﻿CLAYS 
  OF 
  NEW 
  YORK 
  573 
  

  

  The 
  mellowed 
  outcrops 
  of 
  many 
  of 
  the 
  shale 
  formations 
  occur- 
  

   ring 
  within 
  the 
  stato 
  should 
  also, 
  perhaps, 
  be 
  classed 
  under 
  the 
  

   head 
  of 
  residual 
  clays. 
  In 
  the 
  latter 
  case 
  however 
  the 
  clay 
  is 
  a 
  

   product 
  of 
  disintegration; 
  in 
  the 
  former, 
  of 
  decomposition. 
  

  

  2 
  Sedimentaxy 
  clays. 
  The 
  soft 
  plastic 
  clays 
  belong 
  to 
  three 
  

   geologic 
  formations, 
  Quaternary, 
  Tertiary 
  and 
  Cretaceous. 
  

  

  The 
  first 
  class 
  is 
  by 
  far 
  the 
  most 
  common. 
  The 
  second 
  class 
  

   is 
  somewhat 
  indefinite 
  in 
  extent, 
  but 
  a 
  large 
  number 
  of 
  the 
  Long 
  

   Island 
  deposits 
  probably 
  belong 
  to 
  it."^ 
  Of 
  the 
  third 
  class 
  there 
  

   are 
  undoubted 
  representatives 
  on 
  Long 
  Island 
  and 
  Stat 
  en 
  Island, 
  

   as 
  well 
  as 
  some 
  additional 
  ones 
  on 
  Long 
  Island, 
  which 
  are 
  

   questionable. 
  The 
  clays 
  of 
  the 
  mainland 
  are 
  all 
  Quaternary 
  so 
  

   far 
  as 
  known. 
  This 
  does 
  not 
  include 
  the 
  shales 
  which 
  are 
  treated 
  

   in 
  a 
  separate 
  chapter. 
  

  

  Many 
  of 
  the 
  deposits 
  are 
  local 
  and 
  basin-shaped, 
  lying 
  in 
  the 
  

   bottoms 
  of 
  valleys 
  which 
  are 
  often 
  broad 
  and 
  fertile. 
  They 
  vary 
  

   in 
  depth 
  from 
  4 
  to 
  20 
  or 
  even 
  50 
  feet 
  and 
  as 
  a 
  rule 
  they 
  are 
  

   underlain 
  by 
  modified 
  drift 
  or 
  by 
  bed 
  rock. 
  The 
  clay 
  is 
  gen- 
  

   erally 
  of 
  a 
  blue 
  color, 
  the 
  uppermost 
  portion 
  for 
  a 
  few 
  feet 
  being 
  

   weathered 
  red 
  or 
  yellow. 
  Stratification 
  is 
  sometimes 
  present, 
  and 
  

   streaks 
  of 
  marl 
  are 
  common. 
  In 
  some 
  of 
  the 
  beds 
  small 
  pebbles, 
  

   usually 
  of 
  limestone, 
  are 
  found, 
  and 
  these 
  have 
  to 
  be 
  separated 
  by 
  

   special 
  machinery 
  in 
  the 
  process 
  of 
  manufacture; 
  at 
  other 
  localitiea 
  

   the 
  clay 
  is 
  covered 
  by 
  a 
  foot 
  or 
  more 
  of 
  peat. 
  

  

  The 
  basin-shaped 
  deposits 
  are 
  no 
  doubt 
  the 
  sites 
  of 
  former 
  ponds 
  

   or 
  lakes, 
  formed 
  commonly 
  by 
  the 
  damming 
  up 
  of 
  the 
  valleys, 
  and 
  

   filled 
  later 
  with 
  the 
  sediment 
  of 
  the 
  streams 
  from 
  the 
  retreating 
  ice 
  

   sheet. 
  The 
  valleys 
  in 
  which 
  these 
  deposits 
  lie 
  are 
  usually 
  broad 
  

   and 
  shallow, 
  that 
  in 
  which 
  the 
  Genesee 
  river 
  flows 
  from 
  Mt 
  Morris 
  

   to 
  Rochester 
  being 
  a 
  good 
  example. 
  The 
  waters 
  of 
  the 
  river 
  were 
  

   backed 
  up 
  by 
  the 
  ice 
  for 
  a 
  time, 
  during 
  which 
  the 
  valley 
  was 
  con- 
  

   verted 
  into 
  a 
  shallow 
  lake 
  in 
  which 
  a 
  large 
  amount 
  of 
  aluminous 
  

   mud 
  was 
  deposited. 
  This 
  material 
  has 
  been 
  employed 
  for 
  common 
  

   brick. 
  

  

  1 
  F. 
  J. 
  H. 
  Merrill. 
  " 
  Geology 
  of 
  Long 
  Island," 
  Ann. 
  N. 
  Y. 
  acad. 
  8ci. 
  Nov. 
  1884. 
  

  

  