﻿GEOLOGY 
  OF 
  SARATOGA 
  SPRINGS 
  AND 
  VICINITY 
  7 
  

  

  Hudson 
  trough. 
  This 
  is 
  not 
  a 
  mere 
  valley 
  of 
  erosion 
  but 
  a 
  true 
  

   trough, 
  having 
  been 
  repeatedly 
  depressed 
  as 
  compared 
  with 
  the 
  

   districts 
  east 
  and 
  west 
  of 
  it. 
  Erosion 
  has 
  had 
  its 
  part 
  in 
  the 
  

   development 
  of 
  the 
  valley, 
  but 
  as 
  a 
  secondary 
  instead 
  of 
  a 
  primary 
  

   factor. 
  In 
  the 
  mapped 
  district 
  this 
  lowland 
  is 
  seen 
  merging 
  into 
  

   the 
  Mohawk 
  lowland. 
  Across 
  the 
  Hudson, 
  along 
  the 
  east 
  margin 
  

   of 
  the 
  Schuylerville 
  sheet, 
  rises 
  a 
  range 
  of 
  hills, 
  the 
  outlying 
  

   western 
  rampart 
  of 
  the 
  New 
  England 
  plateaus. 
  

  

  Turning 
  from 
  topography 
  to 
  geology 
  we 
  find 
  the 
  old 
  crystalline 
  

   rocks 
  of 
  the 
  Adirondacks 
  coming 
  into 
  the 
  district 
  from 
  the 
  north. 
  

   These 
  are 
  margined 
  by 
  the 
  flat-lying 
  sandstones, 
  limestones 
  and 
  

   shales 
  of 
  early 
  Paleozoic 
  age 
  which 
  were 
  deposited 
  in 
  the 
  Cham- 
  

   plain 
  basin, 
  even 
  in 
  that 
  early 
  time 
  a 
  sinking 
  trough. 
  These 
  in 
  

   turn 
  are 
  adjoined 
  on 
  the 
  east 
  by 
  the 
  series 
  of 
  much 
  disturbed 
  

   shales 
  of 
  the 
  Hudson 
  valley, 
  a 
  quite 
  different 
  series 
  of 
  rocks 
  from 
  

   those 
  of 
  the 
  Champlain 
  basin. 
  They 
  were 
  deposited, 
  also 
  in 
  early 
  

   Paleozoic 
  times, 
  in 
  a 
  wholly 
  separate 
  and 
  more 
  easterly 
  trough 
  

   than 
  the 
  Champlain 
  basin, 
  and 
  have 
  been 
  brought 
  to 
  their 
  present 
  

   location 
  by 
  being 
  thrust 
  over 
  to 
  the 
  west 
  by 
  the 
  action 
  of 
  great 
  

   compressive 
  forces. 
  As 
  rocks 
  they 
  are 
  not 
  indigenous 
  to 
  the 
  

   region, 
  but 
  exotic. 
  Still 
  farther 
  east 
  come 
  the 
  limestones 
  and 
  impure 
  

   shaly 
  rocks 
  of 
  the 
  Bald 
  Mountain 
  ridge, 
  also 
  overthrust 
  into 
  the 
  

   district 
  from 
  the 
  east. 
  These 
  rocks 
  are 
  so 
  different 
  from 
  those 
  

   of 
  the 
  Champlain 
  basin 
  that 
  we 
  are 
  of 
  necessity 
  constrained 
  to 
  

   describe 
  and 
  discuss 
  them 
  in 
  separate 
  chapters. 
  

  

  In 
  two 
  minor 
  features 
  the 
  geology 
  of 
  the 
  region 
  is 
  unique. 
  One 
  

   of 
  the 
  Paleozoic 
  formations 
  of 
  the 
  Champlain 
  basin, 
  the 
  fossil- 
  

   iferous, 
  Upper 
  Cambric 
  limestone 
  which 
  was 
  first 
  described 
  by 
  

   Walcott, 
  occurs 
  as 
  a 
  surface 
  formation 
  in 
  New 
  York 
  only 
  in 
  the 
  

   immediate 
  vicinity 
  of 
  Saratoga. 
  1 
  Just 
  north 
  of 
  Schuylerville 
  there 
  

   outcrops 
  a 
  knob 
  of 
  extrusive 
  igneous 
  rock, 
  first 
  recognized 
  and 
  

   described 
  by 
  Wood 
  worth, 
  which 
  is 
  unlike 
  any 
  other 
  known 
  igneous 
  

   rock 
  of 
  the 
  State, 
  and 
  which 
  has 
  been 
  made 
  to 
  play 
  a 
  part 
  in 
  one 
  

   theory 
  of 
  the 
  origin 
  of 
  the 
  spring 
  waters. 
  2 
  

  

  1 
  U. 
  S. 
  Geol. 
  Surv., 
  Bui. 
  30, 
  p. 
  21-22. 
  

  

  2 
  N. 
  Y. 
  State 
  Gcol. 
  21st 
  Ann. 
  Rep't, 
  p. 
  rJ7~r2r», 
  1901. 
  

  

  