﻿Report 
  of 
  the 
  State 
  Geologist, 
  463 
  

  

  cipal 
  uses 
  of 
  this 
  sand 
  are 
  for 
  tempering 
  brick 
  clays 
  and 
  for 
  

   building. 
  After 
  being 
  screened 
  for 
  mortar, 
  the 
  coarser 
  sand 
  is 
  

   used 
  in 
  great 
  quantities 
  for 
  gravel 
  walks, 
  both 
  loose 
  and 
  as 
  asphalt, 
  

   and 
  for 
  mixing 
  in 
  concrete. 
  Some 
  of 
  the 
  coarser 
  material 
  is 
  used 
  

   for 
  graveling 
  public 
  roads, 
  and 
  the 
  coarsest 
  is 
  employed 
  for 
  paving 
  

   gutters 
  and 
  water-ways 
  and 
  streets. 
  For 
  all 
  of 
  the 
  above 
  pur- 
  

   poses 
  there 
  is 
  an 
  abundance 
  of 
  this 
  material 
  which 
  is 
  very 
  

   accessible. 
  

  

  The 
  brick 
  clays 
  lying 
  above 
  these 
  cross-bedded 
  sands 
  are 
  of 
  

   two 
  kinds, 
  in 
  respect 
  to 
  color. 
  Tbe 
  first, 
  in 
  course 
  from 
  bottom 
  

   upwards, 
  are 
  the 
  laminated 
  blue 
  clays. 
  The 
  next 
  above 
  these 
  

   and 
  separated 
  by 
  a 
  very^distinct 
  line 
  are 
  tbe 
  yellow 
  clays. 
  When 
  

   the 
  clay 
  beds 
  are 
  shallow, 
  from 
  ten 
  to 
  fifteen 
  feet 
  thick, 
  often 
  

   only 
  the 
  yellow 
  clays, 
  well 
  stratified 
  or 
  rather 
  laminated, 
  are 
  

   found. 
  

  

  So 
  far 
  as 
  the 
  writer 
  knows, 
  no 
  analyses 
  have 
  been 
  made 
  

   which 
  show 
  whether 
  or 
  not 
  the 
  difference 
  in 
  color 
  is 
  due 
  to 
  

   chemical 
  composition. 
  The 
  ordinary 
  analysis 
  is 
  usually 
  satisfied 
  

   with 
  the 
  amounts 
  of 
  iron 
  present 
  without 
  determining 
  its 
  state 
  

   of 
  oxidation. 
  It 
  is 
  a 
  fact 
  that 
  all 
  along 
  the 
  Hudson 
  river 
  and 
  in 
  

   New 
  Jersey 
  these 
  two 
  clays 
  are 
  found, 
  and 
  under 
  the 
  same 
  con- 
  

   ditions 
  as 
  to 
  relative 
  position. 
  Considering 
  these 
  positions 
  and 
  

   also 
  the 
  fact 
  that 
  the 
  thinner 
  beds 
  show 
  r>o 
  blue 
  clay, 
  or 
  only 
  in 
  

   patches, 
  it 
  would 
  seem 
  that 
  the 
  difference 
  in 
  color 
  is 
  due 
  to 
  the 
  

   oxidation 
  of 
  the 
  iron. 
  It 
  is 
  probable 
  that 
  the 
  blue 
  clay 
  owes 
  its 
  

   peculiar 
  tint 
  to 
  iron 
  in 
  the 
  protoxide 
  state, 
  while 
  the 
  yellow 
  clays 
  

   owe 
  their 
  color 
  to 
  more 
  or 
  less 
  of 
  the 
  irons 
  existing 
  as 
  a 
  per- 
  

   oxide. 
  The 
  writer 
  is 
  told 
  by 
  brickmakers 
  that 
  the 
  blue 
  clays 
  

   alone 
  do 
  not 
  give 
  as 
  bright 
  a 
  red 
  as 
  the 
  yellow, 
  and 
  that 
  in 
  order 
  

   to 
  get 
  the 
  best 
  results 
  the 
  two 
  are 
  mixed. 
  This 
  could 
  be 
  explained 
  

   by 
  saying, 
  which 
  is 
  probably 
  true, 
  that 
  nearly, 
  if 
  not 
  quite, 
  all 
  of 
  

   the 
  blue 
  clay 
  contains 
  its 
  iron 
  in 
  the 
  protoxide 
  state, 
  and 
  that 
  in 
  

   the 
  process 
  of 
  burning, 
  the 
  iron 
  is 
  not 
  thoroughly 
  oxidized 
  ; 
  while 
  

   in 
  the 
  yellow 
  clays 
  this 
  process 
  has 
  already 
  taken 
  place 
  to 
  a 
  con- 
  

   siderable 
  degree 
  and 
  the 
  burning 
  simply 
  reduces 
  the 
  iron 
  to 
  an 
  

   anhydrous 
  peroxide 
  which 
  is 
  red. 
  

  

  As 
  the 
  clays 
  rest 
  either 
  on 
  the 
  rock 
  or 
  on 
  uneven 
  cross-bedded 
  

   sands, 
  it 
  is, 
  therefore, 
  probable 
  that 
  the 
  clays 
  are 
  everywhere 
  

   younger 
  than 
  the 
  sands 
  and 
  gravel. 
  This 
  would 
  seem 
  to 
  indicate 
  

  

  