﻿CLAYS 
  OF 
  NEW 
  YOEK 
  691 
  

  

  At 
  CoeTTiians 
  Landing 
  the 
  terrace 
  is 
  140 
  feet, 
  and 
  it 
  rises 
  to 
  177 
  

   feet 
  at 
  the 
  West 
  Shore 
  railroad 
  station, 
  about 
  a 
  mile 
  from 
  the 
  river 
  

   then 
  a 
  hill 
  hides 
  the 
  farther 
  continuation 
  of 
  it 
  from 
  view. 
  Between 
  

   South 
  Bethlehem 
  and 
  Callanans 
  Comers 
  the 
  shore 
  line 
  of 
  the 
  

   terrace 
  along 
  the 
  base 
  of 
  the 
  Helderberg 
  escarpment 
  is 
  well 
  seen. 
  

  

  From 
  Catskill 
  up 
  to 
  Albany 
  the 
  terrace 
  at 
  most 
  points 
  is 
  very- 
  

   wide. 
  At 
  Coxsackie 
  it 
  extends 
  behind 
  the 
  hill 
  to 
  the 
  south 
  of 
  

   the 
  town 
  and 
  conies 
  down 
  along 
  Murder 
  creek 
  to 
  Athens. 
  From 
  

   Albany 
  an 
  alluvial 
  plain, 
  belonging 
  to 
  this 
  formation, 
  spreads 
  

   westward, 
  reaching 
  a 
  hight 
  of 
  360 
  feet 
  near 
  Schenectady. 
  The 
  

   surface 
  of 
  these 
  terraces 
  is 
  usually 
  a 
  loamy 
  soil 
  of 
  much 
  agricul- 
  

   tural 
  value. 
  

  

  Following 
  up 
  Croton 
  river 
  as 
  far 
  as 
  Croton 
  lake, 
  remnants 
  of 
  

   terraces 
  are 
  seen 
  at 
  various 
  points, 
  their 
  hight 
  above 
  the 
  river 
  bed 
  

   decreasing 
  as 
  we 
  recede 
  from 
  the 
  Hudson. 
  The 
  majority 
  of 
  these 
  

   detached 
  pieces 
  seem 
  to 
  belong 
  to 
  a 
  terrace 
  formed 
  at 
  the 
  same 
  

   time 
  as 
  the 
  100 
  feet 
  one 
  at 
  Croton 
  landing. 
  There 
  are 
  at 
  a 
  few 
  

   places 
  traces 
  of 
  a 
  second 
  and 
  loAver 
  terrace, 
  and 
  beside 
  this 
  a 
  

   third 
  one, 
  which 
  is 
  being 
  formed 
  by 
  the 
  river 
  during 
  its 
  floods 
  at 
  

   the 
  present 
  day. 
  

  

  From 
  the 
  facts 
  as 
  observed, 
  quoted 
  above, 
  the 
  following 
  may 
  be 
  

   deduced. 
  That 
  during 
  the 
  retreat 
  of 
  the 
  ice 
  sheet 
  from 
  the 
  Hud- 
  

   son 
  valley 
  the 
  glacial 
  streams 
  deposited 
  as 
  kames 
  a 
  great 
  amount 
  

   of 
  ground 
  up 
  material, 
  principally 
  shale, 
  the 
  material 
  found 
  under- 
  

   lying 
  the 
  clays 
  along 
  the 
  upper 
  portions 
  of 
  the 
  valley. 
  

  

  That 
  subsequent 
  to 
  the 
  retreat 
  of 
  the 
  glacier 
  there 
  was 
  a 
  depres- 
  

   sion 
  of 
  the 
  land, 
  which, 
  according 
  to 
  Dr 
  Merrill,^ 
  amounted 
  to 
  80 
  

   feet 
  at 
  ISTew 
  York 
  city 
  and 
  near 
  Schenectady 
  to 
  about 
  360 
  feet. 
  

  

  During 
  this 
  period 
  a 
  great 
  amount 
  of 
  plastic 
  clay 
  was 
  depos- 
  

   ited, 
  produced 
  by 
  glacial 
  attrition 
  of 
  the 
  shales 
  and 
  limestones, 
  

   the 
  latter 
  no 
  doubt 
  giving 
  to 
  it 
  the 
  marly 
  character 
  and 
  influencing 
  

   its 
  color. 
  

  

  The 
  upper 
  portion 
  of 
  the 
  clay 
  is 
  more 
  silicious, 
  and 
  overlying 
  it 
  

   is 
  an 
  extensive 
  deposit 
  of 
  sand, 
  indicating 
  a 
  change 
  in 
  the 
  nature 
  

  

  I 
  Amer. 
  jour. 
  sci. 
  June 
  1891. 
  

  

  