﻿Upper 
  Silurian 
  

  

  826 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  The 
  physical 
  and 
  chemical 
  characters 
  of 
  the 
  shales 
  can 
  be 
  judged 
  

   from 
  some 
  of 
  the 
  tests 
  given 
  beyond 
  under 
  the 
  locality 
  descrip- 
  

   tions. 
  

  

  The 
  shale-bearing 
  formations 
  occurring 
  in 
  'New 
  York 
  "state, 
  be- 
  

   ginning 
  with 
  that 
  geologically 
  oldest, 
  are 
  as 
  follows: 
  

  

  Lower 
  Silurian 
  Hudson 
  river 
  

  

  Medina 
  

   Clinton 
  

   Magara 
  

   ' 
  [ 
  Salina 
  

  

  f 
  Hamilton 
  

   Devonian 
  ^ 
  Portage 
  

  

  I 
  Chemung 
  

  

  A 
  geological 
  map 
  will 
  show 
  the 
  outline 
  of 
  the 
  area 
  underlain 
  

   by 
  the 
  outcropping 
  edges 
  of 
  each 
  shale 
  formation, 
  and 
  it 
  will 
  be 
  

   noticed 
  that 
  they 
  form 
  bands 
  of 
  variable 
  width 
  extending 
  across 
  

   the 
  state 
  from 
  east 
  to 
  west. 
  

  

  As 
  the 
  formations 
  have 
  a 
  slight 
  dip 
  (40-60 
  feet 
  a 
  mile) 
  to 
  the 
  

   south, 
  the 
  belts 
  of 
  shale 
  encountered 
  in 
  crossing 
  the 
  state 
  from 
  

   south 
  to 
  north 
  will 
  be 
  successively 
  older. 
  

  

  Furthermore 
  any 
  one 
  bed 
  will 
  of 
  couse 
  be 
  higher 
  above 
  sea 
  

   level 
  to 
  the 
  north 
  than 
  to 
  the 
  south. 
  The 
  Chemung 
  shales 
  underlie 
  

   the 
  whole 
  surface 
  in 
  the 
  southern 
  part 
  of 
  the 
  state, 
  but 
  as 
  we 
  

   proceed 
  northward 
  they 
  are 
  found 
  only 
  on 
  the 
  ridges 
  of 
  the 
  higher 
  

   hills, 
  the 
  sides 
  and 
  bottom 
  of 
  the 
  valleys 
  being 
  underlain 
  by 
  the 
  

   Portage 
  shale, 
  which 
  in 
  turn 
  succeeds 
  the 
  Chemung 
  as 
  the 
  surface 
  

   formation. 
  

  

  Distribution 
  and 
  properties 
  

  

  Hudson 
  river. 
  This 
  formation 
  is 
  abundantly 
  displayed 
  in 
  the 
  

   counties 
  of 
  Lewis, 
  Oneida, 
  Montgomery, 
  Schenectady 
  and 
  Colum- 
  

   bia. 
  Its 
  tendency 
  is 
  to 
  exhibit 
  silicious 
  or 
  slaty 
  phases, 
  but 
  in 
  

   eastern 
  Ct>lumbia 
  co'. 
  it 
  becomes 
  at 
  times 
  argillaceous 
  and 
  at 
  the 
  

   same 
  time 
  contains 
  considerable 
  iron. 
  

  

  Medina. 
  The 
  Medina 
  formation 
  at 
  times 
  is 
  shale-bearing, 
  as 
  

   along 
  the 
  Genesee 
  river, 
  where 
  it 
  is 
  also 
  marly, 
  but 
  the 
  extent 
  of 
  

  

  