﻿of 
  the 
  Northern 
  Appalachians. 
  419 
  

  

  oped 
  it 
  should 
  probably 
  be 
  assigned 
  a 
  Miocene 
  age. 
  And 
  

   in 
  any 
  case, 
  disregarding 
  exact 
  epochs, 
  it 
  is 
  evident 
  that 
  

   the 
  long-recognized 
  peneplain 
  of 
  western 
  Massachusetts 
  

   and 
  northwestern 
  Connecticut 
  should 
  be 
  considered 
  as 
  

   having 
  been 
  developed 
  in 
  its 
  final 
  stages 
  in 
  Tertiary 
  

   rather 
  than 
  in 
  Cretaceous 
  time. 
  

  

  The 
  foregoing 
  is 
  the 
  conclusion 
  I 
  have 
  come 
  to 
  from 
  a 
  

   study 
  of 
  Professor 
  Barrell's 
  published 
  work 
  and 
  his 
  field 
  

   notes. 
  One 
  consequence 
  which 
  follows 
  from 
  it 
  may 
  be 
  

   noted, 
  namely, 
  that 
  the 
  evidence 
  of 
  fluvial 
  erosion 
  con- 
  

   temporaneous 
  with 
  the 
  cutting 
  of 
  the 
  Pliocene 
  and 
  Pleis- 
  

   tocene 
  marine 
  terraces 
  would 
  presumably 
  be 
  confined 
  

   to 
  composite 
  valley 
  slopes, 
  rock 
  terraces, 
  and 
  stream 
  

   deposits, 
  depending 
  upon 
  existing 
  conditions 
  in 
  any 
  case. 
  

   And 
  further, 
  as 
  the 
  uplifts 
  during 
  these 
  two 
  epochs 
  

   appear 
  to 
  have 
  been 
  rapid 
  and 
  some 
  of 
  the 
  halts 
  short, 
  

   an 
  incomplete 
  record 
  should 
  be 
  expected, 
  when 
  the 
  resist- 
  

   ant 
  nature 
  of 
  the 
  rock 
  formations 
  is 
  considered, 
  even 
  on 
  

   the 
  larger 
  streams 
  and 
  certainly 
  in 
  the 
  headwater 
  regions 
  

   of 
  all 
  streams. 
  

  

  "What 
  Professor 
  Barrell's 
  exact 
  opinion 
  may 
  have 
  been 
  

   as 
  to 
  the 
  age 
  of 
  these 
  subaerial 
  peneplanes 
  I 
  can 
  not 
  per- 
  

   sonally 
  say 
  ; 
  the 
  subject 
  did 
  not 
  come 
  up 
  in 
  conversation 
  

   and 
  I 
  have 
  found 
  nothing 
  that 
  specifically 
  bears 
  on 
  it 
  in 
  

   his 
  notes. 
  Both 
  Dr. 
  Buwalda 
  and 
  Mr. 
  Bissell 
  have 
  told 
  

   me, 
  however, 
  that 
  Professor 
  Barrell 
  stated 
  to 
  them 
  not 
  

   long 
  before 
  his 
  death 
  that 
  he 
  thought 
  none 
  of 
  the 
  Appa- 
  

   lachian 
  erosion 
  surfaces 
  antedated 
  the 
  Tertiary. 
  Dr. 
  

   E. 
  W. 
  Shaw 
  writes 
  : 
  "As 
  I 
  understood 
  Professor 
  Barrell 
  

   he 
  thoroughly 
  agreed 
  with 
  my 
  contention 
  that 
  all 
  of 
  the 
  

   surface 
  of 
  the 
  Appalachians 
  has 
  been 
  developed 
  since 
  the 
  

   Cretaceous." 
  

  

  In 
  view 
  of 
  this 
  situation 
  it 
  would 
  seem 
  best 
  not 
  to 
  

   attach 
  too 
  great 
  weight 
  to 
  the 
  exact 
  dates 
  in 
  the 
  sequence 
  

   of 
  events 
  given 
  by 
  Professor 
  Barrell 
  in 
  his 
  original 
  

   paper. 
  It 
  is 
  evident 
  that 
  some 
  of 
  them 
  eventually 
  might 
  

   have 
  been 
  changed. 
  So 
  far 
  as 
  the 
  evidence 
  goes 
  there 
  

   appears 
  no 
  reason 
  why 
  the 
  entire 
  region 
  might 
  not 
  be 
  

   considered 
  as 
  having 
  undergone 
  subaerial 
  erosion 
  during 
  

   both 
  the 
  Eocene 
  and 
  Oligocene 
  and 
  to 
  a 
  large 
  extent 
  have 
  

   been 
  submerged 
  during 
  the 
  Miocene 
  ; 
  and 
  the 
  exact 
  age 
  

   of 
  the 
  youngest 
  terraces 
  also 
  appears 
  at 
  present 
  to 
  be 
  

   open 
  to 
  question. 
  

  

  As 
  those 
  who 
  have 
  made 
  the 
  effort 
  will 
  well 
  appreciate, 
  

  

  