﻿834 
  NEW 
  YOEK 
  STATE 
  MUSEUM 
  

  

  sample 
  gave 
  quite 
  a 
  plastic 
  mass, 
  with 
  21^ 
  of 
  water. 
  The 
  air 
  shrink- 
  

   age 
  was 
  3^. 
  When 
  heated 
  to 
  .06 
  the 
  total 
  was 
  4^, 
  with 
  incipient 
  

   fusion, 
  and 
  the 
  color 
  deep 
  red. 
  The 
  clay 
  vitrifies 
  at 
  1, 
  with 
  a 
  total 
  

   shrinkage 
  of 
  Y^. 
  The 
  shale 
  has 
  .2^ 
  soluble 
  salts. 
  

  

  'No. 
  5 
  of 
  Bishop 
  is 
  also 
  from 
  near 
  Windom. 
  It 
  is 
  a 
  fine-grained 
  

   shale, 
  which 
  worked 
  up 
  to 
  a 
  lean 
  mass 
  with 
  19^ 
  water. 
  Tensile 
  

   strength, 
  35 
  pounds 
  a 
  square 
  inch. 
  The 
  air 
  shrinkage 
  was 
  S^. 
  At 
  

   .03 
  the 
  total 
  shrinkage 
  was 
  Y^, 
  and 
  the 
  bricklet 
  was 
  nearly 
  vitrified. 
  

   It 
  was 
  completely 
  vitrified 
  at 
  1 
  with 
  9^ 
  shrinkage. 
  It 
  became 
  vis- 
  

   cous 
  at 
  5. 
  The 
  soluble 
  salts 
  were 
  .36^. 
  Its 
  composition 
  is: 
  

  

  Silica 
  61.15 
  

  

  Alumina 
  14 
  . 
  57 
  

  

  Ferric 
  oxid 
  7 
  . 
  20 
  

  

  Lime 
  3 
  . 
  06 
  

  

  Magnesia 
  .20 
  

  

  Alkalis 
  1.90 
  

  

  Water 
  5.95 
  

  

  94.03 
  

  

  Portage. 
  (See 
  Hall. 
  Geology 
  of 
  the 
  Uh 
  district 
  of 
  New 
  York. 
  p. 
  

   224.) 
  Another 
  important 
  shale 
  occurs 
  in 
  this 
  member 
  of 
  the 
  Devon- 
  

   ian 
  formation. 
  The 
  group 
  consists 
  of 
  a 
  lower 
  shaly 
  member, 
  the 
  

   Cashaqua 
  shale, 
  a 
  middle 
  member 
  of 
  shales 
  and 
  sandstones, 
  and 
  

   an 
  upper 
  one 
  of 
  sandstones. 
  

  

  The 
  Cashaqua 
  shale 
  is 
  exposed 
  along 
  Cashaqua 
  creek, 
  where 
  it 
  is 
  

   a 
  soft 
  green 
  shale 
  that 
  weathers 
  to 
  a 
  tough 
  clay. 
  It 
  also 
  occurs 
  along 
  

   Seneca 
  lake 
  and 
  at 
  Penn 
  Yan, 
  but 
  east 
  of 
  this 
  becomes 
  very 
  sandy. 
  

   Good 
  exposures 
  are 
  seen 
  along 
  Allen's 
  creek 
  and 
  Tonawanda 
  creek, 
  

   and 
  the 
  branches 
  of 
  Seneca 
  and 
  Cayuga 
  creeks. 
  On 
  Lake 
  Erie 
  at 
  

   Eighteen 
  Mile 
  creek 
  it 
  is 
  33 
  feet 
  thick, 
  while 
  along 
  the 
  Genesee 
  

   river 
  it 
  is 
  150 
  feet 
  thick. 
  

  

  Concerning 
  the 
  Gardeau 
  shales. 
  Prof. 
  Hall 
  states 
  that 
  they 
  

   are 
  exposed 
  along 
  the 
  Genesee 
  river, 
  where 
  the 
  section 
  involves 
  al- 
  

   ternating 
  layers 
  of 
  shales 
  and 
  sandstones. 
  Toward 
  the 
  east 
  the 
  

  

  