﻿NIAGARA 
  FALLS 
  AND 
  VICINITY 
  93 
  

  

  monious 
  with 
  the 
  preceding 
  ones, 
  were 
  laid 
  down 
  on 
  the 
  eroded 
  

   surface. 
  This 
  was 
  repeated 
  a 
  number 
  of 
  times, 
  as 
  is 
  shown 
  by 
  the 
  

   succession 
  of 
  changes 
  in 
  the 
  sandstone 
  layers.^ 
  This 
  structure 
  is 
  

   sometimes 
  shown 
  on 
  a 
  large 
  scale, 
  as 
  in 
  the 
  case 
  of 
  a 
  bed 
  shown 
  

   about 
  200 
  feet 
  north 
  of 
  '' 
  Milk 
  cave 
  ravine 
  ", 
  the 
  second 
  of 
  the 
  small 
  

   ravines 
  met 
  with 
  in 
  coming 
  from 
  the 
  north. 
  Here 
  some 
  of 
  the 
  lay- 
  

   ers 
  are 
  very 
  gently 
  inclined, 
  and 
  may 
  be 
  traced 
  for 
  some 
  distance. 
  

   They 
  are 
  obliquely 
  truncated, 
  other 
  horizontal 
  beds 
  resting 
  on 
  the 
  

   truncated 
  edges 
  (fig. 
  20b). 
  (See 
  also 
  plate 
  14) 
  

  

  Fig, 
  20b 
  Contemporaneous 
  erosion 
  and 
  deposition 
  in 
  Medina 
  sandstone, 
  Niagara 
  gorge. 
  

  

  The 
  Medina 
  Lingula 
  (L. 
  c 
  u 
  n 
  e 
  a 
  t 
  a) 
  is 
  found 
  in 
  these 
  sand- 
  

   stones 
  as 
  in 
  the 
  lower 
  ones, 
  but 
  other 
  fossils 
  are 
  rare. 
  Occasionally 
  

   on 
  the 
  sections 
  the 
  hollows 
  left 
  by 
  the 
  removal 
  of 
  the 
  shells 
  may 
  be 
  

   seen, 
  while 
  similar 
  cavities, 
  caused 
  by 
  the 
  removal 
  of 
  small 
  black 
  peb- 
  

   bles 
  like 
  those 
  found 
  in 
  the 
  lower 
  layers, 
  also 
  occur. 
  In 
  the 
  upper 
  

   portions 
  of 
  this 
  mass, 
  on 
  the 
  under 
  side 
  of 
  some 
  thin 
  sandstone 
  lenses 
  

   resting 
  on 
  and 
  separated 
  by 
  shaly 
  partings, 
  occurs 
  the 
  so-called 
  

   " 
  jointed 
  seaweed 
  " 
  of 
  the 
  Medina 
  formation, 
  known 
  as 
  A 
  r 
  t 
  h 
  r 
  o 
  - 
  

   phycus 
  harlani, 
  and 
  illustrated 
  on 
  plate 
  16. 
  This 
  is 
  a 
  char- 
  

   acteristic 
  Medina 
  sandstone 
  fossil, 
  but 
  in 
  this 
  region 
  it 
  has 
  not 
  been 
  

   found 
  in 
  any 
  of 
  the 
  other 
  sandstone 
  strata. 
  Specimens 
  of 
  this 
  fossil 
  

   were 
  obtained 
  in 
  digging 
  the 
  great 
  power 
  tunnel 
  at 
  Niagara, 
  but 
  

   only 
  from 
  the 
  sandstone 
  layers 
  near 
  the 
  bottom 
  of 
  the 
  tunnel, 
  which 
  

   is 
  about 
  the 
  horizon 
  in 
  which 
  they 
  are 
  found 
  in 
  the 
  gorge 
  section.^ 
  

  

  6 
  The 
  highest 
  member 
  of 
  the 
  Medina 
  in 
  this 
  region 
  is 
  a 
  hard, 
  

   massive 
  bedded 
  and 
  compact 
  quartzose 
  sandstone 
  similar 
  to 
  the 
  

  

  ^Compare 
  with 
  this 
  the 
  cross-bedding 
  structure 
  shown 
  in 
  the 
  uncon- 
  

   solidated 
  sands- 
  and 
  gravels 
  in 
  the 
  Goat 
  island 
  gravel 
  pit, 
  and 
  in 
  the 
  section 
  

   of 
  the 
  old 
  Iroquois 
  beach 
  at 
  Lewiston. 
  

  

  "The 
  restriction 
  of 
  this 
  characteristic 
  Medina 
  fossil 
  to 
  these 
  upper 
  layers 
  

   of 
  sandstone 
  at 
  Niagara 
  was 
  pointed 
  out 
  to 
  me 
  by 
  John 
  MacCormick, 
  the 
  

   watchman 
  of 
  this 
  part 
  of 
  the 
  road, 
  who 
  collects 
  these 
  specimens 
  and 
  keeps 
  

   them 
  for 
  sale. 
  As 
  he 
  is 
  continually 
  handling 
  these 
  rocks 
  and 
  has 
  handled 
  

   them 
  for 
  years, 
  he 
  has 
  become 
  familiar 
  with 
  their 
  characters, 
  and 
  is 
  there- 
  

   fore 
  in 
  a 
  position 
  to 
  obtain 
  knowledge 
  of 
  such 
  facts. 
  

  

  