﻿422 
  J. 
  Barrell 
  — 
  The 
  Piedmont 
  Terraces 
  

  

  posed 
  that 
  the 
  Eocene 
  marine 
  plain 
  and 
  shore-line 
  were 
  

   obliterated 
  by 
  erosion, 
  largely 
  marine, 
  in 
  later 
  times. 
  

  

  During 
  the 
  Oligocene 
  a 
  probable 
  submergence 
  of 
  the 
  

   land 
  occurred 
  and 
  the 
  Cornwall 
  terrace 
  was 
  cut. 
  The 
  

   emergence 
  which 
  followed 
  in 
  the 
  Miocene 
  caused 
  a 
  

   greater 
  retreat 
  of 
  the 
  sea 
  than 
  occurred 
  in 
  the 
  Eocene, 
  as 
  

   shown 
  on 
  an 
  unfinished 
  drawing, 
  and 
  no 
  terrace 
  of 
  this 
  

   age 
  was 
  recognized 
  because, 
  like 
  the 
  Eocene 
  terrace, 
  it 
  

   must 
  have 
  been 
  too 
  greatly 
  modified, 
  or 
  more 
  likely, 
  

   entirely 
  destroyed 
  by 
  later 
  erosion. 
  The 
  sequence 
  of 
  

   events 
  outlined 
  in 
  this 
  and 
  the 
  preceding 
  paragraph 
  is 
  

   based 
  primarily 
  on 
  physiographic 
  evidence 
  from 
  Massa- 
  

   chusetts 
  and 
  Connecticut 
  and 
  should 
  be 
  considered, 
  there- 
  

   fore, 
  as 
  applying 
  particularly 
  to 
  that 
  region. 
  

  

  By 
  the 
  end 
  of 
  the 
  Miocene 
  the 
  tilting 
  which 
  had 
  been 
  in 
  

   progress 
  since 
  the 
  Jurassic 
  had 
  nearly 
  ceased 
  and 
  the 
  

   later 
  movements 
  of 
  the 
  Pliocene 
  and 
  Pleistocene 
  were 
  

   due 
  largely 
  to 
  vertical 
  uplift. 
  For 
  limited 
  areas 
  the 
  tilt- 
  

   ing 
  component 
  of 
  the 
  movement 
  would 
  be 
  too 
  small 
  to 
  be 
  

   detected, 
  but 
  for 
  the 
  entire 
  region 
  under 
  discussion, 
  and 
  

   for 
  a 
  much 
  larger 
  area 
  during 
  the 
  Pleistocene, 
  it 
  would 
  

   appear 
  that 
  the 
  domal 
  uplift 
  recognized 
  in 
  the 
  Creta- 
  

   ceous 
  was 
  still 
  in 
  progress. 
  

  

  The 
  submergent 
  phase 
  at 
  the 
  close 
  of 
  the 
  Miocene 
  or 
  

   beginning 
  of 
  the 
  Pliocene 
  again 
  brought 
  the 
  sea 
  over 
  the 
  

   land 
  and 
  the 
  Goshen 
  terrace 
  was 
  cut 
  in 
  early 
  Pliocene. 
  

   Thereafter 
  intermittent 
  uplift 
  caused 
  retreats 
  of 
  the 
  sea 
  

   and 
  the 
  cutting 
  of 
  the 
  Litchfield- 
  To 
  want 
  ic 
  set 
  of 
  terraces 
  

   in 
  the 
  Pliocene 
  and 
  the 
  lower 
  terraces 
  in 
  the 
  Pleistocene, 
  

   the 
  latter 
  being 
  pre-glacial. 
  And 
  in 
  this 
  connection 
  pre- 
  

   glacial 
  means 
  pre-Wisconsin. 
  As 
  Professor 
  Barrell 
  has 
  

   recognized 
  eight 
  terraces 
  as 
  cut 
  in 
  these 
  two 
  periods 
  it 
  

   may 
  be 
  inferred 
  that 
  no 
  submergent 
  phases 
  of 
  conse- 
  

   quence 
  occurred 
  during 
  this 
  time. 
  The 
  Goshen 
  terrace 
  

   now 
  has 
  an 
  altitude 
  of 
  over 
  1,300 
  feet, 
  which 
  is 
  the 
  basis 
  

   for 
  the 
  statement 
  that 
  "the 
  last 
  strong 
  upward 
  move- 
  

   ments" 
  appear 
  to 
  date 
  from 
  the 
  close 
  of 
  the 
  Miocene. 
  

  

  There 
  is 
  a 
  difficulty 
  in 
  forming 
  a 
  complete 
  idea 
  of 
  

   events 
  due 
  to 
  the 
  lack 
  of 
  information 
  as 
  to 
  the 
  character 
  

   of 
  the 
  land 
  surfaces 
  over 
  which 
  the 
  sea 
  advanced 
  at 
  dif- 
  

   ferent 
  times, 
  or 
  to 
  place 
  the 
  emphasis 
  a 
  little 
  differently, 
  

   the 
  extent 
  of 
  subaerial 
  erosion 
  during 
  the 
  periods 
  of 
  

   emergence 
  which 
  intervened 
  between 
  those 
  of 
  submer- 
  

   gence. 
  It 
  will 
  have 
  been 
  noted 
  that 
  Professor 
  Barrell 
  

  

  