﻿Plate 
  49 
  

  

  The 
  Whirlpool 
  rapids 
  and 
  American 
  bank 
  of 
  Niagara 
  gorge, 
  looking 
  north. 
  The 
  rocks 
  

   are 
  nearly 
  horizontal 
  strata 
  of 
  Siluric 
  age 
  consisting 
  of 
  Lockport 
  or 
  Niagara 
  limestone 
  

   (forming 
  uppermost 
  cliff) 
  followed 
  downward 
  by 
  Rochester 
  shale, 
  Clinton 
  limestone 
  and 
  

   shale 
  (exposed 
  near 
  middle 
  of 
  bank), 
  and 
  Medina 
  sandstone 
  and 
  shale. 
  The 
  gorge 
  is 
  

   here 
  250 
  feet 
  deep. 
  From 
  N. 
  Y. 
  State 
  Mus. 
  Bui. 
  45, 
  pi. 
  10 
  

  

  