﻿Tertiary- 
  Quat 
  ernary 
  

  

  Si 
  

  

  Cretaceous 
  

  

  m 
  

  

  Triassic 
  

  

  Carbonic 
  

   Devonic 
  

  

  mm 
  

  

  Fig. 
  i 
  Geologic 
  map 
  of 
  New 
  York 
  Slate, 
  showing 
  the 
  surface 
  distribution 
  

   the 
  great 
  rock 
  systems 
  

  

  