﻿14 
  . 
  W. 
  TJpham 
  — 
  Champlain 
  Subsidence 
  and 
  

  

  in 
  beds 
  overlying 
  the 
  glacial 
  drift 
  on 
  the 
  shores 
  of 
  southern 
  

   New 
  England, 
  Long 
  Island, 
  and 
  New 
  Jersey, 
  and 
  the 
  water- 
  

   courses 
  which 
  extend 
  from 
  the 
  terminal 
  moraine 
  on 
  Long 
  Is- 
  

   land 
  southward 
  across 
  the 
  adjacent 
  modified 
  drift 
  plain 
  and 
  

   continue 
  beneath 
  the 
  sea 
  level 
  of 
  the 
  Great 
  South 
  bay 
  and 
  

   other 
  bays 
  between 
  the 
  shore 
  and 
  its 
  bordering 
  long 
  beaches, 
  

   prove 
  that 
  this 
  coast 
  stood 
  higher 
  than 
  now 
  when 
  the 
  ice-sheet 
  

   extended 
  to 
  its 
  farthest 
  limit. 
  A 
  measure 
  of 
  this 
  elevation 
  of 
  

   the 
  seaboard 
  in 
  the 
  vicinity 
  of 
  New 
  York 
  during 
  the 
  Cham- 
  

   plain 
  epoch 
  is 
  supplied, 
  as 
  I 
  believe, 
  by 
  the 
  shallow 
  submarine 
  

   channel 
  of 
  the 
  Hudson, 
  which 
  has 
  been 
  traced 
  by 
  the 
  soundings 
  

   of 
  the 
  U. 
  S. 
  Coast 
  Survey 
  from 
  about 
  12 
  miles 
  off 
  Sandy 
  

   Hook 
  to 
  a 
  distance 
  of 
  about 
  90 
  miles 
  southeastward. 
  This 
  

   submerged 
  channel, 
  lying 
  between 
  the 
  present 
  mouth 
  of 
  the 
  

   Hudson 
  and 
  the 
  very 
  deep 
  submarine 
  fjord 
  of 
  this 
  river, 
  

   ranges 
  from 
  10 
  to 
  15 
  fathoms 
  in 
  depth, 
  with 
  an 
  average 
  width 
  

   of 
  1J 
  miles, 
  along 
  its 
  extent 
  of 
  80 
  miles, 
  the 
  depth 
  being 
  

   measured 
  from 
  the 
  top 
  of 
  its 
  banks, 
  which, 
  with 
  the 
  adjacent 
  

   sea-bed, 
  are 
  covered 
  by 
  15 
  to 
  40 
  fathoms 
  of 
  water, 
  increasing 
  

   southeastward 
  with 
  the 
  slope 
  of 
  this 
  margin 
  of 
  the 
  continental 
  

   plateau. 
  During 
  the 
  whole 
  or 
  a 
  considerable 
  part 
  of 
  the 
  time 
  

   of 
  the 
  glacial 
  Lake 
  Iroquois, 
  this 
  area 
  stretching 
  100 
  miles 
  

   southeastward 
  from 
  New 
  York 
  was 
  probably 
  a 
  land 
  surface, 
  

   across 
  which 
  the 
  Hudson 
  flowed 
  with 
  a 
  slight 
  descent 
  to 
  the 
  

   sea. 
  But 
  northward 
  from 
  the 
  present 
  mouth 
  of 
  the 
  Hudson 
  

   the 
  land 
  at 
  that 
  time 
  stood 
  lower 
  than 
  now 
  ; 
  and 
  the 
  amount 
  

   of 
  its 
  depression, 
  beginning 
  near 
  the 
  city 
  of 
  New 
  York 
  and 
  in- 
  

   creasing 
  from 
  south 
  to 
  north, 
  as 
  shown 
  by 
  terraces 
  and 
  deltas 
  

   of 
  the 
  glacial 
  Lake 
  Hudson-Champlain, 
  which 
  were 
  formed 
  

   before 
  this 
  long 
  and 
  narrow 
  lake 
  became 
  merged 
  in 
  the 
  glacial 
  

   Lake 
  St. 
  Lawrence, 
  was 
  nearly 
  180 
  feet 
  at 
  West 
  Point, 
  275 
  

   feet 
  at 
  Catskill, 
  and 
  340 
  feet 
  at 
  Albany 
  and 
  Schenectady. 
  From 
  

   these 
  figures, 
  however, 
  we 
  must 
  subtract 
  the 
  amount 
  of 
  de- 
  

   scent 
  of 
  the 
  Hudson 
  river, 
  which 
  in 
  its 
  channel 
  outside 
  the 
  

   present 
  harbor 
  of 
  New 
  York 
  may 
  probably 
  have 
  been 
  once 
  50 
  

   or 
  60 
  feet 
  in 
  its 
  length 
  of 
  about 
  100 
  miles. 
  

  

  Before 
  the 
  time 
  of 
  disappearance 
  of 
  the 
  ice-barrier 
  from 
  the 
  

   St. 
  Lawrence 
  valley 
  at 
  Quebec, 
  the 
  descent 
  of 
  the 
  Hudson 
  

   river 
  beyond 
  New 
  York 
  city 
  may 
  have 
  diminished, 
  or 
  the 
  sea- 
  

   board 
  at 
  New 
  York 
  may 
  have 
  sunk 
  so 
  as 
  to 
  bring 
  the 
  shore 
  

   line 
  nearly 
  to 
  its 
  present 
  position 
  ; 
  but 
  the 
  Hudson 
  valley 
  

   meanwhile 
  had 
  been 
  uplifted, 
  so 
  that 
  the 
  outflow 
  from 
  the 
  

   Lake 
  St. 
  Lawrence 
  crossed 
  the 
  low 
  divide, 
  now 
  about 
  150 
  feet 
  

   above 
  the 
  sea, 
  between 
  Lake 
  Cham 
  plain 
  and 
  the 
  Hudson. 
  This 
  

   is 
  known 
  by 
  the 
  extension 
  of 
  fossiliferous 
  marine 
  deposits 
  

   along 
  the 
  Lake 
  Champlain 
  basin 
  nearly 
  to 
  its 
  southern 
  end, 
  

   while 
  they 
  are 
  wholly 
  wanting 
  along 
  all 
  the 
  Hudson 
  valley. 
  

  

  