﻿i86 
  

  

  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  Adams 
  also 
  shows, 
  in 
  his 
  valuable 
  paper, 
  the 
  similarity 
  in 
  compo- 
  

   sition 
  of 
  his 
  contact 
  amphibolite 
  with 
  other 
  amphibolites, 
  even 
  some 
  

   of 
  igneous 
  origin. 
  It 
  would 
  seem 
  therefore 
  that 
  we 
  are 
  reasonably 
  

   safe 
  in 
  assuming 
  that 
  analysis 
  4 
  will 
  not 
  depart 
  widely 
  in 
  composi- 
  

   tion 
  from 
  most 
  of 
  the 
  amphibolites 
  of 
  the 
  region, 
  no 
  matter 
  what 
  

   their 
  origin. 
  

  

  The 
  analyses 
  of 
  the 
  two 
  granites 
  have 
  been 
  already 
  discussed. 
  

   No. 
  2 
  does 
  not 
  depart 
  widely 
  from 
  no. 
  i 
  in 
  composition, 
  and 
  might 
  

   well 
  represent 
  a 
  simple 
  variant 
  of 
  the 
  magma. 
  Its 
  field 
  relations, 
  

   however, 
  preclude 
  that 
  supposition 
  and 
  it 
  is 
  to 
  be 
  noted 
  that, 
  when 
  

   compared 
  with 
  analyses 
  i 
  and 
  4, 
  it 
  represents 
  an 
  intermediate 
  stage 
  

   in 
  every 
  single 
  important 
  constituent. 
  On 
  the 
  basis 
  of 
  the 
  silica 
  

   percentage 
  a 
  mixture 
  of 
  six 
  parts 
  of 
  analysis 
  i 
  and 
  one 
  part 
  of 
  

   analysis 
  4 
  would 
  almost 
  give 
  a 
  rock 
  of 
  the 
  composition 
  of 
  analysis 
  2. 
  

   Calculated 
  on 
  that 
  basis 
  the 
  following 
  result 
  is 
  arrived 
  at 
  : 
  

  

  Si02. 
  

  

  AI2O3 
  

  

  Fe203 
  

  

  FeO. 
  , 
  

  

  MgO. 
  

  

  CaO. 
  

  

  Na2{0, 
  

  

  KoO. 
  

  

  I 
  

  

  2 
  

  

  3 
  

  

  

  70.13 
  

  

  70.05 
  

  

  56.58 
  

  

  15-47 
  

  

  14.73 
  

  

  15 
  

  

  54 
  

  

  1.52 
  

  

  1.42 
  

  

  3 
  

  

  80 
  

  

  1.05 
  

  

  1.63 
  

  

  5 
  

  

  41 
  

  

  .85 
  

  

  1. 
  18 
  

  

  2 
  

  

  77 
  

  

  1 
  .60 
  

  

  1.99 
  

  

  4 
  

  

  56 
  

  

  3-72 
  

  

  3-17 
  

  

  2 
  

  

  91 
  

  

  4.39 
  

  

  5.08 
  

  

  4 
  

  

  25 
  

  

  56.62 
  

  

  16.66 
  

  

  3.01 
  

  

  4.14 
  

  

  3.97 
  

  

  5-53 
  

   3-58 
  

   3-79 
  

  

  In 
  column 
  i 
  are 
  given 
  the 
  percentages 
  of 
  the 
  soaked 
  rock 
  shown 
  

   by 
  analysis, 
  and 
  in 
  2 
  the 
  calculated 
  percentages 
  on 
  the 
  basis 
  stated 
  

   above. 
  They 
  seem 
  to 
  us 
  to 
  be 
  sufficiently 
  alike 
  in 
  every 
  constituent 
  

   to 
  afiford 
  a 
  strong 
  probability 
  that 
  the 
  field 
  relations 
  were 
  correctly 
  

   interpreted, 
  and 
  that 
  the 
  rock 
  is 
  a 
  true 
  soaked 
  rock. 
  The 
  greatest 
  

   variation 
  between 
  the 
  two 
  is 
  in 
  the 
  alkali 
  percentages, 
  and 
  these 
  

   are 
  just 
  the 
  ones 
  which 
  vary 
  most 
  in 
  the 
  general 
  granite 
  masses. 
  

   The 
  total 
  amount 
  of 
  alkalies, 
  however, 
  is 
  much 
  the 
  same 
  in 
  each, 
  

   8.115^ 
  in 
  the 
  first 
  case 
  and 
  8.25^ 
  in 
  the 
  second. 
  

  

  The 
  granitized 
  amphibolite 
  is 
  not 
  so 
  definitely 
  a 
  soaked 
  rock 
  as 
  

   the 
  other, 
  since 
  the 
  amount 
  of 
  granite 
  in 
  it 
  is 
  so 
  small, 
  that 
  it 
  is 
  

   an 
  impregnated, 
  rather 
  than 
  a 
  mixed 
  rock. 
  Nevertheless 
  the 
  granite 
  

   is 
  thoroughly 
  disseminated 
  through 
  it, 
  though 
  granitizing 
  it 
  in 
  

   patches 
  rather 
  than 
  uniformly. 
  Column 
  3 
  gives 
  the 
  rock 
  percent- 
  

  

  1 
  

  

  