﻿NIAGARA 
  FALLS 
  AND 
  VICINITY 
  87 
  

  

  the 
  rocks 
  of 
  this 
  region 
  have 
  a 
  gentle 
  southward 
  dip, 
  which 
  permits 
  

   the 
  lower 
  members 
  to 
  appear 
  progressively 
  as 
  we 
  proceed 
  north- 
  

   ward 
  over 
  the 
  surface 
  of 
  the 
  old 
  erosion 
  plane. 
  We 
  may 
  now 
  pro- 
  

   ceed 
  to 
  describe 
  the 
  various 
  members 
  of 
  this 
  series 
  in 
  ascending 
  

  

  order. 
  

  

  Oswego 
  sandstone 
  

  

  This, 
  the 
  lowest 
  member 
  of 
  the 
  Siluric, 
  is 
  not 
  exposed 
  in 
  the 
  

   Niagara 
  region, 
  as 
  its 
  point 
  of 
  outcrop 
  is 
  now 
  covered 
  by 
  the 
  waters 
  

   of 
  Lake 
  Ontario. 
  {Sec 
  sections 
  i 
  and 
  2, 
  fig. 
  7) 
  From 
  borings, 
  

   however, 
  we 
  know 
  its 
  character 
  and 
  thickness, 
  which 
  in 
  this 
  region 
  

   is 
  75 
  feet. 
  

  

  Medina 
  sandstones 
  and 
  shales 
  

  

  Only 
  the 
  upper 
  portion 
  of 
  this 
  formation 
  is 
  exposed 
  in 
  the 
  

   Niagara 
  district, 
  where 
  the 
  total 
  thickness 
  is 
  more 
  than 
  1200 
  feet. 
  

  

  Red 
  Medina 
  shales. 
  The 
  upper 
  beds 
  of 
  this 
  division 
  are 
  the 
  

   lowest 
  exposed 
  beds 
  in 
  this 
  region. 
  They 
  are 
  bright 
  red 
  sandy 
  

   shales, 
  generally 
  of 
  a 
  very 
  uniform 
  character, 
  though 
  occasionally 
  

   a 
  bed 
  which 
  might 
  almost 
  be 
  called 
  a 
  sandstone 
  occurs. 
  Wherever 
  

   this 
  rock 
  is 
  exposed 
  to 
  the 
  atmosphere, 
  it 
  rapidly 
  breaks 
  down 
  into 
  

   small 
  angular 
  fragments, 
  which 
  quickly 
  form 
  a 
  debris 
  slope 
  or 
  talus 
  

   at 
  the 
  foot 
  of 
  every 
  cliff. 
  In 
  the 
  faces 
  of 
  the 
  older 
  clififs 
  this 
  rock 
  

   is 
  so 
  friable, 
  that 
  it 
  can 
  readily 
  be 
  removed 
  by 
  the 
  hand, 
  the 
  frag- 
  

   ments 
  themselves 
  being 
  easily 
  crushed 
  between 
  the 
  fingers. 
  In 
  the 
  

   course 
  of 
  time 
  these 
  fragments 
  disintegrate 
  into 
  a 
  fine 
  reddish 
  clay 
  

   soil, 
  which 
  when 
  wet 
  has 
  a 
  rather 
  tenacious 
  character. 
  

  

  As 
  the 
  lower 
  part 
  of 
  the 
  Niagara 
  river 
  from 
  Lewiston 
  to 
  Lake 
  

   Ontario 
  is 
  wholly 
  excavated 
  in 
  this 
  rock, 
  it 
  may 
  be 
  seen 
  wherever 
  

   the 
  banks 
  are 
  kept 
  fresh 
  by 
  the 
  river, 
  or 
  where 
  small 
  lateral 
  streams 
  

   enter 
  the 
  Niagara, 
  Where 
  erosion 
  is 
  not 
  active, 
  the 
  shale 
  bank 
  is 
  

   soon 
  reduced 
  to 
  a 
  slope 
  of 
  red 
  clayey 
  soil, 
  which 
  generally 
  becomes 
  

   covered 
  with 
  vegetation. 
  

  

  A 
  good 
  place 
  for 
  the 
  study 
  of 
  this 
  shale 
  is 
  on 
  the 
  New 
  York 
  side 
  

   of 
  the 
  Lewiston 
  suspension 
  bridge, 
  where 
  a 
  fresh 
  cut 
  reveals 
  about 
  

   50 
  feet 
  of 
  the 
  rock. 
  The 
  bridge 
  is 
  65 
  feet 
  above 
  the 
  river, 
  and 
  the 
  

   total 
  thickness 
  of 
  red 
  shale 
  above 
  the 
  water 
  at 
  this 
  point 
  is 
  therefore 
  

   115 
  feet. 
  The 
  shale 
  here 
  as 
  elsewhere 
  will 
  be 
  found 
  to 
  be 
  seamed 
  

  

  