﻿330 
  J. 
  Barrell— 
  The 
  Piedmont 
  Terraces 
  

  

  Devonic 
  times, 
  shows 
  especially 
  a 
  complete 
  revolution 
  of 
  

   ideas 
  based 
  on 
  the 
  recognition 
  of 
  many 
  unconformities 
  

   and 
  disconformities. 
  On 
  the 
  maps 
  by 
  Willis, 
  however, 
  

   the 
  transgressions 
  of 
  the 
  sea 
  are 
  still 
  limited 
  to 
  their 
  

   present 
  outcrops. 
  

  

  For 
  the 
  upper 
  Mesozoic 
  and 
  Tertiary 
  of 
  the 
  Atlantic 
  

   Coastal 
  Plain 
  the 
  shore-lines 
  are 
  restricted 
  to 
  the 
  land- 
  

   ward 
  limits 
  of 
  the 
  present 
  outcrops. 
  In 
  fact, 
  the 
  Poto- 
  

   mac 
  deposits 
  are 
  not 
  represented 
  at 
  all; 
  the 
  area 
  of 
  their 
  

   occurrence 
  is 
  covered 
  by 
  the 
  general 
  symbol 
  indicating 
  

   "Land 
  or 
  sea, 
  more 
  likely 
  land." 
  

  

  In 
  the 
  same 
  year 
  that 
  the 
  foregoing 
  volume 
  appeared 
  

   (1910) 
  Schuchert 
  published 
  his 
  important 
  paper 
  on 
  

   i 
  l 
  The 
  Paleogeography 
  of 
  North 
  America, 
  ' 
  ' 
  dealing 
  with 
  

   the 
  subject 
  of 
  the 
  former 
  distributions 
  of 
  land 
  and 
  sea 
  

   much 
  more 
  critically 
  than 
  had 
  any 
  previous 
  writer. 
  

   From 
  lower 
  Cambrian 
  to 
  Pliocene, 
  inclusive, 
  fifty-seven 
  

   maps 
  are 
  given 
  for 
  successive 
  periods. 
  As 
  former 
  maps 
  

   had 
  fallen 
  into 
  error 
  by 
  showing 
  the 
  epeiric 
  seas 
  much 
  

   more 
  continuous 
  and 
  broad 
  than 
  the 
  evidence 
  really 
  war- 
  

   ranted, 
  Schuchert 
  considered 
  the 
  seas 
  as 
  extending 
  only 
  

   so 
  far 
  as 
  the 
  evidence 
  warranted, 
  recognizing 
  that 
  future 
  

   detailed 
  study 
  would 
  extend 
  many 
  of 
  the 
  transgressions 
  

   beyond 
  the 
  limits 
  given 
  by 
  him. 
  His 
  maps 
  are 
  most 
  

   notable 
  for 
  bringing 
  out 
  the 
  recurrent 
  emergencies 
  of 
  

   the 
  continent 
  and 
  draining 
  of 
  the 
  shallow 
  seas. 
  They 
  

   express 
  a 
  far-reaching 
  idea 
  which 
  was 
  not 
  existent 
  in 
  

   American 
  geology 
  twenty 
  years 
  before. 
  Time 
  and 
  time 
  

   again 
  the 
  seas 
  expanded 
  many 
  hundreds 
  of 
  miles 
  across 
  

   the 
  interior 
  of 
  the 
  continent 
  and 
  again 
  withdrew. 
  

  

  On 
  the 
  maps, 
  however, 
  the 
  seas 
  are 
  shown 
  as 
  not 
  ex- 
  

   tending 
  many 
  miles 
  beyond 
  present 
  outcrops 
  except 
  

   where 
  faunal 
  resemblances 
  necessitated 
  oceanic 
  connec- 
  

   tions 
  across 
  areas 
  where 
  the 
  former 
  deposits 
  had 
  been 
  

   later 
  buried 
  or 
  eroded. 
  This 
  limitation, 
  as 
  noted, 
  was 
  

   due 
  in 
  part 
  to 
  the 
  adoption 
  of 
  the 
  definite 
  and 
  scientific 
  

   procedure 
  of 
  requiring 
  proof, 
  but 
  in 
  greater 
  part 
  it 
  

   marked 
  the 
  general 
  persistence 
  among 
  paleontologists 
  

   of 
  an 
  idea 
  which 
  physiographers 
  had 
  shown 
  to 
  be 
  un- 
  

   founded. 
  This 
  was 
  the 
  idea 
  that 
  rock 
  formations 
  were 
  

   able 
  to 
  maintain 
  themselves 
  as 
  land 
  through 
  all 
  geologic, 
  

   time 
  notwithstanding 
  the 
  effects 
  of 
  subaerial 
  denudation. 
  

   Thus 
  the 
  Adirondacks 
  were 
  spoken 
  of 
  as 
  the 
  relics 
  of 
  

   Archean 
  mountains 
  and 
  the 
  Cambrian 
  strata 
  about 
  them 
  

  

  