﻿208 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  Shale 
  is 
  to 
  be 
  avoided, 
  as 
  it 
  breaks 
  up 
  rapidly, 
  forming 
  a 
  sticky 
  

   mud. 
  

  

  Gravel, 
  while 
  making 
  a 
  serviceable 
  road, 
  does 
  not 
  pack 
  well, 
  

   and 
  is 
  not 
  durable. 
  If 
  it 
  has 
  to 
  be 
  used, 
  some 
  of 
  the 
  difficulty 
  

   may 
  be 
  overcome 
  by 
  cracking 
  the 
  pebbles 
  so 
  as 
  to 
  produce 
  an 
  

   angular 
  form. 
  

  

  Clay 
  and 
  Clay 
  Products" 
  

  

  Deposits 
  of 
  clay 
  occur 
  in 
  nearly 
  every 
  county 
  of 
  New 
  York. 
  

   They 
  belong 
  to 
  three 
  geological 
  periods, 
  namely: 
  

  

  Quaternary, 
  Tertiary 
  and 
  Cretaceous. 
  

  

  The 
  clays 
  of 
  the 
  first 
  age 
  are 
  by 
  far 
  the 
  most 
  common. 
  Those 
  

   of 
  the 
  seooud- 
  are 
  somewhat 
  indefinite 
  in 
  extent, 
  but 
  they 
  prob- 
  

   ably 
  include 
  a 
  large 
  number 
  of 
  the 
  Long 
  Island 
  deposits. 
  Of 
  

   the 
  third 
  cla&s 
  there 
  are 
  undoubted 
  representatives 
  on 
  Long 
  Is- 
  

   land 
  and 
  Staten 
  Island. 
  

  

  The 
  clays 
  of 
  the 
  mainland 
  are 
  all 
  Quaternary 
  so 
  far 
  as 
  known. 
  

   The 
  problems 
  of 
  Quaternary 
  geology 
  in 
  New 
  Y^ork 
  are 
  by 
  no 
  

   means 
  solved, 
  and 
  it 
  is 
  not 
  always 
  possible 
  to 
  decide 
  on 
  the 
  

   causes 
  leading 
  to 
  the 
  deposition 
  of 
  any 
  particular 
  body 
  of 
  clay 
  

   by 
  a 
  single 
  visit 
  to 
  the 
  locality. 
  

  

  A 
  great 
  majority 
  of 
  the 
  deposits 
  are 
  local, 
  lying 
  in 
  the 
  bottoma 
  

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

   depth 
  from 
  four 
  to 
  20 
  or 
  even 
  50 
  feet; 
  as 
  a 
  rule 
  they 
  are 
  under- 
  

   laid 
  by 
  modified 
  drift 
  or 
  by 
  bed 
  rock. 
  The 
  clay 
  is 
  generally 
  of 
  

   a 
  blue 
  color, 
  the 
  upper 
  few 
  feet 
  being 
  weathered 
  mostly 
  to 
  red 
  

   or 
  yellow. 
  Stratification 
  is 
  rarely 
  present, 
  but 
  streaks 
  of 
  marl 
  

   are 
  common. 
  In 
  some 
  of 
  the 
  beds 
  small 
  pebbles, 
  usually 
  of 
  lime- 
  

   stone, 
  are 
  found, 
  and 
  these 
  have 
  to 
  be 
  separated 
  by 
  special 
  ma- 
  

   chinery 
  in 
  the 
  process 
  of 
  manufacture. 
  In 
  many 
  instances 
  the 
  

   clay 
  is 
  covered 
  by 
  a 
  foot 
  or 
  more 
  of 
  peat. 
  

  

  These 
  basin 
  deposits 
  are 
  no 
  doubt 
  the 
  sites 
  of 
  former 
  ponds 
  

   or 
  lakes, 
  formed 
  in 
  many 
  instances 
  by 
  the 
  damming 
  up 
  of 
  val- 
  

   leys, 
  which 
  have 
  been 
  filled 
  later 
  with 
  the 
  sediment 
  of 
  the 
  

   streams 
  from 
  the 
  retreating 
  ice 
  sheet. 
  The 
  valleys 
  in 
  which 
  

  

  a 
  A.bride:ed 
  from 
  Bulletin 
  No. 
  12 
  New 
  York 
  Stixte 
  Museum, 
  by 
  Heinrich 
  Ries. 
  

  

  