﻿THE 
  GEOLOGICAL 
  HISTORY 
  OF 
  NEW 
  YORK 
  STATE 
  69 
  

  

  raised 
  Cretacic 
  peneplain. 
  This 
  being 
  the 
  case, 
  are 
  any 
  remnants 
  

   of 
  that 
  upraised 
  surface 
  still 
  left 
  ? 
  In 
  the 
  affirmative 
  answer 
  to 
  this 
  

   inquiry 
  we 
  have 
  the 
  most 
  positive 
  evidence 
  for 
  the 
  former 
  existence 
  

   of 
  the 
  Cretacic 
  peneplain. 
  We 
  have 
  said 
  that 
  the 
  most 
  perfect 
  

   development 
  of 
  the 
  peneplain 
  was 
  from 
  central 
  Pennsylvania 
  to 
  

   Virginia, 
  and 
  it 
  is 
  just 
  here 
  where 
  we 
  should 
  expect 
  to 
  find 
  the 
  

   best 
  remnants 
  of 
  that 
  old 
  surface. 
  In 
  this 
  region 
  the 
  typical 
  Ap- 
  

   palachian 
  ridges 
  and 
  valleys, 
  which 
  run 
  parallel 
  to 
  the 
  trend 
  of 
  the 
  

   mountain 
  range, 
  are 
  very 
  well 
  developed. 
  These 
  valleys 
  are 
  the 
  

   trenches 
  cut 
  along 
  the 
  belts 
  of 
  soft 
  rock 
  and 
  to 
  below 
  the 
  surface 
  

   of 
  the 
  upraised 
  peneplain, 
  while 
  the 
  ridges 
  have 
  developed 
  along 
  

   •the 
  belts 
  of 
  hard 
  rock 
  and 
  their 
  summits 
  actually 
  represent 
  portions 
  

   oi 
  the 
  old 
  peneplain 
  surface. 
  These 
  ridges 
  all 
  rise 
  to 
  the 
  same 
  

   general 
  level 
  for 
  miles 
  around, 
  and 
  as 
  viewed 
  from 
  the 
  summit 
  

   of 
  any 
  one 
  of 
  them 
  the 
  concordant 
  altitudes 
  give 
  rise 
  to 
  what 
  is 
  

   called 
  the 
  " 
  even 
  sky 
  line" 
  which 
  is 
  a 
  most 
  striking 
  feature 
  of 
  the 
  

   landscape. 
  Plate 
  35 
  gives 
  an 
  excellent 
  idea 
  of 
  the 
  even 
  sky 
  line 
  

   across 
  these 
  ridges. 
  

  

  In 
  New 
  York 
  State 
  the 
  concordant 
  altitudes 
  are 
  not 
  so 
  well 
  

   shown 
  both 
  because 
  the 
  peneplain 
  was 
  here 
  not 
  so 
  perfectly 
  de- 
  

   veloped 
  and 
  because 
  the 
  attitude 
  of 
  the 
  strata 
  has 
  largely 
  been 
  

   unfavorable 
  to 
  the 
  formation 
  of 
  long, 
  distinct 
  ridges. 
  Remnants 
  

   of 
  the 
  peneplain 
  are, 
  however, 
  unmistakably 
  present 
  in 
  New 
  York 
  

   as, 
  for 
  example, 
  on 
  a 
  very 
  large 
  scale 
  over 
  the 
  great 
  Southwestern 
  

   plateau 
  whose 
  high 
  points 
  nearly 
  always 
  rise 
  to 
  altitudes 
  of 
  about 
  

   2000 
  feet. 
  This 
  plateau 
  is 
  simply 
  a 
  part 
  of 
  the 
  upraised 
  and 
  dis- 
  

   sected 
  Cretacic 
  peneplain, 
  and 
  the 
  slight 
  downward 
  sag 
  toward 
  the 
  

   middle 
  (already 
  noted 
  in 
  chapter 
  2) 
  is 
  no 
  doubt 
  due 
  to 
  a 
  slight 
  

   downwarping 
  of 
  the 
  general 
  level 
  during 
  the 
  process 
  of 
  uplift. 
  

   The 
  topographic 
  map 
  (plate 
  4) 
  well 
  illustrates 
  the 
  character 
  of 
  

   this 
  dissected 
  plateau. 
  The 
  present 
  elevation 
  of 
  the 
  peneplain 
  

   remnants 
  does 
  not 
  necessarily 
  indicate 
  the 
  maximum 
  amount 
  of 
  

   uplift. 
  In 
  the 
  next 
  chapter 
  evidence 
  will 
  be 
  presented 
  to 
  show 
  

   that, 
  for 
  the 
  New 
  York 
  area 
  at 
  least, 
  the 
  land 
  was 
  considerably 
  

   higher 
  in 
  the 
  Tertiary 
  period 
  than 
  it 
  is 
  at 
  present. 
  

  

  The 
  summit 
  of 
  the 
  Tug 
  Hill 
  province 
  is 
  a 
  small 
  plateau 
  at 
  an 
  

   altitude 
  of 
  about 
  2000 
  feet, 
  and 
  is 
  merely 
  a 
  remnant 
  of 
  the 
  upraised 
  

   peneplain 
  which 
  was 
  formerly 
  connected 
  with 
  the 
  Southwestern 
  

   plateau. 
  As 
  one 
  stands 
  at 
  the 
  summit 
  of 
  Tug 
  hill 
  and 
  looks 
  out 
  

   over 
  the 
  western 
  slope 
  of 
  the 
  Adirondacks, 
  he 
  is 
  impressed 
  by 
  the 
  

   remarkably 
  even 
  sky 
  line 
  there 
  shown 
  at 
  an 
  altitude 
  of 
  a 
  little 
  over 
  

   2000 
  feet. 
  The 
  east-central 
  Adirondacks 
  and 
  the 
  Catskills 
  present 
  

   exceptions 
  because 
  these 
  regions 
  stood 
  out 
  above 
  the 
  old 
  peneplain. 
  

  

  