﻿30 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  accumulations 
  have 
  obliterated 
  its 
  topographic 
  relief. 
  Eastward 
  

   and 
  westward 
  however 
  it 
  becomes 
  prominent. 
  A 
  drive 
  along 
  Main 
  

   street 
  from 
  Buffalo 
  to 
  Akron 
  at 
  the 
  Erie 
  county 
  line 
  will 
  reveal 
  the 
  

   fact 
  that 
  it 
  gradually 
  increases 
  in 
  hight 
  and 
  boldness, 
  till 
  at 
  the 
  

   latter 
  place 
  it 
  rises 
  nearly 
  a 
  hundred 
  feet 
  above 
  the 
  Tonawanda 
  val- 
  

   ley, 
  which 
  itself 
  is 
  drift 
  filled 
  to 
  a 
  not 
  inconsiderable 
  extent. 
  If 
  we 
  

   trace 
  this 
  escarpment 
  into 
  eastern 
  New 
  York, 
  we 
  find 
  it 
  progress- 
  

   ively 
  increasing 
  in 
  hight^ 
  owing 
  to 
  the 
  interpolation, 
  between 
  the 
  

   Manlius 
  and 
  Onondaga 
  limestones, 
  of 
  the 
  thick 
  beds 
  of 
  the 
  Helder- 
  

   bergian 
  series, 
  which, 
  with 
  the 
  other 
  lower 
  Devonic 
  beds, 
  are 
  

   entirely 
  absent 
  in 
  the 
  Niagara 
  region, 
  where 
  their 
  place 
  is 
  marked 
  

   by 
  an 
  unconformity. 
  {See 
  figs.i 
  and 
  21-24) 
  

  

  If 
  the 
  observer 
  changes 
  his 
  position 
  to 
  some 
  elevated 
  point 
  near 
  

   Bufifalo, 
  he 
  may 
  note 
  that 
  the 
  plain 
  which 
  extends 
  southward 
  from 
  

   the 
  edge 
  of 
  the 
  second 
  escarpment, 
  presents 
  again 
  a 
  scarcely 
  modi- 
  

   fied 
  and 
  almost 
  level 
  surface, 
  which 
  south 
  of 
  Buffalo 
  gently 
  de- 
  

   scends 
  to 
  a 
  third 
  lowland, 
  that 
  of 
  Buffalo 
  creek 
  and 
  Lake 
  Erie. 
  

   Like 
  the 
  other 
  lowlands, 
  this 
  one 
  is 
  carved 
  out 
  of 
  soft 
  rocks 
  (Mar- 
  

   cellus 
  and 
  Hamilton 
  shales) 
  and 
  has 
  subsequently 
  been 
  filled 
  to 
  

   some 
  extent 
  by 
  drift 
  deposits. 
  This 
  has 
  been 
  proved 
  by 
  borings 
  

   which 
  show 
  that 
  the 
  bedrock 
  in 
  the 
  valley 
  of 
  Buffalo 
  creek 
  is 
  83 
  

   feet 
  below 
  the 
  surface 
  of 
  Lake 
  Erie.^ 
  There 
  are 
  other 
  excellent 
  

   reasons 
  for 
  believing 
  that 
  the 
  western 
  end 
  of 
  this 
  lowland, 
  now 
  occu- 
  

   pied 
  by 
  Lake 
  Erie, 
  was 
  once 
  considerably 
  lower 
  than 
  at 
  present. 
  

  

  On 
  the 
  south 
  the 
  Erie 
  lowland 
  is 
  defined 
  by 
  a 
  range 
  of 
  hills, 
  the 
  

   northern 
  edge 
  of 
  the 
  great 
  Allegany 
  plateau, 
  which 
  forms 
  the 
  high- 
  

   lands 
  of 
  southern 
  New 
  York 
  and 
  northern 
  Pennsylvania. 
  There 
  

   are 
  no 
  very 
  pronounced 
  declivities 
  in 
  the 
  northern 
  edge 
  of 
  this 
  

   plateau 
  in 
  the 
  Lake 
  Erie 
  region, 
  owing 
  no 
  doubt 
  to 
  the 
  relatively 
  

   uniform 
  character 
  of 
  the 
  rocks 
  composing 
  it, 
  there 
  being 
  no 
  re- 
  

   sistant 
  capping 
  bed 
  of 
  sufficient 
  magnitude 
  to 
  produce 
  an 
  escarp- 
  

   ment. 
  Farther 
  east, 
  however, 
  owing 
  to 
  the 
  increasing 
  thickness 
  of 
  

   the 
  beds 
  and 
  their 
  more 
  resistant 
  character, 
  a 
  prominent 
  escarp- 
  

   ment 
  is 
  developed, 
  which 
  near 
  the 
  Hudson 
  unites 
  with 
  the 
  escarp- 
  

   ment 
  of 
  the 
  lower 
  series, 
  and 
  with 
  it 
  constitutes 
  the 
  prominent 
  Hel- 
  

  

  ^Pohlman. 
  Life 
  history 
  of 
  Niagara- 
  1888. 
  p. 
  4. 
  

  

  