﻿592 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  of 
  the 
  material 
  washed 
  into 
  the 
  estuary. 
  During 
  the 
  period 
  of 
  

   submergence 
  much 
  of 
  the 
  silicious 
  matter 
  washed 
  into 
  the 
  estuary 
  

   was 
  deposited 
  at 
  the 
  mouths 
  of 
  the 
  tributary 
  streams 
  to 
  form 
  deltas. 
  

  

  It 
  has 
  been 
  suggested 
  by 
  Dr 
  Merrill^ 
  that 
  the 
  change 
  in 
  the 
  

   estuary 
  deposits 
  from 
  clay 
  to 
  sand 
  might 
  be 
  due 
  to 
  the 
  exposure 
  

   by 
  elevation 
  of 
  an 
  area 
  of 
  land 
  around 
  the 
  basin, 
  which 
  would 
  

   afford 
  more 
  silicious 
  matter. 
  

  

  An 
  elevation 
  would 
  be 
  accompanied 
  by 
  an 
  acceleration 
  of 
  the 
  

   streams, 
  and 
  much 
  of 
  the 
  silicious 
  matter 
  transported 
  by 
  them 
  

   would 
  be 
  carried 
  farther 
  out 
  into 
  the 
  estuary 
  and 
  spread 
  over 
  its 
  

   bottom, 
  while 
  the 
  finer 
  clayey 
  sediment 
  would 
  be 
  carried 
  out 
  to 
  

   sea. 
  A 
  readvance 
  of 
  the 
  ice, 
  it 
  would 
  seem, 
  would 
  likewise 
  cause 
  

   an 
  acceleration 
  of 
  the 
  streams, 
  and 
  with 
  the 
  results 
  stated 
  above. 
  

  

  To 
  account 
  for 
  the 
  isolated 
  boulders 
  in 
  the 
  clay, 
  it 
  seems 
  highly 
  

   probable 
  that 
  icebergs 
  or 
  icefloes 
  having 
  stones 
  and 
  dirt 
  imprisoned 
  

   within 
  their 
  mass 
  detached 
  themselves 
  from 
  the 
  retreating 
  glacier, 
  

   and, 
  floating 
  down 
  the 
  estuary 
  to 
  the 
  sea, 
  dropped 
  their 
  burdens. 
  

  

  The 
  unstratifled 
  material 
  found 
  with 
  it 
  and 
  in 
  some 
  cases 
  over- 
  

   lying 
  the 
  stratified 
  delta 
  deposits 
  is 
  a 
  matter 
  of 
  interest 
  as 
  con- 
  

   corns 
  its 
  origin. 
  Three 
  things 
  may 
  be 
  noticed 
  regarding 
  it. 
  

  

  1 
  The 
  material 
  is 
  sand, 
  pebbles 
  and 
  cobblestones 
  lying 
  mixed 
  

   together 
  without 
  any 
  separation 
  of 
  the 
  coarse 
  from 
  the 
  fine.^ 
  

  

  2 
  The 
  pebbles 
  and 
  stone 
  are 
  rounded 
  and 
  do 
  not 
  show 
  any 
  

   scratches. 
  

  

  3 
  The 
  materials 
  are 
  mostly 
  of 
  the 
  same 
  character 
  as 
  the 
  rocks 
  of 
  

   the 
  vicinity. 
  

  

  Xow 
  as 
  the 
  land 
  rose 
  from 
  its 
  submergence 
  the 
  velocity 
  and 
  

   with 
  it 
  the 
  transporting 
  power 
  of 
  the 
  streams 
  would 
  increase, 
  

   washing 
  down 
  quantities 
  of 
  large 
  stones 
  and 
  gravel. 
  Dr 
  Merrill 
  

   considers 
  that 
  a 
  rapid 
  flow 
  of 
  water 
  took 
  place 
  do^vn 
  through 
  the 
  

   Hudson 
  valley 
  in 
  the 
  late 
  Quaternary. 
  This 
  water 
  must 
  have 
  come 
  

  

  1 
  Amer. 
  jour. 
  sci. 
  June 
  1891. 
  

  

  2 
  The 
  only 
  locality 
  where 
  stratification 
  was 
  observable 
  was 
  at 
  Timoney's 
  

   yard, 
  near 
  Dutchess 
  Junction. 
  

  

  