﻿98 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  type, 
  such 
  as 
  Spirifer 
  niagarensis 
  and 
  others. 
  A 
  com- 
  

   mon 
  brachiopod 
  is 
  Strop 
  h 
  on 
  ella 
  patent 
  a, 
  a 
  flat, 
  thin, 
  sub- 
  

   semicircular 
  shell 
  with 
  a 
  straight 
  hinge 
  line 
  and 
  fine 
  surface 
  

   striations. 
  

  

  A 
  characteristic 
  feature 
  of 
  this 
  upper 
  limestone 
  stratum 
  is 
  the 
  

   strong 
  development 
  of 
  stylolite 
  structures. 
  These 
  stylolites 
  are 
  

   vertically 
  striated 
  columns, 
  from 
  a 
  fragment 
  of 
  an 
  inch 
  to 
  several 
  

   inches 
  in 
  length, 
  and 
  ranged 
  on 
  either 
  side 
  of 
  a 
  horizontal 
  suture 
  

   or 
  fissure 
  plane 
  in 
  the 
  limestone 
  bed. 
  Projecting 
  from 
  both 
  upper 
  

   and 
  lower 
  beds, 
  they 
  interlock 
  with 
  each 
  other 
  and 
  so 
  produce 
  a 
  

   strongly 
  marked 
  irregular 
  suture. 
  This 
  structure 
  is 
  characteristic 
  

   of 
  limestone 
  beds 
  of 
  this 
  type, 
  but 
  its 
  origin 
  is 
  still 
  obscure. 
  

   Pressure 
  of 
  superincumbent 
  layers 
  of 
  rock 
  seems 
  to 
  have 
  been 
  the 
  

   chief 
  cause 
  of 
  their 
  production, 
  this 
  pressure 
  acting 
  unequally 
  on 
  the 
  

   rock 
  mass, 
  from 
  the 
  presence 
  of 
  fossils 
  or 
  from 
  other 
  causes. 
  A 
  

   characteristic 
  feature 
  is 
  the 
  open 
  suture 
  at 
  the 
  ends 
  of 
  the 
  columns, 
  

   which 
  gives 
  the 
  layers 
  the 
  aspect 
  of 
  having 
  separated 
  by 
  shrinkage 
  

   along 
  an 
  irregular 
  plane. 
  The 
  vertical 
  striations 
  indicate 
  motion 
  

   either 
  upward 
  or 
  downward. 
  

  

  The 
  Clinton 
  limestones 
  may 
  be 
  seen 
  in 
  both 
  banks 
  of 
  the 
  river 
  

   where 
  not 
  covered 
  by 
  vegetation, 
  from 
  the 
  mouth 
  of 
  the 
  gorge 
  to 
  

   within 
  a 
  short 
  distance 
  of 
  the 
  falls, 
  near 
  which 
  they 
  are 
  covered 
  by 
  

   taluSo 
  They 
  always 
  form 
  a 
  clif¥ 
  in 
  the 
  profile 
  of 
  the 
  gorge, 
  the 
  6 
  

   feet 
  of 
  shale 
  below 
  them 
  forming 
  a 
  sloping 
  talus-covered 
  bank, 
  

   below 
  which 
  there 
  is 
  another 
  clifif 
  formed 
  by 
  the 
  hard 
  upper 
  Medina 
  

   sandstone, 
  the 
  lower 
  members 
  forming 
  one 
  or 
  more 
  talus-covered 
  

   slopes 
  down 
  to 
  the 
  quartzose 
  bed 
  of 
  the 
  Medina. 
  This 
  latter 
  is 
  

   again 
  a 
  cliff-maker, 
  and 
  generally 
  projects 
  from 
  the 
  bank, 
  while 
  the 
  

   soft 
  red 
  shale 
  below 
  invariably 
  produces 
  a 
  sloping 
  talus-covered 
  

   bank. 
  Above 
  the 
  Clinton 
  limestones 
  is 
  another 
  slope 
  and 
  talus 
  

   formed 
  by 
  the 
  soft 
  Rochester 
  shale, 
  above 
  which 
  a 
  precipitous 
  cliff 
  

   is 
  formed 
  by 
  the 
  Lockport 
  limestone. 
  

  

  At 
  the 
  base 
  of 
  the 
  cHfifs, 
  fallen 
  rocks 
  of 
  the 
  CHnton 
  limestones 
  are 
  

   mingled 
  with 
  those 
  from 
  the 
  overlying 
  Lockport 
  limestones, 
  and 
  

   care 
  must 
  be 
  exercised 
  in 
  discriminating 
  between 
  these 
  when 
  col- 
  

   lecting 
  fossils. 
  Halfway 
  between 
  the 
  third 
  and 
  fourth 
  watchman's 
  

  

  