﻿184 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  small 
  amounts 
  of 
  hornblende, 
  muscovite, 
  zircon 
  and 
  pyrite. 
  The 
  

   femic 
  minerals 
  constitute 
  is^ 
  of 
  the 
  rock 
  analyzed. 
  The 
  feldspar 
  

   is 
  chiefly 
  microcline 
  and 
  oligoclase, 
  though 
  with 
  some 
  microper- 
  

   thite. 
  Both 
  feldspars 
  occur 
  as 
  augen, 
  with 
  trains 
  of 
  granulated 
  ma- 
  

   terial 
  running 
  away 
  from 
  them, 
  between 
  which 
  are 
  foliae 
  of 
  quartz, 
  

   feldspar 
  and 
  biotite. 
  To 
  a 
  considerable 
  extent 
  the 
  quartz 
  and 
  

   biotite 
  seem 
  to 
  have 
  resulted 
  from 
  recrystallization 
  of 
  feldspar. 
  

   Tlie 
  certain 
  Alexandria 
  syenite 
  runs 
  into 
  very 
  gneissoid 
  and 
  mica- 
  

   ceous 
  border 
  phases, 
  which 
  lie 
  between 
  its 
  massive 
  core, 
  and 
  the 
  

   augen 
  gneiss 
  beyond. 
  These 
  varieties 
  are 
  much 
  more 
  micaceous, 
  

   and 
  much 
  more 
  quartzose 
  than 
  the 
  massive 
  portion, 
  and 
  in 
  them 
  

   also 
  much 
  biotite 
  and 
  quartz 
  have 
  resulted 
  from 
  feldspar 
  re- 
  

   crystallization. 
  They 
  are 
  thus 
  ver^^ 
  similar 
  'to 
  the 
  augen 
  gneiss. 
  It 
  

   was 
  this 
  apparent 
  gradation 
  from 
  one 
  rock 
  to 
  the 
  other 
  in 
  the 
  field 
  

   which 
  gave 
  us 
  the 
  impression 
  that 
  the 
  whole 
  represented 
  a 
  single 
  

   intrusion. 
  It 
  is 
  a 
  matter 
  of 
  very 
  minor 
  importance 
  in 
  the 
  local 
  

   geolog}', 
  and 
  must 
  for 
  the 
  present 
  be 
  left 
  as 
  undetermined. 
  

  

  Granitized 
  amphibolite 
  and 
  amphibolitized 
  granite 
  (soaked 
  

  

  rocks) 
  

  

  Practically 
  all 
  observers 
  who 
  have 
  worked 
  in 
  Laurentian 
  areas, 
  

   have 
  seen 
  and 
  recorded 
  the 
  e^-idences, 
  which 
  meet 
  one 
  on 
  every 
  hand, 
  

   of 
  the 
  attack 
  of 
  the 
  granite 
  upon 
  the 
  amphibolite 
  inclusions, 
  large 
  

   and 
  small, 
  which 
  occur 
  nearly 
  everywhere, 
  and 
  are 
  often 
  abundant. 
  

   The 
  action 
  consists 
  of 
  an 
  injection 
  of 
  granite 
  into 
  the 
  amphibolite, 
  

   at 
  first 
  along 
  the 
  foliation 
  planes, 
  from 
  which 
  the 
  granite 
  spreads 
  

   out 
  more 
  of 
  less 
  into 
  the 
  adjacent 
  rock, 
  injecting 
  itself 
  between 
  and 
  

   inclosing 
  the 
  grains, 
  but 
  with 
  the 
  distinction 
  between 
  the 
  two 
  ma- 
  

   terials 
  still 
  sharp. 
  In 
  later 
  stages 
  this 
  sharpness 
  disappears, 
  the 
  

   two 
  materials 
  seem 
  to 
  merge, 
  or 
  fade 
  into 
  one 
  another, 
  and 
  as 
  a 
  

   final 
  stage 
  a 
  rock 
  is 
  produced 
  which 
  seems 
  a 
  true 
  mixed 
  rock, 
  in 
  

   which 
  a 
  distinction 
  between 
  the 
  two 
  elements 
  is 
  no 
  longer 
  possible, 
  

   and 
  whose 
  origin 
  would 
  be 
  problematic 
  except 
  for 
  the 
  occurrence 
  

   of 
  the 
  less 
  advanced 
  phases 
  of 
  the 
  change. 
  Needless 
  to 
  say 
  the 
  

   granite 
  must 
  be 
  very 
  thoroughly 
  molten 
  in 
  order 
  to 
  produce 
  these 
  

   mixed 
  rocks. 
  It 
  was 
  our 
  purpose 
  to 
  investigate 
  these 
  rocks 
  some- 
  

   what 
  thoroughly 
  chemically. 
  Unfortunately 
  however 
  no 
  material 
  

   which 
  seemed 
  to 
  us 
  sufficiently 
  fresh 
  to 
  warrant 
  chemical 
  investi- 
  

   gation 
  was 
  obtained 
  from 
  rocks 
  which 
  seemed 
  distinctly 
  interme- 
  

   diate. 
  A 
  beginning 
  was 
  made, 
  however, 
  by 
  the 
  investigation 
  of 
  two 
  

   rocks, 
  one 
  a 
  granite 
  slightly 
  tinctured 
  with 
  amphibolite, 
  and 
  the 
  

  

  