﻿PLEISTOCENE 
  GEOLOGY 
  OF 
  NASSAU 
  CO. 
  AND 
  BOROUGH 
  OF 
  QUEENS 
  631 
  

  

  Fig. 
  7 
  A 
  fold-fault 
  in 
  clays 
  at 
  southern 
  end 
  of 
  Center 
  

   island 
  in 
  Oyster 
  Bay 
  harbor 
  

  

  overlain 
  by 
  at 
  least 
  20 
  feet 
  of 
  clayey 
  sands 
  passing 
  above 
  into 
  

   cleaner 
  sand. 
  These 
  beds 
  dip 
  gently 
  east. 
  

  

  The 
  second 
  cnt 
  west 
  shows 
  more 
  of 
  the 
  white 
  sands, 
  dip 
  uncer- 
  

   tain, 
  overlain 
  by 
  glacial 
  gravel 
  with 
  small 
  boulders. 
  The 
  third 
  cut 
  

   w^est 
  exhibits 
  cross-bedded, 
  white 
  clayey 
  sands, 
  presumably 
  Creta- 
  

   ceous, 
  overlain 
  by 
  10 
  or 
  12 
  feet 
  of 
  glacial 
  gravels 
  and 
  sands 
  w^ith 
  

   small 
  boulders. 
  The 
  section 
  shows 
  no 
  dislocation. 
  

  

  In 
  the 
  first 
  of 
  these 
  sections 
  the 
  measured 
  exposure 
  is 
  evidently 
  a 
  

   part 
  of 
  the 
  Columbia 
  ; 
  in 
  the 
  second 
  cut, 
  the 
  glacial 
  gravels 
  mantle 
  

   the 
  eroded 
  surface 
  of 
  the 
  pre-Pleistocene 
  series, 
  having 
  been 
  

   deposited 
  subsequently 
  to 
  the 
  deformation 
  and 
  gullying 
  of 
  the 
  beds. 
  

   These 
  top 
  beds, 
  by 
  their 
  

   boulders 
  and 
  lack 
  of 
  strat- 
  

   ification, 
  as 
  well 
  as 
  their 
  

   relation 
  to 
  the 
  eroded 
  

   clays, 
  evidently 
  pertain 
  

   to 
  the 
  last 
  drift. 
  The 
  

   sections 
  show, 
  however, 
  

   that 
  the 
  Columbia 
  man- 
  

   tles 
  over 
  and 
  is 
  wrapped 
  about 
  masses 
  of 
  the 
  pre-Pleistocene 
  series, 
  

   as 
  previously 
  stated 
  on 
  p. 
  622. 
  Similar 
  partial 
  sections 
  occur 
  on 
  

   Great 
  E"eck 
  near 
  Manhasset. 
  

  

  In 
  the 
  sand 
  pits 
  northwest 
  of 
  Port 
  Washington, 
  the 
  pre-Pleisto- 
  

   cene 
  clays 
  are 
  also 
  involved 
  in 
  folds, 
  giving 
  rise 
  to 
  a 
  structure, 
  the 
  

   upper 
  member 
  of 
  which 
  is 
  a 
  gravel 
  and 
  sand 
  bed 
  of 
  the 
  Columbia 
  

   formation, 
  itself 
  clearly 
  older 
  than 
  the 
  sands 
  of 
  the 
  Port 
  Washing- 
  

   ton 
  delta 
  yet 
  to 
  be 
  described 
  (p. 
  646). 
  In 
  this 
  instance 
  the 
  axis 
  of 
  

   the 
  anticlinal 
  structure 
  lies 
  north 
  and 
  south, 
  and 
  the 
  dislocation 
  

   may 
  be 
  of 
  a 
  relatively 
  late 
  date, 
  even 
  so 
  late 
  as 
  the 
  time 
  of 
  forma- 
  

   tion 
  of 
  the 
  delta 
  named, 
  when 
  the 
  ice 
  lay 
  deeply 
  embayed 
  along 
  

   the 
  north 
  shore 
  of 
  Manhasset 
  neck 
  and 
  wdien 
  an 
  easterly 
  movement 
  

   in 
  the 
  mass 
  might 
  be 
  expected, 
  since 
  the 
  ice 
  at 
  this 
  locality 
  w^as 
  on 
  

   the 
  eastern 
  margin 
  of 
  a 
  glacial 
  lobe 
  at 
  the 
  mouth 
  of 
  the 
  Hudson 
  

   valley. 
  

  

  The 
  deposit 
  of 
  sands 
  and 
  fine 
  gravels 
  forming 
  the 
  tabular 
  hillock 
  

   whose 
  frontage 
  on 
  Manhasset 
  bay 
  near 
  Port 
  Washington 
  is 
  known 
  

   as 
  Tom 
  point 
  is 
  a 
  unique 
  example 
  of 
  the 
  deformation 
  and 
  erosion 
  of 
  

  

  