﻿94 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  Hudson 
  past 
  Albany 
  and 
  Cohoes 
  on 
  to 
  the 
  Saratoga 
  and 
  Schuyler- 
  

   ville 
  quadrangles. 
  

  

  The 
  formation 
  was 
  first 
  distinguished 
  by 
  the 
  writer 
  from 
  the 
  

   " 
  Hudson 
  River 
  formation 
  " 
  in 
  the 
  neighborhood 
  of 
  Albany 
  (1901) 
  

   and 
  partly 
  referred 
  to 
  as 
  middle 
  Trenton 
  shale 
  and 
  partly 
  as 
  Utica 
  

   shale 
  and 
  later 
  correlated 
  with 
  the 
  Magog 
  shale 
  of 
  Canada. 
  

   Mainly 
  on 
  account 
  of 
  the 
  large 
  and 
  distinguishing 
  faunas 
  obtained 
  

   around 
  Albany, 
  Green 
  Island 
  and 
  Cohoes, 
  and 
  especially 
  at 
  Snake 
  

   hill 
  on 
  the 
  shore 
  of 
  Saratoga 
  lake, 
  the 
  formation 
  has 
  recently 
  

   (1912) 
  been 
  considered 
  as 
  a 
  separate 
  formation 
  by 
  the 
  writer 
  and 
  

   named 
  the 
  Snake 
  Hill 
  beds 
  from 
  the 
  most 
  fossiliferous 
  outcrop. 
  

  

  Lithologically, 
  the 
  formation 
  is 
  similar 
  to 
  the 
  Normanskill 
  beds, 
  

   but 
  it 
  lacks 
  the 
  strong 
  development 
  of 
  the 
  grits 
  and 
  white 
  beds 
  

   as 
  distinct 
  divisions, 
  though 
  both 
  are 
  present 
  in 
  thinner 
  intercala- 
  

   tions. 
  Besides 
  it 
  possesses 
  a 
  conglomerate 
  with 
  characters 
  peculiar 
  

   to 
  itself. 
  The 
  preponderating 
  portions 
  of 
  the 
  formation, 
  however, 
  

   are 
  dark 
  gray 
  to 
  black, 
  bluish 
  and 
  greenish 
  gray 
  argillaceous 
  shales 
  

   which 
  are 
  difficult 
  of 
  separation 
  from 
  the 
  Normanskill 
  shales, 
  save 
  

   by 
  the 
  inclosed 
  faunas. 
  

  

  The 
  argillaceous 
  shales 
  prevail 
  so 
  much 
  in 
  the 
  Snake 
  Hill 
  forma- 
  

   tion 
  that 
  we 
  have 
  not 
  observed 
  in 
  the 
  belt 
  in 
  Albany 
  county 
  any 
  

   grits 
  and 
  are 
  aware 
  of 
  only 
  one 
  outcrop 
  there 
  with 
  cherty-looking 
  

   silicious 
  shales. 
  Also 
  on 
  the 
  Schuylerville 
  quadrangle 
  the 
  con- 
  

   glomerate, 
  the 
  grit 
  and 
  the 
  cherty 
  beds 
  have 
  been 
  observed 
  each 
  

   only 
  in 
  a 
  couple 
  of 
  outcrops, 
  the 
  rest 
  all 
  being 
  soft 
  shale. 
  Thus, 
  

   the 
  large 
  area 
  in 
  the 
  northeast 
  corner 
  of 
  the 
  sheet, 
  north 
  of 
  Moses 
  

   kill, 
  which 
  has 
  a 
  rocky 
  surface 
  throughout, 
  consists 
  entirely 
  of 
  

   shale. 
  The 
  uniform 
  composition 
  of 
  the 
  formation 
  of 
  shale 
  is 
  also 
  

   well 
  shown 
  in 
  the 
  new 
  barge 
  canal 
  about 
  Fort 
  Miller, 
  where 
  half 
  a 
  

   mile 
  of 
  rock 
  exposure 
  exhibits 
  nothing 
  but 
  dark 
  gray 
  shales. 
  

  

  Black, 
  carbonaceous, 
  graptolitiferous 
  bands 
  or 
  seams 
  are 
  more 
  

   frequently 
  found 
  than 
  in 
  the 
  Normanskill 
  shale, 
  but 
  they 
  contain 
  

   a 
  much 
  impoverished 
  graptolite 
  fauna 
  as 
  compared 
  with 
  that 
  of 
  

   the 
  Normanskill 
  formation. 
  On 
  the 
  other 
  hand, 
  small 
  lamelli- 
  

   branchs, 
  gastropods, 
  brachiopods 
  and 
  trilobites 
  are 
  frequently 
  seen 
  

   in 
  the 
  shale, 
  while 
  but 
  traces 
  of 
  such 
  have 
  as 
  yet 
  been 
  observed 
  in 
  

   the 
  Normanskill 
  shale. 
  

  

  The 
  dark 
  shales 
  contain 
  not 
  infrequently 
  thin, 
  sandy 
  bands 
  and 
  

   still 
  oftener 
  intercalations 
  of 
  sandy 
  limestones 
  and 
  also 
  gray 
  crystal- 
  

   line 
  limestone, 
  reaching 
  half 
  a 
  foot 
  in 
  thickness. 
  These 
  bands 
  fre- 
  

   quently 
  contain 
  a 
  faunule 
  of 
  brachiopods, 
  crinoid 
  joints, 
  etc., 
  and 
  

  

  