﻿-±16 
  J. 
  Barrell 
  — 
  The 
  Piedmont 
  Terraces 
  

  

  wholly 
  the 
  result 
  of 
  that 
  process 
  ; 
  on 
  the 
  other 
  hand 
  the 
  

   region 
  southeast 
  of 
  that 
  shore-line 
  has 
  been 
  undergoing 
  

   subaerial 
  erosion 
  for 
  a 
  much 
  shorter 
  time 
  and 
  conse- 
  

   quently 
  evidence 
  of 
  marine 
  planation 
  should 
  be 
  expected 
  

   to 
  remain, 
  that 
  is, 
  the 
  present 
  topography 
  represents 
  the 
  

   combined 
  effects 
  of 
  marine 
  and 
  later 
  subaerial 
  erosion. 
  

   To 
  discriminate 
  definitely 
  between 
  them 
  requires 
  the 
  

   development 
  of 
  new 
  criteria 
  and 
  the 
  use 
  of 
  highly 
  refined 
  

   methods 
  of 
  study 
  in 
  the 
  field. 
  

  

  The 
  positions 
  of 
  the 
  restored 
  surfaces 
  indicate 
  the 
  

   extent 
  to 
  which 
  the 
  present 
  surface 
  is 
  supposed 
  to 
  have 
  

   been 
  lowered 
  by 
  subaerial 
  erosion 
  since 
  the 
  different 
  

   terraces 
  were 
  cut, 
  The 
  amount 
  ranges 
  from 
  nothing 
  for 
  

   many 
  of 
  the 
  hills 
  in 
  the 
  localities 
  covered 
  by 
  the 
  lowest 
  

   and 
  youngest 
  terraces 
  to 
  fifty 
  feet 
  for 
  the 
  highest 
  hills 
  

   in 
  the 
  localities 
  covered 
  by 
  the 
  oldest 
  terraces. 
  It 
  is 
  

   entirely 
  reasonable 
  to 
  suppose 
  that 
  unreduced 
  remnants 
  

   of 
  the 
  Pleistocene 
  terraces 
  may 
  exist 
  where 
  the 
  rocks 
  are 
  

   resistant 
  and 
  it 
  is 
  a 
  rather 
  common 
  assumption 
  that 
  prac- 
  

   tically 
  unreduced 
  remnants 
  of 
  the 
  Cretaceous 
  peneplain 
  

   also 
  still 
  exist. 
  It 
  has 
  seemed 
  to 
  me, 
  however, 
  that 
  the 
  

   logic 
  of 
  Professor 
  Barrell 
  's 
  argument 
  in 
  favor 
  of 
  many 
  

   cycles 
  of 
  marine 
  erosion 
  with 
  the 
  probable 
  reduction 
  of 
  

   the 
  land 
  in 
  one 
  or 
  more 
  of 
  the 
  later 
  fluvial 
  erosion 
  cycles 
  

   to 
  as 
  low 
  a 
  relief 
  as 
  it 
  had 
  in 
  Cretaceous 
  time 
  calls 
  for 
  a 
  

   greater 
  degradation 
  of 
  the 
  oldest 
  marine 
  terraces 
  than 
  

   has 
  been 
  assumed. 
  

  

  The 
  slopes 
  of 
  the 
  restored 
  terraces 
  appear 
  to 
  be 
  drawn 
  

   in 
  a 
  systematic 
  manner. 
  Those 
  of 
  the 
  terraces 
  from 
  the 
  

   Becket 
  to 
  the 
  Prospect, 
  inclusive, 
  are 
  essentially 
  parallel 
  

   and 
  average 
  seven 
  feet 
  per 
  mile, 
  that 
  of 
  the 
  Towantic 
  is 
  

   four 
  feet, 
  whereas 
  for 
  the 
  lower 
  terraces 
  it 
  is 
  two 
  feet 
  

   per 
  mile. 
  All 
  slopes 
  are 
  toward 
  the 
  south. 
  As 
  the 
  ter- 
  

   races 
  are 
  assigned 
  a 
  marine 
  origin 
  it 
  is 
  to 
  be 
  assumed 
  

   that 
  they 
  had 
  an 
  initial 
  seaward 
  slope 
  of 
  five 
  to 
  ten 
  feet 
  

   per 
  mile, 
  within 
  which 
  range 
  the 
  slopes 
  of 
  the 
  upper 
  

   terraces 
  fall. 
  On 
  the 
  other 
  hand 
  the 
  slope 
  given 
  the 
  

   lower 
  terraces, 
  which 
  are 
  less 
  well 
  developed, 
  may 
  be 
  

   supposed 
  to 
  represent 
  the 
  planation 
  of 
  interfluvial 
  ridges 
  

   without 
  the 
  establishment 
  of 
  a 
  profile 
  of 
  equilibrium. 
  

   On 
  this 
  basis 
  it 
  would 
  appear 
  necessary 
  to 
  conclude 
  that 
  

   the 
  region 
  covered 
  by 
  the 
  entire 
  profile 
  had 
  experienced 
  

   only 
  vertical 
  uplift 
  because 
  the 
  present 
  slopes 
  of 
  the 
  ter- 
  

   races, 
  as 
  restored, 
  are 
  the 
  same 
  as 
  the 
  initial 
  slopes 
  devel- 
  

   oped 
  below 
  sea-level. 
  

  

  