﻿12 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  islands, 
  and 
  to 
  a 
  small 
  extent 
  on 
  the 
  mainland, 
  and 
  which 
  is 
  named 
  

   from 
  Picton 
  (Robbins) 
  island, 
  where 
  the 
  most 
  extensive 
  quarries 
  

   occur. 
  Thi5 
  rock 
  shows 
  little 
  or 
  no 
  signs 
  of 
  the 
  crushing 
  which 
  

   has 
  affected 
  the 
  other 
  Precambric 
  intrusives 
  in 
  greater 
  or 
  less 
  de- 
  

   gree^ 
  though 
  it 
  becomes 
  fine 
  grained 
  in 
  certain 
  situations, 
  chiefly 
  

   marginal, 
  and 
  notably 
  so 
  in 
  many 
  of 
  the 
  dikes 
  which 
  it 
  sends 
  out 
  

   into 
  the 
  adjoining 
  rocks. 
  

  

  The 
  rock 
  holds 
  a 
  multitude 
  of 
  inclusions, 
  of 
  Grenville 
  quartzites 
  

   and 
  schists, 
  of 
  Laurentian 
  granite 
  gneiss, 
  and 
  of 
  the 
  augen 
  

   gneiss 
  associated 
  with 
  the 
  Alexandria 
  syenite. 
  Over 
  much 
  of 
  

   Wellesley 
  island 
  the 
  abundant 
  inclusions 
  are 
  but 
  little 
  disturbed. 
  

   in 
  other 
  words 
  their 
  dips 
  and 
  strikes 
  are 
  concordant 
  and 
  in 
  accord 
  

   with 
  those 
  of 
  the 
  neighboring 
  Grenville 
  rocks, 
  and 
  with 
  these 
  un- 
  

   changed 
  dips 
  and 
  strikes 
  the 
  inclusions 
  occur 
  in 
  linear 
  belts, 
  now 
  

   of 
  quartzite, 
  now 
  of 
  schists 
  and 
  again 
  of 
  granite 
  gneiss, 
  so 
  that 
  

   the 
  original 
  distribution 
  of 
  these 
  rocks 
  can 
  be 
  mapped 
  as 
  con- 
  

   fidently 
  as 
  though 
  the 
  granite 
  invasion 
  had 
  never 
  been. 
  This 
  in- 
  

   dicates 
  that 
  here 
  we 
  are 
  near 
  the 
  very 
  roof 
  of 
  the 
  granite 
  bathy- 
  

   lith, 
  where 
  cooling 
  had 
  rendered 
  it 
  so 
  stiff 
  and 
  pasty 
  as 
  to 
  be 
  no 
  

   longer 
  able 
  to 
  pluck 
  away 
  and 
  engulf 
  blocks 
  from 
  its 
  roof, 
  the 
  

   present 
  inclusions 
  being 
  such 
  as 
  had 
  been 
  last 
  broken 
  away 
  but 
  

   were 
  unable 
  to 
  founder 
  and 
  retained 
  their 
  original 
  orientation. 
  

  

  The 
  utter 
  lack 
  of 
  signs 
  of 
  crushing 
  in 
  the 
  rock 
  leads 
  to 
  the 
  rather 
  

   confident 
  belief 
  that 
  it 
  is 
  the 
  youngest 
  of 
  all 
  these 
  early 
  Precam- 
  

   bric 
  intrusives, 
  though 
  there 
  is 
  some 
  question 
  as 
  to 
  whether 
  it 
  is 
  

   actually 
  younger 
  than 
  the 
  syenite 
  and 
  the 
  gabbro 
  about 
  Theresa, 
  

   and 
  with 
  no 
  possibility 
  of 
  definitely 
  settling 
  the 
  matter. 
  

  

  The 
  bathylith 
  is 
  also 
  of 
  large 
  size, 
  extending 
  out 
  of 
  New 
  York 
  

   into 
  Canada 
  among 
  the 
  islands 
  and 
  on 
  the 
  mainland. 
  The 
  granite 
  

   which 
  outcrops 
  about 
  Kingston 
  seems 
  surely 
  identical, 
  and 
  is 
  dis- 
  

   tant 
  17 
  miles 
  from 
  the 
  nearest 
  outcrops 
  of 
  the 
  rock 
  on 
  the 
  west 
  

   end 
  of 
  Grindstone 
  island. 
  

  

  The 
  molten 
  mass 
  of 
  the 
  granite 
  was 
  also 
  richly 
  charged 
  with 
  

   mineralizing 
  fluids 
  and 
  hence 
  exhibits 
  prominent 
  contact 
  effects 
  on 
  

   the 
  adjacent 
  rocks, 
  much 
  more 
  prominent 
  than 
  those 
  shown 
  by 
  any 
  

   of 
  the 
  other 
  intrusives 
  of 
  the 
  immediate 
  region. 
  

  

  When 
  compared 
  with 
  the 
  Precambric 
  rocks 
  of 
  the 
  general 
  Adiron- 
  

   dack 
  region 
  (the 
  rocks 
  hereabouts 
  comprising 
  the 
  extreme 
  western 
  

   edge 
  of 
  the 
  Precambric 
  of 
  northern 
  New 
  York) 
  the 
  most 
  obvious 
  

   difference 
  to 
  be 
  noted 
  is 
  the 
  comparative 
  scarcity 
  of 
  igneous 
  rocks 
  

   belonging 
  to 
  the 
  syenites 
  and 
  gabbros 
  in 
  this 
  western 
  area. 
  

  

  It 
  seems 
  also 
  to 
  be 
  the 
  case 
  that 
  metamorphism 
  is 
  not 
  so 
  extreme 
  

  

  