﻿GEOLOGY 
  OF 
  WASHINGTON, 
  WARREN 
  COUNTIES, 
  ETC. 
  513 
  

  

  gneisses. 
  The 
  familiar 
  green 
  aggregate 
  of 
  quartz 
  and 
  pyroxene 
  

   that 
  so 
  often 
  accompanies 
  the 
  exposures 
  in 
  Essex 
  co. 
  is 
  present. 
  

  

  Series 
  3. 
  The 
  dark, 
  basic 
  gabbros 
  appear 
  at 
  several 
  points 
  on 
  

   the 
  Lake 
  George 
  shore 
  in 
  the 
  southwestern 
  corner 
  of 
  the 
  town. 
  

   They 
  have 
  not 
  escaped 
  dynamic 
  metamorphism, 
  being 
  now 
  all 
  

   more 
  or 
  less 
  foliated 
  but 
  the 
  gabbroic 
  character 
  is 
  still 
  recog- 
  

   nizable. 
  They 
  consist 
  of 
  granulated 
  labradorite, 
  augite, 
  hypers- 
  

   thene, 
  hornblende, 
  magnetite 
  and 
  garnet. 
  In 
  two 
  places 
  a 
  differ- 
  

   ent 
  type 
  of 
  igneous 
  rock 
  has 
  been 
  found 
  that 
  probably 
  should 
  be 
  

   placed 
  in 
  this 
  series. 
  It 
  must 
  have 
  been 
  originally 
  a 
  thoroughly 
  

   crystalline 
  porphyritic 
  rock, 
  with 
  large 
  phenocrysts 
  of 
  plagio- 
  

   clase, 
  up 
  to 
  one 
  inch 
  across, 
  and 
  was 
  probably 
  a 
  porphyritic 
  dio- 
  

   rite. 
  At 
  both 
  exposures 
  it 
  has 
  however 
  been 
  compressed 
  and 
  

   sheared 
  so 
  that 
  it 
  is 
  now 
  an 
  augen-gneiss. 
  The 
  phenocrysts 
  

   and 
  groundsmars 
  are 
  thoroughly 
  granulated 
  and 
  much 
  biotite, 
  

   presumably 
  secondary 
  has 
  been 
  formed. 
  In 
  no. 
  4 
  garnet 
  rims 
  

   surround 
  the 
  phenocrysts, 
  appearing 
  only 
  along 
  their 
  outer 
  edges* 
  

   The 
  mass 
  of 
  the 
  rock 
  impresses 
  one 
  as 
  a 
  coarse 
  sandy 
  aggregate, 
  

   although 
  the 
  grains 
  are 
  now 
  firmly 
  bound 
  together. 
  Similar 
  rocks 
  

   to 
  these 
  were 
  earlier 
  met 
  in 
  Ticonderoga, 
  and 
  are 
  referred 
  to 
  on 
  

   p. 
  454, 
  of 
  the 
  Report 
  of 
  the 
  state 
  geologist, 
  1893. 
  

  

  Series 
  4. 
  Some 
  extremely 
  interesting 
  outcrops 
  of 
  the 
  paleozoic 
  

   sediments 
  appear 
  in 
  Putnam. 
  The 
  Potsdam 
  is 
  the 
  most 
  extensive 
  

   of 
  these 
  and 
  covers 
  three 
  or 
  four 
  square 
  miles. 
  Only 
  a 
  thin 
  cross- 
  

   section 
  is 
  however 
  seen 
  resting 
  on 
  the 
  underlying 
  gneiss. 
  The 
  

   beds 
  are 
  quartzites, 
  which 
  are 
  often 
  quite 
  coarse 
  conglomerates. 
  

   In 
  the 
  southern 
  area, 
  near 
  specimen 
  32, 
  the 
  conglomerate 
  con- 
  

   tains 
  quartz 
  boulders 
  up 
  to 
  6 
  inches 
  in 
  diameter. 
  In 
  the 
  finer 
  

   varieties 
  ripple-marks 
  are 
  at 
  times 
  well 
  developed. 
  The 
  quartzite 
  

   is 
  often 
  very 
  feldspathic 
  and 
  is 
  practically 
  arkose. 
  The 
  clastic 
  

   material 
  has 
  been 
  derived 
  from 
  the 
  neighboring 
  gneisses. 
  The 
  

   Calciferous 
  is 
  the 
  usual, 
  blue 
  siliceous 
  variety, 
  characteristic 
  of 
  

   the 
  Ohamplain 
  valley. 
  Its 
  contacts 
  against 
  the 
  Potsdam 
  were 
  in 
  

   each 
  case 
  along 
  faults. 
  The 
  dip 
  of 
  both 
  is 
  in 
  all 
  cases 
  flat 
  and 
  

   nw 
  or 
  n. 
  

  

  Series 
  5. 
  No 
  trap 
  dikes 
  were 
  found. 
  , 
  i 
  

  

  