﻿of 
  the 
  Northern 
  Appalachians. 
  

  

  413 
  

  

  Professor 
  Barrell 
  selected 
  this 
  particular 
  region 
  for 
  

   illustrating 
  the 
  terraces 
  because 
  throughout 
  its 
  extent 
  

   they 
  extend 
  across 
  the 
  strike 
  of 
  the 
  geologic 
  formations, 
  

   or 
  it 
  might 
  be 
  more 
  proper 
  to 
  say, 
  they 
  were 
  developed 
  

   on 
  a 
  complex 
  of 
  metamorphic 
  and 
  igneous 
  rocks 
  the 
  gen- 
  

   erally 
  resistant 
  nature 
  of 
  which 
  has 
  favored 
  preserva- 
  

   tion 
  of 
  the 
  broader 
  erosional 
  features. 
  This 
  profile 
  can 
  

   be 
  adequately 
  understood 
  only 
  by 
  studying 
  it 
  in 
  connec- 
  

   tion 
  with 
  the 
  topographic 
  and 
  geologic 
  maps 
  of 
  the 
  area 
  

   covered, 
  or 
  better 
  still 
  in 
  the 
  field, 
  and 
  in 
  the 
  light 
  of 
  

   the 
  sequence 
  of 
  events 
  outlined 
  by 
  Professor 
  Barrell 
  in 
  

   his 
  paper 
  on 
  " 
  Post- 
  Jurassic 
  History 
  of 
  tlie 
  Northern 
  

   Appalachians. 
  ' 
  ' 
  32 
  The 
  terraces 
  shown 
  on 
  the 
  profile 
  are 
  

   those 
  recognized 
  by 
  Professor 
  Barrell 
  in 
  1912 
  and 
  in 
  the 
  

   absence 
  of 
  any 
  definite 
  evidence 
  to 
  the 
  contrary 
  may 
  be 
  

   accepted 
  as 
  final. 
  

  

  The 
  names, 
  elevation 
  of 
  the 
  inner 
  restored 
  margins, 
  

   and 
  the 
  age 
  of 
  the 
  terraces 
  are 
  as 
  follows 
  : 
  

  

  Becket 
  

  

  2,450 
  

  

  Cretaceous 
  

  

  Canaan 
  

  

  2,000 
  

  

  i 
  i 
  

  

  Cornwall 
  

  

  1,720 
  

  

  Oligocene 
  

  

  Goshen 
  

  

  1,380 
  

  

  Pliocene 
  

  

  Litchfield 
  

  

  1,140 
  

  

  i 
  c 
  

  

  Prospect 
  

  

  , 
  940 
  

  

  i 
  i 
  

  

  Towantic 
  

  

  740 
  

  

  c 
  i 
  

  

  Appomattox 
  

  

  540 
  

  

  c 
  i 
  

  

  New 
  Canaan 
  

  

  400 
  

  

  Pleistocene 
  

  

  Sunderland 
  

  

  240 
  

  

  i 
  t 
  

  

  Wicomico 
  

  

  120 
  

  

  i 
  i 
  

  

  A 
  study 
  of 
  the 
  profile 
  should 
  convince 
  one 
  that 
  the 
  

   hilltops 
  which 
  form 
  the 
  sky-line 
  can 
  not 
  well 
  be 
  consid- 
  

   ered 
  parts 
  of 
  a 
  single 
  uplifted 
  and 
  tilted 
  peneplane. 
  It 
  

   may 
  be 
  said 
  that 
  the 
  sky-line 
  consists 
  of 
  several 
  parts 
  

   with 
  roughly 
  concave 
  outlines 
  and 
  as 
  the 
  erosion 
  surface, 
  

   broadly 
  considered, 
  is 
  quite 
  independent 
  of 
  the 
  nature 
  

   and 
  structure 
  of 
  the 
  rock 
  formations, 
  it 
  would 
  be 
  neces- 
  

   sary 
  to 
  assume 
  a 
  very 
  special 
  and 
  arbitrary 
  form 
  of 
  

   warping 
  to 
  fit 
  it. 
  This 
  point 
  would 
  be 
  still 
  more 
  evident 
  

   if 
  the 
  profile 
  were 
  extended 
  across 
  Long 
  Island 
  so 
  as 
  to 
  

   show 
  the 
  seaward 
  extension 
  of 
  the 
  bed-rock 
  surface 
  and 
  

   the 
  overlying 
  sedimentary 
  formations. 
  

  

  When 
  that 
  part 
  of 
  the 
  profile 
  below 
  the 
  Cornwall 
  ter- 
  

  

  32 
  Bull. 
  Geol. 
  Soc. 
  Amer., 
  vol. 
  24, 
  690-691, 
  1913. 
  See, 
  also, 
  the 
  latter 
  

   part 
  of 
  this 
  section 
  and 
  the 
  entire 
  following 
  section. 
  

  

  