﻿56 
  

  

  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  stone. 
  As 
  is 
  the 
  case 
  with 
  the 
  Siluric, 
  the 
  rock 
  formations 
  are 
  

   piled 
  one 
  upon 
  another 
  like 
  great 
  sheets 
  and 
  all 
  show 
  a 
  gentle 
  

   southward 
  dip 
  (see 
  figures 
  3 
  and 
  5). 
  Beginning 
  at 
  the 
  'bottom, 
  the 
  

   Helderberg 
  limestone 
  was 
  succeeded 
  in 
  regular 
  order 
  by 
  the 
  Oris- 
  

   kany 
  sandstone, 
  Onondaga 
  limestone, 
  Marcellus 
  and 
  Hamilton 
  

  

  Fig. 
  18 
  Generalized 
  map 
  of 
  North 
  America 
  in 
  the 
  Devonic 
  period, 
  show- 
  

   ing 
  the 
  relations 
  of 
  land 
  and 
  water. 
  Horizontal 
  lined 
  areas 
  = 
  land; 
  blank 
  

   areas 
  = 
  water. 
  Only 
  the 
  northern 
  and 
  extreme 
  southeastern 
  portions 
  of 
  the 
  

   New 
  York 
  State 
  area 
  were 
  land. 
  The 
  western 
  shore 
  of 
  Appalachia 
  was 
  far- 
  

   ther 
  west 
  than 
  during 
  the 
  Ordovicic, 
  due 
  to 
  the 
  addition 
  of 
  the 
  Taconic 
  

   mountain 
  area 
  

  

  shales, 
  all 
  of 
  which 
  were 
  deposited 
  over 
  the 
  whole 
  Devonic 
  basin 
  

   in 
  New 
  York. 
  Above 
  these 
  come 
  the 
  Tully 
  limestone 
  and 
  Genesee 
  

   shale 
  which 
  extend 
  from 
  east-central 
  to 
  western 
  New 
  York. 
  Still 
  

   higher, 
  and 
  forming 
  the 
  summit 
  of 
  the 
  Devonic, 
  are 
  the 
  Portage 
  

   shales 
  and 
  sandstones 
  and 
  the 
  Chemung 
  (or 
  Catskill) 
  sandstones 
  

  

  