﻿434 
  Forty- 
  seventh 
  Report 
  on 
  the 
  State 
  Museum. 
  

  

  The 
  maximum 
  thickness 
  of 
  the 
  Oneonta 
  formation 
  exposed 
  in 
  

   Albany 
  county 
  is 
  about 
  1000 
  feet, 
  but 
  there 
  are 
  higher 
  beds 
  of 
  

   the 
  formation 
  to 
  the 
  southward 
  in 
  the 
  northern 
  front 
  of 
  the 
  

   Catskills. 
  In 
  mapping 
  the 
  Oneonta 
  formation 
  in 
  Albany 
  county 
  

   I 
  have 
  assumed 
  that 
  its 
  base 
  was 
  at 
  the 
  bottom 
  of 
  the 
  lowest 
  red 
  

   shale 
  member, 
  because 
  this 
  was 
  the 
  only 
  distinguishing 
  feature 
  

   that 
  I 
  could 
  use 
  as 
  a 
  guide. 
  Probably 
  this 
  horizon 
  will 
  prove, 
  on 
  

   detailed 
  examination, 
  to 
  be 
  somewhat 
  variable, 
  but 
  I 
  believe 
  not 
  

   with 
  very 
  wide 
  limits. 
  

  

  Hamilton 
  flags 
  and 
  shales. 
  — 
  Underlying 
  the 
  Oneonta 
  forma- 
  

   tion 
  there 
  is 
  a 
  great 
  series 
  of 
  thin-bedded 
  sandstones 
  of 
  various 
  

   kinds, 
  with 
  intercalated 
  beds 
  of 
  dark-colored 
  shales 
  The 
  flaggy 
  

   members 
  are 
  the 
  more 
  prominent 
  because 
  they 
  give 
  rise 
  to 
  con- 
  

   spicuous 
  outcrops 
  and 
  to 
  a 
  characteristically 
  terraced 
  topography. 
  

   The 
  shales 
  constitute 
  about 
  an 
  equal 
  proportion 
  of 
  the 
  series, 
  and 
  

   give 
  rise 
  to 
  the 
  slopes 
  between 
  the 
  terraces. 
  The 
  flags 
  are 
  dark- 
  

   gray, 
  moderately 
  fine-grained 
  sandstones 
  varying 
  in 
  thickness 
  

   from 
  one-half 
  inch 
  to 
  three 
  inches, 
  and 
  in 
  greater 
  part 
  separating 
  

   readily 
  along 
  their 
  bedding 
  planes. 
  They 
  have 
  been 
  quarried 
  to 
  

   a 
  considerable 
  extent 
  for 
  the 
  market, 
  and 
  are 
  highly 
  esteemed 
  

   for 
  flagging. 
  The 
  thickness 
  of 
  the 
  beds 
  of 
  flags 
  is 
  exceedingly 
  

   variable, 
  ten 
  to 
  fifteen 
  feet 
  is 
  frequent, 
  but 
  there 
  are 
  beds 
  which 
  

   have 
  much 
  less 
  thickness. 
  It 
  is 
  found 
  that 
  in 
  part 
  some 
  of 
  

   the 
  flag 
  beds 
  give 
  place 
  to 
  black 
  shales 
  and 
  they 
  also 
  vary 
  con- 
  

   siderably 
  in 
  thickness 
  of 
  bedding, 
  in 
  texture 
  and 
  in 
  color 
  in 
  the 
  

   same 
  bed. 
  The 
  intercalated 
  shales 
  are 
  in 
  greater 
  part 
  moderately 
  

   hard, 
  dark 
  in 
  color, 
  and 
  have 
  a 
  thickness 
  ranging 
  from 
  fifteen 
  

   feet 
  to 
  a 
  few 
  inches. 
  JSTo 
  definite 
  stratigraphy 
  was 
  made 
  out 
  in 
  

   the 
  flagstone 
  belt, 
  owing 
  to 
  considerable 
  obscurity 
  of 
  outcrops 
  

   by 
  drift 
  and 
  the 
  frequent 
  changes 
  in 
  the 
  character 
  of 
  the 
  deposits. 
  

   The 
  amount 
  of 
  workable 
  flagstone 
  in 
  the 
  series 
  is 
  very 
  great, 
  

   but 
  on 
  account 
  of 
  the 
  distance 
  from 
  adequate 
  means 
  of 
  transpor- 
  

   tation 
  and 
  the 
  consequent 
  great 
  expense 
  of 
  hauling, 
  it 
  is 
  now 
  

   practicable 
  to 
  work 
  only 
  those 
  beds 
  which 
  yield 
  stone 
  at 
  the 
  

   very 
  least 
  cost. 
  Owing 
  to 
  the 
  variability 
  in 
  the 
  character 
  of 
  the 
  

   flags, 
  and 
  to 
  the 
  presence 
  of 
  large 
  amounts 
  of 
  waste 
  material 
  

   which 
  has 
  to 
  be 
  stripped, 
  there 
  are 
  many 
  areas 
  underlaid 
  by 
  

   excellent 
  flagstone 
  which 
  cannot 
  be 
  profitably 
  worked. 
  This 
  is 
  

   particularly 
  the 
  case 
  on 
  steep 
  slopes, 
  where 
  the 
  flags 
  dip 
  into 
  the 
  

  

  