibly 
  about 
  

   Baker 
  Lake 
  near 
  the 
  head 
  of 
  Chesterfield 
  Inlet, 
  as 
  well 
  as 
  on 
  

   the 
  west 
  coast 
  of 
  Hudson 
  Bay 
  and 
  also 
  at 
  Cross 
  Lake 
  on 
  the 
  

   Nelson 
  River. 
  

  

  The 
  Fundamental 
  Gneiss 
  consists 
  of 
  various 
  igneous 
  rocks 
  

   closely 
  allied 
  in 
  petrographical 
  character 
  to 
  granites, 
  diorites 
  

   and 
  gabbros, 
  and 
  which 
  almost 
  invariably 
  have 
  a 
  more 
  or 
  less 
  

   distinct 
  foliation. 
  Where 
  this 
  foliation 
  is 
  scarcely 
  perceptible 
  

   it 
  becomes 
  very 
  difficult 
  to 
  decide 
  whether 
  the 
  rock 
  is 
  an 
  intru- 
  

   sive 
  granite 
  or 
  diorite, 
  or 
  a 
  very 
  massive 
  form 
  of 
  the 
  gneiss 
  m 
  

   question. 
  The 
  different 
  varieties 
  of 
  gneissic 
  rock 
  alternate 
  

   with 
  or 
  succeed 
  one 
  another 
  across 
  the 
  strike, 
  or 
  sometimes 
  cut 
  

   one 
  another 
  off, 
  suggesting 
  a 
  complicated 
  intrusion 
  of 
  one 
  mass 
  

   through 
  the 
  other, 
  but 
  there 
  is 
  usually 
  a 
  general 
  direction 
  of 
  

   strike 
  to 
  which, 
  in 
  any 
  particular 
  district, 
  the 
  foliation 
  of 
  all 
  

   the 
  varieties 
  conform. 
  The 
  associated 
  basic 
  rocks 
  are 
  very 
  

   dark 
  or 
  black 
  in 
  color 
  and 
  are 
  usually 
  foliated, 
  but 
  sometimes 
  

   this 
  foliation 
  is 
  absent 
  and 
  the 
  rock 
  occurs 
  in 
  masses 
  of 
  all 
  

   sizes 
  and 
  shapes 
  scattered 
  through 
  the 
  acid 
  gneisses, 
  and 
  in 
  the 
  

   great 
  majority 
  of 
  cases 
  so 
  intimately 
  associated 
  with 
  the 
  latter 
  

   that 
  it 
  is 
  impossible 
  to 
  separate 
  the 
  two 
  in 
  mapping. 
  The 
  

   smaller 
  of 
  these 
  masses 
  can 
  be 
  distinctly 
  seen 
  to 
  have 
  been 
  torn 
  

   from 
  the 
  larger, 
  which 
  latter 
  are 
  often 
  of 
  enormous 
  size. 
  This 
  

   process 
  can 
  be 
  observed 
  in 
  all 
  its 
  stages. 
  The 
  granitic 
  

   gneiss 
  invades 
  the 
  great 
  basic 
  masses, 
  sending 
  off 
  wedge-like 
  

   arms 
  into 
  them, 
  which 
  tear 
  them 
  apart 
  and 
  anastomose 
  through 
  

   them 
  in 
  the 
  most 
  complicated 
  manner. 
  These 
  smaller 
  masses 
  

   can 
  then 
  be 
  observed 
  to 
  be 
  separated 
  into 
  still 
  smaller 
  frag- 
  

   ments, 
  which 
  either 
  from 
  the 
  fact 
  that 
  they 
  split 
  most 
  readily 
  

   in 
  the 
  direction 
  of 
  their 
  foliation 
  or 
  owing 
  to 
  subsequent 
  

   movements, 
  when 
  the 
  rock 
  was 
  in 
  a 
  more 
  or 
  less 
  plastic 
  condi- 
  

   tion, 
  often 
  assume 
  long 
  ribbon-like 
  forms. 
  That 
  great 
  move- 
  

   ments 
  have 
  taken 
  place 
  in 
  the 
  whole 
  series 
  during 
  or 
  after 
  this 
  

   invasion 
  is 
  shown 
  by 
  the 
  complicated 
  twisting 
  of 
  these 
  darker 
  

   bands 
  and 
  masses 
  into 
  all 
  manner 
  of 
  curious 
  and 
  intricate 
  

   forms, 
  as 
  well 
  as 
  in 
  the 
  frequent 
  rolling 
  out 
  of 
  great 
  blocks 
  of 
  

   the 
  amphibolite, 
  after 
  having 
  been 
  penetrated 
  in 
  all 
  directions 
  

   by 
  small 
  pegmatite 
  veins, 
  resulting 
  in 
  masses 
  of 
  a 
  dark 
  basic 
  

   gneissoid 
  rock, 
  filled 
  with 
  strings, 
  bunches, 
  separated 
  frag- 
  

   ments 
  or 
  grains 
  of 
  quartz 
  or 
  feldspar, 
  giving 
  to 
  the 
  mass 
  a 
  

   pseudo-conglomeratic 
  appearance. 
  

  

  