﻿NIAGARA 
  FALLS 
  AND 
  VICINITY 
  I29 
  

  

  a 
  long 
  period 
  of 
  time 
  remained 
  above 
  the 
  sea. 
  During 
  this 
  time, 
  

   the 
  Helderbergian 
  and 
  other 
  Lower 
  Devonic 
  strata 
  were 
  deposited 
  

   in 
  the 
  Appalachian 
  region, 
  which 
  by 
  that 
  time 
  had 
  estabUshed 
  a 
  

   southern 
  connection 
  with 
  the 
  open 
  Atlantic. 
  

  

  Finally, 
  toward 
  the 
  middle 
  of 
  the 
  Devonic 
  era, 
  the 
  sea 
  once 
  more 
  

   transgressed 
  on 
  the 
  abandoned 
  continent, 
  and 
  again 
  all 
  this 
  region 
  

   was 
  covered 
  by 
  oceanic 
  waters. 
  On 
  the 
  land 
  surface 
  of 
  early 
  Devonic 
  

   times, 
  now 
  grew 
  corals 
  in 
  great 
  luxuriance; 
  and 
  reefs 
  of 
  great 
  ex- 
  

   tent, 
  with 
  their 
  accompanying 
  deposits 
  of 
  coral 
  sands, 
  and 
  their 
  

   wealth 
  of 
  new 
  life, 
  again 
  characterized 
  the 
  interior 
  Paleozoic 
  sea. 
  It 
  

   Was 
  not 
  till 
  long 
  ages 
  after, 
  that 
  this 
  portion 
  of 
  the 
  continent 
  was 
  

   again 
  raised 
  above 
  the 
  sea. 
  This 
  last 
  elevation, 
  which 
  took 
  place 
  

   toward 
  the 
  close 
  of 
  Paleozoic 
  time, 
  was 
  a 
  permanent 
  one, 
  with 
  the 
  ex- 
  

   ception 
  of 
  a 
  possible 
  slight 
  resubmergence 
  of 
  some 
  parts 
  of 
  this 
  region 
  

   after 
  the 
  close 
  of 
  the 
  glacial 
  period. 
  With 
  the 
  last 
  great 
  emergence 
  

   of 
  the 
  land 
  were 
  inaugurated 
  those 
  long 
  cycles 
  of 
  erosion 
  outlined 
  

   in 
  chapter 
  i, 
  which 
  resulted 
  in 
  the 
  formation 
  of 
  the 
  great 
  topo- 
  

   graphic 
  features 
  of 
  this 
  region, 
  and 
  which 
  came 
  to 
  a 
  close 
  only 
  with 
  

   the 
  envelopment 
  of 
  this 
  region 
  in 
  the 
  snow 
  and 
  ice 
  of 
  the 
  great 
  

   glacial 
  winter. 
  

  

  