﻿28 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  organic 
  bodies 
  in 
  this 
  rock 
  are 
  Orthocerata, 
  some 
  of 
  which 
  attain 
  

   the 
  length 
  of 
  more 
  than 
  lo 
  feet, 
  and 
  have 
  a 
  diameter 
  of 
  i 
  foot 
  or 
  

   more. 
  Associated 
  with 
  these 
  are 
  several 
  species 
  of 
  Cephalopoda 
  

   belonging 
  to 
  other 
  genera, 
  and 
  some 
  species 
  of 
  Gastropoda 
  which 
  

   subsequently 
  appear 
  in 
  the 
  succeeding 
  limestone." 
  These 
  distinctive 
  

   features 
  cause 
  the 
  formation 
  to 
  stand 
  out 
  as 
  a 
  clearly 
  defined 
  

   horizon 
  and 
  there 
  are 
  many 
  excellent 
  exposures 
  within 
  the 
  

   quadrangle. 
  

  

  Within 
  the 
  map 
  limits 
  the 
  Black 
  River 
  limestone 
  varies 
  in 
  thick- 
  

   ness 
  from 
  6 
  or 
  8 
  to 
  15 
  or 
  16 
  feet 
  and 
  although 
  it 
  is 
  so 
  thin 
  it 
  

   is 
  persistently 
  present. 
  It 
  is 
  nowhere 
  seen 
  in 
  outcrop 
  on 
  the 
  Rem- 
  

   sen 
  quadrangle 
  although 
  it 
  does 
  most 
  likely 
  occur. 
  In 
  the 
  vicinity 
  

   of 
  Little 
  Falls 
  it 
  is 
  occasionally 
  present 
  but 
  only 
  a 
  few 
  feet 
  thick, 
  

   while 
  at 
  Canajoharie 
  it 
  is 
  absent 
  altogether. 
  

  

  In 
  connection 
  with 
  the 
  Black 
  River 
  limestone 
  certain 
  erosion 
  

   features 
  are 
  noteworthy. 
  Directly 
  overlying 
  the 
  hard, 
  massive 
  

   Black 
  River 
  beds 
  are 
  thin 
  beds 
  of 
  Trenton 
  with 
  pronounced 
  shale 
  

   partings. 
  The 
  latter 
  beds 
  are 
  more 
  readily 
  worn 
  back 
  than 
  the 
  

   former, 
  the 
  result 
  being 
  that 
  the 
  Black 
  River 
  nearly 
  always 
  stands 
  

   out 
  as 
  a 
  terrace 
  or 
  platform 
  back 
  of 
  which 
  the 
  Trenton 
  rises 
  rather 
  

   abruptly. 
  This 
  platform 
  is 
  of 
  sufficient 
  topographic 
  importance 
  to 
  

   be 
  shown 
  on 
  the 
  contour 
  map. 
  At 
  times 
  of 
  high 
  water 
  the 
  Trenton 
  

   is 
  now 
  being 
  stripped 
  off 
  the 
  Black 
  River 
  along 
  Dry 
  Sugar 
  river 
  

   and 
  along 
  Black 
  river 
  a 
  little 
  over 
  a 
  mile 
  above 
  the 
  mouth 
  of 
  Sugar 
  

   river. 
  At 
  the 
  latter 
  place 
  the 
  high 
  water 
  has 
  cut 
  back 
  the 
  Trenton 
  

   limestone 
  so 
  as 
  to 
  leave 
  a 
  distinct 
  and 
  remarkably 
  regular 
  platform 
  

   of 
  Black 
  River 
  limestone 
  which 
  extends 
  for 
  several 
  hundred 
  yards. 
  

   During 
  low 
  water 
  the 
  river 
  occupies 
  a 
  channel 
  which 
  has 
  been 
  worn 
  

   into 
  the 
  Black 
  River 
  limestone 
  [see 
  pi. 
  5]. 
  

  

  The 
  composition, 
  texture, 
  and 
  massive 
  character 
  of 
  the 
  rock 
  are 
  

   favorable 
  for 
  the 
  development 
  of 
  "potholes." 
  A 
  magnificent 
  dis- 
  

   play 
  of 
  "potholes" 
  may 
  be 
  seen 
  along 
  Sugar 
  river 
  (Dry 
  Sugar 
  

   river) 
  from 
  the 
  canal 
  crossing 
  to 
  near 
  its 
  mouth. 
  The 
  bed 
  of 
  the 
  

   stream, 
  which 
  is 
  here 
  dry 
  except 
  during 
  high 
  water, 
  is 
  literally 
  

   honeycombed 
  vv^ith 
  hundreds 
  of 
  " 
  potholes," 
  some 
  of 
  them 
  attain- 
  

   ing 
  a 
  depth 
  of 
  6 
  or 
  8 
  feet 
  and 
  a 
  diameter 
  of 
  several 
  feet 
  [see 
  pi. 
  6]. 
  

  

  Trenton 
  limestone 
  

  

  The 
  Trenton 
  limestone 
  has 
  its 
  type 
  locality 
  at 
  Trenton 
  Falls 
  

   some 
  20 
  miles 
  southward. 
  From 
  the 
  standpoint 
  of 
  areal 
  extent 
  

   and 
  thickness 
  this 
  formation 
  is 
  the 
  second 
  most 
  important 
  one 
  

  

  