﻿CLAYS 
  OF 
  iS'EW 
  YORK 
  827 
  

  

  the 
  shalj 
  layers 
  is 
  ■unimportant. 
  (Hall. 
  Geology 
  of 
  the 
  Jfth 
  dis- 
  

   trict 
  of 
  New 
  York. 
  p. 
  38) 
  

  

  The 
  shale 
  beds 
  are, 
  however, 
  well 
  developed 
  at 
  Lewiston, 
  where 
  

   they 
  are 
  exposed 
  in 
  the 
  sides 
  of 
  the 
  gorge 
  on 
  both 
  the 
  American 
  

   and 
  Canadian 
  shore. 
  From 
  this 
  point 
  they 
  extend 
  eastward 
  and 
  are 
  

   to 
  be 
  seen 
  at 
  a 
  number 
  of 
  points 
  in 
  the 
  terrace 
  escarpment. 
  

  

  The 
  shale 
  is 
  rather 
  soft 
  and 
  crumbly, 
  and 
  in 
  places 
  contains 
  

   abundant 
  mica 
  flakes. 
  It 
  is 
  highly 
  ferruginous 
  and 
  weathers 
  to 
  a 
  

   red 
  clay, 
  which 
  is 
  more 
  plastic 
  than 
  the 
  mass 
  produced 
  by 
  grind- 
  

   ing 
  the 
  partially 
  weathered 
  shale 
  and 
  mixing 
  it 
  with 
  water. 
  

  

  This 
  material 
  has 
  not 
  thus 
  far 
  been 
  utilized 
  in 
  New 
  York 
  state, 
  

   yet 
  it 
  is 
  extensively 
  employed 
  at 
  several 
  localities 
  in 
  Ontario, 
  nota- 
  

   bly 
  Beamsville, 
  for 
  the 
  manufacture 
  of 
  pressed 
  brick. 
  

  

  A 
  sample 
  collected 
  from 
  the 
  exposures 
  at 
  Lewiston 
  was 
  tested 
  

   with 
  the 
  folloAving 
  results. 
  

  

  The 
  partially 
  weathered 
  shale 
  gave 
  a 
  lean 
  mass 
  when 
  mixed 
  

   with 
  16^ 
  of 
  water. 
  The 
  air 
  shrinkage 
  of 
  the 
  bricks 
  was 
  Sfo, 
  and 
  

   the 
  tensile 
  strength 
  of 
  the 
  air-dried 
  clay 
  was 
  15 
  pounds 
  a 
  square 
  

   inch. 
  

  

  The 
  clay 
  contains 
  .6^ 
  of 
  soluble 
  salts. 
  In 
  burning 
  it 
  shrinks 
  

   very 
  slowly, 
  and 
  at 
  1 
  the 
  shrinkage 
  was 
  only 
  6^. 
  At 
  this 
  point 
  

   the 
  shale 
  had 
  vitrified 
  and 
  showed 
  a 
  deep 
  red 
  color. 
  Incipient 
  fusion 
  

   occurred 
  at 
  .04, 
  the 
  clay 
  burning 
  bright 
  red. 
  It 
  became 
  viscous 
  

   at 
  above 
  4. 
  

  

  Its 
  composition 
  is 
  : 
  

  

  Silica 
  59 
  . 
  50 
  

  

  Alumina 
  20 
  . 
  60 
  

  

  Ferric 
  oxid 
  8.00 
  

  

  Lime 
  80 
  

  

  Mag-nesia 
  .35 
  

  

  Alkalis 
  3.60 
  

  

  Water 
  5.50 
  

  

  Total 
  98.35 
  

  

  