﻿CLAYS 
  OF 
  NEW 
  YORK 
  593 
  

  

  down 
  through 
  the 
  valleys 
  of 
  the 
  tributary 
  streams, 
  having 
  a 
  much 
  

   greater 
  velocity 
  in 
  their 
  valleys 
  than 
  it 
  would 
  have 
  after 
  it 
  turned 
  

   into 
  the 
  Hudson 
  valley, 
  and 
  the 
  checking 
  of 
  its 
  velocity 
  as 
  it 
  

   reached 
  the 
  Hudson 
  would 
  cause 
  the 
  deposition 
  of 
  the 
  greater 
  part 
  

   of 
  its 
  load. 
  A 
  large 
  stream 
  rushing 
  doA\Ti 
  the 
  valley 
  of 
  the 
  Fish- 
  

   kill 
  would 
  drop 
  its 
  burden 
  specially 
  below 
  it, 
  where 
  we 
  find 
  them 
  

   heaviest 
  as 
  the 
  flow 
  of 
  the 
  water 
  was 
  toward 
  the 
  south. 
  Again, 
  

   Peekskill 
  would 
  behave 
  in 
  a 
  similar 
  manner. 
  

  

  A 
  curious 
  and 
  interesting 
  phenomenon 
  is 
  the 
  crumpling 
  of 
  the 
  

   clay 
  at 
  many 
  localities. 
  This 
  disturbance 
  often 
  extends 
  through- 
  

   out 
  the 
  section, 
  and 
  has 
  been 
  caused 
  by 
  slips 
  or 
  pressure 
  from 
  

   above, 
  as 
  when 
  the 
  clay 
  is 
  covered 
  by 
  a 
  thick 
  delta 
  deposit. 
  

   Prof. 
  R. 
  P. 
  Whitfield 
  has 
  told 
  the 
  writer 
  of 
  instances 
  where 
  the 
  

   clay 
  layers 
  had 
  been 
  disturbed 
  tx) 
  a 
  depth 
  of 
  several 
  feet 
  from 
  

   the 
  surface 
  by 
  the 
  weight 
  of 
  boulders 
  and 
  large 
  trees. 
  In 
  many 
  

   instances 
  there 
  occurs 
  a 
  crumpled 
  strip 
  of 
  clay 
  between 
  layers 
  

   which 
  are 
  entirely 
  undisturbed; 
  this 
  has 
  been 
  actually 
  observed 
  

   by 
  the 
  writer 
  to 
  have 
  been 
  caused 
  by 
  slipping 
  of 
  the 
  clay. 
  

  

  Clay 
  concretions. 
  These 
  are 
  of 
  common 
  occurrence, 
  specially 
  

   in 
  the 
  yellow 
  clay. 
  They 
  are 
  of 
  varying 
  form 
  and 
  size. 
  Many 
  

   of 
  them 
  have 
  a 
  cylindric 
  hole 
  in 
  the 
  center, 
  which 
  is 
  lined 
  with 
  

   carbonaceous 
  material. 
  The 
  flat 
  concretions 
  are 
  found 
  parallel 
  

   to 
  the 
  layers 
  of 
  the 
  clay, 
  and 
  in 
  many 
  instances 
  at 
  a 
  depth 
  from 
  

   the 
  surface 
  to 
  which 
  the 
  roots 
  penetrate. 
  

  

  Those 
  found 
  at 
  a 
  greater 
  depth 
  did 
  not 
  have 
  the 
  central 
  cylin- 
  

   dric 
  cavity. 
  They 
  are 
  very 
  abundant 
  in 
  the 
  yellow 
  clay 
  at 
  

   Haverstraw. 
  Poots 
  penetrating 
  the 
  clay 
  at 
  this 
  locality 
  were 
  

   surrounded 
  by 
  lumps 
  of 
  clay 
  in 
  the 
  form 
  of 
  concentric 
  rings. 
  

   These 
  might 
  seem 
  to 
  indicate 
  the 
  method 
  of 
  formation 
  described 
  

   by 
  Prof. 
  J. 
  D. 
  Dana 
  (Manual 
  of 
  geol. 
  p. 
  628). 
  Again 
  in 
  the 
  

   yellow 
  clay 
  near 
  the 
  surface 
  at 
  Coxsackie 
  were 
  found 
  some 
  forms 
  

   which 
  were 
  similar 
  in 
  appearance 
  to 
  what 
  Dr 
  J. 
  I. 
  ISTorthrup 
  has 
  

   described 
  as 
  rhizomorphs."^ 
  Tliey 
  may 
  be 
  due 
  to 
  the 
  roots 
  which 
  

  

  1 
  Trans. 
  N. 
  Y. 
  acad. 
  sot. 
  13 
  Oct. 
  1890. 
  

  

  