﻿NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  GENERAL 
  TOPOGRAPHY 
  

  

  BY 
  H. 
  P. 
  CUSHING 
  

  

  ADIRONDACK 
  HIGHLAND 
  

  

  The 
  surface 
  rocks 
  of 
  the 
  Adirondack 
  highland 
  are 
  ancient 
  

   crystalline 
  rocks 
  of 
  Precambric 
  age. 
  The 
  district 
  is 
  one 
  with 
  an 
  

   inherent 
  tendency 
  to 
  be 
  elevated 
  and 
  to 
  move 
  upward 
  rather 
  than 
  

   downward, 
  or 
  at 
  least 
  not 
  to 
  participate 
  in 
  the 
  sagging 
  tendency 
  

   of 
  adjacent 
  territory 
  during 
  times 
  of 
  oscillations 
  in 
  the 
  crust 
  of 
  

   the 
  earth. 
  Such 
  a 
  region 
  is 
  spoken 
  of 
  as 
  a 
  positive 
  one, 
  to 
  dis- 
  

   tinguish 
  it 
  from 
  districts 
  of 
  the 
  negative 
  type, 
  whose 
  tendency 
  is 
  

   to 
  depress. 
  At 
  certain 
  times 
  in 
  the 
  past 
  the 
  margins 
  of 
  the 
  high- 
  

   land 
  have 
  been 
  sufficiently 
  depressed 
  to 
  pass 
  beneath 
  sea 
  level 
  

   and 
  become 
  covered 
  by 
  marine 
  deposits. 
  But 
  the 
  central 
  area 
  

   of 
  the 
  plateau 
  seems 
  never 
  to 
  have 
  been 
  depressed 
  in 
  this 
  manner, 
  

   or 
  at 
  least 
  not 
  since 
  very 
  early 
  in 
  Precambric 
  time 
  ; 
  since 
  then 
  it 
  

   has 
  had 
  a 
  continuous 
  existence 
  as 
  a 
  land 
  area. 
  From 
  time 
  to 
  time 
  

   it 
  has 
  been 
  uplifted 
  and 
  its 
  surface 
  has 
  experienced 
  much 
  erosion. 
  

   Between 
  the 
  periodic 
  uplifts 
  long 
  ages 
  of 
  stability 
  have 
  intervened. 
  

   During 
  these 
  stable 
  intervals 
  the 
  surface 
  has 
  been 
  the 
  scene 
  of 
  

   incessant 
  erosion, 
  chiefly 
  by 
  stream 
  and 
  rain 
  action. 
  The 
  ulti- 
  

   mate 
  effect 
  of 
  such 
  prolonged 
  erosion 
  on 
  a 
  stable 
  land 
  area 
  is 
  

   to 
  wear 
  it 
  down 
  to 
  a 
  comparatively 
  even 
  surface 
  with 
  low 
  altitude. 
  

   Such 
  an 
  erosion 
  plain 
  is 
  called 
  a 
  peneplain. 
  If 
  a 
  peneplained 
  dis- 
  

   trict 
  be 
  again 
  uplifted, 
  stream 
  activity 
  is 
  renewed 
  and 
  the 
  whole 
  

   erosion 
  process 
  again 
  set 
  in 
  motion. 
  

  

  The 
  Adirondack 
  highland 
  has 
  certainly 
  been 
  peneplained 
  twice 
  

   during 
  its 
  history, 
  and 
  quite 
  likely 
  more 
  than 
  twice. 
  The 
  earlier 
  

   of 
  the 
  two 
  peneplains 
  was 
  completed 
  in 
  Precambric 
  time, 
  and 
  it 
  

   was 
  upon 
  this 
  peneplained 
  surface 
  that 
  the 
  early 
  Paleozoic 
  deposits 
  

   of 
  northern 
  New 
  York 
  were 
  laid 
  down, 
  about 
  the 
  margins 
  of 
  the 
  

   Adirondacks. 
  These 
  covered 
  and 
  preserved 
  this 
  old 
  erosion 
  sur- 
  

   face 
  and 
  portions 
  of 
  it 
  are 
  reappearing 
  at 
  the 
  present-day 
  surface, 
  

   as 
  the 
  Paleozoic 
  cover 
  is 
  stripped 
  away 
  from 
  it 
  by 
  modern 
  erosion. 
  1 
  

   Its 
  comparative 
  evenness 
  is 
  surprising, 
  when 
  the 
  great 
  variation 
  

   of 
  the 
  rocks 
  composing 
  it 
  in 
  resistance 
  to 
  erosion 
  is 
  considered. 
  

  

  In 
  considerable 
  part 
  the 
  present 
  Precambric 
  surfaces 
  of 
  the 
  

   Saratoga 
  quadrangle 
  represent 
  fragments 
  of 
  this 
  old 
  peneplain, 
  

   though 
  somewhat 
  modified 
  by 
  comparatively 
  modern 
  erosion. 
  This 
  

   Precambric 
  peneplain 
  was 
  developed 
  over 
  a 
  wide 
  area 
  and 
  is 
  

  

  1 
  N. 
  Y. 
  State 
  Mus. 
  Bui. 
  145, 
  p. 
  54-6a 
  

  

  