﻿GEOLOGY 
  OF 
  SARATOGA 
  SPRINGS 
  AND 
  VICINITY 
  167 
  

  

  possibility 
  of 
  the 
  continuation 
  to 
  the 
  present 
  time 
  of 
  these 
  processes 
  

   that 
  metamorphose 
  the 
  shales, 
  limestone 
  and 
  sandstones 
  into 
  schists 
  

   and 
  gneisses 
  in 
  the 
  depths 
  of 
  the 
  mountains 
  is 
  not 
  at 
  all 
  disproved. 
  

   At 
  the 
  same 
  time 
  it 
  is 
  also 
  possible 
  that 
  these 
  same 
  limestones 
  and 
  

   sandstones 
  come 
  within 
  the 
  influence 
  of 
  deep-seated, 
  still 
  heated 
  

   igneous 
  rocks, 
  thence 
  deriving 
  their 
  carbonic 
  acid, 
  and 
  at 
  the 
  same 
  

   time 
  that 
  they 
  gather 
  " 
  connate 
  " 
  waters 
  (original 
  sea 
  water 
  de- 
  

   posited 
  with 
  the 
  rocks) 
  from 
  a 
  large 
  area 
  and 
  held 
  in 
  the 
  depths, 
  

   to 
  which 
  they 
  descend, 
  through 
  the 
  thick 
  covering 
  masses 
  of 
  shales. 
  

  

  One 
  naturally 
  asks 
  here 
  why 
  these 
  waters 
  only 
  come 
  up 
  in 
  the 
  

   Gurnspring-Saratoga-Ballston 
  belt, 
  a 
  stretch 
  altogether 
  not 
  more 
  

   that 
  about 
  12 
  miles 
  long. 
  The 
  geologic 
  structure 
  of 
  the 
  region 
  is 
  

   responsible 
  for 
  this 
  phenomenon 
  (see 
  diagram, 
  text 
  fig. 
  17). 
  

  

  South 
  of 
  Ballston 
  the 
  shales 
  again 
  thicken 
  rapidly 
  on 
  account 
  of 
  

   the 
  southward 
  dip 
  of 
  the 
  beds, 
  until 
  at 
  Schenectady 
  they 
  reach 
  no 
  

   doubt 
  more 
  than 
  3000 
  feet 
  in 
  thickness, 
  thus 
  shutting 
  the 
  waters 
  

   off 
  from 
  the 
  surface 
  to 
  the 
  south 
  of 
  the 
  Saratoga 
  mineral 
  springs 
  

   region. 
  Northward 
  of 
  this 
  region 
  the 
  structural 
  relations 
  are 
  not 
  

   yet 
  well 
  understood 
  and 
  the 
  reasons 
  for 
  the 
  absence 
  of 
  the 
  springs 
  

   not 
  apparent. 
  At 
  Glens 
  Falls 
  the 
  " 
  Trenton 
  " 
  and 
  Black 
  River 
  

   limestones 
  come 
  again 
  to 
  the 
  surface 
  but 
  without 
  bringing 
  any 
  

   mineral 
  water. 
  This 
  outcrop 
  is 
  apparently 
  the 
  southern 
  spur 
  of 
  

   a 
  fault 
  block. 
  It 
  probably 
  fails 
  to 
  intercept 
  the 
  mineral 
  waters 
  

   coming 
  from 
  the 
  east 
  because 
  it 
  lies 
  west 
  of 
  another 
  large 
  fault, 
  

   which 
  is 
  indicated 
  by 
  the 
  Fort 
  Ann 
  spur 
  of 
  Precambric 
  rocks 
  and 
  

   which 
  extends 
  close 
  to 
  or 
  into 
  the 
  crumpled 
  shales 
  of 
  the 
  eastern 
  

   basin, 
  thus 
  shutting 
  off 
  the 
  mineral 
  waters 
  from 
  access 
  to 
  more 
  

   western 
  regions 
  or 
  to 
  the 
  surface 
  altogether. 
  We 
  have 
  seen 
  before 
  

   that 
  the 
  Precambric 
  rocks 
  west 
  of 
  the 
  Spring 
  fault 
  form 
  a 
  barrier 
  

   for 
  the 
  waters 
  in 
  that 
  direction 
  and 
  that 
  the 
  thick 
  masses 
  of 
  shales 
  

   east 
  of 
  the 
  area 
  serve 
  there 
  as 
  a 
  competent 
  cover. 
  The 
  Spring 
  belt 
  

   is 
  thus 
  shut 
  in 
  on 
  all 
  four 
  sides 
  by 
  either 
  thick 
  masses 
  of 
  shales 
  

   (east 
  and 
  south) 
  or 
  barriers 
  of 
  Precambric 
  rocks 
  (west 
  and 
  north) 
  

   and 
  in 
  the 
  belt 
  itself 
  the 
  waters 
  are 
  brought 
  nearest 
  to 
  the 
  surface 
  

   in 
  following 
  the 
  routes 
  of 
  least 
  resistance. 
  

  

  