﻿26 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  progressive 
  increase 
  in 
  amount 
  of 
  metamorphism 
  from 
  west 
  to 
  

   east, 
  so 
  that, 
  when 
  the 
  eastern 
  border 
  is 
  reached, 
  the 
  relations 
  of 
  

   the 
  rock 
  groups 
  to 
  one 
  another 
  have 
  become 
  much 
  disguised 
  and 
  

   difficult 
  to 
  decipher. 
  If 
  this 
  white 
  rock 
  be 
  really 
  an 
  igneous 
  

   granite, 
  then 
  its 
  relations 
  to 
  the 
  Grenville 
  are 
  apparently 
  just 
  those 
  

   which 
  are 
  diagnostic 
  of 
  the 
  Laurentian 
  in 
  western 
  New 
  York 
  and 
  

   in 
  Ontario. 
  The 
  apparently 
  confused 
  commingling 
  of 
  the 
  two 
  

   rocks, 
  the 
  apparent 
  interbedding, 
  arid 
  the 
  abundant 
  development 
  of 
  

   pink 
  garnet 
  both 
  in 
  the 
  schists 
  and 
  in 
  the 
  intrusive, 
  are 
  the 
  expres- 
  

   sion 
  of 
  the 
  greater 
  severity 
  of 
  metamorphism. 
  

  

  The 
  syenite. 
  The 
  surface 
  rocks 
  of 
  much 
  of 
  the 
  Adirondack 
  

   region 
  are 
  intrusive 
  igneous 
  rocks 
  of 
  early 
  Precambric 
  age, 
  but 
  

   younger 
  than 
  the 
  Grenville 
  and 
  the 
  Laurentian. 
  There 
  are 
  four 
  

   groups 
  of 
  these 
  rocks 
  — 
  anorthosite, 
  syenite, 
  gabbro 
  and 
  granite 
  — 
  

   named 
  in 
  order 
  of 
  age. 
  The 
  first 
  two 
  occur 
  in 
  much 
  greater 
  volume 
  

   than 
  the 
  last 
  two. 
  In 
  distribution, 
  the 
  anorthosite 
  differs 
  from 
  the 
  

   syenite 
  in 
  occuring 
  chiefly 
  in 
  a 
  single 
  great 
  bathylitic 
  mass 
  whose 
  

   area 
  at 
  the 
  present-day 
  surface 
  is 
  about 
  1500 
  square 
  miles 
  in 
  the 
  

   eastern 
  and 
  central 
  Adirondacks. 
  There 
  are 
  small 
  outlying 
  masses 
  

   to 
  be 
  sure, 
  but 
  neither 
  abundant 
  enough 
  nor 
  large 
  enough 
  materially 
  

   to 
  qualify 
  the 
  general 
  statement. 
  The 
  southern 
  edge 
  of 
  this 
  mass 
  

   is 
  well 
  north 
  of 
  the 
  Saratoga 
  quadrangle 
  so 
  that, 
  except 
  for 
  an 
  

   occasional 
  glacial 
  boulder, 
  the 
  rock 
  is 
  not 
  found 
  here. 
  

  

  The 
  syenite 
  contrasts 
  quite 
  sharply 
  with 
  the 
  anorthosite 
  in 
  dis- 
  

   tribution. 
  Instead 
  of 
  appearing 
  in 
  one 
  huge 
  mass 
  it 
  forms 
  many 
  

   small 
  ones 
  ; 
  instead 
  of 
  being 
  an 
  abundant 
  rock 
  in 
  part 
  of 
  the 
  

   region 
  and 
  wholly 
  lacking 
  in 
  the 
  remainder, 
  it 
  is 
  found 
  everywhere 
  

   throughout 
  the 
  Adirondacks. 
  Every 
  detailed 
  map 
  of 
  part 
  of 
  the 
  

   region 
  shows 
  it 
  present 
  ; 
  and 
  we 
  know 
  also 
  that 
  it 
  is 
  abundantly 
  

   present 
  in 
  the 
  remainder 
  which 
  has 
  been 
  covered 
  merely 
  by 
  recon- 
  

   naissance 
  work. 
  Because 
  of 
  this 
  scattered 
  distribution 
  we 
  are 
  

   wholly 
  unable 
  as 
  yet 
  to 
  give 
  any 
  estimate 
  of 
  any 
  value 
  concerning 
  

   the 
  area 
  which 
  the 
  rock 
  occupies; 
  we 
  can, 
  however, 
  now 
  say 
  that 
  

   syenite 
  is 
  the 
  surface 
  rock 
  of 
  a 
  much 
  greater 
  area 
  in 
  the 
  Adiron- 
  

   dacks 
  than 
  that 
  occupied 
  by 
  anorthosite, 
  large 
  as 
  the 
  latter 
  is, 
  and 
  

   that 
  the 
  area 
  of 
  syenite 
  is 
  a 
  notable 
  one 
  when 
  compared 
  with 
  any 
  

   other 
  known 
  area 
  the 
  world 
  over. 
  

  

  There 
  are 
  three 
  main 
  areas 
  of 
  syenite 
  within 
  the 
  mapped 
  limits. 
  

   The 
  largest 
  is 
  the 
  one 
  which 
  forms 
  the 
  main 
  mass 
  of 
  the 
  Mt 
  

   McGregor 
  range 
  and 
  its 
  back 
  country. 
  The 
  modern 
  gorge 
  of 
  the 
  

  

  

  