﻿GEOLOGY 
  OF 
  SARATOGA 
  SPRINGS 
  AND 
  VICINITY 
  1 
  7 
  

  

  granite 
  and 
  gabbro, 
  in 
  the 
  order 
  named. 
  These 
  probably 
  repre- 
  

   sent 
  a 
  group 
  of 
  closely 
  related 
  intrusions 
  not 
  widely 
  separated 
  in 
  

   time 
  from 
  one 
  another. 
  Much 
  later 
  came 
  renewed 
  igneous 
  activity 
  

   with 
  intrusion 
  of 
  diabase 
  (trap), 
  found 
  exclusively 
  as 
  dikes 
  cutting 
  

   all 
  the 
  other 
  Precambric 
  rocks. 
  

  

  Representatives 
  of 
  all 
  these 
  rock 
  groups 
  occur 
  in 
  the 
  Saratoga 
  

   region. 
  The 
  Grenville 
  rocks 
  are 
  abundantly 
  represented 
  ; 
  Laurentian 
  

   granite 
  is 
  probably 
  present, 
  that 
  is 
  to 
  say 
  there 
  is 
  abundance 
  of 
  a 
  

   granitic 
  rock 
  which 
  we 
  regard 
  as 
  probably 
  Laurentian 
  ; 
  the 
  second 
  

   group 
  of 
  intrusions 
  is 
  represented 
  by 
  abundant 
  syenite 
  and 
  ap- 
  

   parently 
  by 
  that 
  alone 
  ; 
  and 
  occasional 
  trap 
  dikes 
  of 
  large 
  size 
  

   belong 
  to 
  the 
  last 
  group. 
  

  

  GRENVILLE 
  SERIES 
  

  

  The 
  Grenville 
  series 
  in 
  the 
  Adirondacks 
  exhibits 
  an 
  enormous 
  

   thickness 
  of 
  limestones, 
  quartzites 
  and 
  various 
  sorts 
  of 
  schists. 
  

   On 
  the 
  Saratoga 
  quadrangle 
  the 
  bulk 
  of 
  the 
  Grenville 
  consists 
  of 
  

   schists, 
  but 
  there 
  is 
  also 
  a 
  considerable 
  amount 
  of 
  quartzite. 
  Lime- 
  

   stone 
  is 
  present 
  only 
  as 
  occasional 
  thin 
  bands 
  in 
  the 
  quartzite 
  

   series. 
  A 
  few 
  miles 
  farther 
  north, 
  however, 
  much 
  more 
  lime- 
  

   stone 
  comes 
  in. 
  A 
  considerable 
  belt 
  in 
  which 
  there 
  is 
  much 
  quartz- 
  

   ite, 
  interbedded 
  with 
  thin 
  bands 
  of 
  schist 
  and 
  limestone, 
  con- 
  

   trasts 
  so 
  strongly 
  with 
  the 
  remainder 
  of 
  the 
  Grenville 
  that 
  we 
  have 
  

   mapped 
  it 
  separately. 
  With 
  this 
  exception 
  the 
  intricate 
  admixture 
  

   of 
  various 
  schists 
  absolutely 
  defies 
  detailed 
  mapping. 
  

  

  In 
  addition, 
  the 
  series 
  is 
  everywhere 
  cut 
  to 
  pieces 
  by 
  a 
  white, 
  

   granitic 
  rock 
  of 
  somewhat 
  peculiar 
  type, 
  that 
  we 
  have 
  heretofore 
  

   been 
  regarding 
  as 
  a 
  Grenville 
  sediment. 
  The 
  reasons 
  for 
  regarding 
  

   it 
  as 
  an 
  igneous 
  rock 
  will 
  shortly 
  appear. 
  We 
  have 
  mapped 
  sepa- 
  

   rately 
  three 
  areas 
  of 
  this 
  rock, 
  but 
  the 
  mapping 
  is 
  vague 
  and 
  highly 
  

   conventional. 
  The 
  rock 
  is 
  found 
  everywhere 
  throughout 
  the 
  Gren- 
  

   ville 
  area, 
  inextricably 
  mingled 
  with 
  the 
  schists. 
  In 
  these 
  three 
  

   areas 
  it 
  exceeds 
  the 
  schists 
  in 
  quantity 
  and 
  is 
  mapped 
  separately 
  

   to 
  give 
  conventional 
  expression 
  to 
  our 
  views 
  respecting 
  its 
  nature 
  

   and 
  relationships. 
  We 
  are 
  provisionally 
  regarding 
  it 
  as 
  Lauren- 
  

   tian, 
  that 
  being 
  the 
  term 
  applied 
  to 
  the 
  ancient 
  granitic 
  rocks 
  which, 
  

   throughout 
  Canada, 
  the 
  Upper 
  Lake 
  region 
  and 
  the 
  Adirondacks, 
  

   invade 
  and 
  cut 
  to 
  pieces 
  the 
  oldest 
  known 
  clastic 
  deposits. 
  The 
  

   uncertain 
  feature 
  of 
  this 
  correlation, 
  so 
  far 
  as 
  the 
  Adirondacks 
  

   is 
  concerned, 
  is 
  that 
  the 
  Laurentian 
  granite, 
  in 
  the 
  Lake 
  Superior 
  

   region, 
  is 
  older 
  than 
  the 
  Lower 
  Huronian. 
  hence 
  the 
  use 
  of 
  the 
  

  

  