﻿GEOLOGY 
  OF 
  SARATOGA 
  SPRINGS 
  AND 
  VICINITY 
  IO9 
  

  

  Taconic 
  ' 
  are 
  there 
  pushed 
  over 
  on 
  to 
  the 
  Chazy 
  Terrane, 
  and 
  that 
  

   the 
  ' 
  Upper 
  Taconic 
  ' 
  is 
  not 
  unconformably 
  subjacent 
  to 
  the 
  latter 
  

   or 
  to 
  the 
  Calciferous 
  sandrock." 
  

  

  The 
  fossiliferous 
  limestone 
  of 
  the 
  downthrow 
  block 
  is 
  Beekman- 
  

   town; 
  the 
  lower, 
  darker 
  dolomitic 
  beds 
  belong 
  to 
  the 
  same 
  forma- 
  

   tion 
  with 
  the 
  upper, 
  lighter, 
  purer 
  limestones, 
  being 
  separated 
  at 
  

   Bald 
  mountain 
  by 
  an 
  inthrust 
  wedge 
  of 
  shale 
  and 
  conglomerate. 
  

   The 
  black 
  slates 
  which 
  Emmons 
  considered 
  as 
  the 
  Taconic 
  black 
  

   slates 
  underlying 
  the 
  " 
  calciferous 
  sandrock 
  " 
  are 
  the 
  Snake 
  Hill 
  

   shales, 
  and 
  his 
  conception 
  of 
  the 
  structure 
  of 
  Bald 
  mountain 
  has 
  

   thus 
  become 
  completely 
  reversed. 
  

  

  The 
  Bald 
  mountain 
  section 
  is 
  of 
  great 
  interest, 
  not 
  only 
  in 
  

   regard 
  to 
  the 
  Taconic 
  controversy 
  and 
  the 
  different 
  explanations 
  

   offered 
  for 
  it, 
  but 
  especially 
  as 
  distinctly 
  showing 
  an 
  overthrust 
  

   of 
  the 
  Georgian 
  rocks 
  upon 
  the 
  Ordovicic 
  beds 
  and 
  the 
  thrust- 
  

   shattered 
  condition 
  of 
  all 
  the 
  beds 
  involved 
  in 
  the 
  section. 
  The 
  

   photographs 
  on 
  plates 
  12-14 
  show 
  the 
  limestones 
  much 
  broken 
  by 
  

   thrust 
  planes 
  auxiliary 
  to 
  the 
  master 
  overthrust, 
  and 
  overlain 
  by 
  

   masses 
  of 
  mylonite 
  (see 
  page 
  84) 
  upon 
  which 
  rest 
  the 
  Georgian 
  

   shale 
  and 
  shaly 
  limestone. 
  There 
  remain 
  standing 
  detached 
  cliffs 
  

   or 
  blocks 
  consisting 
  of 
  conglomerate 
  and 
  shale 
  on 
  the 
  south 
  side 
  

   and 
  in 
  front 
  of 
  the 
  quarry, 
  which 
  indicate 
  the 
  former 
  extent 
  of 
  

   this 
  formation, 
  while 
  to 
  the 
  southwest 
  and 
  west 
  of 
  the 
  quarry 
  

   there 
  outcrop 
  in 
  several 
  places 
  the 
  dark 
  dolomites 
  (see 
  diagram 
  

   of 
  front 
  of 
  mountain, 
  plate 
  of 
  sections). 
  It 
  thus 
  appears 
  as 
  if 
  

   the 
  shales 
  and 
  conglomerates 
  separate 
  the 
  pure 
  limestone 
  above 
  

   and 
  the 
  dark 
  dolomite 
  below. 
  As 
  we 
  have 
  stated 
  in 
  another 
  place, 
  

   these 
  two 
  divisions 
  both 
  north 
  and 
  south 
  of 
  Bald 
  mountain 
  grade 
  

   into 
  each 
  other 
  and 
  form 
  one 
  formation. 
  It 
  is 
  therefore 
  probable 
  

   that 
  the 
  shales 
  and 
  conglomerate 
  in 
  front 
  of 
  Bald 
  mountain 
  form 
  

   only 
  a 
  wedge 
  thrust 
  in 
  between 
  the 
  limestones 
  and 
  dolomite. 
  

  

  Dale 
  (op. 
  cit. 
  } 
  page 
  293), 
  from 
  his 
  elaborate 
  investigation 
  of 
  the 
  

   New 
  York- 
  Vermont 
  slate 
  belt, 
  arrived 
  at 
  the 
  conclusion 
  that 
  the 
  

   overthrusting 
  at 
  the 
  western 
  margin 
  of 
  the 
  Cambric 
  area 
  is 
  only 
  

   local 
  in 
  the 
  shale 
  region 
  of 
  New 
  York- 
  Vermont. 
  He 
  says 
  : 
  

  

  The 
  striking 
  features 
  in 
  all 
  these 
  localities, 
  leaving 
  out 
  the 
  last, 
  are 
  the 
  

   uniformity 
  of 
  the 
  dip, 
  the 
  great 
  thickness 
  of 
  the 
  Lower 
  Cambrian, 
  and 
  

   the 
  thrusting 
  over 
  of 
  the 
  latter 
  on 
  the 
  Trenton. 
  These 
  features 
  imply 
  great 
  

   rigidity 
  in 
  the 
  beds 
  and 
  relief 
  of 
  compression 
  through 
  faulting. 
  These, 
  how- 
  

   ever, 
  are 
  just 
  the 
  features 
  which 
  are 
  wanting 
  along 
  the 
  slate 
  belt. 
  The 
  

  

  