﻿PLEISTOCENE 
  GEOLOGY 
  OF 
  NASSAU 
  CO. 
  AND 
  BOROUGH 
  OF 
  QUEENS 
  657 
  

  

  other 
  similar 
  passes 
  at 
  higher 
  levels. 
  Their 
  coincidence 
  of 
  level 
  is 
  

   apparently 
  accidental 
  ; 
  but 
  their 
  repetition 
  not 
  only 
  determined 
  the 
  

   level 
  to 
  which 
  delta 
  construction 
  should 
  reach 
  in 
  the 
  temporary 
  

   lake 
  behind 
  the 
  moraine 
  at 
  this 
  stage, 
  but 
  the 
  fact 
  also 
  explains 
  the 
  

   failure 
  to 
  depart 
  from 
  that 
  approximate 
  level 
  while 
  the 
  ice 
  main- 
  

   tained 
  its 
  position. 
  With 
  the 
  possibility 
  of 
  the 
  water 
  spilling 
  over 
  

   through 
  several 
  or 
  all 
  of 
  these 
  channels, 
  the 
  drainage, 
  if 
  the 
  time 
  

   were 
  short, 
  would 
  hardly 
  concentrate 
  on 
  any 
  one 
  of 
  them. 
  That 
  

   the 
  time 
  was 
  short, 
  is 
  shown 
  by 
  the 
  small 
  delta 
  built 
  at 
  this 
  level. 
  

   Where 
  the 
  outpouring 
  stream 
  from 
  the 
  ice 
  was 
  strongest, 
  the 
  delta 
  

   pushed 
  out 
  about 
  a 
  mile. 
  

  

  The 
  deep 
  drainage 
  furrow 
  dissecting 
  the 
  delta 
  on 
  a 
  north 
  and 
  

   south 
  line 
  indicates 
  a 
  sudden 
  falling 
  off 
  in 
  the 
  water 
  level. 
  This 
  

   undoubtedly 
  points 
  to 
  a 
  change 
  in 
  the 
  position 
  or 
  in 
  the 
  solidity 
  of 
  

   the 
  ice 
  barrier 
  on 
  the 
  west, 
  such 
  as 
  to 
  permit 
  the 
  confined 
  waters 
  to 
  

   escape 
  into 
  New 
  York 
  bay 
  at 
  a 
  lower 
  level 
  than 
  the 
  passes 
  in 
  the 
  

   moraine. 
  The 
  fact 
  of 
  such 
  a 
  change 
  of 
  level 
  is 
  indicated 
  in 
  a 
  small 
  

   delta 
  at 
  about 
  40 
  feet 
  in 
  the 
  vicinity 
  of 
  College 
  Point. 
  

  

  College 
  Point 
  delta 
  

  

  A 
  poorly 
  developed 
  delta 
  fringes 
  the 
  southern 
  slope 
  of 
  the 
  bar 
  of 
  

   glacial 
  drift 
  which 
  connects 
  College 
  Point 
  with 
  the 
  village 
  of 
  White- 
  

   stone. 
  The 
  northern 
  slope 
  and 
  much 
  of 
  the 
  crest 
  of 
  this 
  ridge 
  are 
  

   morainal, 
  though 
  sands 
  are 
  exposed 
  here 
  and 
  there 
  beneath 
  this 
  ice- 
  

   laid 
  coating. 
  At 
  a 
  point 
  about 
  due 
  south 
  of 
  the 
  bottom 
  of 
  Powell 
  

   cove, 
  a 
  section 
  open 
  in 
  June 
  1900 
  showed 
  the 
  fore 
  set 
  and 
  top 
  set 
  

   beds 
  of 
  a 
  typical 
  delta 
  structure 
  extending 
  southward. 
  The 
  struc- 
  

   ture 
  as 
  in 
  fig. 
  9 
  indicates 
  a 
  period 
  of 
  building 
  at 
  about 
  35 
  feet 
  above 
  

   the 
  present 
  sealevel, 
  followed 
  by 
  a 
  rise 
  of 
  the 
  water 
  level 
  of 
  about 
  5 
  

   feet, 
  the 
  whole 
  indicating 
  clearly 
  a 
  water 
  body 
  north 
  of 
  the 
  main 
  

   moraine 
  at 
  about 
  40 
  feet 
  above 
  the 
  present 
  sealevel. 
  

  

  The 
  ice 
  front 
  had 
  now 
  evidently 
  retreated 
  along 
  a 
  part 
  of 
  the 
  

   line 
  somewhat 
  north 
  of 
  its 
  position 
  at 
  the 
  Port 
  Washington 
  stage. 
  

   That 
  this 
  retreat 
  was 
  not 
  without 
  slight 
  advances, 
  is 
  probably 
  indi- 
  

   cated 
  by 
  the 
  evidence 
  of 
  rising 
  water 
  level 
  in 
  the 
  College 
  Point 
  

   delta 
  ; 
  but 
  the 
  opening 
  of 
  crevasses 
  in 
  the 
  ice 
  margin 
  and 
  their 
  sub- 
  

  

  