﻿54 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  cient 
  Dundas 
  river. 
  Throughout 
  western 
  Ontario 
  this 
  escarpment 
  

   is 
  buried 
  by 
  drift, 
  but 
  its 
  presence 
  is 
  indicated 
  by 
  borings, 
  which 
  

   also 
  prove 
  the 
  continuance 
  of 
  the 
  lowland 
  accompanying 
  it. 
  This 
  

   escarpment, 
  the 
  inface 
  of 
  the 
  second 
  cuesta, 
  becomes 
  a 
  very 
  promi- 
  

   nent 
  feature 
  in 
  Lake 
  Huron, 
  where 
  it 
  is 
  entirely 
  submerged. 
  It 
  is 
  

   however 
  perfectly 
  traceable 
  from 
  north 
  of 
  Goderich 
  in 
  Canada 
  to 
  

   the 
  island 
  of 
  Mackinaw. 
  Soundings 
  prove 
  it 
  to 
  have 
  a 
  hight 
  of 
  

   from 
  350 
  to 
  500 
  feet 
  or 
  more 
  above 
  the 
  lowland 
  which 
  it 
  faces. 
  This 
  

   lowland 
  constitutes 
  the 
  deeper 
  portions 
  of 
  Lake 
  Huron, 
  the 
  shal- 
  

   lower 
  southwestern 
  area 
  being 
  a 
  part 
  of 
  the 
  upland 
  drowned 
  by 
  the 
  

   backward 
  setting 
  of 
  the 
  water 
  over 
  the 
  top' 
  of 
  the 
  escarpment. 
  The 
  

   following 
  cross-section 
  (fig. 
  9) 
  from 
  Point 
  au 
  Sable, 
  north 
  of 
  

   Saginaw 
  bay, 
  to 
  Cape 
  Hurd, 
  the 
  northern 
  extremity 
  of 
  the 
  Indian 
  

   peninsula, 
  passes 
  across 
  the 
  highest 
  portion 
  of 
  this 
  escarpment 
  at 
  

   the 
  9 
  fathom 
  ledge 
  and 
  diagonally 
  across 
  the 
  deepest 
  portion 
  of 
  the 
  

   Huron 
  lowland, 
  where 
  the 
  soundings 
  reach 
  a 
  depth 
  of 
  750 
  feet. 
  

   This 
  apparently 
  marks 
  the 
  location 
  of 
  the 
  preglacial 
  Saginaw 
  river, 
  

   w^hich 
  probably 
  breached 
  the 
  second 
  cuesta 
  to 
  the 
  south 
  of 
  the 
  9 
  

   iathom 
  ledge, 
  though 
  no 
  channel 
  is 
  indicated 
  by 
  the 
  soundings. 
  

  

  Fig. 
  9 
  Section 
  across 
  Lake 
  Huron 
  from 
  Point 
  au 
  Sable, 
  a) 
  across 
  9 
  fatliom 
  ledge, 
  b) 
  to 
  Cape 
  Hurd, 
  

   c) 
  (For 
  location 
  of 
  section 
  see 
  fig. 
  6). 
  

  

  We 
  have 
  now 
  traced 
  the 
  development 
  of 
  the 
  topographic 
  features 
  

   of 
  the 
  Niagara 
  district, 
  and 
  have 
  found 
  this 
  to 
  be 
  in 
  conformity 
  with 
  

   the 
  laws 
  governing 
  the 
  normal 
  development 
  of 
  drainage 
  systems 
  on 
  

   an 
  ancient 
  coastal 
  plain. 
  The 
  only 
  abnormal 
  features 
  which 
  need 
  

   to 
  be 
  considered 
  now 
  are 
  the 
  tilting 
  of 
  the 
  land 
  and 
  the 
  filling 
  of 
  

   most 
  of 
  the 
  old 
  channels 
  by 
  drift, 
  converting 
  the 
  lowlands 
  into 
  lake 
  

   basins 
  and 
  reversing 
  the 
  drainage 
  of 
  the 
  unfilled 
  channels. 
  These 
  

   were 
  the 
  catastrophes 
  which 
  immediately 
  preceded 
  the 
  birth 
  of 
  

   Niagara 
  and 
  which 
  were 
  directly 
  responsible 
  for 
  its 
  existence. 
  To 
  

   these 
  and 
  the 
  life 
  history 
  of 
  Niagara, 
  attention 
  will 
  now 
  be 
  invited. 
  

  

  