﻿652 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  both 
  of 
  which 
  are 
  an 
  effect 
  of 
  the 
  early 
  invasion 
  of 
  this 
  part 
  of 
  the 
  

   island 
  by 
  tlie 
  ice. 
  

  

  On 
  the 
  other 
  hand, 
  it 
  is 
  possible 
  that 
  this 
  bar 
  may 
  be 
  the 
  inner 
  

   margin 
  of 
  a 
  stratum 
  of 
  these 
  yellow 
  gravels, 
  the 
  low 
  ground 
  north 
  

   of 
  it 
  being 
  the 
  unfilled 
  portion 
  of 
  a 
  longitudinal 
  valley 
  but 
  it 
  does 
  

   not 
  seem 
  possible 
  at 
  present 
  to 
  demonstrate 
  this 
  view. 
  

  

  Glaciated 
  ledges 
  

  

  Frontal 
  moraines 
  mark 
  the 
  position 
  of 
  the 
  ice 
  front. 
  The 
  motion 
  

   of 
  tlie 
  ice, 
  at 
  least 
  near 
  its 
  margin, 
  will 
  tend 
  to 
  be 
  toward 
  that 
  front 
  ; 
  

   hence, 
  since 
  the 
  moraine 
  in 
  this 
  part 
  of 
  the 
  island 
  trends 
  to 
  the 
  south 
  

   of 
  west, 
  forming 
  a 
  lobate 
  line 
  across 
  this 
  region 
  and 
  that 
  adjacent 
  

   in 
  'New 
  Jersey, 
  glacial 
  striae 
  in 
  this 
  part 
  of 
  the 
  island 
  should 
  run 
  

   to 
  the 
  east 
  of 
  south. 
  A 
  number 
  of 
  ledges 
  of 
  gneiss 
  in 
  Long 
  Island 
  

   City 
  meet 
  this 
  requirement. 
  One 
  of 
  the 
  largest 
  exposures 
  of 
  bed 
  

   rock 
  occupies 
  a 
  vacant 
  lot 
  adjoining 
  tlie 
  Queens 
  county 
  courthouse 
  

   on 
  tlie 
  west. 
  The 
  ledge 
  is 
  heavily 
  glaciated, 
  forming 
  a 
  long, 
  low 
  

   roche 
  moutonnee. 
  The 
  striae 
  range 
  in 
  direction 
  from 
  29° 
  to 
  30° 
  

   west 
  (magnetic). 
  A 
  few 
  striae 
  run 
  from 
  n 
  15 
  w, 
  and 
  one 
  set 
  of 
  

   scratches 
  lies 
  in 
  a 
  northwest 
  direction. 
  The 
  strike 
  of 
  the 
  foliation 
  

   of 
  the 
  gneiss 
  is 
  n 
  25 
  e 
  magnetic. 
  Other 
  outcrops 
  occur 
  to 
  the 
  north- 
  

   east 
  with 
  striae 
  running 
  from 
  the 
  north 
  northwest. 
  A 
  series 
  of 
  

   shallow 
  oval 
  depressions 
  extends 
  in 
  a 
  northwest 
  and 
  southeast 
  direc- 
  

   tion 
  across 
  one 
  outcrop, 
  the 
  whole 
  bearing 
  evidence 
  of 
  water 
  action, 
  

   presumably 
  that 
  of 
  a 
  subglacial 
  stream. 
  

  

  The 
  southeastward 
  movement 
  of 
  the 
  ice 
  on 
  this 
  side 
  of 
  the 
  Hud- 
  

   son 
  valley 
  is 
  further 
  attested 
  by 
  the 
  drift. 
  The 
  moraine 
  from 
  

   Brooklyn 
  as 
  far 
  east 
  as 
  Oyster 
  Bay 
  contains 
  trap 
  boulders, 
  the 
  

   nearest 
  known 
  site 
  of 
  which 
  rock 
  is 
  in 
  the 
  Palisade 
  trap 
  ridge 
  on 
  

   the 
  west 
  bank 
  of 
  the 
  Hudson 
  river. 
  

  

  Stratified 
  red 
  sands, 
  also 
  undoubtedly 
  derived 
  from 
  the 
  area 
  of 
  

   Triassic 
  red 
  sandstones 
  now 
  found 
  only 
  on 
  the 
  west 
  bank 
  of 
  the 
  Hud- 
  

   son, 
  occur 
  in 
  a 
  section 
  by 
  the 
  roadside 
  from 
  Corona 
  to 
  Astoria, 
  being 
  

   there 
  overlain 
  by 
  8 
  or 
  9 
  feet 
  of 
  gray 
  till 
  with 
  trap 
  boulders.^ 
  

  

  ^ 
  Boulders 
  of 
  trap 
  and 
  red 
  sandstone 
  were 
  seen 
  by 
  Sir 
  Charles 
  Lyell 
  in 
  an 
  exca- 
  

   vation 
  made 
  in 
  a 
  boulder 
  bed 
  at 
  the 
  Brooklyn 
  navy 
  yard. 
  See 
  Lyell, 
  Charles. 
  

   Travels 
  in 
  North 
  America. 
  N. 
  Y. 
  1845. 
  1 
  : 
  189-90. 
  

  

  