﻿302 
  

  

  W. 
  A. 
  Verwiebe 
  — 
  Correlation 
  of 
  the 
  

  

  Sbenango 
  sandstone 
  toward 
  the 
  east 
  and 
  is 
  largely 
  absent 
  

   because 
  of 
  erosion 
  toward 
  the 
  west. 
  It 
  is 
  generally 
  a 
  bluish 
  

   gray, 
  argillaceous 
  shale 
  though 
  locally 
  also 
  very 
  sandy. 
  Its 
  

   maximum 
  thickness 
  is 
  perhaps 
  50 
  feet, 
  but, 
  on 
  account 
  of 
  the 
  

   unconformity 
  at 
  the 
  top, 
  usually 
  less 
  than 
  this 
  is 
  found. 
  

  

  Shenango 
  Sandstone 
  /Asa 
  key 
  horizon 
  to 
  the 
  stratigraphy 
  

   of 
  western 
  Pennsylvania 
  this 
  is 
  a 
  most 
  important 
  formation. 
  

   It 
  received 
  its 
  name 
  from 
  the 
  Shenango 
  River 
  of 
  Crawford 
  

  

  Fig. 
  1. 
  

  

  %t 
  

  

  "lv 
  

  

  _T»?- 
  

  

  l 
  f~ 
  

  

  <&s£*- 
  

  

  sw 
  

  

  .Y* 
  

  

  4 
  

  

  Sh 
  ,e 
  

  

  rj/f 
  

  

  m 
  ,3 
  h 
  

  

  'iti\ 
  

  

  nanqo 
  

  

  -Sand 
  

  

  '••'■;■'-' 
  

  

  Storxz 
  

  

  Fig. 
  1. 
  Sections 
  showing 
  the 
  character 
  and 
  thickness 
  of 
  the 
  Shenango 
  

   formation. 
  The 
  map 
  on 
  p. 
  312 
  (fig. 
  6) 
  inserted 
  shows 
  location 
  of 
  sections. 
  

  

  and 
  Mercer 
  counties. 
  In 
  lithologic 
  character 
  it 
  is 
  unique. 
  

   Always 
  coarse 
  and 
  quartzitic, 
  it 
  is 
  marked 
  as 
  well 
  by 
  the 
  great 
  

   amount 
  of 
  iron 
  present 
  in 
  concretionary 
  form, 
  in 
  secretions, 
  

   and 
  in 
  veinlets. 
  The 
  solution 
  and 
  redeposition 
  of 
  this 
  sub- 
  

   stance 
  has 
  given 
  it 
  a 
  deep 
  brown 
  color 
  throughout, 
  but 
  espe- 
  

   cially 
  on 
  exposed 
  surfaces. 
  In 
  thickness 
  it 
  is 
  very 
  uniform, 
  

   ranging 
  gradually 
  from 
  15 
  feet 
  in 
  the 
  west 
  to 
  about 
  40 
  feet 
  in 
  

   the 
  east. 
  Farther 
  east 
  and 
  south 
  of 
  the 
  region 
  studied 
  it 
  

   merges 
  more 
  and 
  more 
  closely 
  with 
  the 
  overlying 
  shale 
  and 
  

   has 
  been 
  named 
  as 
  a 
  unit 
  the 
  Burgoon 
  formation.* 
  

  

  In 
  fig. 
  1 
  are 
  platted 
  sections 
  to 
  show 
  the 
  nature 
  and 
  thick- 
  

  

  * 
  Butts, 
  Chas., 
  U. 
  S. 
  G. 
  S. 
  Folio 
  No. 
  115, 
  p. 
  5. 
  

  

  