﻿Plate 
  18 
  

  

  The 
  Grand 
  Flume 
  of 
  Ausable 
  chasm, 
  Clinton 
  county. 
  The 
  rock 
  is 
  

   Potsdam 
  sandstone 
  in 
  horizontal 
  layers 
  and 
  the 
  gorge 
  is 
  postglacial. 
  

  

  From 
  N. 
  Y. 
  State 
  Mu3. 
  Bui. 
  19, 
  pi. 
  22 
  

  

  