﻿74 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  grains. 
  One 
  part 
  of 
  the 
  formation 
  is 
  characterized 
  by 
  a 
  number 
  

   of 
  calcareous 
  sandstone 
  beds 
  ^ 
  to 
  i 
  foot 
  thick, 
  which 
  weather 
  into 
  

   a 
  characteristic 
  chestnut-brown 
  sandy 
  crust. 
  Through 
  the 
  contor- 
  

   tions 
  of 
  the 
  beds 
  these 
  rocks 
  are 
  mostly 
  broken 
  into 
  strings 
  of 
  brown 
  

   boulderlike 
  blocks. 
  

  

  In 
  the 
  river 
  bed 
  where 
  the 
  beds 
  are 
  seen 
  on 
  edge, 
  they 
  appear 
  

   as 
  greenish 
  gray 
  shales 
  with 
  frequent 
  black 
  shale 
  bands 
  and 
  brown 
  

   calcareous 
  sandstone 
  beds 
  and 
  some 
  thicker 
  beds 
  of 
  argillaceous 
  

   mudrock. 
  

  

  These 
  Schaghticoke 
  shales 
  of 
  Schuylerville 
  very 
  much 
  resemble 
  

   in 
  the 
  alternation 
  of 
  the 
  greenish 
  gray 
  and 
  black 
  argillaceous 
  shales, 
  

   giving 
  the 
  outcrops 
  on 
  edge 
  a 
  very 
  characteristic 
  banded 
  appear- 
  

   ance, 
  the 
  typical 
  Schaghticoke 
  shale 
  as 
  described 
  by 
  the 
  author 
  from 
  

   the 
  bed 
  of 
  the 
  Hoosic 
  river 
  at 
  Schaghticoke, 
  lacking, 
  however, 
  the 
  

   intercalated 
  thin 
  limestone 
  bands 
  observed 
  there. 
  They 
  are 
  distin- 
  

   guished 
  from 
  the 
  surrounding 
  Normanskill 
  shale 
  by 
  the 
  absence 
  

   of 
  white-weathering 
  chert 
  layers 
  and 
  the 
  presence 
  of 
  the 
  chocolate- 
  

   brown 
  weathering 
  calcareous 
  sandstone; 
  but 
  of 
  course 
  none 
  of 
  these 
  

   criteria 
  is 
  sufficient 
  to 
  recognize 
  them 
  without 
  the 
  fossil 
  evidence. 
  

   It 
  is 
  for 
  this 
  reason 
  that 
  they 
  may 
  be 
  outcropping 
  in 
  other 
  localities 
  

   without 
  having 
  been 
  recognized. 
  

  

  When 
  the 
  author 
  described 
  the 
  Dictyonema 
  flabelli- 
  

   forme 
  or 
  Schaghticoke 
  shale, 
  1 
  he 
  followed 
  the 
  consensus 
  of 
  the 
  

   preceding 
  European 
  authors 
  who 
  considered 
  the 
  shale 
  with 
  Dic- 
  

   tyonema 
  flabelliforme 
  as 
  marking 
  the 
  top 
  of 
  the 
  Cambric. 
  

   Since 
  that 
  time 
  stratigraphers 
  have, 
  especially 
  in 
  Sweden, 
  advanced 
  

   arguments 
  for 
  placing 
  the 
  Dictyonema 
  bed 
  at 
  the 
  base 
  of 
  the 
  

   Ordovicic, 
  a 
  proceeding 
  which 
  would 
  also 
  seem 
  to 
  agree 
  well 
  with 
  

   the 
  condition 
  in 
  the 
  slate 
  belt, 
  since 
  the 
  Dictyonema 
  shale 
  is 
  on 
  

   one 
  hand 
  separated 
  by 
  a 
  great 
  hiatus 
  from 
  the 
  underlying 
  Georgic, 
  

   but 
  on 
  the 
  other 
  by 
  its 
  lithologic 
  character 
  and 
  probably 
  also 
  strati- 
  

   graphically 
  is 
  closely 
  connected 
  with 
  the 
  following 
  Deep 
  Kill 
  shales. 
  

   Lately 
  Ulrich 
  2 
  has 
  also 
  argued 
  for 
  the 
  close 
  stratigraphic 
  connec- 
  

   tion 
  of 
  the 
  Dictyonema 
  flabelliforme 
  zone 
  with 
  the 
  

   Tetragraptus 
  zone 
  (the 
  lowest 
  of 
  the 
  Deep 
  Kill 
  zones), 
  and 
  placed 
  

   the 
  Dictyonema 
  flabelliforme 
  zone 
  in 
  his 
  Canadian 
  

   system 
  (which 
  comprises 
  the 
  Tribes 
  Hill 
  limestone 
  and 
  Beekman- 
  

   town 
  B-E). 
  

  

  1 
  Ruedemann, 
  R. 
  Cambric 
  Dictyonema 
  Fauna 
  in 
  the 
  Slate 
  Belt 
  of 
  Eastern 
  

   New 
  York. 
  Pal. 
  .Rep't 
  (for 
  1902) 
  1903, 
  p. 
  934. 
  

  

  2 
  Ulrich, 
  E. 
  O. 
  Revision 
  of 
  the 
  Paleozoic 
  Systems, 
  pts 
  1-3. 
  Geol. 
  Soc. 
  

   Amer. 
  Bui., 
  v. 
  22, 
  no. 
  3, 
  p. 
  678. 
  

  

  