﻿134 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  If 
  the 
  drill 
  should 
  show 
  that 
  the 
  Bald 
  Mountain 
  limestone 
  was 
  

   absent 
  below 
  ground 
  at 
  the 
  knob, 
  a 
  quite 
  different 
  face 
  would 
  be 
  

   put 
  upon 
  the 
  matter. 
  But 
  the 
  drill 
  has 
  not 
  been 
  at 
  work 
  in 
  the 
  

   vicinity. 
  

  

  The 
  age 
  of 
  the 
  lava. 
  Since 
  the 
  suggestion 
  was 
  made 
  that 
  the 
  

   igneous 
  rock 
  of 
  the 
  knob 
  might 
  ha 
  e 
  some 
  significance 
  in 
  connec- 
  

   tion 
  with 
  the 
  theory 
  of 
  the 
  juvenile 
  origin 
  of 
  the 
  Saratoga 
  waters, 
  

   the 
  question 
  of 
  the 
  geologic 
  age 
  of 
  the 
  rock 
  becomes 
  of 
  more 
  

   moment 
  than 
  would 
  otherwise 
  be 
  the 
  case. 
  Unfortunately 
  precise 
  

   data 
  are 
  quite 
  lacking. 
  

  

  When 
  Woodworth 
  and 
  Cushing 
  considered 
  this 
  matter, 
  at 
  the 
  

   time 
  of 
  the 
  original 
  description 
  of 
  the 
  knob, 
  a 
  Newark 
  (Triassic) 
  

   age 
  was 
  suggested 
  by 
  each 
  of 
  them, 
  independently, 
  as 
  most 
  prob- 
  

   able. 
  Then, 
  as 
  now, 
  the 
  only 
  positive 
  statement 
  that 
  could 
  be 
  made 
  

   is 
  that 
  the 
  igneous 
  rock 
  must 
  be 
  younger 
  than 
  'the 
  shales, 
  which 
  

   surround 
  it. 
  Even 
  this 
  is 
  not 
  necessarily 
  true, 
  if 
  it 
  has 
  been 
  over- 
  

   thrust. 
  The 
  shales 
  are 
  of 
  Ordovicic 
  age. 
  There 
  are 
  known 
  in. 
  

   New 
  York 
  three 
  groups 
  of 
  igneous 
  rocks 
  which 
  fulfil 
  that 
  age 
  

   requirement, 
  the 
  dikes 
  of 
  the 
  Champlain 
  valley, 
  the 
  dikes 
  of 
  cen- 
  

   tral 
  New 
  York, 
  and 
  the 
  traps 
  of 
  the 
  Newark 
  series. 
  The 
  rock, 
  

   in 
  its 
  characters, 
  does 
  not 
  at 
  all 
  suggest 
  the 
  Champlain 
  dikes 
  ; 
  still 
  

   less 
  does 
  it 
  in 
  any 
  way 
  resemble 
  the 
  peridotites 
  of 
  central 
  New 
  

   York; 
  but 
  it 
  is 
  quite 
  similar 
  to 
  some 
  phases 
  of 
  the 
  Newark 
  traps. 
  

   Unless 
  we 
  referred 
  it 
  to 
  the 
  Newark 
  we 
  had 
  no 
  alternative 
  but 
  to 
  

   regard 
  it 
  as 
  representing 
  igneous 
  action 
  of 
  some 
  other 
  date, 
  with 
  

   no 
  other 
  known 
  representatives 
  in 
  the 
  State. 
  

  

  That 
  still 
  seems 
  to 
  us 
  the 
  most 
  logical 
  view 
  to 
  take 
  in 
  default 
  

   of 
  actual 
  evidence 
  to 
  the 
  contrary. 
  The 
  amount 
  of 
  deformation 
  

   experienced 
  by 
  the 
  knob 
  seems 
  a 
  positive 
  evidence 
  of 
  antiquity. 
  

   The 
  dislocations 
  already 
  described 
  indicate 
  deformation 
  under 
  

   load, 
  under 
  a 
  considerable 
  thickness 
  of 
  overlying 
  rock 
  which 
  has 
  

   since 
  been 
  eroded. 
  The 
  lava 
  is 
  of 
  the 
  effusive 
  type, 
  either 
  a 
  vol- 
  

   canic 
  neck 
  or 
  a 
  fragment 
  of 
  a 
  lava 
  flow. 
  Since 
  its 
  formation 
  it 
  

   has 
  been 
  buried 
  under 
  other 
  rock, 
  deformed, 
  and 
  the 
  overlying 
  

   material 
  removed 
  by 
  erosion. 
  When 
  or 
  under 
  what 
  it 
  was 
  buried 
  

   we 
  have 
  no 
  means 
  of 
  knowing, 
  since 
  all 
  trace 
  of 
  the 
  material 
  has 
  

   since 
  been 
  removed 
  ; 
  but 
  if 
  the 
  lava 
  is 
  in 
  place, 
  continental 
  deposits 
  

   of 
  Newark 
  age 
  seems 
  the 
  most 
  likely 
  supposition. 
  It 
  might 
  have 
  

   been 
  later 
  continental 
  deposits. 
  To 
  be 
  sure, 
  the 
  knob 
  lies 
  in 
  a 
  

   main 
  valley 
  of 
  erosion 
  surrounded 
  by 
  relatively 
  weak 
  rocks, 
  so 
  

   that 
  conditions 
  are 
  favorable 
  to 
  rapid 
  wear. 
  But 
  even 
  making 
  

  

  