﻿PLEISTOCENE 
  GEOLOGY 
  OF 
  NASSAU 
  CO. 
  AND 
  BOROUGH 
  OF 
  QUEENS 
  653 
  

  

  This 
  fanning 
  of 
  the 
  ice 
  sheet 
  to 
  the 
  eastward 
  on 
  the 
  east 
  side 
  of 
  

   the 
  lower 
  Hudson 
  and 
  to 
  the 
  westward 
  on 
  the 
  west 
  side 
  is 
  consistent 
  

   with 
  the 
  form 
  of 
  the 
  moraine 
  across 
  the 
  mouth 
  of 
  the 
  river. 
  The 
  

   axis 
  of 
  the 
  lobe 
  thus 
  indicated 
  has 
  been 
  fixed 
  by 
  Salisbury 
  on 
  the 
  

   west 
  side 
  of 
  the 
  Palisade 
  trap 
  ridge.^ 
  

  

  Fi-om 
  what 
  has 
  been 
  stated, 
  it 
  would 
  appear 
  that 
  the 
  western 
  end 
  

   of 
  Long 
  Island 
  is 
  occupied 
  by 
  a 
  moraine 
  and 
  a 
  contemporaneous 
  

   outwash 
  "plain 
  built 
  along 
  the 
  margin 
  of 
  the 
  ice 
  sheet, 
  when 
  it 
  had, 
  

   in 
  this 
  region 
  adjacent 
  to 
  the 
  mouth 
  of 
  the 
  Hudson, 
  pushed 
  a 
  lobate 
  

   mass 
  somewhat 
  farther 
  south 
  than 
  the 
  limit 
  attained 
  by 
  an 
  earlier 
  

   stand 
  of 
  the 
  ice 
  front, 
  marked 
  eastward 
  by 
  the 
  outer 
  moraine 
  from 
  

   near 
  Roslyn 
  to 
  Nantucket 
  ; 
  that 
  the 
  frontal 
  plain 
  in 
  this 
  district 
  rises 
  

   to 
  slightly 
  different 
  levels 
  against 
  the 
  front 
  of 
  the 
  moraine, 
  a 
  feature 
  

   which 
  is 
  constructional 
  and 
  not 
  due 
  to 
  post-glacial 
  warping 
  ; 
  and 
  that 
  

   the 
  front 
  of 
  the 
  moraine 
  as 
  a 
  whole 
  presents 
  no 
  decisive 
  evidence 
  

   of 
  having 
  been 
  subjected 
  to 
  marine 
  action 
  above 
  the 
  present 
  level 
  

   of 
  the 
  sea. 
  

  

  With 
  this 
  statement 
  of 
  the 
  observations 
  bearing 
  on 
  the 
  marine 
  

   limit 
  at 
  the 
  time 
  of 
  the 
  last 
  ice 
  invasion, 
  it 
  is 
  necessary 
  to 
  return 
  to 
  

   the 
  later 
  ice 
  phenomena 
  exhibited 
  in 
  connection 
  with 
  the 
  Port 
  

   Washington 
  stage 
  of 
  the 
  retreat. 
  

  

  Port 
  Washington 
  glacial 
  lake 
  

  

  It 
  has 
  already 
  been 
  pointed 
  out 
  that 
  the 
  last 
  evidence 
  of 
  the 
  pres- 
  

   ence 
  of 
  the 
  ice 
  sheet 
  on 
  the 
  area 
  covered 
  by 
  the 
  Oyster 
  bay 
  quad- 
  

   rangle 
  is 
  found 
  in 
  a 
  well 
  defined 
  delta 
  and 
  attendant 
  ice-laid 
  deposits 
  

   occupying 
  the 
  semicircular 
  tip 
  of 
  Manhasset 
  neck. 
  The 
  phenomena 
  

   indicating 
  a 
  halt 
  of 
  the 
  ice 
  front 
  against 
  this 
  headland 
  for 
  a 
  brief 
  

   time 
  subsequent 
  to 
  the 
  retreat 
  from 
  the 
  inner 
  moraine 
  at 
  Roslyn 
  are 
  

   very 
  clear. 
  The 
  conclusion 
  having 
  been 
  reached 
  that 
  the 
  area 
  has 
  

   not 
  been 
  submerged 
  to 
  the 
  depth 
  of 
  80 
  feet 
  since 
  the 
  beginning 
  of 
  

   the 
  deposition 
  of 
  moraines 
  in 
  this 
  part 
  of 
  the 
  island, 
  it 
  seems 
  neces- 
  

   sary 
  to 
  further 
  examine 
  the 
  region 
  to 
  determine 
  the 
  possibility 
  of 
  

   this 
  delta 
  having 
  been 
  built 
  in 
  a 
  temporary 
  glacial 
  lake. 
  

  

  To 
  the 
  north 
  and 
  west 
  of 
  Port 
  Washington 
  occur 
  a 
  number 
  of 
  

   gravel 
  and 
  sand 
  pits 
  opened 
  in 
  a 
  characteristic 
  glacial 
  delta, 
  whose' 
  

  

  1 
  Salisbury, 
  R. 
  D. 
  N. 
  J. 
  geol. 
  sur. 
  An. 
  rep't 
  state 
  geol. 
  for 
  1893. 
  1894. 
  p. 
  161. 
  

  

  