﻿314 
  NEW 
  YORK 
  STATE 
  MUSEiUM 
  

  

  genia 
  catsJcillensis 
  (Van.) 
  Hall. 
  The 
  formation 
  has 
  a 
  thickness 
  of 
  

   550 
  feet 
  in 
  the 
  Chenango 
  valley 
  and 
  as 
  the 
  physical 
  conditions 
  

   under 
  which 
  the 
  Oneonta 
  was 
  deposited 
  appeared 
  earlier 
  to 
  the 
  

   eastward 
  it 
  gradually 
  thickens 
  in 
  that 
  direction 
  till 
  in 
  Albany 
  

   and 
  Greene 
  counties 
  it 
  completely 
  replaces 
  the 
  Ithaca 
  formation. 
  

  

  7 
  The 
  Chemung 
  formation 
  east 
  of 
  the 
  Susquehanna 
  river 
  rapid- 
  

   ly 
  thins 
  to 
  the 
  eastward 
  on 
  account 
  of 
  the 
  earlier 
  appearance 
  of 
  

   the 
  physical 
  conditions 
  which 
  prevailed 
  during 
  the 
  deposition 
  of 
  

   the 
  Catskill 
  formation, 
  so 
  that 
  the 
  lithologic 
  characters 
  of 
  the 
  

   Chemung 
  are 
  gradually 
  replaced 
  by 
  those 
  of 
  the 
  Catskill, 
  and 
  

   as 
  this 
  change 
  takes 
  place 
  the 
  Chemung 
  fauna 
  disappears 
  till 
  the 
  

   farthest 
  east 
  it 
  was 
  noted 
  was 
  near 
  Spring 
  lake 
  northwest 
  of 
  

   Delhi 
  where 
  a 
  small 
  Chemung 
  faunule 
  occurs 
  above 
  red 
  shales. 
  

   Search 
  in 
  the 
  rocks 
  occurring 
  at 
  the 
  horizon 
  of 
  the 
  Chemursg 
  

   formation 
  east 
  of 
  the 
  Delaware 
  river 
  was 
  not 
  rewarded 
  with 
  any 
  

   fossils 
  and 
  the 
  lithologic 
  appearance 
  of 
  these 
  rocks 
  is 
  similar 
  to 
  

   that 
  of 
  those 
  composing 
  the 
  Oneonta 
  and 
  Catskill 
  formations. 
  

  

  8 
  In 
  eastern 
  New 
  York 
  in 
  Albany, 
  Greene, 
  Ulster 
  and 
  Sullivan 
  

   counties 
  the 
  physical 
  conditions 
  under 
  which 
  the 
  Oneonta 
  and 
  

   Catskill 
  formations 
  were 
  deposited 
  began. 
  as 
  early 
  as 
  Sherburne 
  

   time 
  and 
  continued 
  throughout 
  the. 
  remainder 
  of 
  the 
  Devonian 
  

   period. 
  The 
  representation 
  of 
  the 
  Ithaca 
  or 
  Chemung 
  faunas 
  is 
  

   very 
  slight 
  and 
  this 
  great 
  mass 
  of 
  rocks 
  consists 
  mainly 
  of 
  alter- 
  

   nations 
  of 
  red 
  and 
  green 
  shales 
  and 
  sandstones 
  and 
  gray 
  to 
  green- 
  

   ish 
  gray, 
  coarse 
  grained 
  sandstones 
  with 
  some 
  conglomerates 
  in 
  

   the 
  Catskill 
  mountains. 
  In 
  the 
  Delaware 
  valley 
  the 
  red 
  rocks 
  

   do 
  not 
  appear 
  as 
  early 
  and 
  there 
  is 
  some 
  representation 
  of 
  the 
  

   Ithaca 
  fauna 
  which 
  is 
  more 
  pronounced 
  in 
  northeastern 
  Pennsyl- 
  

   vania. 
  As 
  this 
  series 
  of 
  rocks 
  is 
  followed 
  along 
  the 
  Appalach- 
  

   ians 
  southwesterly 
  across 
  Pennsylvania, 
  Maryland 
  and 
  the 
  Vir- 
  

   ginias 
  it 
  is 
  found 
  that 
  the 
  reds 
  gradually 
  appear 
  later 
  and 
  the 
  

   Chemung 
  fauna 
  is 
  present. 
  For 
  in 
  western 
  Maryland, 
  succeed- 
  

   ing 
  the 
  black 
  shales 
  with 
  a 
  Genesee 
  fauna 
  at 
  the 
  top 
  of 
  the 
  Ham- 
  

   ilton, 
  are 
  first 
  nearly 
  barren 
  smooth 
  shales 
  and 
  sandstones 
  like 
  

   the 
  Portage 
  of 
  western 
  New 
  York, 
  then 
  rougher 
  shales 
  and 
  rather 
  

   mealy 
  sandstones 
  containing 
  an 
  abundant 
  Chemung 
  fauna 
  with 
  

  

  