﻿622 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  The 
  fact 
  that, 
  wherever 
  these 
  older 
  clays 
  are 
  now 
  seen 
  in 
  the 
  cliffs, 
  

   and 
  exposures 
  about 
  tlie 
  north 
  shore 
  of 
  Long 
  Island, 
  thej 
  ai'e 
  

   involved 
  in 
  folds 
  and 
  disturbances 
  with 
  tlie 
  earlier 
  glacial 
  gravels 
  

   and 
  sands 
  is 
  evidence 
  that 
  thej 
  have 
  been 
  disturbed 
  during 
  Pleisto- 
  

   cene 
  time 
  by 
  the 
  same 
  agency 
  which 
  produced 
  dislocations 
  in 
  the 
  

   earlier 
  glacial 
  deposits. 
  Since 
  they 
  have 
  been 
  thus 
  displaced, 
  their 
  

   present 
  relief 
  can 
  not 
  be 
  taken 
  as 
  evidence 
  of 
  the 
  form 
  of 
  the 
  land 
  

   surface 
  on 
  which 
  the 
  glacial 
  deposits 
  were 
  laid 
  down. 
  It 
  is 
  even 
  

   uncertain 
  whether 
  the 
  depression 
  known 
  as 
  Long 
  Island 
  sound 
  had 
  

   any 
  existence 
  prior 
  to 
  the 
  disturbances 
  in 
  which 
  these 
  clays 
  were 
  

   involved 
  in 
  Pleistocene 
  time. 
  Everywhere 
  the 
  existing 
  relief 
  of 
  

   these 
  clay 
  masses 
  above 
  sealevel 
  is 
  a 
  function 
  of 
  their 
  displacement. 
  

   The 
  entire 
  absence 
  of 
  any 
  relatively 
  hard 
  or 
  resistant 
  layer 
  in 
  the 
  

   series 
  makes 
  it 
  even 
  doubtful 
  if 
  the 
  seaward 
  migrating 
  outcrops 
  of 
  

   the 
  Cretaceous 
  series 
  presented 
  at 
  the 
  time 
  of 
  the 
  first 
  ice 
  invasion, 
  

   anywhere 
  along 
  the 
  line 
  from 
  Cape 
  Cod 
  or 
  JSTantucket 
  westward, 
  to 
  

   ISTew 
  Jersey, 
  anything 
  like 
  a 
  bluff 
  or 
  inface 
  of 
  strata 
  overlooking 
  the 
  

   bared, 
  hard 
  rock 
  terrane 
  on 
  the 
  north, 
  such 
  as 
  might 
  be 
  expected 
  

   were 
  the 
  rocks 
  of 
  a 
  firmer 
  character 
  or 
  of 
  greater 
  lithologic 
  variety. 
  

   At 
  most, 
  where 
  these 
  older 
  clays 
  now 
  rise 
  highest 
  in 
  dislocated 
  

   masses, 
  it 
  may 
  be 
  that 
  remnants 
  of 
  the 
  old 
  coastal 
  plain, 
  similar 
  in 
  

   origin 
  to 
  the 
  highlands 
  of 
  Navesink 
  on 
  the 
  New 
  Jersey 
  coast, 
  stood 
  

   up 
  on 
  the 
  interstream 
  areas. 
  The 
  deep 
  reentrants 
  of 
  the 
  northern 
  

   coast, 
  as 
  in 
  the 
  case 
  of 
  Hempstead 
  bay, 
  appear 
  to 
  be 
  features 
  of 
  

   Pleistocene 
  date, 
  across 
  whose 
  site 
  the 
  Cretaceous 
  clays 
  previously 
  

   extended 
  unbroken. 
  In 
  short, 
  no 
  definite 
  trace 
  of 
  an 
  older 
  detail 
  of 
  

   land 
  surface 
  is 
  now 
  discernible 
  beneath 
  the 
  glacial 
  materials 
  within 
  

   the 
  limits 
  of 
  this 
  report. 
  The 
  absence, 
  however, 
  of 
  deposits 
  inter- 
  

   mediate 
  in 
  date 
  between 
  the 
  older 
  Pleistocene 
  and 
  the 
  ancient 
  clays 
  

   warrants 
  the 
  supposition 
  that 
  at 
  least 
  the 
  northern 
  part 
  of 
  the 
  island 
  

   was 
  an 
  area 
  of 
  erosion 
  by 
  ordinary 
  meteoric 
  agencies. 
  

  

  Beneath 
  the 
  Cretaceous 
  and 
  Potomac 
  clays 
  should 
  come 
  the 
  hard 
  

   rocks 
  exposed 
  on 
  the 
  mainland. 
  These 
  hard 
  rocks 
  in 
  the 
  form 
  of 
  

   gneiss 
  appear 
  at 
  the 
  surface 
  westward 
  in 
  Long 
  Island 
  City 
  and 
  

   have 
  been 
  met 
  in 
  borings 
  in 
  Brooklyn. 
  The 
  precise 
  depth 
  at 
  which 
  

   they 
  occur 
  beneath 
  this 
  area 
  is 
  at 
  present 
  a 
  matter 
  of 
  conjecture. 
  

  

  The 
  entire 
  absence 
  of 
  hard 
  rocks 
  in 
  fixed 
  ledges 
  or 
  outcrops 
  within 
  

  

  